Removed the SegmentCollector type from the Generics of the

FilterCollector

CHANGELOG.md

@@ -8,7 +8,6 @@ Tantivy 0.14.0
 - Added helper for building intersections and unions in BooleanQuery (@guilload)
 - Bugfix in `Query::explain`
 - Removed dependency on `notify` #924. Replaced with `FileWatcher` struct that polls meta file every 500ms in background thread. (@halvorboe @guilload)
-- Added `FilterCollector`, which wraps another collector and filters docs using a predicate over a fast field (@barrotsteindev)
 
 Tantivy 0.13.2
 ===================

Cargo.toml

@@ -26,7 +26,6 @@ snap = "1"
 tempfile = {version="3", optional=true}
 log = "0.4"
 serde = {version="1", features=["derive"]}
-serde_cbor = "0.11"
 serde_json = "1"
 num_cpus = "1"
 fs2={version="0.4", optional=true}

examples/faceted_search_with_tweaked_score.rs

@@ -61,7 +61,7 @@ fn main() -> tantivy::Result<()> {
 
                 let query_ords: HashSet<u64> = facets
                     .iter()
-                    .filter_map(|key| facet_dict.term_ord(key.encoded_str()).unwrap())
+                    .filter_map(|key| facet_dict.term_ord(key.encoded_str()))
                     .collect();
 
                 let mut facet_ords_buffer: Vec<u64> = Vec::with_capacity(20);

src/collector/facet_collector.rs

@@ -274,7 +274,7 @@ impl Collector for FacetCollector {
         let mut collapse_facet_it = self.facets.iter().peekable();
         collapse_facet_ords.push(0);
         {
-            let mut facet_streamer = facet_reader.facet_dict().range().into_stream()?;
+            let mut facet_streamer = facet_reader.facet_dict().range().into_stream();
             if facet_streamer.advance() {
                 'outer: loop {
                     // at the begining of this loop, facet_streamer
@@ -368,12 +368,9 @@ impl SegmentCollector for FacetSegmentCollector {
             }
             let mut facet = vec![];
             let facet_ord = self.collapse_facet_ords[collapsed_facet_ord];
-            // TODO handle errors.
-            if facet_dict.ord_to_term(facet_ord as u64, &mut facet).is_ok() {
-                if let Ok(facet) = Facet::from_encoded(facet) {
-                    facet_counts.insert(facet, count);
-                }
-            }
+            facet_dict.ord_to_term(facet_ord as u64, &mut facet);
+            // TODO
+            facet_counts.insert(Facet::from_encoded(facet).unwrap(), count);
         }
         FacetCounts { facet_counts }
     }

src/collector/filter_collector_wrapper.rs

@@ -41,37 +41,33 @@ use crate::{Score, SegmentReader, TantivyError};
 ///
 /// let query_parser = QueryParser::for_index(&index, vec![title]);
 /// let query = query_parser.parse_query("diary").unwrap();
-/// let no_filter_collector = FilterCollector::new(price, &|value| value > 20_120u64, TopDocs::with_limit(2));
+/// let no_filter_collector = FilterCollector::new(price, &|value| true, TopDocs::with_limit(2));
 /// let top_docs = searcher.search(&query, &no_filter_collector).unwrap();
 ///
-/// assert_eq!(top_docs.len(), 1);
+/// assert_eq!(top_docs.len(), 2);
 /// assert_eq!(top_docs[0].1, DocAddress(0, 1));
+/// assert_eq!(top_docs[1].1, DocAddress(0, 3));
 ///
-/// let filter_all_collector = FilterCollector::new(price, &|value| value < 5u64, TopDocs::with_limit(2));
+/// let filter_all_collector = FilterCollector::new(price, &|value| false, TopDocs::with_limit(2));
 /// let filtered_top_docs = searcher.search(&query, &filter_all_collector).unwrap();
 ///
 /// assert_eq!(filtered_top_docs.len(), 0);
 /// ```
-pub struct FilterCollector<TCollector, TPredicate>
-where
-    TPredicate: 'static,
-{
+pub struct FilterCollector<TCollector> {
     field: Field,
     collector: TCollector,
-    predicate: &'static TPredicate,
+    predicate: &'static (dyn Fn(u64) -> bool + Send + Sync),
 }
 
-impl<TCollector, TPredicate> FilterCollector<TCollector, TPredicate>
+impl<TCollector> FilterCollector<TCollector>
 where
     TCollector: Collector + Send + Sync,
-    TPredicate: Fn(u64) -> bool + Send + Sync,
 {
-    /// Create a new FilterCollector.
     pub fn new(
         field: Field,
-        predicate: &'static TPredicate,
+        predicate: &'static (dyn Fn(u64) -> bool + Send + Sync),
         collector: TCollector,
-    ) -> FilterCollector<TCollector, TPredicate> {
+    ) -> FilterCollector<TCollector> {
         FilterCollector {
             field,
             predicate,
@@ -80,22 +76,21 @@ where
     }
 }
 
-impl<TCollector, TPredicate> Collector for FilterCollector<TCollector, TPredicate>
+impl<TCollector> Collector for FilterCollector<TCollector>
 where
     TCollector: Collector + Send + Sync,
-    TPredicate: 'static + Fn(u64) -> bool + Send + Sync,
 {
     // That's the type of our result.
     // Our standard deviation will be a float.
     type Fruit = TCollector::Fruit;
 
-    type Child = FilterSegmentCollector<TCollector::Child, TPredicate>;
+    type Child = FilterSegmentCollector<TCollector::Child>;
 
     fn for_segment(
         &self,
         segment_local_id: u32,
         segment_reader: &SegmentReader,
-    ) -> crate::Result<FilterSegmentCollector<TCollector::Child, TPredicate>> {
+    ) -> crate::Result<FilterSegmentCollector<TCollector::Child>> {
         let fast_field_reader = segment_reader
             .fast_fields()
             .u64(self.field)
@@ -111,7 +106,7 @@ where
             .for_segment(segment_local_id, segment_reader)?;
         Ok(FilterSegmentCollector {
             fast_field_reader,
-            segment_collector,
+            segment_collector: segment_collector,
             predicate: self.predicate,
         })
     }
@@ -128,20 +123,15 @@ where
     }
 }
 
-pub struct FilterSegmentCollector<TSegmentCollector, TPredicate>
-where
-    TPredicate: 'static,
-{
+pub struct FilterSegmentCollector<TSegmentCollector> {
     fast_field_reader: FastFieldReader<u64>,
     segment_collector: TSegmentCollector,
-    predicate: &'static TPredicate,
+    predicate: &'static (dyn Fn(u64) -> bool + Send + Sync),
 }
 
-impl<TSegmentCollector, TPredicate> SegmentCollector
-    for FilterSegmentCollector<TSegmentCollector, TPredicate>
+impl<TSegmentCollector> SegmentCollector for FilterSegmentCollector<TSegmentCollector>
 where
     TSegmentCollector: SegmentCollector,
-    TPredicate: 'static + Fn(u64) -> bool + Send + Sync,
 {
     type Fruit = TSegmentCollector::Fruit;
 

src/collector/top_score_collector.rs

@@ -728,7 +728,7 @@ mod tests {
     }
 
     #[test]
-    fn test_top_collector_not_at_capacity_without_offset() {
+    fn test_top_collector_not_at_capacity() {
         let index = make_index();
         let field = index.schema().get_field("text").unwrap();
         let query_parser = QueryParser::for_index(&index, vec![field]);

src/common/counting_writer.rs

@@ -20,10 +20,9 @@ impl<W: Write> CountingWriter<W> {
         self.written_bytes
     }
 
-    /// Returns the underlying write object.
-    /// Note that this method does not trigger any flushing.
-    pub fn finish(self) -> W {
-        self.underlying
+    pub fn finish(mut self) -> io::Result<(W, u64)> {
+        self.flush()?;
+        Ok((self.underlying, self.written_bytes))
     }
 }
 
@@ -47,6 +46,7 @@ impl<W: Write> Write for CountingWriter<W> {
 
 impl<W: TerminatingWrite> TerminatingWrite for CountingWriter<W> {
     fn terminate_ref(&mut self, token: AntiCallToken) -> io::Result<()> {
+        self.flush()?;
         self.underlying.terminate_ref(token)
     }
 }
@@ -63,9 +63,8 @@ mod test {
         let mut counting_writer = CountingWriter::wrap(buffer);
         let bytes = (0u8..10u8).collect::<Vec<u8>>();
         counting_writer.write_all(&bytes).unwrap();
-        let len = counting_writer.written_bytes();
-        let buffer_restituted: Vec<u8> = counting_writer.finish();
+        let (w, len): (Vec<u8>, u64) = counting_writer.finish().unwrap();
         assert_eq!(len, 10u64);
-        assert_eq!(buffer_restituted.len(), 10);
+        assert_eq!(w.len(), 10);
     }
 }

src/core/index.rs

@@ -511,28 +511,28 @@ mod tests {
         }
 
         #[test]
-        fn test_index_manual_policy_mmap() -> crate::Result<()> {
+        fn test_index_manual_policy_mmap() {
             let schema = throw_away_schema();
             let field = schema.get_field("num_likes").unwrap();
-            let mut index = Index::create_from_tempdir(schema)?;
-            let mut writer = index.writer_for_tests()?;
-            writer.commit()?;
+            let mut index = Index::create_from_tempdir(schema).unwrap();
+            let mut writer = index.writer_for_tests().unwrap();
+            writer.commit().unwrap();
             let reader = index
                 .reader_builder()
                 .reload_policy(ReloadPolicy::Manual)
-                .try_into()?;
+                .try_into()
+                .unwrap();
             assert_eq!(reader.searcher().num_docs(), 0);
             writer.add_document(doc!(field=>1u64));
             let (sender, receiver) = crossbeam::channel::unbounded();
             let _handle = index.directory_mut().watch(WatchCallback::new(move || {
                 let _ = sender.send(());
             }));
-            writer.commit()?;
+            writer.commit().unwrap();
             assert!(receiver.recv().is_ok());
             assert_eq!(reader.searcher().num_docs(), 0);
-            reader.reload()?;
+            reader.reload().unwrap();
             assert_eq!(reader.searcher().num_docs(), 1);
-            Ok(())
         }
 
         #[test]

src/core/inverted_index_reader.rs

@@ -66,7 +66,7 @@ impl InvertedIndexReader {
     }
 
     /// Returns the term info associated with the term.
-    pub fn get_term_info(&self, term: &Term) -> io::Result<Option<TermInfo>> {
+    pub fn get_term_info(&self, term: &Term) -> Option<TermInfo> {
         self.termdict.get(term.value_bytes())
     }
 
@@ -106,9 +106,10 @@ impl InvertedIndexReader {
         term: &Term,
         option: IndexRecordOption,
     ) -> io::Result<Option<BlockSegmentPostings>> {
-        self.get_term_info(term)?
+        Ok(self
+            .get_term_info(term)
             .map(move |term_info| self.read_block_postings_from_terminfo(&term_info, option))
-            .transpose()
+            .transpose()?)
     }
 
     /// Returns a block postings given a `term_info`.
@@ -180,7 +181,7 @@ impl InvertedIndexReader {
         term: &Term,
         option: IndexRecordOption,
     ) -> io::Result<Option<SegmentPostings>> {
-        self.get_term_info(term)?
+        self.get_term_info(term)
             .map(move |term_info| self.read_postings_from_terminfo(&term_info, option))
             .transpose()
     }
@@ -190,7 +191,7 @@ impl InvertedIndexReader {
         term: &Term,
         option: IndexRecordOption,
     ) -> io::Result<Option<SegmentPostings>> {
-        self.get_term_info(term)?
+        self.get_term_info(term)
             .map(|term_info| self.read_postings_from_terminfo(&term_info, option))
             .transpose()
     }
@@ -198,7 +199,7 @@ impl InvertedIndexReader {
     /// Returns the number of documents containing the term.
     pub fn doc_freq(&self, term: &Term) -> io::Result<u32> {
         Ok(self
-            .get_term_info(term)?
+            .get_term_info(term)
             .map(|term_info| term_info.doc_freq)
             .unwrap_or(0u32))
     }

src/core/mod.rs

@@ -12,7 +12,7 @@ pub use self::executor::Executor;
 pub use self::index::Index;
 pub use self::index_meta::{IndexMeta, SegmentMeta, SegmentMetaInventory};
 pub use self::inverted_index_reader::InvertedIndexReader;
-pub use self::searcher::Searcher;
+pub use self::searcher::{FieldSearcher, Searcher};
 pub use self::segment::Segment;
 pub use self::segment::SerializableSegment;
 pub use self::segment_component::SegmentComponent;

src/core/searcher.rs

@@ -1,16 +1,17 @@
 use crate::collector::Collector;
 use crate::core::Executor;
-
+use crate::core::InvertedIndexReader;
 use crate::core::SegmentReader;
 use crate::query::Query;
 use crate::schema::Document;
 use crate::schema::Schema;
-use crate::schema::Term;
+use crate::schema::{Field, Term};
 use crate::space_usage::SearcherSpaceUsage;
 use crate::store::StoreReader;
+use crate::termdict::TermMerger;
 use crate::DocAddress;
 use crate::Index;
-
+use std::sync::Arc;
 use std::{fmt, io};
 
 /// Holds a list of `SegmentReader`s ready for search.
@@ -147,6 +148,16 @@ impl Searcher {
         collector.merge_fruits(fruits)
     }
 
+    /// Return the field searcher associated to a `Field`.
+    pub fn field(&self, field: Field) -> crate::Result<FieldSearcher> {
+        let inv_index_readers: Vec<Arc<InvertedIndexReader>> = self
+            .segment_readers
+            .iter()
+            .map(|segment_reader| segment_reader.inverted_index(field))
+            .collect::<crate::Result<Vec<_>>>()?;
+        Ok(FieldSearcher::new(inv_index_readers))
+    }
+
     /// Summarize total space usage of this searcher.
     pub fn space_usage(&self) -> io::Result<SearcherSpaceUsage> {
         let mut space_usage = SearcherSpaceUsage::new();
@@ -157,6 +168,32 @@ impl Searcher {
     }
 }
 
+/// **Experimental API** `FieldSearcher` only gives access to a stream over the terms of a field.
+pub struct FieldSearcher {
+    inv_index_readers: Vec<Arc<InvertedIndexReader>>,
+}
+
+impl FieldSearcher {
+    fn new(inv_index_readers: Vec<Arc<InvertedIndexReader>>) -> FieldSearcher {
+        FieldSearcher { inv_index_readers }
+    }
+
+    /// Returns a Stream over all of the sorted unique terms of
+    /// for the given field.
+    ///
+    /// This method does not take into account which documents are deleted, so
+    /// in presence of deletes some terms may not actually exist in any document
+    /// anymore.
+    pub fn terms(&self) -> TermMerger {
+        let term_streamers: Vec<_> = self
+            .inv_index_readers
+            .iter()
+            .map(|inverted_index| inverted_index.terms().stream())
+            .collect();
+        TermMerger::new(term_streamers)
+    }
+}
+
 impl fmt::Debug for Searcher {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         let segment_ids = self

src/directory/directory.rs

@@ -1,8 +1,8 @@
 use crate::directory::directory_lock::Lock;
 use crate::directory::error::LockError;
 use crate::directory::error::{DeleteError, OpenReadError, OpenWriteError};
+use crate::directory::WatchCallback;
 use crate::directory::WatchHandle;
-use crate::directory::{FileHandle, WatchCallback};
 use crate::directory::{FileSlice, WritePtr};
 use std::fmt;
 use std::io;
@@ -108,13 +108,10 @@ fn retry_policy(is_blocking: bool) -> RetryPolicy {
 /// should be your default choice.
 /// - The [`RAMDirectory`](struct.RAMDirectory.html), which
 /// should be used mostly for tests.
+///
 pub trait Directory: DirectoryClone + fmt::Debug + Send + Sync + 'static {
-    /// Opens a file and returns a boxed `FileHandle`.
+    /// Opens a virtual file for read.
     ///
-    /// Users of `Directory` should typically call `Directory::open_read(...)`,
-    /// while `Directory` implementor should implement `get_file_handle()`.
-    fn get_file_handle(&self, path: &Path) -> Result<Box<dyn FileHandle>, OpenReadError>;
-
     /// Once a virtual file is open, its data may not
     /// change.
     ///
@@ -122,10 +119,7 @@ pub trait Directory: DirectoryClone + fmt::Debug + Send + Sync + 'static {
     /// have no effect on the returned `FileSlice` object.
     ///
     /// You should only use this to read files create with [Directory::open_write].
-    fn open_read(&self, path: &Path) -> Result<FileSlice, OpenReadError> {
-        let file_handle = self.get_file_handle(path)?;
-        Ok(FileSlice::new(file_handle))
-    }
+    fn open_read(&self, path: &Path) -> Result<FileSlice, OpenReadError>;
 
     /// Removes a file
     ///

src/directory/file_slice.rs

@@ -2,11 +2,10 @@ use stable_deref_trait::StableDeref;
 
 use crate::common::HasLen;
 use crate::directory::OwnedBytes;
-use std::sync::{Arc, Weak};
+use std::sync::Arc;
 use std::{io, ops::Deref};
 
-pub type ArcBytes = Arc<dyn Deref<Target = [u8]> + Send + Sync + 'static>;
-pub type WeakArcBytes = Weak<dyn Deref<Target = [u8]> + Send + Sync + 'static>;
+pub type BoxedData = Box<dyn Deref<Target = [u8]> + Send + Sync + 'static>;
 
 /// Objects that represents files sections in tantivy.
 ///
@@ -41,7 +40,7 @@ where
     B: StableDeref + Deref<Target = [u8]> + 'static + Send + Sync,
 {
     fn from(bytes: B) -> FileSlice {
-        FileSlice::new(Box::new(OwnedBytes::new(bytes)))
+        FileSlice::new(OwnedBytes::new(bytes))
     }
 }
 
@@ -51,25 +50,22 @@ where
 ///
 #[derive(Clone)]
 pub struct FileSlice {
-    data: Arc<dyn FileHandle>,
+    data: Arc<Box<dyn FileHandle>>,
     start: usize,
     stop: usize,
 }
 
 impl FileSlice {
     /// Wraps a FileHandle.
-    pub fn new(file_handle: Box<dyn FileHandle>) -> Self {
-        let num_bytes = file_handle.len();
-        FileSlice::new_with_num_bytes(file_handle, num_bytes)
-    }
-
-    /// Wraps a FileHandle.
-    #[doc(hidden)]
-    pub fn new_with_num_bytes(file_handle: Box<dyn FileHandle>, num_bytes: usize) -> Self {
+    pub fn new<D>(data: D) -> Self
+    where
+        D: FileHandle,
+    {
+        let len = data.len();
         FileSlice {
-            data: Arc::from(file_handle),
+            data: Arc::new(Box::new(data)),
             start: 0,
-            stop: num_bytes,
+            stop: len,
         }
     }
 
@@ -150,12 +146,6 @@ impl FileSlice {
     }
 }
 
-impl FileHandle for FileSlice {
-    fn read_bytes(&self, from: usize, to: usize) -> io::Result<OwnedBytes> {
-        self.read_bytes_slice(from, to)
-    }
-}
-
 impl HasLen for FileSlice {
     fn len(&self) -> usize {
         self.stop - self.start
@@ -170,7 +160,7 @@ mod tests {
 
     #[test]
     fn test_file_slice() -> io::Result<()> {
-        let file_slice = FileSlice::new(Box::new(b"abcdef".as_ref()));
+        let file_slice = FileSlice::new(b"abcdef".as_ref());
         assert_eq!(file_slice.len(), 6);
         assert_eq!(file_slice.slice_from(2).read_bytes()?.as_slice(), b"cdef");
         assert_eq!(file_slice.slice_to(2).read_bytes()?.as_slice(), b"ab");
@@ -214,7 +204,7 @@ mod tests {
 
     #[test]
     fn test_slice_simple_read() -> io::Result<()> {
-        let slice = FileSlice::new(Box::new(&b"abcdef"[..]));
+        let slice = FileSlice::new(&b"abcdef"[..]);
         assert_eq!(slice.len(), 6);
         assert_eq!(slice.read_bytes()?.as_ref(), b"abcdef");
         assert_eq!(slice.slice(1, 4).read_bytes()?.as_ref(), b"bcd");
@@ -223,7 +213,7 @@ mod tests {
 
     #[test]
     fn test_slice_read_slice() -> io::Result<()> {
-        let slice_deref = FileSlice::new(Box::new(&b"abcdef"[..]));
+        let slice_deref = FileSlice::new(&b"abcdef"[..]);
         assert_eq!(slice_deref.read_bytes_slice(1, 4)?.as_ref(), b"bcd");
         Ok(())
     }
@@ -231,14 +221,14 @@ mod tests {
     #[test]
     #[should_panic(expected = "assertion failed: from <= to")]
     fn test_slice_read_slice_invalid_range() {
-        let slice_deref = FileSlice::new(Box::new(&b"abcdef"[..]));
+        let slice_deref = FileSlice::new(&b"abcdef"[..]);
         assert_eq!(slice_deref.read_bytes_slice(1, 0).unwrap().as_ref(), b"bcd");
     }
 
     #[test]
     #[should_panic(expected = "`to` exceeds the fileslice length")]
     fn test_slice_read_slice_invalid_range_exceeds() {
-        let slice_deref = FileSlice::new(Box::new(&b"abcdef"[..]));
+        let slice_deref = FileSlice::new(&b"abcdef"[..]);
         assert_eq!(
             slice_deref.read_bytes_slice(0, 10).unwrap().as_ref(),
             b"bcd"

src/directory/managed_directory.rs

@@ -1,10 +1,10 @@
 use crate::core::{MANAGED_FILEPATH, META_FILEPATH};
 use crate::directory::error::{DeleteError, LockError, OpenReadError, OpenWriteError};
 use crate::directory::footer::{Footer, FooterProxy};
+use crate::directory::DirectoryLock;
 use crate::directory::GarbageCollectionResult;
 use crate::directory::Lock;
 use crate::directory::META_LOCK;
-use crate::directory::{DirectoryLock, FileHandle};
 use crate::directory::{FileSlice, WritePtr};
 use crate::directory::{WatchCallback, WatchHandle};
 use crate::error::DataCorruption;
@@ -274,11 +274,6 @@ impl ManagedDirectory {
 }
 
 impl Directory for ManagedDirectory {
-    fn get_file_handle(&self, path: &Path) -> Result<Box<dyn FileHandle>, OpenReadError> {
-        let file_slice = self.open_read(path)?;
-        Ok(Box::new(file_slice))
-    }
-
     fn open_read(&self, path: &Path) -> result::Result<FileSlice, OpenReadError> {
         let file_slice = self.directory.open_read(path)?;
         let (footer, reader) = Footer::extract_footer(file_slice)

src/directory/mmap_directory.rs

@@ -2,13 +2,14 @@ use crate::core::META_FILEPATH;
 use crate::directory::error::LockError;
 use crate::directory::error::{DeleteError, OpenDirectoryError, OpenReadError, OpenWriteError};
 use crate::directory::file_watcher::FileWatcher;
+use crate::directory::AntiCallToken;
+use crate::directory::BoxedData;
 use crate::directory::Directory;
 use crate::directory::DirectoryLock;
+use crate::directory::FileSlice;
 use crate::directory::Lock;
 use crate::directory::WatchCallback;
 use crate::directory::WatchHandle;
-use crate::directory::{AntiCallToken, FileHandle, OwnedBytes};
-use crate::directory::{ArcBytes, WeakArcBytes};
 use crate::directory::{TerminatingWrite, WritePtr};
 use fs2::FileExt;
 use memmap::Mmap;
@@ -24,6 +25,7 @@ use std::path::{Path, PathBuf};
 use std::result;
 use std::sync::Arc;
 use std::sync::RwLock;
+use std::sync::Weak;
 use std::{collections::HashMap, ops::Deref};
 use tempfile::TempDir;
 
@@ -76,7 +78,7 @@ pub struct CacheInfo {
 
 struct MmapCache {
     counters: CacheCounters,
-    cache: HashMap<PathBuf, WeakArcBytes>,
+    cache: HashMap<PathBuf, Weak<BoxedData>>,
 }
 
 impl Default for MmapCache {
@@ -110,7 +112,7 @@ impl MmapCache {
     }
 
     // Returns None if the file exists but as a len of 0 (and hence is not mmappable).
-    fn get_mmap(&mut self, full_path: &Path) -> Result<Option<ArcBytes>, OpenReadError> {
+    fn get_mmap(&mut self, full_path: &Path) -> Result<Option<Arc<BoxedData>>, OpenReadError> {
         if let Some(mmap_weak) = self.cache.get(full_path) {
             if let Some(mmap_arc) = mmap_weak.upgrade() {
                 self.counters.hit += 1;
@@ -121,7 +123,7 @@ impl MmapCache {
         self.counters.miss += 1;
         let mmap_opt = open_mmap(full_path)?;
         Ok(mmap_opt.map(|mmap| {
-            let mmap_arc: ArcBytes = Arc::new(mmap);
+            let mmap_arc: Arc<BoxedData> = Arc::new(Box::new(mmap));
             let mmap_weak = Arc::downgrade(&mmap_arc);
             self.cache.insert(full_path.to_owned(), mmap_weak);
             mmap_arc
@@ -159,7 +161,7 @@ impl MmapDirectoryInner {
             mmap_cache: Default::default(),
             _temp_directory: temp_directory,
             watcher: FileWatcher::new(&root_path.join(*META_FILEPATH)),
-            root_path,
+            root_path: root_path,
         }
     }
 
@@ -314,7 +316,7 @@ impl TerminatingWrite for SafeFileWriter {
 }
 
 #[derive(Clone)]
-struct MmapArc(Arc<dyn Deref<Target = [u8]> + Send + Sync>);
+struct MmapArc(Arc<Box<dyn Deref<Target = [u8]> + Send + Sync>>);
 
 impl Deref for MmapArc {
     type Target = [u8];
@@ -344,7 +346,7 @@ pub(crate) fn atomic_write(path: &Path, content: &[u8]) -> io::Result<()> {
 }
 
 impl Directory for MmapDirectory {
-    fn get_file_handle(&self, path: &Path) -> result::Result<Box<dyn FileHandle>, OpenReadError> {
+    fn open_read(&self, path: &Path) -> result::Result<FileSlice, OpenReadError> {
         debug!("Open Read {:?}", path);
         let full_path = self.resolve_path(path);
 
@@ -357,16 +359,11 @@ impl Directory for MmapDirectory {
             let io_err = make_io_err(msg);
             OpenReadError::wrap_io_error(io_err, path.to_path_buf())
         })?;
-
-        let owned_bytes = mmap_cache
-            .get_mmap(&full_path)?
-            .map(|mmap_arc| {
-                let mmap_arc_obj = MmapArc(mmap_arc);
-                OwnedBytes::new(mmap_arc_obj)
-            })
-            .unwrap_or_else(OwnedBytes::empty);
-
-        Ok(Box::new(owned_bytes))
+        if let Some(mmap_arc) = mmap_cache.get_mmap(&full_path)? {
+            Ok(FileSlice::from(MmapArc(mmap_arc)))
+        } else {
+            Ok(FileSlice::empty())
+        }
     }
 
     /// Any entry associated to the path in the mmap will be
@@ -449,8 +446,7 @@ impl Directory for MmapDirectory {
     fn atomic_write(&self, path: &Path, content: &[u8]) -> io::Result<()> {
         debug!("Atomic Write {:?}", path);
         let full_path = self.resolve_path(path);
-        atomic_write(&full_path, content)?;
-        self.sync_directory()
+        atomic_write(&full_path, content)
     }
 
     fn acquire_lock(&self, lock: &Lock) -> Result<DirectoryLock, LockError> {

src/directory/mod.rs

@@ -23,7 +23,7 @@ pub mod error;
 pub use self::directory::DirectoryLock;
 pub use self::directory::{Directory, DirectoryClone};
 pub use self::directory_lock::{Lock, INDEX_WRITER_LOCK, META_LOCK};
-pub(crate) use self::file_slice::{ArcBytes, WeakArcBytes};
+pub(crate) use self::file_slice::BoxedData;
 pub use self::file_slice::{FileHandle, FileSlice};
 pub use self::owned_bytes::OwnedBytes;
 pub use self::ram_directory::RAMDirectory;

src/directory/owned_bytes.rs

@@ -1,6 +1,5 @@
 use crate::directory::FileHandle;
 use stable_deref_trait::StableDeref;
-use std::convert::TryInto;
 use std::mem;
 use std::ops::Deref;
 use std::sync::Arc;
@@ -96,24 +95,6 @@ impl OwnedBytes {
     pub fn advance(&mut self, advance_len: usize) {
         self.data = &self.data[advance_len..]
     }
-
-    /// Reads an `u8` from the `OwnedBytes` and advance by one byte.
-    pub fn read_u8(&mut self) -> u8 {
-        assert!(!self.is_empty());
-
-        let byte = self.as_slice()[0];
-        self.advance(1);
-        byte
-    }
-
-    /// Reads an `u64` encoded as little-endian from the `OwnedBytes` and advance by 8 bytes.
-    pub fn read_u64(&mut self) -> u64 {
-        assert!(self.len() > 7);
-
-        let octlet: [u8; 8] = self.as_slice()[..8].try_into().unwrap();
-        self.advance(8);
-        u64::from_le_bytes(octlet)
-    }
 }
 
 impl fmt::Debug for OwnedBytes {
@@ -249,22 +230,6 @@ mod tests {
         Ok(())
     }
 
-    #[test]
-    fn test_owned_bytes_read_u8() -> io::Result<()> {
-        let mut bytes = OwnedBytes::new(b"\xFF".as_ref());
-        assert_eq!(bytes.read_u8(), 255);
-        assert_eq!(bytes.len(), 0);
-        Ok(())
-    }
-
-    #[test]
-    fn test_owned_bytes_read_u64() -> io::Result<()> {
-        let mut bytes = OwnedBytes::new(b"\0\xFF\xFF\xFF\xFF\xFF\xFF\xFF".as_ref());
-        assert_eq!(bytes.read_u64(), u64::MAX - 255);
-        assert_eq!(bytes.len(), 0);
-        Ok(())
-    }
-
     #[test]
     fn test_owned_bytes_split() {
         let bytes = OwnedBytes::new(b"abcdefghi".as_ref());

src/directory/ram_directory.rs

@@ -12,8 +12,6 @@ use std::path::{Path, PathBuf};
 use std::result;
 use std::sync::{Arc, RwLock};
 
-use super::FileHandle;
-
 /// Writer associated with the `RAMDirectory`
 ///
 /// The Writer just writes a buffer.
@@ -165,11 +163,6 @@ impl RAMDirectory {
 }
 
 impl Directory for RAMDirectory {
-    fn get_file_handle(&self, path: &Path) -> Result<Box<dyn FileHandle>, OpenReadError> {
-        let file_slice = self.open_read(path)?;
-        Ok(Box::new(file_slice))
-    }
-
     fn open_read(&self, path: &Path) -> result::Result<FileSlice, OpenReadError> {
         self.fs.read().unwrap().open_read(path)
     }

src/directory/watch_event_router.rs

@@ -6,12 +6,12 @@ use std::sync::Weak;
 
 /// Cloneable wrapper for callbacks registered when watching files of a `Directory`.
 #[derive(Clone)]
-pub struct WatchCallback(Arc<dyn Fn() + Sync + Send>);
+pub struct WatchCallback(Arc<Box<dyn Fn() + Sync + Send>>);
 
 impl WatchCallback {
     /// Wraps a `Fn()` to create a WatchCallback.
     pub fn new<F: Fn() + Sync + Send + 'static>(op: F) -> Self {
-        WatchCallback(Arc::new(op))
+        WatchCallback(Arc::new(Box::new(op)))
     }
 
     fn call(&self) {

src/docset.rs

@@ -10,7 +10,7 @@ use std::borrow::BorrowMut;
 pub const TERMINATED: DocId = std::i32::MAX as u32;
 
 /// Represents an iterable set of sorted doc ids.
-pub trait DocSet: Send {
+pub trait DocSet {
     /// Goes to the next element.
     ///
     /// The DocId of the next element is returned.
@@ -129,14 +129,6 @@ impl<'a> DocSet for &'a mut dyn DocSet {
     fn size_hint(&self) -> u32 {
         (**self).size_hint()
     }
-
-    fn count(&mut self, delete_bitset: &DeleteBitSet) -> u32 {
-        (**self).count(delete_bitset)
-    }
-
-    fn count_including_deleted(&mut self) -> u32 {
-        (**self).count_including_deleted()
-    }
 }
 
 impl<TDocSet: DocSet + ?Sized> DocSet for Box<TDocSet> {

src/fastfield/facet_reader.rs

@@ -1,5 +1,4 @@
 use super::MultiValueIntFastFieldReader;
-use crate::error::DataCorruption;
 use crate::schema::Facet;
 use crate::termdict::TermDictionary;
 use crate::termdict::TermOrdinal;
@@ -63,13 +62,12 @@ impl FacetReader {
         &mut self,
         facet_ord: TermOrdinal,
         output: &mut Facet,
-    ) -> crate::Result<()> {
+    ) -> Result<(), str::Utf8Error> {
         let found_term = self
             .term_dict
-            .ord_to_term(facet_ord as u64, &mut self.buffer)?;
+            .ord_to_term(facet_ord as u64, &mut self.buffer);
         assert!(found_term, "Term ordinal {} no found.", facet_ord);
-        let facet_str = str::from_utf8(&self.buffer[..])
-            .map_err(|utf8_err| DataCorruption::comment_only(utf8_err.to_string()))?;
+        let facet_str = str::from_utf8(&self.buffer[..])?;
         output.set_facet_str(facet_str);
         Ok(())
     }

src/fieldnorm/reader.rs

@@ -61,38 +61,16 @@ impl FieldNormReaders {
 /// precompute computationally expensive functions of the fieldnorm
 /// in a very short array.
 #[derive(Clone)]
-pub struct FieldNormReader(ReaderImplEnum);
-
-impl From<ReaderImplEnum> for FieldNormReader {
-    fn from(reader_enum: ReaderImplEnum) -> FieldNormReader {
-        FieldNormReader(reader_enum)
-    }
-}
-
-#[derive(Clone)]
-enum ReaderImplEnum {
-    FromData(OwnedBytes),
-    Const {
-        num_docs: u32,
-        fieldnorm_id: u8,
-        fieldnorm: u32,
-    },
+pub struct FieldNormReader {
+    data: OwnedBytes,
 }
 
 impl FieldNormReader {
     /// Creates a `FieldNormReader` with a constant fieldnorm.
-    ///
-    /// The fieldnorm will be subjected to compression as if it was coming
-    /// from an array-backed fieldnorm reader.
     pub fn constant(num_docs: u32, fieldnorm: u32) -> FieldNormReader {
         let fieldnorm_id = fieldnorm_to_id(fieldnorm);
-        let fieldnorm = id_to_fieldnorm(fieldnorm_id);
-        ReaderImplEnum::Const {
-            num_docs,
-            fieldnorm_id,
-            fieldnorm,
-        }
-        .into()
+        let field_norms_data = OwnedBytes::new(vec![fieldnorm_id; num_docs as usize]);
+        FieldNormReader::new(field_norms_data)
     }
 
     /// Opens a field norm reader given its file.
@@ -102,15 +80,12 @@ impl FieldNormReader {
     }
 
     fn new(data: OwnedBytes) -> Self {
-        ReaderImplEnum::FromData(data).into()
+        FieldNormReader { data }
     }
 
     /// Returns the number of documents in this segment.
     pub fn num_docs(&self) -> u32 {
-        match &self.0 {
-            ReaderImplEnum::FromData(data) => data.len() as u32,
-            ReaderImplEnum::Const { num_docs, .. } => *num_docs,
-        }
+        self.data.len() as u32
     }
 
     /// Returns the `fieldnorm` associated to a doc id.
@@ -123,25 +98,14 @@ impl FieldNormReader {
     /// The fieldnorm is effectively decoded from the
     /// `fieldnorm_id` by doing a simple table lookup.
     pub fn fieldnorm(&self, doc_id: DocId) -> u32 {
-        match &self.0 {
-            ReaderImplEnum::FromData(data) => {
-                let fieldnorm_id = data.as_slice()[doc_id as usize];
-                id_to_fieldnorm(fieldnorm_id)
-            }
-            ReaderImplEnum::Const { fieldnorm, .. } => *fieldnorm,
-        }
+        let fieldnorm_id = self.fieldnorm_id(doc_id);
+        id_to_fieldnorm(fieldnorm_id)
     }
 
     /// Returns the `fieldnorm_id` associated to a document.
     #[inline(always)]
     pub fn fieldnorm_id(&self, doc_id: DocId) -> u8 {
-        match &self.0 {
-            ReaderImplEnum::FromData(data) => {
-                let fieldnorm_id = data.as_slice()[doc_id as usize];
-                fieldnorm_id
-            }
-            ReaderImplEnum::Const { fieldnorm_id, .. } => *fieldnorm_id,
-        }
+        self.data.as_slice()[doc_id as usize]
     }
 
     /// Converts a `fieldnorm_id` into a fieldnorm.
@@ -165,7 +129,9 @@ impl FieldNormReader {
             .map(FieldNormReader::fieldnorm_to_id)
             .collect::<Vec<u8>>();
         let field_norms_data = OwnedBytes::new(field_norms_id);
-        FieldNormReader::new(field_norms_data)
+        FieldNormReader {
+            data: field_norms_data,
+        }
     }
 }
 
@@ -184,20 +150,4 @@ mod tests {
         assert_eq!(fieldnorm_reader.fieldnorm(3), 4);
         assert_eq!(fieldnorm_reader.fieldnorm(4), 983_064);
     }
-
-    #[test]
-    fn test_const_fieldnorm_reader_small_fieldnorm_id() {
-        let fieldnorm_reader = FieldNormReader::constant(1_000_000u32, 10u32);
-        assert_eq!(fieldnorm_reader.num_docs(), 1_000_000u32);
-        assert_eq!(fieldnorm_reader.fieldnorm(0u32), 10u32);
-        assert_eq!(fieldnorm_reader.fieldnorm_id(0u32), 10u8);
-    }
-
-    #[test]
-    fn test_const_fieldnorm_reader_large_fieldnorm_id() {
-        let fieldnorm_reader = FieldNormReader::constant(1_000_000u32, 300u32);
-        assert_eq!(fieldnorm_reader.num_docs(), 1_000_000u32);
-        assert_eq!(fieldnorm_reader.fieldnorm(0u32), 280u32);
-        assert_eq!(fieldnorm_reader.fieldnorm_id(0u32), 72u8);
-    }
 }

src/indexer/delete_queue.rs

@@ -53,7 +53,7 @@ impl DeleteQueue {
             return block;
         }
         let block = Arc::new(Block {
-            operations: Arc::new([]),
+            operations: Arc::default(),
             next: NextBlock::from(self.clone()),
         });
         wlock.last_block = Arc::downgrade(&block);
@@ -108,7 +108,7 @@ impl DeleteQueue {
         let delete_operations = mem::replace(&mut self_wlock.writer, vec![]);
 
         let new_block = Arc::new(Block {
-            operations: Arc::from(delete_operations.into_boxed_slice()),
+            operations: Arc::new(delete_operations.into_boxed_slice()),
             next: NextBlock::from(self.clone()),
         });
 
@@ -167,7 +167,7 @@ impl NextBlock {
 }
 
 struct Block {
-    operations: Arc<[DeleteOperation]>,
+    operations: Arc<Box<[DeleteOperation]>>,
     next: NextBlock,
 }
 

src/indexer/index_writer.rs

@@ -449,7 +449,7 @@ impl IndexWriter {
     }
 
     /// Accessor to the merge policy.
-    pub fn get_merge_policy(&self) -> Arc<dyn MergePolicy> {
+    pub fn get_merge_policy(&self) -> Arc<Box<dyn MergePolicy>> {
         self.segment_updater.get_merge_policy()
     }
 

src/indexer/merger.rs

@@ -503,6 +503,7 @@ impl IndexMerger {
         let mut positions_buffer: Vec<u32> = Vec::with_capacity(1_000);
         let mut delta_computer = DeltaComputer::new();
 
+        let mut field_term_streams = Vec::new();
         let mut max_term_ords: Vec<TermOrdinal> = Vec::new();
 
         let field_readers: Vec<Arc<InvertedIndexReader>> = self
@@ -511,13 +512,10 @@ impl IndexMerger {
             .map(|reader| reader.inverted_index(indexed_field))
             .collect::<crate::Result<Vec<_>>>()?;
 
-        let mut field_term_streams = Vec::new();
-
         for field_reader in &field_readers {
             let terms = field_reader.terms();
+            field_term_streams.push(terms.stream());
             max_term_ords.push(terms.num_terms() as u64);
-            let term_stream = terms.stream()?;
-            field_term_streams.push(term_stream);
         }
 
         let mut term_ord_mapping_opt = if *field_type == FieldType::HierarchicalFacet {

src/indexer/operation.rs

@@ -9,15 +9,6 @@ pub struct DeleteOperation {
     pub term: Term,
 }
 
-impl Default for DeleteOperation {
-    fn default() -> Self {
-        DeleteOperation {
-            opstamp: 0u64,
-            term: Term::new(),
-        }
-    }
-}
-
 /// Timestamped Add operation.
 #[derive(Eq, PartialEq, Debug)]
 pub struct AddOperation {

src/indexer/segment_updater.rs

@@ -154,7 +154,7 @@ pub(crate) struct InnerSegmentUpdater {
 
     index: Index,
     segment_manager: SegmentManager,
-    merge_policy: RwLock<Arc<dyn MergePolicy>>,
+    merge_policy: RwLock<Arc<Box<dyn MergePolicy>>>,
     killed: AtomicBool,
     stamper: Stamper,
     merge_operations: MergeOperationInventory,
@@ -193,19 +193,19 @@ impl SegmentUpdater {
             merge_thread_pool,
             index,
             segment_manager,
-            merge_policy: RwLock::new(Arc::new(DefaultMergePolicy::default())),
+            merge_policy: RwLock::new(Arc::new(Box::new(DefaultMergePolicy::default()))),
             killed: AtomicBool::new(false),
             stamper,
             merge_operations: Default::default(),
         })))
     }
 
-    pub fn get_merge_policy(&self) -> Arc<dyn MergePolicy> {
+    pub fn get_merge_policy(&self) -> Arc<Box<dyn MergePolicy>> {
         self.merge_policy.read().unwrap().clone()
     }
 
     pub fn set_merge_policy(&self, merge_policy: Box<dyn MergePolicy>) {
-        let arc_merge_policy = Arc::from(merge_policy);
+        let arc_merge_policy = Arc::new(merge_policy);
         *self.merge_policy.write().unwrap() = arc_merge_policy;
     }
 

src/lib.rs

@@ -160,7 +160,7 @@ pub use self::docset::{DocSet, TERMINATED};
 pub use crate::common::HasLen;
 pub use crate::common::{f64_to_u64, i64_to_u64, u64_to_f64, u64_to_i64};
 pub use crate::core::{Executor, SegmentComponent};
-pub use crate::core::{Index, IndexMeta, Searcher, Segment, SegmentId, SegmentMeta};
+pub use crate::core::{FieldSearcher, Index, IndexMeta, Searcher, Segment, SegmentId, SegmentMeta};
 pub use crate::core::{InvertedIndexReader, SegmentReader};
 pub use crate::directory::Directory;
 pub use crate::indexer::operation::UserOperation;

src/positions/serializer.rs

@@ -8,7 +8,7 @@ use std::io::{self, Write};
 pub struct PositionSerializer<W: io::Write> {
     bit_packer: BitPacker4x,
     write_stream: CountingWriter<W>,
-    write_skip_index: W,
+    write_skiplist: W,
     block: Vec<u32>,
     buffer: Vec<u8>,
     num_ints: u64,
@@ -16,11 +16,11 @@ pub struct PositionSerializer<W: io::Write> {
 }
 
 impl<W: io::Write> PositionSerializer<W> {
-    pub fn new(write_stream: W, write_skip_index: W) -> PositionSerializer<W> {
+    pub fn new(write_stream: W, write_skiplist: W) -> PositionSerializer<W> {
         PositionSerializer {
             bit_packer: BitPacker4x::new(),
             write_stream: CountingWriter::wrap(write_stream),
-            write_skip_index,
+            write_skiplist,
             block: Vec::with_capacity(128),
             buffer: vec![0u8; 128 * 4],
             num_ints: 0u64,
@@ -52,7 +52,7 @@ impl<W: io::Write> PositionSerializer<W> {
 
     fn flush_block(&mut self) -> io::Result<()> {
         let num_bits = self.bit_packer.num_bits(&self.block[..]);
-        self.write_skip_index.write_all(&[num_bits])?;
+        self.write_skiplist.write_all(&[num_bits])?;
         let written_len = self
             .bit_packer
             .compress(&self.block[..], &mut self.buffer, num_bits);
@@ -70,10 +70,10 @@ impl<W: io::Write> PositionSerializer<W> {
             self.flush_block()?;
         }
         for &long_skip in &self.long_skips {
-            long_skip.serialize(&mut self.write_skip_index)?;
+            long_skip.serialize(&mut self.write_skiplist)?;
         }
-        (self.long_skips.len() as u32).serialize(&mut self.write_skip_index)?;
-        self.write_skip_index.flush()?;
+        (self.long_skips.len() as u32).serialize(&mut self.write_skiplist)?;
+        self.write_skiplist.flush()?;
         self.write_stream.flush()?;
         Ok(())
     }

src/postings/block_segment_postings.rs

@@ -469,7 +469,7 @@ mod tests {
         let segment_reader = searcher.segment_reader(0);
         let inverted_index = segment_reader.inverted_index(int_field).unwrap();
         let term = Term::from_field_u64(int_field, 0u64);
-        let term_info = inverted_index.get_term_info(&term).unwrap().unwrap();
+        let term_info = inverted_index.get_term_info(&term).unwrap();
         inverted_index
             .read_block_postings_from_terminfo(&term_info, IndexRecordOption::Basic)
             .unwrap()
@@ -513,7 +513,7 @@ mod tests {
         {
             let term = Term::from_field_u64(int_field, 0u64);
             let inverted_index = segment_reader.inverted_index(int_field)?;
-            let term_info = inverted_index.get_term_info(&term)?.unwrap();
+            let term_info = inverted_index.get_term_info(&term).unwrap();
             block_segments = inverted_index
                 .read_block_postings_from_terminfo(&term_info, IndexRecordOption::Basic)?;
         }
@@ -521,7 +521,7 @@ mod tests {
         {
             let term = Term::from_field_u64(int_field, 1u64);
             let inverted_index = segment_reader.inverted_index(int_field)?;
-            let term_info = inverted_index.get_term_info(&term)?.unwrap();
+            let term_info = inverted_index.get_term_info(&term).unwrap();
             inverted_index.reset_block_postings_from_terminfo(&term_info, &mut block_segments)?;
         }
         assert_eq!(block_segments.docs(), &[1, 3, 5]);

src/postings/mod.rs

@@ -54,7 +54,7 @@ pub mod tests {
     use crate::DocId;
     use crate::HasLen;
     use crate::Score;
-    use std::{iter, mem};
+    use std::iter;
 
     #[test]
     pub fn test_position_write() -> crate::Result<()> {
@@ -71,7 +71,6 @@ pub mod tests {
             field_serializer.write_doc(doc_id, 4, &delta_positions)?;
         }
         field_serializer.close_term()?;
-        mem::drop(field_serializer);
         posting_serializer.close()?;
         let read = segment.open_read(SegmentComponent::POSITIONS)?;
         assert!(read.len() <= 140);
@@ -180,7 +179,7 @@ pub mod tests {
             let inverted_index = segment_reader.inverted_index(text_field)?;
             assert_eq!(inverted_index.terms().num_terms(), 1);
             let mut bytes = vec![];
-            assert!(inverted_index.terms().ord_to_term(0, &mut bytes)?);
+            assert!(inverted_index.terms().ord_to_term(0, &mut bytes));
             assert_eq!(&bytes, b"hello");
         }
         {
@@ -192,7 +191,7 @@ pub mod tests {
             let inverted_index = segment_reader.inverted_index(text_field)?;
             assert_eq!(inverted_index.terms().num_terms(), 1);
             let mut bytes = vec![];
-            assert!(inverted_index.terms().ord_to_term(0, &mut bytes)?);
+            assert!(inverted_index.terms().ord_to_term(0, &mut bytes));
             assert_eq!(&bytes[..], ok_token_text.as_bytes());
         }
         Ok(())

src/query/automaton_weight.rs

@@ -7,7 +7,6 @@ use crate::schema::{Field, IndexRecordOption};
 use crate::termdict::{TermDictionary, TermStreamer};
 use crate::TantivyError;
 use crate::{DocId, Score};
-use std::io;
 use std::sync::Arc;
 use tantivy_fst::Automaton;
 
@@ -20,7 +19,6 @@ pub struct AutomatonWeight<A> {
 impl<A> AutomatonWeight<A>
 where
     A: Automaton + Send + Sync + 'static,
-    A::State: Clone,
 {
     /// Create a new AutomationWeight
     pub fn new<IntoArcA: Into<Arc<A>>>(field: Field, automaton: IntoArcA) -> AutomatonWeight<A> {
@@ -30,10 +28,7 @@ where
         }
     }
 
-    fn automaton_stream<'a>(
-        &'a self,
-        term_dict: &'a TermDictionary,
-    ) -> io::Result<TermStreamer<'a, &'a A>> {
+    fn automaton_stream<'a>(&'a self, term_dict: &'a TermDictionary) -> TermStreamer<'a, &'a A> {
         let automaton: &A = &*self.automaton;
         let term_stream_builder = term_dict.search(automaton);
         term_stream_builder.into_stream()
@@ -43,14 +38,13 @@ where
 impl<A> Weight for AutomatonWeight<A>
 where
     A: Automaton + Send + Sync + 'static,
-    A::State: Clone,
 {
     fn scorer(&self, reader: &SegmentReader, boost: Score) -> crate::Result<Box<dyn Scorer>> {
         let max_doc = reader.max_doc();
         let mut doc_bitset = BitSet::with_max_value(max_doc);
         let inverted_index = reader.inverted_index(self.field)?;
         let term_dict = inverted_index.terms();
-        let mut term_stream = self.automaton_stream(term_dict)?;
+        let mut term_stream = self.automaton_stream(term_dict);
         while term_stream.advance() {
             let term_info = term_stream.value();
             let mut block_segment_postings = inverted_index
@@ -104,7 +98,6 @@ mod tests {
         index
     }
 
-    #[derive(Clone, Copy)]
     enum State {
         Start,
         NotMatching,

src/query/bm25.rs

@@ -106,7 +106,7 @@ impl BM25Weight {
         BM25Weight::new(idf_explain, avg_fieldnorm)
     }
 
-    pub(crate) fn new(idf_explain: Explanation, average_fieldnorm: Score) -> BM25Weight {
+    fn new(idf_explain: Explanation, average_fieldnorm: Score) -> BM25Weight {
         let weight = idf_explain.value() * (1.0 + K1);
         BM25Weight {
             idf_explain,

src/query/boolean_query/boolean_weight.rs

@@ -1,5 +1,3 @@
-use rayon::iter::IntoParallelRefIterator;
-
 use crate::core::SegmentReader;
 use crate::postings::FreqReadingOption;
 use crate::query::explanation::does_not_match;
@@ -24,7 +22,7 @@ enum SpecializedScorer {
 
 fn scorer_union<TScoreCombiner>(scorers: Vec<Box<dyn Scorer>>) -> SpecializedScorer
 where
-    TScoreCombiner: ScoreCombiner + Send,
+    TScoreCombiner: ScoreCombiner,
 {
     assert!(!scorers.is_empty());
     if scorers.len() == 1 {
@@ -54,7 +52,7 @@ where
     SpecializedScorer::Other(Box::new(Union::<_, TScoreCombiner>::from(scorers)))
 }
 
-fn into_box_scorer<TScoreCombiner: ScoreCombiner + Send>(scorer: SpecializedScorer) -> Box<dyn Scorer> {
+fn into_box_scorer<TScoreCombiner: ScoreCombiner>(scorer: SpecializedScorer) -> Box<dyn Scorer> {
     match scorer {
         SpecializedScorer::TermUnion(term_scorers) => {
             let union_scorer = Union::<TermScorer, TScoreCombiner>::from(term_scorers);
@@ -82,32 +80,18 @@ impl BooleanWeight {
         reader: &SegmentReader,
         boost: Score,
     ) -> crate::Result<HashMap<Occur, Vec<Box<dyn Scorer>>>> {
-        use rayon::iter::ParallelIterator;
-        use rayon::iter::IndexedParallelIterator;
         let mut per_occur_scorers: HashMap<Occur, Vec<Box<dyn Scorer>>> = HashMap::new();
-        let mut items_res: Vec<crate::Result<(Occur, Box<dyn Scorer>)>> = Vec::new();
-        let pool = rayon::ThreadPoolBuilder::new().num_threads(self.weights.len()).build().unwrap();
-        pool.install(|| {
-        self.weights.iter()
-            .collect::<Vec<_>>()
-            .par_iter()
-            .map(|(occur, subweight)| {
-                let sub_scorer: Box<dyn Scorer> = subweight.scorer(reader, boost)?;
-                Ok((*occur, sub_scorer))
-            })
-            .collect_into_vec(&mut items_res);
-        });
-        for item_res in items_res {
-            let (occur, sub_scorer) = item_res?;
+        for &(ref occur, ref subweight) in &self.weights {
+            let sub_scorer: Box<dyn Scorer> = subweight.scorer(reader, boost)?;
             per_occur_scorers
-                .entry(occur)
+                .entry(*occur)
                 .or_insert_with(Vec::new)
                 .push(sub_scorer);
         }
         Ok(per_occur_scorers)
     }
 
-    fn complex_scorer<TScoreCombiner: ScoreCombiner >(
+    fn complex_scorer<TScoreCombiner: ScoreCombiner>(
         &self,
         reader: &SegmentReader,
         boost: Score,

src/query/range_query.rs

@@ -11,7 +11,6 @@ use crate::schema::{Field, IndexRecordOption, Term};
 use crate::termdict::{TermDictionary, TermStreamer};
 use crate::{DocId, Score};
 use std::collections::Bound;
-use std::io;
 use std::ops::Range;
 
 fn map_bound<TFrom, TTo, Transform: Fn(&TFrom) -> TTo>(
@@ -275,7 +274,7 @@ pub struct RangeWeight {
 }
 
 impl RangeWeight {
-    fn term_range<'a>(&self, term_dict: &'a TermDictionary) -> io::Result<TermStreamer<'a>> {
+    fn term_range<'a>(&self, term_dict: &'a TermDictionary) -> TermStreamer<'a> {
         use std::collections::Bound::*;
         let mut term_stream_builder = term_dict.range();
         term_stream_builder = match self.left_bound {
@@ -299,7 +298,7 @@ impl Weight for RangeWeight {
 
         let inverted_index = reader.inverted_index(self.field)?;
         let term_dict = inverted_index.terms();
-        let mut term_range = self.term_range(term_dict)?;
+        let mut term_range = self.term_range(term_dict);
         while term_range.advance() {
             let term_info = term_range.value();
             let mut block_segment_postings = inverted_index

src/query/reqopt_scorer.rs

@@ -12,7 +12,7 @@ use std::marker::PhantomData;
 /// This is useful for queries like `+somethingrequired somethingoptional`.
 ///
 /// Note that `somethingoptional` has no impact on the `DocSet`.
-pub struct RequiredOptionalScorer<TReqScorer, TOptScorer, TScoreCombiner: ScoreCombiner> {
+pub struct RequiredOptionalScorer<TReqScorer, TOptScorer, TScoreCombiner> {
     req_scorer: TReqScorer,
     opt_scorer: TOptScorer,
     score_cache: Option<Score>,
@@ -23,7 +23,6 @@ impl<TReqScorer, TOptScorer, TScoreCombiner>
     RequiredOptionalScorer<TReqScorer, TOptScorer, TScoreCombiner>
 where
     TOptScorer: DocSet,
-    TScoreCombiner: ScoreCombiner,
 {
     /// Creates a new `RequiredOptionalScorer`.
     pub fn new(
@@ -44,7 +43,6 @@ impl<TReqScorer, TOptScorer, TScoreCombiner> DocSet
 where
     TReqScorer: DocSet,
     TOptScorer: DocSet,
-    TScoreCombiner: ScoreCombiner,
 {
     fn advance(&mut self) -> DocId {
         self.score_cache = None;

src/query/score_combiner.rs

@@ -3,7 +3,7 @@ use crate::Score;
 
 /// The `ScoreCombiner` trait defines how to compute
 /// an overall score given a list of scores.
-pub trait ScoreCombiner: Default + Clone + Send + Copy + 'static {
+pub trait ScoreCombiner: Default + Clone + Copy + 'static {
     /// Aggregates the score combiner with the given scorer.
     ///
     /// The `ScoreCombiner` may decide to call `.scorer.score()`

src/query/term_query/term_query.rs

@@ -1,7 +1,7 @@
 use super::term_weight::TermWeight;
 use crate::query::bm25::BM25Weight;
+use crate::query::Query;
 use crate::query::Weight;
-use crate::query::{Explanation, Query};
 use crate::schema::IndexRecordOption;
 use crate::Searcher;
 use crate::Term;
@@ -100,13 +100,7 @@ impl TermQuery {
                 field_entry.name()
             )));
         }
-        let bm25_weight;
-        if scoring_enabled {
-            bm25_weight = BM25Weight::for_terms(searcher, &[term])?;
-        } else {
-            bm25_weight =
-                BM25Weight::new(Explanation::new("<no score>".to_string(), 1.0f32), 1.0f32);
-        }
+        let bm25_weight = BM25Weight::for_terms(searcher, &[term])?;
         let index_record_option = if scoring_enabled {
             self.index_record_option
         } else {

src/query/term_query/term_weight.rs

@@ -45,7 +45,7 @@ impl Weight for TermWeight {
         } else {
             let field = self.term.field();
             let inv_index = reader.inverted_index(field)?;
-            let term_info = inv_index.get_term_info(&self.term)?;
+            let term_info = inv_index.get_term_info(&self.term);
             Ok(term_info.map(|term_info| term_info.doc_freq).unwrap_or(0))
         }
     }

src/schema/facet.rs

@@ -233,7 +233,6 @@ mod tests {
         assert_eq!(Facet::root(), Facet::from("/"));
         assert_eq!(format!("{}", Facet::root()), "/");
         assert!(Facet::root().is_root());
-        assert_eq!(Facet::root().encoded_str(), "");
     }
 
     #[test]

src/store/index/skip_index.rs

@@ -19,7 +19,7 @@ impl<'a> Iterator for LayerCursor<'a> {
                 return None;
             }
             let (block_mut, remaining_mut) = (&mut self.block, &mut self.remaining);
-            if block_mut.deserialize(remaining_mut).is_err() {
+            if let Err(_) = block_mut.deserialize(remaining_mut) {
                 return None;
             }
             self.cursor = 0;
@@ -50,7 +50,8 @@ impl Layer {
 
     fn seek_start_at_offset(&self, target: DocId, offset: u64) -> Option<Checkpoint> {
         self.cursor_at_offset(offset)
-            .find(|checkpoint| checkpoint.end_doc > target)
+            .filter(|checkpoint| checkpoint.end_doc > target)
+            .next()
     }
 }
 

src/termdict/fst_termdict/mod.rs

@@ -1,27 +0,0 @@
-/*!
-The term dictionary main role is to associate the sorted [`Term`s](../struct.Term.html) to
-a [`TermInfo`](../postings/struct.TermInfo.html) struct that contains some meta-information
-about the term.
-
-Internally, the term dictionary relies on the `fst` crate to store
-a sorted mapping that associate each term to its rank in the lexicographical order.
-For instance, in a dictionary containing the sorted terms "abba", "bjork", "blur" and "donovan",
-the `TermOrdinal` are respectively `0`, `1`, `2`, and `3`.
-
-For `u64`-terms, tantivy explicitely uses a `BigEndian` representation to ensure that the
-lexicographical order matches the natural order of integers.
-
-`i64`-terms are transformed to `u64` using a continuous mapping `val ⟶ val - i64::min_value()`
-and then treated as a `u64`.
-
-`f64`-terms are transformed to `u64` using a mapping that preserve order, and are then treated
-as `u64`.
-
-A second datastructure makes it possible to access a [`TermInfo`](../postings/struct.TermInfo.html).
-*/
-mod streamer;
-mod term_info_store;
-mod termdict;
-
-pub use self::streamer::{TermStreamer, TermStreamerBuilder};
-pub use self::termdict::{TermDictionary, TermDictionaryBuilder};

src/termdict/mod.rs

@@ -20,39 +20,438 @@ as `u64`.
 A second datastructure makes it possible to access a [`TermInfo`](../postings/struct.TermInfo.html).
 */
 
-use tantivy_fst::automaton::AlwaysMatch;
-
-// mod fst_termdict;
-// use fst_termdict as termdict;
-mod sstable_termdict;
-use sstable_termdict as termdict;
-
-mod merger;
-
-#[cfg(test)]
-mod tests;
-
 /// Position of the term in the sorted list of terms.
 pub type TermOrdinal = u64;
 
-/// The term dictionary contains all of the terms in
-/// `tantivy index` in a sorted manner.
-pub type TermDictionary = self::termdict::TermDictionary;
+mod merger;
+mod streamer;
+mod term_info_store;
+mod termdict;
 
-/// Builder for the new term dictionary.
-///
-/// Inserting must be done in the order of the `keys`.
-pub type TermDictionaryBuilder<W> = self::termdict::TermDictionaryBuilder<W>;
+pub use self::merger::TermMerger;
+pub use self::streamer::{TermStreamer, TermStreamerBuilder};
+pub use self::termdict::{TermDictionary, TermDictionaryBuilder};
 
-/// Given a list of sorted term streams,
-/// returns an iterator over sorted unique terms.
-///
-/// The item yield is actually a pair with
-/// - the term
-/// - a slice with the ordinal of the segments containing
-/// the terms.
-pub type TermMerger<'a> = self::merger::TermMerger<'a>;
+#[cfg(test)]
+mod tests {
+    use super::{TermDictionary, TermDictionaryBuilder, TermStreamer};
+    use crate::core::Index;
+    use crate::directory::{Directory, FileSlice, RAMDirectory};
+    use crate::postings::TermInfo;
+    use crate::schema::{Schema, TEXT};
+    use std::path::PathBuf;
+    use std::str;
 
-/// `TermStreamer` acts as a cursor over a range of terms of a segment.
-/// Terms are guaranteed to be sorted.
-pub type TermStreamer<'a, A = AlwaysMatch> = self::termdict::TermStreamer<'a, A>;
+    const BLOCK_SIZE: usize = 1_500;
+
+    fn make_term_info(term_ord: u64) -> TermInfo {
+        let offset = |term_ord: u64| term_ord * 100 + term_ord * term_ord;
+        TermInfo {
+            doc_freq: term_ord as u32,
+            postings_start_offset: offset(term_ord),
+            postings_stop_offset: offset(term_ord + 1),
+            positions_idx: offset(term_ord) * 2u64,
+        }
+    }
+
+    #[test]
+    fn test_empty_term_dictionary() {
+        let empty = TermDictionary::empty();
+        assert!(empty.stream().next().is_none());
+    }
+
+    #[test]
+    fn test_term_ordinals() -> crate::Result<()> {
+        const COUNTRIES: [&'static str; 7] = [
+            "San Marino",
+            "Serbia",
+            "Slovakia",
+            "Slovenia",
+            "Spain",
+            "Sweden",
+            "Switzerland",
+        ];
+        let directory = RAMDirectory::create();
+        let path = PathBuf::from("TermDictionary");
+        {
+            let write = directory.open_write(&path)?;
+            let mut term_dictionary_builder = TermDictionaryBuilder::create(write)?;
+            for term in COUNTRIES.iter() {
+                term_dictionary_builder.insert(term.as_bytes(), &make_term_info(0u64))?;
+            }
+            term_dictionary_builder.finish()?;
+        }
+        let term_file = directory.open_read(&path)?;
+        let term_dict: TermDictionary = TermDictionary::open(term_file)?;
+        for (term_ord, term) in COUNTRIES.iter().enumerate() {
+            assert_eq!(term_dict.term_ord(term).unwrap(), term_ord as u64);
+            let mut bytes = vec![];
+            assert!(term_dict.ord_to_term(term_ord as u64, &mut bytes));
+            assert_eq!(bytes, term.as_bytes());
+        }
+        Ok(())
+    }
+
+    #[test]
+    fn test_term_dictionary_simple() -> crate::Result<()> {
+        let directory = RAMDirectory::create();
+        let path = PathBuf::from("TermDictionary");
+        {
+            let write = directory.open_write(&path)?;
+            let mut term_dictionary_builder = TermDictionaryBuilder::create(write)?;
+            term_dictionary_builder.insert("abc".as_bytes(), &make_term_info(34u64))?;
+            term_dictionary_builder.insert("abcd".as_bytes(), &make_term_info(346u64))?;
+            term_dictionary_builder.finish()?;
+        }
+        let file = directory.open_read(&path)?;
+        let term_dict: TermDictionary = TermDictionary::open(file)?;
+        assert_eq!(term_dict.get("abc").unwrap().doc_freq, 34u32);
+        assert_eq!(term_dict.get("abcd").unwrap().doc_freq, 346u32);
+        let mut stream = term_dict.stream();
+        {
+            {
+                let (k, v) = stream.next().unwrap();
+                assert_eq!(k.as_ref(), "abc".as_bytes());
+                assert_eq!(v.doc_freq, 34u32);
+            }
+            assert_eq!(stream.key(), "abc".as_bytes());
+            assert_eq!(stream.value().doc_freq, 34u32);
+        }
+        {
+            {
+                let (k, v) = stream.next().unwrap();
+                assert_eq!(k, "abcd".as_bytes());
+                assert_eq!(v.doc_freq, 346u32);
+            }
+            assert_eq!(stream.key(), "abcd".as_bytes());
+            assert_eq!(stream.value().doc_freq, 346u32);
+        }
+        assert!(!stream.advance());
+        Ok(())
+    }
+
+    #[test]
+    fn test_term_iterator() -> crate::Result<()> {
+        let mut schema_builder = Schema::builder();
+        let text_field = schema_builder.add_text_field("text", TEXT);
+        let index = Index::create_in_ram(schema_builder.build());
+        {
+            let mut index_writer = index.writer_for_tests()?;
+            index_writer.add_document(doc!(text_field=>"a b d f"));
+            index_writer.commit()?;
+            index_writer.add_document(doc!(text_field=>"a b c d f"));
+            index_writer.commit()?;
+            index_writer.add_document(doc!(text_field => "e f"));
+            index_writer.commit()?;
+        }
+        let searcher = index.reader()?.searcher();
+
+        let field_searcher = searcher.field(text_field)?;
+        let mut term_it = field_searcher.terms();
+        let mut term_string = String::new();
+        while term_it.advance() {
+            //let term = Term::from_bytes(term_it.key());
+            term_string.push_str(str::from_utf8(term_it.key()).expect("test"));
+        }
+        assert_eq!(&*term_string, "abcdef");
+        Ok(())
+    }
+
+    #[test]
+    fn test_term_dictionary_stream() -> crate::Result<()> {
+        let ids: Vec<_> = (0u32..10_000u32)
+            .map(|i| (format!("doc{:0>6}", i), i))
+            .collect();
+        let buffer: Vec<u8> = {
+            let mut term_dictionary_builder = TermDictionaryBuilder::create(vec![]).unwrap();
+            for &(ref id, ref i) in &ids {
+                term_dictionary_builder
+                    .insert(id.as_bytes(), &make_term_info(*i as u64))
+                    .unwrap();
+            }
+            term_dictionary_builder.finish().unwrap()
+        };
+        let term_file = FileSlice::from(buffer);
+        let term_dictionary: TermDictionary = TermDictionary::open(term_file)?;
+        {
+            let mut streamer = term_dictionary.stream();
+            let mut i = 0;
+            while let Some((streamer_k, streamer_v)) = streamer.next() {
+                let &(ref key, ref v) = &ids[i];
+                assert_eq!(streamer_k.as_ref(), key.as_bytes());
+                assert_eq!(streamer_v, &make_term_info(*v as u64));
+                i += 1;
+            }
+        }
+
+        let &(ref key, ref val) = &ids[2047];
+        assert_eq!(
+            term_dictionary.get(key.as_bytes()),
+            Some(make_term_info(*val as u64))
+        );
+        Ok(())
+    }
+
+    #[test]
+    fn test_stream_high_range_prefix_suffix() -> crate::Result<()> {
+        let buffer: Vec<u8> = {
+            let mut term_dictionary_builder = TermDictionaryBuilder::create(vec![]).unwrap();
+            // term requires more than 16bits
+            term_dictionary_builder.insert("abcdefghijklmnopqrstuvwxy", &make_term_info(1))?;
+            term_dictionary_builder.insert("abcdefghijklmnopqrstuvwxyz", &make_term_info(2))?;
+            term_dictionary_builder.insert("abr", &make_term_info(3))?;
+            term_dictionary_builder.finish()?
+        };
+        let term_dict_file = FileSlice::from(buffer);
+        let term_dictionary: TermDictionary = TermDictionary::open(term_dict_file)?;
+        let mut kv_stream = term_dictionary.stream();
+        assert!(kv_stream.advance());
+        assert_eq!(kv_stream.key(), "abcdefghijklmnopqrstuvwxy".as_bytes());
+        assert_eq!(kv_stream.value(), &make_term_info(1));
+        assert!(kv_stream.advance());
+        assert_eq!(kv_stream.key(), "abcdefghijklmnopqrstuvwxyz".as_bytes());
+        assert_eq!(kv_stream.value(), &make_term_info(2));
+        assert!(kv_stream.advance());
+        assert_eq!(kv_stream.key(), "abr".as_bytes());
+        assert_eq!(kv_stream.value(), &make_term_info(3));
+        assert!(!kv_stream.advance());
+        Ok(())
+    }
+
+    #[test]
+    fn test_stream_range() -> crate::Result<()> {
+        let ids: Vec<_> = (0u32..10_000u32)
+            .map(|i| (format!("doc{:0>6}", i), i))
+            .collect();
+        let buffer: Vec<u8> = {
+            let mut term_dictionary_builder = TermDictionaryBuilder::create(vec![]).unwrap();
+            for &(ref id, ref i) in &ids {
+                term_dictionary_builder
+                    .insert(id.as_bytes(), &make_term_info(*i as u64))
+                    .unwrap();
+            }
+            term_dictionary_builder.finish().unwrap()
+        };
+
+        let file = FileSlice::from(buffer);
+
+        let term_dictionary: TermDictionary = TermDictionary::open(file)?;
+        {
+            for i in (0..20).chain(6000..8_000) {
+                let &(ref target_key, _) = &ids[i];
+                let mut streamer = term_dictionary
+                    .range()
+                    .ge(target_key.as_bytes())
+                    .into_stream();
+                for j in 0..3 {
+                    let (streamer_k, streamer_v) = streamer.next().unwrap();
+                    let &(ref key, ref v) = &ids[i + j];
+                    assert_eq!(str::from_utf8(streamer_k.as_ref()).unwrap(), key);
+                    assert_eq!(streamer_v.doc_freq, *v);
+                    assert_eq!(streamer_v, &make_term_info(*v as u64));
+                }
+            }
+        }
+
+        {
+            for i in (0..20).chain(BLOCK_SIZE - 10..BLOCK_SIZE + 10) {
+                let &(ref target_key, _) = &ids[i];
+                let mut streamer = term_dictionary
+                    .range()
+                    .gt(target_key.as_bytes())
+                    .into_stream();
+                for j in 0..3 {
+                    let (streamer_k, streamer_v) = streamer.next().unwrap();
+                    let &(ref key, ref v) = &ids[i + j + 1];
+                    assert_eq!(streamer_k.as_ref(), key.as_bytes());
+                    assert_eq!(streamer_v.doc_freq, *v);
+                }
+            }
+        }
+
+        {
+            for i in (0..20).chain(BLOCK_SIZE - 10..BLOCK_SIZE + 10) {
+                for j in 0..3 {
+                    let &(ref fst_key, _) = &ids[i];
+                    let &(ref last_key, _) = &ids[i + j];
+                    let mut streamer = term_dictionary
+                        .range()
+                        .ge(fst_key.as_bytes())
+                        .lt(last_key.as_bytes())
+                        .into_stream();
+                    for _ in 0..j {
+                        assert!(streamer.next().is_some());
+                    }
+                    assert!(streamer.next().is_none());
+                }
+            }
+        }
+        Ok(())
+    }
+
+    #[test]
+    fn test_empty_string() -> crate::Result<()> {
+        let buffer: Vec<u8> = {
+            let mut term_dictionary_builder = TermDictionaryBuilder::create(vec![]).unwrap();
+            term_dictionary_builder
+                .insert(&[], &make_term_info(1 as u64))
+                .unwrap();
+            term_dictionary_builder
+                .insert(&[1u8], &make_term_info(2 as u64))
+                .unwrap();
+            term_dictionary_builder.finish().unwrap()
+        };
+        let file = FileSlice::from(buffer);
+        let term_dictionary: TermDictionary = TermDictionary::open(file)?;
+        let mut stream = term_dictionary.stream();
+        assert!(stream.advance());
+        assert!(stream.key().is_empty());
+        assert!(stream.advance());
+        assert_eq!(stream.key(), &[1u8]);
+        assert!(!stream.advance());
+        Ok(())
+    }
+
+    #[test]
+    fn test_stream_range_boundaries() -> crate::Result<()> {
+        let buffer: Vec<u8> = {
+            let mut term_dictionary_builder = TermDictionaryBuilder::create(Vec::new())?;
+            for i in 0u8..10u8 {
+                let number_arr = [i; 1];
+                term_dictionary_builder.insert(&number_arr, &make_term_info(i as u64))?;
+            }
+            term_dictionary_builder.finish()?
+        };
+        let file = FileSlice::from(buffer);
+        let term_dictionary: TermDictionary = TermDictionary::open(file)?;
+
+        let value_list = |mut streamer: TermStreamer<'_>, backwards: bool| {
+            let mut res: Vec<u32> = vec![];
+            while let Some((_, ref v)) = streamer.next() {
+                res.push(v.doc_freq);
+            }
+            if backwards {
+                res.reverse();
+            }
+            res
+        };
+        {
+            let range = term_dictionary.range().backward().into_stream();
+            assert_eq!(
+                value_list(range, true),
+                vec![0u32, 1u32, 2u32, 3u32, 4u32, 5u32, 6u32, 7u32, 8u32, 9u32]
+            );
+        }
+        {
+            let range = term_dictionary.range().ge([2u8]).into_stream();
+            assert_eq!(
+                value_list(range, false),
+                vec![2u32, 3u32, 4u32, 5u32, 6u32, 7u32, 8u32, 9u32]
+            );
+        }
+        {
+            let range = term_dictionary.range().ge([2u8]).backward().into_stream();
+            assert_eq!(
+                value_list(range, true),
+                vec![2u32, 3u32, 4u32, 5u32, 6u32, 7u32, 8u32, 9u32]
+            );
+        }
+        {
+            let range = term_dictionary.range().gt([2u8]).into_stream();
+            assert_eq!(
+                value_list(range, false),
+                vec![3u32, 4u32, 5u32, 6u32, 7u32, 8u32, 9u32]
+            );
+        }
+        {
+            let range = term_dictionary.range().gt([2u8]).backward().into_stream();
+            assert_eq!(
+                value_list(range, true),
+                vec![3u32, 4u32, 5u32, 6u32, 7u32, 8u32, 9u32]
+            );
+        }
+        {
+            let range = term_dictionary.range().lt([6u8]).into_stream();
+            assert_eq!(
+                value_list(range, false),
+                vec![0u32, 1u32, 2u32, 3u32, 4u32, 5u32]
+            );
+        }
+        {
+            let range = term_dictionary.range().lt([6u8]).backward().into_stream();
+            assert_eq!(
+                value_list(range, true),
+                vec![0u32, 1u32, 2u32, 3u32, 4u32, 5u32]
+            );
+        }
+        {
+            let range = term_dictionary.range().le([6u8]).into_stream();
+            assert_eq!(
+                value_list(range, false),
+                vec![0u32, 1u32, 2u32, 3u32, 4u32, 5u32, 6u32]
+            );
+        }
+        {
+            let range = term_dictionary.range().le([6u8]).backward().into_stream();
+            assert_eq!(
+                value_list(range, true),
+                vec![0u32, 1u32, 2u32, 3u32, 4u32, 5u32, 6u32]
+            );
+        }
+        {
+            let range = term_dictionary.range().ge([0u8]).lt([5u8]).into_stream();
+            assert_eq!(value_list(range, false), vec![0u32, 1u32, 2u32, 3u32, 4u32]);
+        }
+        {
+            let range = term_dictionary
+                .range()
+                .ge([0u8])
+                .lt([5u8])
+                .backward()
+                .into_stream();
+            assert_eq!(value_list(range, true), vec![0u32, 1u32, 2u32, 3u32, 4u32]);
+        }
+        Ok(())
+    }
+
+    #[test]
+    fn test_automaton_search() -> crate::Result<()> {
+        use crate::query::DFAWrapper;
+        use levenshtein_automata::LevenshteinAutomatonBuilder;
+
+        const COUNTRIES: [&'static str; 7] = [
+            "San Marino",
+            "Serbia",
+            "Slovakia",
+            "Slovenia",
+            "Spain",
+            "Sweden",
+            "Switzerland",
+        ];
+
+        let directory = RAMDirectory::create();
+        let path = PathBuf::from("TermDictionary");
+        {
+            let write = directory.open_write(&path)?;
+            let mut term_dictionary_builder = TermDictionaryBuilder::create(write)?;
+            for term in COUNTRIES.iter() {
+                term_dictionary_builder.insert(term.as_bytes(), &make_term_info(0u64))?;
+            }
+            term_dictionary_builder.finish()?;
+        }
+        let file = directory.open_read(&path)?;
+        let term_dict: TermDictionary = TermDictionary::open(file)?;
+
+        // We can now build an entire dfa.
+        let lev_automaton_builder = LevenshteinAutomatonBuilder::new(2, true);
+        let automaton = DFAWrapper(lev_automaton_builder.build_dfa("Spaen"));
+
+        let mut range = term_dict.search(automaton).into_stream();
+
+        // get the first finding
+        assert!(range.advance());
+        assert_eq!("Spain".as_bytes(), range.key());
+        assert!(!range.advance());
+        Ok(())
+    }
+}

src/termdict/sstable_termdict/mod.rs

@@ -1,148 +0,0 @@
-use std::io;
-
-mod sstable;
-mod streamer;
-mod termdict;
-
-use self::sstable::value::{ValueReader, ValueWriter};
-use self::sstable::{BlockReader, SSTable};
-
-use crate::common::VInt;
-use crate::postings::TermInfo;
-
-pub use self::streamer::{TermStreamer, TermStreamerBuilder};
-pub use self::termdict::{TermDictionary, TermDictionaryBuilder};
-
-pub struct TermSSTable;
-
-impl SSTable for TermSSTable {
-    type Value = TermInfo;
-    type Reader = TermInfoReader;
-    type Writer = TermInfoWriter;
-}
-
-#[derive(Default)]
-pub struct TermInfoReader {
-    term_infos: Vec<TermInfo>,
-}
-
-impl ValueReader for TermInfoReader {
-    type Value = TermInfo;
-
-    fn value(&self, idx: usize) -> &TermInfo {
-        &self.term_infos[idx]
-    }
-
-    fn read(&mut self, reader: &mut BlockReader) -> io::Result<()> {
-        self.term_infos.clear();
-        let num_els = VInt::deserialize_u64(reader)?;
-        let mut start_offset = VInt::deserialize_u64(reader)?;
-        let mut positions_idx = 0;
-        for _ in 0..num_els {
-            let doc_freq = VInt::deserialize_u64(reader)? as u32;
-            let posting_num_bytes = VInt::deserialize_u64(reader)?;
-            let stop_offset = start_offset + posting_num_bytes;
-            let delta_positions_idx = VInt::deserialize_u64(reader)?;
-            positions_idx += delta_positions_idx;
-            let term_info = TermInfo {
-                doc_freq,
-                postings_start_offset: start_offset,
-                postings_stop_offset: stop_offset,
-                positions_idx,
-            };
-            self.term_infos.push(term_info);
-            start_offset = stop_offset;
-        }
-        Ok(())
-    }
-}
-
-#[derive(Default)]
-pub struct TermInfoWriter {
-    term_infos: Vec<TermInfo>,
-}
-
-impl ValueWriter for TermInfoWriter {
-    type Value = TermInfo;
-
-    fn write(&mut self, term_info: &TermInfo) {
-        self.term_infos.push(term_info.clone());
-    }
-
-    fn write_block(&mut self, buffer: &mut Vec<u8>) {
-        VInt(self.term_infos.len() as u64).serialize_into_vec(buffer);
-        if self.term_infos.is_empty() {
-            return;
-        }
-        let mut prev_position_idx = 0u64;
-        VInt(self.term_infos[0].postings_start_offset).serialize_into_vec(buffer);
-        for term_info in &self.term_infos {
-            VInt(term_info.doc_freq as u64).serialize_into_vec(buffer);
-            VInt(term_info.postings_stop_offset - term_info.postings_start_offset)
-                .serialize_into_vec(buffer);
-            VInt(term_info.positions_idx - prev_position_idx).serialize_into_vec(buffer);
-            prev_position_idx = term_info.positions_idx;
-        }
-        self.term_infos.clear();
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use std::io;
-
-    use super::BlockReader;
-
-    use crate::directory::OwnedBytes;
-    use crate::postings::TermInfo;
-    use crate::termdict::sstable_termdict::sstable::value::{ValueReader, ValueWriter};
-    use crate::termdict::sstable_termdict::TermInfoReader;
-
-    #[test]
-    fn test_block_terminfos() -> io::Result<()> {
-        let mut term_info_writer = super::TermInfoWriter::default();
-        term_info_writer.write(&TermInfo {
-            doc_freq: 120u32,
-            postings_start_offset: 17u64,
-            postings_stop_offset: 45u64,
-            positions_idx: 10u64,
-        });
-        term_info_writer.write(&TermInfo {
-            doc_freq: 10u32,
-            postings_start_offset: 45u64,
-            postings_stop_offset: 450u64,
-            positions_idx: 104u64,
-        });
-        term_info_writer.write(&TermInfo {
-            doc_freq: 17u32,
-            postings_start_offset: 450u64,
-            postings_stop_offset: 462u64,
-            positions_idx: 210u64,
-        });
-        let mut buffer = Vec::new();
-        term_info_writer.write_block(&mut buffer);
-        let mut block_reader = make_block_reader(&buffer[..]);
-        let mut term_info_reader = TermInfoReader::default();
-        term_info_reader.read(&mut block_reader)?;
-        assert_eq!(
-            term_info_reader.value(0),
-            &TermInfo {
-                doc_freq: 120u32,
-                postings_start_offset: 17u64,
-                postings_stop_offset: 45u64,
-                positions_idx: 10u64
-            }
-        );
-        assert!(block_reader.buffer().is_empty());
-        Ok(())
-    }
-
-    fn make_block_reader(data: &[u8]) -> BlockReader {
-        let mut buffer = (data.len() as u32).to_le_bytes().to_vec();
-        buffer.extend_from_slice(data);
-        let owned_bytes = OwnedBytes::new(buffer);
-        let mut block_reader = BlockReader::new(Box::new(owned_bytes));
-        block_reader.read_block().unwrap();
-        block_reader
-    }
-}

src/termdict/sstable_termdict/sstable/block_reader.rs

@@ -1,84 +0,0 @@
-use byteorder::{LittleEndian, ReadBytesExt};
-use std::io::{self, Read};
-
-pub struct BlockReader<'a> {
-    buffer: Vec<u8>,
-    reader: Box<dyn io::Read + 'a>,
-    offset: usize,
-}
-
-impl<'a> BlockReader<'a> {
-    pub fn new(reader: Box<dyn io::Read + 'a>) -> BlockReader<'a> {
-        BlockReader {
-            buffer: Vec::new(),
-            reader,
-            offset: 0,
-        }
-    }
-
-    pub fn deserialize_u64(&mut self) -> u64 {
-        let (num_bytes, val) = super::vint::deserialize_read(self.buffer());
-        self.advance(num_bytes);
-        val
-    }
-
-    #[inline(always)]
-    pub fn buffer_from_to(&self, start: usize, end: usize) -> &[u8] {
-        &self.buffer[start..end]
-    }
-
-    pub fn buffer_from(&self, start: usize) -> &[u8] {
-        &self.buffer[start..]
-    }
-
-    pub fn read_block(&mut self) -> io::Result<bool> {
-        self.offset = 0;
-        let block_len_res = self.reader.read_u32::<LittleEndian>();
-        if let Err(err) = &block_len_res {
-            if err.kind() == io::ErrorKind::UnexpectedEof {
-                return Ok(false);
-            }
-        }
-        let block_len = block_len_res?;
-        if block_len == 0u32 {
-            self.buffer.clear();
-            return Ok(false);
-        }
-        self.buffer.resize(block_len as usize, 0u8);
-        self.reader.read_exact(&mut self.buffer[..])?;
-        Ok(true)
-    }
-
-    pub fn offset(&self) -> usize {
-        self.offset
-    }
-
-    pub fn advance(&mut self, num_bytes: usize) {
-        self.offset += num_bytes;
-    }
-
-    pub fn buffer(&self) -> &[u8] {
-        &self.buffer[self.offset..]
-    }
-}
-
-impl<'a> io::Read for BlockReader<'a> {
-    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
-        let len = self.buffer().read(buf)?;
-        self.advance(len);
-        Ok(len)
-    }
-
-    fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
-        let len = self.buffer.len();
-        buf.extend_from_slice(self.buffer());
-        self.advance(len);
-        Ok(len)
-    }
-
-    fn read_exact(&mut self, buf: &mut [u8]) -> io::Result<()> {
-        self.buffer().read_exact(buf)?;
-        self.advance(buf.len());
-        Ok(())
-    }
-}

src/termdict/sstable_termdict/sstable/delta.rs

@@ -1,203 +0,0 @@
-use std::io::{self, BufWriter, Write};
-
-use crate::common::CountingWriter;
-
-use super::value::ValueWriter;
-use super::{value, vint, BlockReader};
-
-const FOUR_BIT_LIMITS: usize = 1 << 4;
-const VINT_MODE: u8 = 1u8;
-const BLOCK_LEN: usize = 256_000;
-
-pub struct DeltaWriter<W, TValueWriter>
-where
-    W: io::Write,
-{
-    block: Vec<u8>,
-    write: CountingWriter<BufWriter<W>>,
-    value_writer: TValueWriter,
-}
-
-impl<W, TValueWriter> DeltaWriter<W, TValueWriter>
-where
-    W: io::Write,
-    TValueWriter: ValueWriter,
-{
-    pub fn new(wrt: W) -> Self {
-        DeltaWriter {
-            block: Vec::with_capacity(BLOCK_LEN * 2),
-            write: CountingWriter::wrap(BufWriter::new(wrt)),
-            value_writer: TValueWriter::default(),
-        }
-    }
-}
-
-impl<W, TValueWriter> DeltaWriter<W, TValueWriter>
-where
-    W: io::Write,
-    TValueWriter: value::ValueWriter,
-{
-    pub fn flush_block(&mut self) -> io::Result<Option<(u64, u64)>> {
-        if self.block.is_empty() {
-            return Ok(None);
-        }
-        let start_offset = self.write.written_bytes();
-        // TODO avoid buffer allocation
-        let mut buffer = Vec::new();
-        self.value_writer.write_block(&mut buffer);
-        let block_len = buffer.len() + self.block.len();
-        self.write.write_all(&(block_len as u32).to_le_bytes())?;
-        self.write.write_all(&buffer[..])?;
-        self.write.write_all(&mut self.block[..])?;
-        let end_offset = self.write.written_bytes();
-        self.block.clear();
-        Ok(Some((start_offset, end_offset)))
-    }
-
-    fn encode_keep_add(&mut self, keep_len: usize, add_len: usize) {
-        if keep_len < FOUR_BIT_LIMITS && add_len < FOUR_BIT_LIMITS {
-            let b = (keep_len | add_len << 4) as u8;
-            self.block.extend_from_slice(&[b])
-        } else {
-            let mut buf = [VINT_MODE; 20];
-            let mut len = 1 + vint::serialize(keep_len as u64, &mut buf[1..]);
-            len += vint::serialize(add_len as u64, &mut buf[len..]);
-            self.block.extend_from_slice(&mut buf[..len])
-        }
-    }
-
-    pub(crate) fn write_suffix(&mut self, common_prefix_len: usize, suffix: &[u8]) {
-        let keep_len = common_prefix_len;
-        let add_len = suffix.len();
-        self.encode_keep_add(keep_len, add_len);
-        self.block.extend_from_slice(suffix);
-    }
-
-    pub(crate) fn write_value(&mut self, value: &TValueWriter::Value) {
-        self.value_writer.write(value);
-    }
-
-    pub fn write_delta(
-        &mut self,
-        common_prefix_len: usize,
-        suffix: &[u8],
-        value: &TValueWriter::Value,
-    ) {
-        self.write_suffix(common_prefix_len, suffix);
-        self.write_value(value);
-    }
-
-    pub fn flush_block_if_required(&mut self) -> io::Result<Option<(u64, u64)>> {
-        if self.block.len() > BLOCK_LEN {
-            return self.flush_block();
-        }
-        Ok(None)
-    }
-
-    pub fn finalize(mut self) -> CountingWriter<BufWriter<W>> {
-        self.write
-    }
-}
-
-pub struct DeltaReader<'a, TValueReader> {
-    common_prefix_len: usize,
-    suffix_start: usize,
-    suffix_end: usize,
-    value_reader: TValueReader,
-    block_reader: BlockReader<'a>,
-    idx: usize,
-}
-
-impl<'a, TValueReader> DeltaReader<'a, TValueReader>
-where
-    TValueReader: value::ValueReader,
-{
-    pub fn new<R: io::Read + 'a>(reader: R) -> Self {
-        DeltaReader {
-            idx: 0,
-            common_prefix_len: 0,
-            suffix_start: 0,
-            suffix_end: 0,
-            value_reader: TValueReader::default(),
-            block_reader: BlockReader::new(Box::new(reader)),
-        }
-    }
-
-    fn deserialize_vint(&mut self) -> u64 {
-        self.block_reader.deserialize_u64()
-    }
-
-    fn read_keep_add(&mut self) -> Option<(usize, usize)> {
-        let b = {
-            let buf = &self.block_reader.buffer();
-            if buf.is_empty() {
-                return None;
-            }
-            buf[0]
-        };
-        self.block_reader.advance(1);
-        match b {
-            VINT_MODE => {
-                let keep = self.deserialize_vint() as usize;
-                let add = self.deserialize_vint() as usize;
-                Some((keep, add))
-            }
-            b => {
-                let keep = (b & 0b1111) as usize;
-                let add = (b >> 4) as usize;
-                Some((keep, add))
-            }
-        }
-    }
-
-    fn read_delta_key(&mut self) -> bool {
-        if let Some((keep, add)) = self.read_keep_add() {
-            self.common_prefix_len = keep;
-            self.suffix_start = self.block_reader.offset();
-            self.suffix_end = self.suffix_start + add;
-            self.block_reader.advance(add);
-            true
-        } else {
-            false
-        }
-    }
-
-    pub fn advance(&mut self) -> io::Result<bool> {
-        if self.block_reader.buffer().is_empty() {
-            if !self.block_reader.read_block()? {
-                return Ok(false);
-            }
-            self.value_reader.read(&mut self.block_reader)?;
-            self.idx = 0;
-        } else {
-            self.idx += 1;
-        }
-        if !self.read_delta_key() {
-            return Ok(false);
-        }
-        Ok(true)
-    }
-
-    pub fn common_prefix_len(&self) -> usize {
-        self.common_prefix_len
-    }
-
-    pub fn suffix(&self) -> &[u8] {
-        &self
-            .block_reader
-            .buffer_from_to(self.suffix_start, self.suffix_end)
-    }
-
-    pub fn suffix_from(&self, offset: usize) -> &[u8] {
-        &self.block_reader.buffer_from_to(
-            self.suffix_start
-                .wrapping_add(offset)
-                .wrapping_sub(self.common_prefix_len),
-            self.suffix_end,
-        )
-    }
-
-    pub fn value(&self) -> &TValueReader::Value {
-        self.value_reader.value(self.idx)
-    }
-}

src/termdict/sstable_termdict/sstable/merge/heap_merge.rs

@@ -1,72 +0,0 @@
-use crate::termdict::sstable_termdict::sstable::{Reader, SSTable, Writer};
-
-use super::SingleValueMerger;
-use super::ValueMerger;
-use std::cmp::Ordering;
-use std::collections::binary_heap::PeekMut;
-use std::collections::BinaryHeap;
-use std::io;
-
-struct HeapItem<B: AsRef<[u8]>>(B);
-
-impl<B: AsRef<[u8]>> Ord for HeapItem<B> {
-    fn cmp(&self, other: &Self) -> Ordering {
-        other.0.as_ref().cmp(self.0.as_ref())
-    }
-}
-impl<B: AsRef<[u8]>> PartialOrd for HeapItem<B> {
-    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
-        Some(other.0.as_ref().cmp(self.0.as_ref()))
-    }
-}
-
-impl<B: AsRef<[u8]>> Eq for HeapItem<B> {}
-impl<B: AsRef<[u8]>> PartialEq for HeapItem<B> {
-    fn eq(&self, other: &Self) -> bool {
-        self.0.as_ref() == other.0.as_ref()
-    }
-}
-
-pub fn merge_sstable<SST: SSTable, W: io::Write, M: ValueMerger<SST::Value>>(
-    readers: Vec<Reader<SST::Reader>>,
-    mut writer: Writer<W, SST::Writer>,
-    mut merger: M,
-) -> io::Result<()> {
-    let mut heap: BinaryHeap<HeapItem<Reader<SST::Reader>>> =
-        BinaryHeap::with_capacity(readers.len());
-    for mut reader in readers {
-        if reader.advance()? {
-            heap.push(HeapItem(reader));
-        }
-    }
-    loop {
-        let len = heap.len();
-        let mut value_merger;
-        if let Some(mut head) = heap.peek_mut() {
-            writer.write_key(head.0.key());
-            value_merger = merger.new_value(head.0.value());
-            if !head.0.advance()? {
-                PeekMut::pop(head);
-            }
-        } else {
-            break;
-        }
-        for _ in 0..len - 1 {
-            if let Some(mut head) = heap.peek_mut() {
-                if head.0.key() == writer.current_key() {
-                    value_merger.add(head.0.value());
-                    if !head.0.advance()? {
-                        PeekMut::pop(head);
-                    }
-                    continue;
-                }
-            }
-            break;
-        }
-        let value = value_merger.finish();
-        writer.write_value(&value);
-        writer.flush_block_if_required()?;
-    }
-    writer.finalize()?;
-    Ok(())
-}

src/termdict/sstable_termdict/sstable/merge/mod.rs

@@ -1,184 +0,0 @@
-mod heap_merge;
-
-pub use self::heap_merge::merge_sstable;
-
-pub trait SingleValueMerger<V> {
-    fn add(&mut self, v: &V);
-    fn finish(self) -> V;
-}
-
-pub trait ValueMerger<V> {
-    type TSingleValueMerger: SingleValueMerger<V>;
-    fn new_value(&mut self, v: &V) -> Self::TSingleValueMerger;
-}
-
-#[derive(Default)]
-pub struct KeepFirst;
-
-pub struct FirstVal<V>(V);
-
-impl<V: Clone> ValueMerger<V> for KeepFirst {
-    type TSingleValueMerger = FirstVal<V>;
-
-    fn new_value(&mut self, v: &V) -> FirstVal<V> {
-        FirstVal(v.clone())
-    }
-}
-
-impl<V> SingleValueMerger<V> for FirstVal<V> {
-    fn add(&mut self, _: &V) {}
-
-    fn finish(self) -> V {
-        self.0
-    }
-}
-
-pub struct VoidMerge;
-impl ValueMerger<()> for VoidMerge {
-    type TSingleValueMerger = ();
-
-    fn new_value(&mut self, _: &()) -> () {
-        ()
-    }
-}
-
-pub struct U64Merge;
-impl ValueMerger<u64> for U64Merge {
-    type TSingleValueMerger = u64;
-
-    fn new_value(&mut self, val: &u64) -> u64 {
-        *val
-    }
-}
-
-impl SingleValueMerger<u64> for u64 {
-    fn add(&mut self, val: &u64) {
-        *self += *val;
-    }
-
-    fn finish(self) -> u64 {
-        self
-    }
-}
-
-impl SingleValueMerger<()> for () {
-    fn add(&mut self, _: &()) {}
-
-    fn finish(self) -> () {
-        ()
-    }
-}
-
-#[cfg(test)]
-mod tests {
-
-    use super::super::SSTable;
-    use super::super::{SSTableMonotonicU64, VoidSSTable};
-    use super::U64Merge;
-    use super::VoidMerge;
-    use std::collections::{BTreeMap, BTreeSet};
-    use std::str;
-
-    fn write_sstable(keys: &[&'static str]) -> Vec<u8> {
-        let mut buffer: Vec<u8> = vec![];
-        {
-            let mut sstable_writer = VoidSSTable::writer(&mut buffer);
-            for &key in keys {
-                assert!(sstable_writer.write(key.as_bytes(), &()).is_ok());
-            }
-            assert!(sstable_writer.finalize().is_ok());
-        }
-        dbg!(&buffer);
-        buffer
-    }
-
-    fn write_sstable_u64(keys: &[(&'static str, u64)]) -> Vec<u8> {
-        let mut buffer: Vec<u8> = vec![];
-        {
-            let mut sstable_writer = SSTableMonotonicU64::writer(&mut buffer);
-            for (key, val) in keys {
-                assert!(sstable_writer.write(key.as_bytes(), val).is_ok());
-            }
-            assert!(sstable_writer.finalize().is_ok());
-        }
-        buffer
-    }
-
-    fn merge_test_aux(arrs: &[&[&'static str]]) {
-        let sstables = arrs.iter().cloned().map(write_sstable).collect::<Vec<_>>();
-        let sstables_ref: Vec<&[u8]> = sstables.iter().map(|s| s.as_ref()).collect();
-        let mut merged = BTreeSet::new();
-        for &arr in arrs.iter() {
-            for &s in arr {
-                merged.insert(s.to_string());
-            }
-        }
-        let mut w = Vec::new();
-        assert!(VoidSSTable::merge(sstables_ref, &mut w, VoidMerge).is_ok());
-        let mut reader = VoidSSTable::reader(&w[..]);
-        for k in merged {
-            assert!(reader.advance().unwrap());
-            assert_eq!(reader.key(), k.as_bytes());
-        }
-        assert!(!reader.advance().unwrap());
-    }
-
-    fn merge_test_u64_monotonic_aux(arrs: &[&[(&'static str, u64)]]) {
-        let sstables = arrs
-            .iter()
-            .cloned()
-            .map(write_sstable_u64)
-            .collect::<Vec<_>>();
-        let sstables_ref: Vec<&[u8]> = sstables.iter().map(|s| s.as_ref()).collect();
-        let mut merged = BTreeMap::new();
-        for &arr in arrs.iter() {
-            for (key, val) in arr {
-                let entry = merged.entry(key.to_string()).or_insert(0u64);
-                *entry += val;
-            }
-        }
-        let mut w = Vec::new();
-        assert!(SSTableMonotonicU64::merge(sstables_ref, &mut w, U64Merge).is_ok());
-        let mut reader = SSTableMonotonicU64::reader(&w[..]);
-        for (k, v) in merged {
-            assert!(reader.advance().unwrap());
-            assert_eq!(reader.key(), k.as_bytes());
-            assert_eq!(reader.value(), &v);
-        }
-        assert!(!reader.advance().unwrap());
-    }
-
-    #[test]
-    fn test_merge_simple_reproduce() {
-        let sstable_data = write_sstable(&["a"]);
-        let mut reader = VoidSSTable::reader(&sstable_data[..]);
-        assert!(reader.advance().unwrap());
-        assert_eq!(reader.key(), b"a");
-        assert!(!reader.advance().unwrap());
-    }
-
-    #[test]
-    fn test_merge() {
-        merge_test_aux(&[]);
-        merge_test_aux(&[&["a"]]);
-        merge_test_aux(&[&["a", "b"], &["ab"]]); // a, ab, b
-        merge_test_aux(&[&["a", "b"], &["a", "b"]]);
-        merge_test_aux(&[
-            &["happy", "hello", "payer", "tax"],
-            &["habitat", "hello", "zoo"],
-            &[],
-            &["a"],
-        ]);
-        merge_test_aux(&[&["a"]]);
-        merge_test_aux(&[&["a", "b"], &["ab"]]);
-        merge_test_aux(&[&["a", "b"], &["a", "b"]]);
-    }
-
-    #[test]
-    fn test_merge_u64() {
-        merge_test_u64_monotonic_aux(&[]);
-        merge_test_u64_monotonic_aux(&[&[("a", 1u64)]]);
-        merge_test_u64_monotonic_aux(&[&[("a", 1u64), ("b", 3u64)], &[("ab", 2u64)]]); // a, ab, b
-        merge_test_u64_monotonic_aux(&[&[("a", 1u64), ("b", 2u64)], &[("a", 16u64), ("b", 23u64)]]);
-    }
-}

src/termdict/sstable_termdict/sstable/mod.rs

@@ -1,365 +0,0 @@
-use merge::ValueMerger;
-use std::io::{self, Write};
-use std::usize;
-
-mod delta;
-pub mod merge;
-pub mod value;
-
-pub(crate) mod sstable_index;
-
-pub(crate) use self::sstable_index::{SSTableIndex, SSTableIndexBuilder};
-pub(crate) mod vint;
-
-mod block_reader;
-pub use self::delta::DeltaReader;
-use self::delta::DeltaWriter;
-use self::value::{U64MonotonicReader, U64MonotonicWriter, ValueReader, ValueWriter};
-
-pub use self::block_reader::BlockReader;
-pub use self::merge::VoidMerge;
-
-const DEFAULT_KEY_CAPACITY: usize = 50;
-
-pub(crate) fn common_prefix_len(left: &[u8], right: &[u8]) -> usize {
-    left.iter()
-        .cloned()
-        .zip(right.iter().cloned())
-        .take_while(|(left, right)| left == right)
-        .count()
-}
-
-pub trait SSTable: Sized {
-    type Value;
-    type Reader: ValueReader<Value = Self::Value>;
-    type Writer: ValueWriter<Value = Self::Value>;
-
-    fn delta_writer<W: io::Write>(write: W) -> DeltaWriter<W, Self::Writer> {
-        DeltaWriter::new(write)
-    }
-
-    fn writer<W: io::Write>(write: W) -> Writer<W, Self::Writer> {
-        Writer {
-            previous_key: Vec::with_capacity(DEFAULT_KEY_CAPACITY),
-            num_terms: 0u64,
-            index_builder: SSTableIndexBuilder::default(),
-            delta_writer: Self::delta_writer(write),
-            first_ordinal_of_the_block: 0u64,
-        }
-    }
-
-    fn delta_reader<'a, R: io::Read + 'a>(reader: R) -> DeltaReader<'a, Self::Reader> {
-        DeltaReader::new(reader)
-    }
-
-    fn reader<'a, R: io::Read + 'a>(reader: R) -> Reader<'a, Self::Reader> {
-        Reader {
-            key: Vec::with_capacity(DEFAULT_KEY_CAPACITY),
-            delta_reader: Self::delta_reader(reader),
-        }
-    }
-
-    fn merge<R: io::Read, W: io::Write, M: ValueMerger<Self::Value>>(
-        io_readers: Vec<R>,
-        w: W,
-        merger: M,
-    ) -> io::Result<()> {
-        let readers: Vec<_> = io_readers.into_iter().map(Self::reader).collect();
-        let writer = Self::writer(w);
-        merge::merge_sstable::<Self, _, _>(readers, writer, merger)
-    }
-}
-
-pub struct VoidSSTable;
-
-impl SSTable for VoidSSTable {
-    type Value = ();
-    type Reader = value::VoidReader;
-    type Writer = value::VoidWriter;
-}
-
-pub struct SSTableMonotonicU64;
-
-impl SSTable for SSTableMonotonicU64 {
-    type Value = u64;
-
-    type Reader = U64MonotonicReader;
-
-    type Writer = U64MonotonicWriter;
-}
-
-pub struct Reader<'a, TValueReader> {
-    key: Vec<u8>,
-    delta_reader: DeltaReader<'a, TValueReader>,
-}
-
-impl<'a, TValueReader> Reader<'a, TValueReader>
-where
-    TValueReader: ValueReader,
-{
-    pub fn advance(&mut self) -> io::Result<bool> {
-        if !self.delta_reader.advance()? {
-            return Ok(false);
-        }
-        let common_prefix_len = self.delta_reader.common_prefix_len();
-        let suffix = self.delta_reader.suffix();
-        let new_len = self.delta_reader.common_prefix_len() + suffix.len();
-        self.key.resize(new_len, 0u8);
-        self.key[common_prefix_len..].copy_from_slice(suffix);
-        Ok(true)
-    }
-
-    pub fn key(&self) -> &[u8] {
-        &self.key
-    }
-
-    pub fn value(&self) -> &TValueReader::Value {
-        self.delta_reader.value()
-    }
-
-    pub(crate) fn into_delta_reader(self) -> DeltaReader<'a, TValueReader> {
-        assert!(self.key.is_empty());
-        self.delta_reader
-    }
-}
-
-impl<'a, TValueReader> AsRef<[u8]> for Reader<'a, TValueReader> {
-    fn as_ref(&self) -> &[u8] {
-        &self.key
-    }
-}
-
-pub struct Writer<W, TValueWriter>
-where
-    W: io::Write,
-{
-    previous_key: Vec<u8>,
-    index_builder: SSTableIndexBuilder,
-    delta_writer: DeltaWriter<W, TValueWriter>,
-    num_terms: u64,
-    first_ordinal_of_the_block: u64,
-}
-
-impl<W, TValueWriter> Writer<W, TValueWriter>
-where
-    W: io::Write,
-    TValueWriter: value::ValueWriter,
-{
-    pub(crate) fn current_key(&self) -> &[u8] {
-        &self.previous_key[..]
-    }
-
-    pub fn write_key(&mut self, key: &[u8]) {
-        let keep_len = common_prefix_len(&self.previous_key, key);
-        let add_len = key.len() - keep_len;
-        let increasing_keys = add_len > 0 && (self.previous_key.len() == keep_len)
-            || self.previous_key.is_empty()
-            || self.previous_key[keep_len] < key[keep_len];
-        assert!(
-            increasing_keys,
-            "Keys should be increasing. ({:?} > {:?})",
-            self.previous_key, key
-        );
-        self.previous_key.resize(key.len(), 0u8);
-        self.previous_key[keep_len..].copy_from_slice(&key[keep_len..]);
-        self.delta_writer.write_suffix(keep_len, &key[keep_len..]);
-    }
-
-    pub(crate) fn into_delta_writer(self) -> DeltaWriter<W, TValueWriter> {
-        self.delta_writer
-    }
-
-    pub fn write(&mut self, key: &[u8], value: &TValueWriter::Value) -> io::Result<()> {
-        self.write_key(key);
-        self.write_value(value)?;
-        Ok(())
-    }
-
-    pub fn write_value(&mut self, value: &TValueWriter::Value) -> io::Result<()> {
-        self.delta_writer.write_value(value);
-        self.num_terms += 1u64;
-        self.flush_block_if_required()
-    }
-
-    pub fn flush_block_if_required(&mut self) -> io::Result<()> {
-        if let Some((start_offset, end_offset)) = self.delta_writer.flush_block_if_required()? {
-            self.index_builder.add_block(
-                &self.previous_key[..],
-                start_offset,
-                end_offset,
-                self.first_ordinal_of_the_block,
-            );
-            self.first_ordinal_of_the_block = self.num_terms;
-            self.previous_key.clear();
-        }
-        Ok(())
-    }
-
-    pub fn finalize(mut self) -> io::Result<W> {
-        if let Some((start_offset, end_offset)) = self.delta_writer.flush_block()? {
-            self.index_builder.add_block(
-                &self.previous_key[..],
-                start_offset,
-                end_offset,
-                self.first_ordinal_of_the_block,
-            );
-            self.first_ordinal_of_the_block = self.num_terms;
-        }
-        let mut wrt = self.delta_writer.finalize();
-        wrt.write_all(&0u32.to_le_bytes())?;
-
-        let offset = wrt.written_bytes();
-
-        self.index_builder.serialize(&mut wrt)?;
-        wrt.write_all(&offset.to_le_bytes())?;
-        wrt.write_all(&self.num_terms.to_le_bytes())?;
-        let wrt = wrt.finish();
-        Ok(wrt.into_inner()?)
-    }
-}
-#[cfg(test)]
-mod test {
-    use std::io;
-
-    use super::SSTable;
-    use super::VoidMerge;
-    use super::VoidSSTable;
-    use super::{common_prefix_len, SSTableMonotonicU64};
-
-    fn aux_test_common_prefix_len(left: &str, right: &str, expect_len: usize) {
-        assert_eq!(
-            common_prefix_len(left.as_bytes(), right.as_bytes()),
-            expect_len
-        );
-        assert_eq!(
-            common_prefix_len(right.as_bytes(), left.as_bytes()),
-            expect_len
-        );
-    }
-
-    #[test]
-    fn test_common_prefix_len() {
-        aux_test_common_prefix_len("a", "ab", 1);
-        aux_test_common_prefix_len("", "ab", 0);
-        aux_test_common_prefix_len("ab", "abc", 2);
-        aux_test_common_prefix_len("abde", "abce", 2);
-    }
-
-    #[test]
-    fn test_long_key_diff() {
-        let long_key = (0..1_024).map(|x| (x % 255) as u8).collect::<Vec<_>>();
-        let long_key2 = (1..300).map(|x| (x % 255) as u8).collect::<Vec<_>>();
-        let mut buffer = vec![];
-        {
-            let mut sstable_writer = VoidSSTable::writer(&mut buffer);
-            assert!(sstable_writer.write(&long_key[..], &()).is_ok());
-            assert!(sstable_writer.write(&[0, 3, 4], &()).is_ok());
-            assert!(sstable_writer.write(&long_key2[..], &()).is_ok());
-            assert!(sstable_writer.finalize().is_ok());
-        }
-        let mut sstable_reader = VoidSSTable::reader(&buffer[..]);
-        assert!(sstable_reader.advance().unwrap());
-        assert_eq!(sstable_reader.key(), &long_key[..]);
-        assert!(sstable_reader.advance().unwrap());
-        assert_eq!(sstable_reader.key(), &[0, 3, 4]);
-        assert!(sstable_reader.advance().unwrap());
-        assert_eq!(sstable_reader.key(), &long_key2[..]);
-        assert!(!sstable_reader.advance().unwrap());
-    }
-
-    #[test]
-    fn test_simple_sstable() {
-        let mut buffer = vec![];
-        {
-            let mut sstable_writer = VoidSSTable::writer(&mut buffer);
-            assert!(sstable_writer.write(&[17u8], &()).is_ok());
-            assert!(sstable_writer.write(&[17u8, 18u8, 19u8], &()).is_ok());
-            assert!(sstable_writer.write(&[17u8, 20u8], &()).is_ok());
-            assert!(sstable_writer.finalize().is_ok());
-        }
-        assert_eq!(
-            &buffer,
-            &[
-                // block len
-                7u8, 0u8, 0u8, 0u8, // keep 0 push 1 |  ""
-                16u8, 17u8, // keep 1 push 2 | 18 19
-                33u8, 18u8, 19u8, // keep 1 push 1 | 20
-                17u8, 20u8, 0u8, 0u8, 0u8, 0u8, // no more blocks
-                // index
-                161, 102, 98, 108, 111, 99, 107, 115, 129, 162, 104, 108, 97, 115, 116, 95, 107,
-                101, 121, 130, 17, 20, 106, 98, 108, 111, 99, 107, 95, 97, 100, 100, 114, 163, 108,
-                115, 116, 97, 114, 116, 95, 111, 102, 102, 115, 101, 116, 0, 106, 101, 110, 100,
-                95, 111, 102, 102, 115, 101, 116, 11, 109, 102, 105, 114, 115, 116, 95, 111, 114,
-                100, 105, 110, 97, 108, 0, 15, 0, 0, 0, 0, 0, 0, 0, // offset for the index
-                3u8, 0u8, 0u8, 0u8, 0u8, 0u8, 0u8, 0u8 // num terms
-            ]
-        );
-        let mut sstable_reader = VoidSSTable::reader(&buffer[..]);
-        assert!(sstable_reader.advance().unwrap());
-        assert_eq!(sstable_reader.key(), &[17u8]);
-        assert!(sstable_reader.advance().unwrap());
-        assert_eq!(sstable_reader.key(), &[17u8, 18u8, 19u8]);
-        assert!(sstable_reader.advance().unwrap());
-        assert_eq!(sstable_reader.key(), &[17u8, 20u8]);
-        assert!(!sstable_reader.advance().unwrap());
-    }
-
-    #[test]
-    #[should_panic]
-    fn test_simple_sstable_non_increasing_key() {
-        let mut buffer = vec![];
-        let mut sstable_writer = VoidSSTable::writer(&mut buffer);
-        assert!(sstable_writer.write(&[17u8], &()).is_ok());
-        assert!(sstable_writer.write(&[16u8], &()).is_ok());
-    }
-
-    #[test]
-    fn test_merge_abcd_abe() {
-        let mut buffer = Vec::new();
-        {
-            let mut writer = VoidSSTable::writer(&mut buffer);
-            writer.write(b"abcd", &()).unwrap();
-            writer.write(b"abe", &()).unwrap();
-            writer.finalize().unwrap();
-        }
-        let mut output = Vec::new();
-        assert!(VoidSSTable::merge(vec![&buffer[..], &buffer[..]], &mut output, VoidMerge).is_ok());
-        assert_eq!(&output[..], &buffer[..]);
-    }
-
-    #[test]
-    fn test_sstable() {
-        let mut buffer = Vec::new();
-        {
-            let mut writer = VoidSSTable::writer(&mut buffer);
-            writer.write(b"abcd", &()).unwrap();
-            writer.write(b"abe", &()).unwrap();
-            writer.finalize().unwrap();
-        }
-        let mut output = Vec::new();
-        assert!(VoidSSTable::merge(vec![&buffer[..], &buffer[..]], &mut output, VoidMerge).is_ok());
-        assert_eq!(&output[..], &buffer[..]);
-    }
-
-    #[test]
-    fn test_sstable_u64() -> io::Result<()> {
-        let mut buffer = Vec::new();
-        let mut writer = SSTableMonotonicU64::writer(&mut buffer);
-        writer.write(b"abcd", &1u64)?;
-        writer.write(b"abe", &4u64)?;
-        writer.write(b"gogo", &4324234234234234u64)?;
-        writer.finalize()?;
-        let mut reader = SSTableMonotonicU64::reader(&buffer[..]);
-        assert!(reader.advance()?);
-        assert_eq!(reader.key(), b"abcd");
-        assert_eq!(reader.value(), &1u64);
-        assert!(reader.advance()?);
-        assert_eq!(reader.key(), b"abe");
-        assert_eq!(reader.value(), &4u64);
-        assert!(reader.advance()?);
-        assert_eq!(reader.key(), b"gogo");
-        assert_eq!(reader.value(), &4324234234234234u64);
-        assert!(!reader.advance()?);
-        Ok(())
-    }
-}

src/termdict/sstable_termdict/sstable/sstable_index.rs

@@ -1,90 +0,0 @@
-use std::io;
-
-use serde;
-use serde::{Deserialize, Serialize};
-
-#[derive(Default, Debug, Serialize, Deserialize)]
-pub struct SSTableIndex {
-    blocks: Vec<BlockMeta>,
-}
-
-impl SSTableIndex {
-    pub fn load(data: &[u8]) -> SSTableIndex {
-        // TODO
-        serde_cbor::de::from_slice(data).unwrap()
-    }
-
-    pub fn search(&self, key: &[u8]) -> Option<BlockAddr> {
-        self.blocks
-            .iter()
-            .find(|block| &block.last_key[..] >= &key)
-            .map(|block| block.block_addr)
-    }
-}
-
-#[derive(Clone, Eq, PartialEq, Debug, Copy, Serialize, Deserialize)]
-pub struct BlockAddr {
-    pub start_offset: u64,
-    pub end_offset: u64,
-    pub first_ordinal: u64,
-}
-
-#[derive(Debug, Serialize, Deserialize)]
-struct BlockMeta {
-    pub last_key: Vec<u8>,
-    pub block_addr: BlockAddr,
-}
-
-#[derive(Default)]
-pub struct SSTableIndexBuilder {
-    index: SSTableIndex,
-}
-
-impl SSTableIndexBuilder {
-    pub fn add_block(
-        &mut self,
-        last_key: &[u8],
-        start_offset: u64,
-        stop_offset: u64,
-        first_ordinal: u64,
-    ) {
-        self.index.blocks.push(BlockMeta {
-            last_key: last_key.to_vec(),
-            block_addr: BlockAddr {
-                start_offset,
-                end_offset: stop_offset,
-                first_ordinal,
-            },
-        })
-    }
-
-    pub fn serialize(&self, wrt: &mut dyn io::Write) -> io::Result<()> {
-        serde_cbor::ser::to_writer(wrt, &self.index).unwrap();
-        Ok(())
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use super::{BlockAddr, SSTableIndex, SSTableIndexBuilder};
-
-    #[test]
-    fn test_sstable_index() {
-        let mut sstable_builder = SSTableIndexBuilder::default();
-        sstable_builder.add_block(b"aaa", 10u64, 20u64, 0u64);
-        sstable_builder.add_block(b"bbbbbbb", 20u64, 30u64, 564);
-        sstable_builder.add_block(b"ccc", 30u64, 40u64, 10u64);
-        sstable_builder.add_block(b"dddd", 40u64, 50u64, 15u64);
-        let mut buffer: Vec<u8> = Vec::new();
-        sstable_builder.serialize(&mut buffer).unwrap();
-        let sstable = SSTableIndex::load(&buffer[..]);
-        assert_eq!(
-            sstable.search(b"bbbde"),
-            Some(BlockAddr {
-                first_ordinal: 10u64,
-                start_offset: 30u64,
-                end_offset: 40u64
-            })
-        );
-    }
-}

src/termdict/sstable_termdict/sstable/value.rs

@@ -1,94 +0,0 @@
-use super::{vint, BlockReader};
-use std::io;
-
-pub trait ValueReader: Default {
-    type Value;
-
-    fn value(&self, idx: usize) -> &Self::Value;
-
-    fn read(&mut self, reader: &mut BlockReader) -> io::Result<()>;
-}
-
-pub trait ValueWriter: Default {
-    type Value;
-
-    fn write(&mut self, val: &Self::Value);
-
-    fn write_block(&mut self, writer: &mut Vec<u8>);
-}
-
-#[derive(Default)]
-pub struct VoidReader;
-
-impl ValueReader for VoidReader {
-    type Value = ();
-
-    fn value(&self, _idx: usize) -> &() {
-        &()
-    }
-
-    fn read(&mut self, _reader: &mut BlockReader) -> io::Result<()> {
-        Ok(())
-    }
-}
-
-#[derive(Default)]
-pub struct VoidWriter;
-
-impl ValueWriter for VoidWriter {
-    type Value = ();
-
-    fn write(&mut self, _val: &()) {}
-
-    fn write_block(&mut self, _writer: &mut Vec<u8>) {}
-}
-
-#[derive(Default)]
-pub struct U64MonotonicWriter {
-    vals: Vec<u64>,
-}
-
-impl ValueWriter for U64MonotonicWriter {
-    type Value = u64;
-
-    fn write(&mut self, val: &Self::Value) {
-        self.vals.push(*val);
-    }
-
-    fn write_block(&mut self, writer: &mut Vec<u8>) {
-        let mut prev_val = 0u64;
-        vint::serialize_into_vec(self.vals.len() as u64, writer);
-        for &val in &self.vals {
-            let delta = val - prev_val;
-            vint::serialize_into_vec(delta, writer);
-            prev_val = val;
-        }
-        self.vals.clear();
-    }
-}
-
-#[derive(Default)]
-pub struct U64MonotonicReader {
-    vals: Vec<u64>,
-}
-
-impl ValueReader for U64MonotonicReader {
-    type Value = u64;
-
-    fn value(&self, idx: usize) -> &Self::Value {
-        &self.vals[idx]
-    }
-
-    fn read(&mut self, reader: &mut BlockReader) -> io::Result<()> {
-        let len = reader.deserialize_u64() as usize;
-        self.vals.clear();
-        let mut prev_val = 0u64;
-        for _ in 0..len {
-            let delta = reader.deserialize_u64() as u64;
-            let val = prev_val + delta;
-            self.vals.push(val);
-            prev_val = val;
-        }
-        Ok(())
-    }
-}

src/termdict/sstable_termdict/sstable/vint.rs

@@ -1,74 +0,0 @@
-use super::BlockReader;
-
-const CONTINUE_BIT: u8 = 128u8;
-
-pub fn serialize(mut val: u64, buffer: &mut [u8]) -> usize {
-    for (i, b) in buffer.iter_mut().enumerate() {
-        let next_byte: u8 = (val & 127u64) as u8;
-        val = val >> 7;
-        if val == 0u64 {
-            *b = next_byte;
-            return i + 1;
-        } else {
-            *b = next_byte | CONTINUE_BIT;
-        }
-    }
-    10 //< actually unreachable
-}
-
-pub fn serialize_into_vec(val: u64, buffer: &mut Vec<u8>) {
-    let mut buf = [0u8; 10];
-    let num_bytes = serialize(val, &mut buf[..]);
-    buffer.extend_from_slice(&buf[..num_bytes]);
-}
-
-// super slow but we don't care
-pub fn deserialize_read(buf: &[u8]) -> (usize, u64) {
-    let mut result = 0u64;
-    let mut shift = 0u64;
-    let mut consumed = 0;
-
-    for &b in buf {
-        consumed += 1;
-        result |= u64::from(b % 128u8) << shift;
-        if b < CONTINUE_BIT {
-            break;
-        }
-        shift += 7;
-    }
-    (consumed, result)
-}
-
-pub fn deserialize_from_block(block: &mut BlockReader) -> u64 {
-    let (num_bytes, val) = deserialize_read(block.buffer());
-    block.advance(num_bytes);
-    val
-}
-
-#[cfg(test)]
-mod tests {
-    use super::{deserialize_read, serialize};
-    use std::u64;
-
-    fn aux_test_int(val: u64, expect_len: usize) {
-        let mut buffer = [0u8; 14];
-        assert_eq!(serialize(val, &mut buffer[..]), expect_len);
-        assert_eq!(deserialize_read(&buffer), (expect_len, val));
-    }
-
-    #[test]
-    fn test_vint() {
-        aux_test_int(0u64, 1);
-        aux_test_int(17u64, 1);
-        aux_test_int(127u64, 1);
-        aux_test_int(128u64, 2);
-        aux_test_int(123423418u64, 4);
-        for i in 1..63 {
-            let power_of_two = 1u64 << i;
-            aux_test_int(power_of_two + 1, (i / 7) + 1);
-            aux_test_int(power_of_two, (i / 7) + 1);
-            aux_test_int(power_of_two - 1, ((i - 1) / 7) + 1);
-        }
-        aux_test_int(u64::MAX, 10);
-    }
-}

src/termdict/sstable_termdict/streamer.rs

@@ -1,227 +0,0 @@
-use super::TermDictionary;
-use crate::postings::TermInfo;
-use crate::termdict::sstable_termdict::TermInfoReader;
-use crate::termdict::TermOrdinal;
-use std::io;
-use std::ops::Bound;
-use tantivy_fst::automaton::AlwaysMatch;
-use tantivy_fst::Automaton;
-
-/// `TermStreamerBuilder` is a helper object used to define
-/// a range of terms that should be streamed.
-pub struct TermStreamerBuilder<'a, A = AlwaysMatch>
-where
-    A: Automaton,
-    A::State: Clone,
-{
-    term_dict: &'a TermDictionary,
-    automaton: A,
-    lower: Bound<Vec<u8>>,
-    upper: Bound<Vec<u8>>,
-}
-
-impl<'a, A> TermStreamerBuilder<'a, A>
-where
-    A: Automaton,
-    A::State: Clone,
-{
-    pub(crate) fn new(term_dict: &'a TermDictionary, automaton: A) -> Self {
-        TermStreamerBuilder {
-            term_dict,
-            automaton,
-            lower: Bound::Unbounded,
-            upper: Bound::Unbounded,
-        }
-    }
-
-    /// Limit the range to terms greater or equal to the bound
-    pub fn ge<T: AsRef<[u8]>>(mut self, bound: T) -> Self {
-        self.lower = Bound::Included(bound.as_ref().to_owned());
-        self
-    }
-
-    /// Limit the range to terms strictly greater than the bound
-    pub fn gt<T: AsRef<[u8]>>(mut self, bound: T) -> Self {
-        self.lower = Bound::Excluded(bound.as_ref().to_owned());
-        self
-    }
-
-    /// Limit the range to terms lesser or equal to the bound
-    pub fn le<T: AsRef<[u8]>>(mut self, bound: T) -> Self {
-        self.upper = Bound::Included(bound.as_ref().to_owned());
-        self
-    }
-
-    /// Limit the range to terms lesser or equal to the bound
-    pub fn lt<T: AsRef<[u8]>>(mut self, bound: T) -> Self {
-        self.lower = Bound::Excluded(bound.as_ref().to_owned());
-        self
-    }
-
-    pub fn backward(mut self) -> Self {
-        unimplemented!()
-    }
-
-    /// Creates the stream corresponding to the range
-    /// of terms defined using the `TermStreamerBuilder`.
-    pub fn into_stream(self) -> io::Result<TermStreamer<'a, A>> {
-        let start_state = self.automaton.start();
-        let delta_reader = self.term_dict.sstable_delta_reader()?;
-        Ok(TermStreamer {
-            automaton: self.automaton,
-            states: vec![start_state],
-            delta_reader,
-            key: Vec::new(),
-            term_ord: 0u64,
-        })
-    }
-}
-
-/// `TermStreamer` acts as a cursor over a range of terms of a segment.
-/// Terms are guaranteed to be sorted.
-pub struct TermStreamer<'a, A = AlwaysMatch>
-where
-    A: Automaton,
-    A::State: Clone,
-{
-    automaton: A,
-    states: Vec<A::State>,
-    delta_reader: super::sstable::DeltaReader<'a, TermInfoReader>,
-    key: Vec<u8>,
-    term_ord: TermOrdinal,
-}
-
-impl<'a, A> TermStreamer<'a, A>
-where
-    A: Automaton,
-    A::State: Clone,
-{
-    /// Advance position the stream on the next item.
-    /// Before the first call to `.advance()`, the stream
-    /// is an unitialized state.
-    pub fn advance(&mut self) -> bool {
-        while self.delta_reader.advance().unwrap() {
-            self.term_ord += 1u64;
-            let common_prefix_len = self.delta_reader.common_prefix_len();
-            self.states.truncate(common_prefix_len + 1);
-            self.key.truncate(common_prefix_len);
-            let mut state: A::State = self.states.last().unwrap().clone();
-            for &b in self.delta_reader.suffix() {
-                state = self.automaton.accept(&state, b);
-                self.states.push(state.clone());
-            }
-            self.key.extend_from_slice(self.delta_reader.suffix());
-            if self.automaton.is_match(&state) {
-                return true;
-            }
-        }
-        false
-    }
-
-    /// Returns the `TermOrdinal` of the given term.
-    ///
-    /// May panic if the called as `.advance()` as never
-    /// been called before.
-    pub fn term_ord(&self) -> TermOrdinal {
-        self.term_ord
-    }
-
-    /// Accesses the current key.
-    ///
-    /// `.key()` should return the key that was returned
-    /// by the `.next()` method.
-    ///
-    /// If the end of the stream as been reached, and `.next()`
-    /// has been called and returned `None`, `.key()` remains
-    /// the value of the last key encountered.
-    ///
-    /// Before any call to `.next()`, `.key()` returns an empty array.
-    pub fn key(&self) -> &[u8] {
-        &self.key
-    }
-
-    /// Accesses the current value.
-    ///
-    /// Calling `.value()` after the end of the stream will return the
-    /// last `.value()` encountered.
-    ///
-    /// # Panics
-    ///
-    /// Calling `.value()` before the first call to `.advance()` returns
-    /// `V::default()`.
-    pub fn value(&self) -> &TermInfo {
-        self.delta_reader.value()
-    }
-
-    /// Return the next `(key, value)` pair.
-    #[cfg_attr(feature = "cargo-clippy", allow(clippy::should_implement_trait))]
-    pub fn next(&mut self) -> Option<(&[u8], &TermInfo)> {
-        if self.advance() {
-            Some((self.key(), self.value()))
-        } else {
-            None
-        }
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use super::super::TermDictionary;
-    use crate::directory::OwnedBytes;
-    use crate::postings::TermInfo;
-
-    fn make_term_info(i: u64) -> TermInfo {
-        TermInfo {
-            doc_freq: 1000u32 + i as u32,
-            positions_idx: i * 500,
-            postings_start_offset: (i + 10) * (i * 10),
-            postings_stop_offset: ((i + 1) + 10) * ((i + 1) * 10),
-        }
-    }
-
-    fn create_test_term_dictionary() -> crate::Result<TermDictionary> {
-        let mut term_dict_builder = super::super::TermDictionaryBuilder::create(Vec::new())?;
-        term_dict_builder.insert(b"abaisance", &make_term_info(0u64))?;
-        term_dict_builder.insert(b"abalation", &make_term_info(1u64))?;
-        term_dict_builder.insert(b"abalienate", &make_term_info(2u64))?;
-        term_dict_builder.insert(b"abandon", &make_term_info(3u64))?;
-        let buffer = term_dict_builder.finish()?;
-        let owned_bytes = OwnedBytes::new(buffer);
-        TermDictionary::from_bytes(owned_bytes)
-    }
-
-    #[test]
-    fn test_sstable_stream() -> crate::Result<()> {
-        let term_dict = create_test_term_dictionary()?;
-        let mut term_streamer = term_dict.stream()?;
-        assert!(term_streamer.advance());
-        assert_eq!(term_streamer.key(), b"abaisance");
-        assert_eq!(term_streamer.value().doc_freq, 1000u32);
-        assert!(term_streamer.advance());
-        assert_eq!(term_streamer.key(), b"abalation");
-        assert_eq!(term_streamer.value().doc_freq, 1001u32);
-        assert!(term_streamer.advance());
-        assert_eq!(term_streamer.key(), b"abalienate");
-        assert_eq!(term_streamer.value().doc_freq, 1002u32);
-        assert!(term_streamer.advance());
-        assert_eq!(term_streamer.key(), b"abandon");
-        assert_eq!(term_streamer.value().doc_freq, 1003u32);
-        assert!(!term_streamer.advance());
-        Ok(())
-    }
-
-    #[test]
-    fn test_sstable_search() -> crate::Result<()> {
-        let term_dict = create_test_term_dictionary()?;
-        let ptn = tantivy_fst::Regex::new("ab.*t.*").unwrap();
-        let mut term_streamer = term_dict.search(ptn).into_stream()?;
-        assert!(term_streamer.advance());
-        assert_eq!(term_streamer.key(), b"abalation");
-        assert_eq!(term_streamer.value().doc_freq, 1001u32);
-        assert!(term_streamer.advance());
-        assert_eq!(term_streamer.key(), b"abalienate");
-        assert_eq!(term_streamer.value().doc_freq, 1002u32);
-        assert!(!term_streamer.advance());
-        Ok(())
-    }
-}

src/termdict/sstable_termdict/termdict.rs

@@ -1,228 +0,0 @@
-use std::io;
-
-use crate::common::BinarySerializable;
-use crate::directory::{FileSlice, OwnedBytes};
-use crate::postings::TermInfo;
-use crate::termdict::sstable_termdict::sstable::sstable_index::BlockAddr;
-use crate::termdict::sstable_termdict::sstable::Writer;
-use crate::termdict::sstable_termdict::sstable::{DeltaReader, SSTable};
-use crate::termdict::sstable_termdict::sstable::{Reader, SSTableIndex};
-use crate::termdict::sstable_termdict::{
-    TermInfoReader, TermInfoWriter, TermSSTable, TermStreamer, TermStreamerBuilder,
-};
-use crate::termdict::TermOrdinal;
-use crate::HasLen;
-use once_cell::sync::Lazy;
-use tantivy_fst::automaton::AlwaysMatch;
-use tantivy_fst::Automaton;
-
-pub struct TermInfoSSTable;
-impl SSTable for TermInfoSSTable {
-    type Value = TermInfo;
-    type Reader = TermInfoReader;
-    type Writer = TermInfoWriter;
-}
-pub struct TermDictionaryBuilder<W: io::Write> {
-    sstable_writer: Writer<W, TermInfoWriter>,
-}
-
-impl<W: io::Write> TermDictionaryBuilder<W> {
-    /// Creates a new `TermDictionaryBuilder`
-    pub fn create(w: W) -> io::Result<Self> {
-        let sstable_writer = TermSSTable::writer(w);
-        Ok(TermDictionaryBuilder { sstable_writer })
-    }
-
-    /// Inserts a `(key, value)` pair in the term dictionary.
-    ///
-    /// *Keys have to be inserted in order.*
-    pub fn insert<K: AsRef<[u8]>>(&mut self, key_ref: K, value: &TermInfo) -> io::Result<()> {
-        let key = key_ref.as_ref();
-        self.insert_key(key)?;
-        self.insert_value(value)?;
-        Ok(())
-    }
-
-    /// # Warning
-    /// Horribly dangerous internal API
-    ///
-    /// If used, it must be used by systematically alternating calls
-    /// to insert_key and insert_value.
-    ///
-    /// Prefer using `.insert(key, value)`
-    pub(crate) fn insert_key(&mut self, key: &[u8]) -> io::Result<()> {
-        self.sstable_writer.write_key(key);
-        Ok(())
-    }
-
-    /// # Warning
-    ///
-    /// Horribly dangerous internal API. See `.insert_key(...)`.
-    pub(crate) fn insert_value(&mut self, term_info: &TermInfo) -> io::Result<()> {
-        self.sstable_writer.write_value(term_info);
-        Ok(())
-    }
-
-    /// Finalize writing the builder, and returns the underlying
-    /// `Write` object.
-    pub fn finish(self) -> io::Result<W> {
-        self.sstable_writer.finalize()
-    }
-}
-
-static EMPTY_TERM_DICT_FILE: Lazy<FileSlice> = Lazy::new(|| {
-    let term_dictionary_data: Vec<u8> = TermDictionaryBuilder::create(Vec::<u8>::new())
-        .expect("Creating a TermDictionaryBuilder in a Vec<u8> should never fail")
-        .finish()
-        .expect("Writing in a Vec<u8> should never fail");
-    FileSlice::from(term_dictionary_data)
-});
-
-/// The term dictionary contains all of the terms in
-/// `tantivy index` in a sorted manner.
-///
-/// The `Fst` crate is used to associate terms to their
-/// respective `TermOrdinal`. The `TermInfoStore` then makes it
-/// possible to fetch the associated `TermInfo`.
-pub struct TermDictionary {
-    sstable_slice: FileSlice,
-    sstable_index: SSTableIndex,
-    num_terms: u64,
-}
-
-impl TermDictionary {
-    pub(crate) fn sstable_reader(&self) -> io::Result<Reader<'static, TermInfoReader>> {
-        let data = self.sstable_slice.read_bytes()?;
-        Ok(TermInfoSSTable::reader(data))
-    }
-
-    pub(crate) fn sstable_reader_block(
-        &self,
-        block_addr: BlockAddr,
-    ) -> io::Result<Reader<'static, TermInfoReader>> {
-        let data = self.sstable_slice.read_bytes_slice(
-            block_addr.start_offset as usize,
-            block_addr.end_offset as usize,
-        )?;
-        Ok(TermInfoSSTable::reader(data))
-    }
-
-    pub(crate) fn sstable_delta_reader(&self) -> io::Result<DeltaReader<'static, TermInfoReader>> {
-        let data = self.sstable_slice.read_bytes()?;
-        Ok(TermInfoSSTable::delta_reader(data))
-    }
-
-    /// Opens a `TermDictionary`.
-    pub fn open(term_dictionary_file: FileSlice) -> crate::Result<Self> {
-        let (main_slice, footer_len_slice) = term_dictionary_file.split_from_end(16);
-        let mut footer_len_bytes: OwnedBytes = footer_len_slice.read_bytes()?;
-        let index_offset = u64::deserialize(&mut footer_len_bytes)?;
-        let num_terms = u64::deserialize(&mut footer_len_bytes)?;
-        let (sstable_slice, index_slice) = main_slice.split(index_offset as usize);
-        // dbg!(index_slice.len());
-        let sstable_index_bytes = index_slice.read_bytes()?;
-        let sstable_index = SSTableIndex::load(sstable_index_bytes.as_slice());
-        // dbg!(&sstable_index);
-        Ok(TermDictionary {
-            sstable_slice,
-            sstable_index,
-            num_terms,
-        })
-    }
-
-    pub fn from_bytes(owned_bytes: OwnedBytes) -> crate::Result<TermDictionary> {
-        TermDictionary::open(FileSlice::new(Box::new(owned_bytes)))
-    }
-
-    /// Creates an empty term dictionary which contains no terms.
-    pub fn empty() -> Self {
-        TermDictionary::open(EMPTY_TERM_DICT_FILE.clone()).unwrap()
-    }
-
-    /// Returns the number of terms in the dictionary.
-    /// Term ordinals range from 0 to `num_terms() - 1`.
-    pub fn num_terms(&self) -> usize {
-        self.num_terms as usize
-    }
-
-    /// Returns the ordinal associated to a given term.
-    pub fn term_ord<K: AsRef<[u8]>>(&self, key: K) -> io::Result<Option<TermOrdinal>> {
-        let mut term_ord = 0u64;
-        let key_bytes = key.as_ref();
-        let mut sstable_reader = self.sstable_reader()?;
-        while sstable_reader.advance().unwrap_or(false) {
-            if sstable_reader.key() == key_bytes {
-                return Ok(Some(term_ord));
-            }
-            term_ord += 1;
-        }
-        Ok(None)
-    }
-
-    /// Returns the term associated to a given term ordinal.
-    ///
-    /// Term ordinals are defined as the position of the term in
-    /// the sorted list of terms.
-    ///
-    /// Returns true iff the term has been found.
-    ///
-    /// Regardless of whether the term is found or not,
-    /// the buffer may be modified.
-    pub fn ord_to_term(&self, ord: TermOrdinal, bytes: &mut Vec<u8>) -> io::Result<bool> {
-        let mut sstable_reader = self.sstable_reader()?;
-        bytes.clear();
-        for _ in 0..(ord + 1) {
-            if !sstable_reader.advance().unwrap_or(false) {
-                return Ok(false);
-            }
-        }
-        bytes.extend_from_slice(sstable_reader.key());
-        Ok(true)
-    }
-
-    /// Returns the number of terms in the dictionary.
-    pub fn term_info_from_ord(&self, term_ord: TermOrdinal) -> io::Result<TermInfo> {
-        let mut sstable_reader = self.sstable_reader()?;
-        for _ in 0..(term_ord + 1) {
-            if !sstable_reader.advance().unwrap_or(false) {
-                return Ok(TermInfo::default());
-            }
-        }
-        Ok(sstable_reader.value().clone())
-    }
-
-    /// Lookups the value corresponding to the key.
-    pub fn get<K: AsRef<[u8]>>(&self, key: K) -> io::Result<Option<TermInfo>> {
-        if let Some(block_addr) = self.sstable_index.search(key.as_ref()) {
-            let mut sstable_reader = self.sstable_reader_block(block_addr)?;
-            let key_bytes = key.as_ref();
-            while sstable_reader.advance().unwrap_or(false) {
-                if sstable_reader.key() == key_bytes {
-                    let term_info = sstable_reader.value().clone();
-                    return Ok(Some(term_info));
-                }
-            }
-        }
-        Ok(None)
-    }
-
-    // Returns a range builder, to stream all of the terms
-    // within an interval.
-    pub fn range(&self) -> TermStreamerBuilder<'_> {
-        TermStreamerBuilder::new(self, AlwaysMatch)
-    }
-
-    // A stream of all the sorted terms. [See also `.stream_field()`](#method.stream_field)
-    pub fn stream(&self) -> io::Result<TermStreamer<'_>> {
-        self.range().into_stream()
-    }
-
-    // Returns a search builder, to stream all of the terms
-    // within the Automaton
-    pub fn search<'a, A: Automaton + 'a>(&'a self, automaton: A) -> TermStreamerBuilder<'a, A>
-    where
-        A::State: Clone,
-    {
-        TermStreamerBuilder::<A>::new(self, automaton)
-    }
-}

src/termdict/streamer.rs

@@ -1,5 +1,3 @@
-use std::io;
-
 use super::TermDictionary;
 use crate::postings::TermInfo;
 use crate::termdict::TermOrdinal;
@@ -61,14 +59,14 @@ where
 
     /// Creates the stream corresponding to the range
     /// of terms defined using the `TermStreamerBuilder`.
-    pub fn into_stream(self) -> io::Result<TermStreamer<'a, A>> {
-        Ok(TermStreamer {
+    pub fn into_stream(self) -> TermStreamer<'a, A> {
+        TermStreamer {
             fst_map: self.fst_map,
             stream: self.stream_builder.into_stream(),
             term_ord: 0u64,
             current_key: Vec::with_capacity(100),
             current_value: TermInfo::default(),
-        })
+        }
     }
 }
 

src/termdict/termdict.rs

@@ -80,6 +80,7 @@ where
                 .serialize(&mut counting_writer)?;
             let footer_size = counting_writer.written_bytes();
             (footer_size as u64).serialize(&mut counting_writer)?;
+            counting_writer.flush()?;
         }
         Ok(file)
     }
@@ -138,8 +139,8 @@ impl TermDictionary {
     }
 
     /// Returns the ordinal associated to a given term.
-    pub fn term_ord<K: AsRef<[u8]>>(&self, key: K) -> io::Result<Option<TermOrdinal>> {
-        Ok(self.fst_index.get(key))
+    pub fn term_ord<K: AsRef<[u8]>>(&self, key: K) -> Option<TermOrdinal> {
+        self.fst_index.get(key)
     }
 
     /// Returns the term associated to a given term ordinal.
@@ -151,7 +152,7 @@ impl TermDictionary {
     ///
     /// Regardless of whether the term is found or not,
     /// the buffer may be modified.
-    pub fn ord_to_term(&self, mut ord: TermOrdinal, bytes: &mut Vec<u8>) -> io::Result<bool> {
+    pub fn ord_to_term(&self, mut ord: TermOrdinal, bytes: &mut Vec<u8>) -> bool {
         bytes.clear();
         let fst = self.fst_index.as_fst();
         let mut node = fst.root();
@@ -166,10 +167,10 @@ impl TermDictionary {
                 let new_node_addr = transition.addr;
                 node = fst.node(new_node_addr);
             } else {
-                return Ok(false);
+                return false;
             }
         }
-        Ok(true)
+        true
     }
 
     /// Returns the number of terms in the dictionary.
@@ -178,10 +179,9 @@ impl TermDictionary {
     }
 
     /// Lookups the value corresponding to the key.
-    pub fn get<K: AsRef<[u8]>>(&self, key: K) -> io::Result<Option<TermInfo>> {
-        Ok(self
-            .term_ord(key)?
-            .map(|term_ord| self.term_info_from_ord(term_ord)))
+    pub fn get<K: AsRef<[u8]>>(&self, key: K) -> Option<TermInfo> {
+        self.term_ord(key)
+            .map(|term_ord| self.term_info_from_ord(term_ord))
     }
 
     /// Returns a range builder, to stream all of the terms
@@ -191,7 +191,7 @@ impl TermDictionary {
     }
 
     /// A stream of all the sorted terms. [See also `.stream_field()`](#method.stream_field)
-    pub fn stream(&self) -> io::Result<TermStreamer<'_>> {
+    pub fn stream(&self) -> TermStreamer<'_> {
         self.range().into_stream()
     }
 

src/termdict/tests.rs

@@ -1,393 +0,0 @@
-use super::{TermDictionary, TermDictionaryBuilder, TermStreamer};
-
-use crate::directory::{Directory, FileSlice, RAMDirectory, TerminatingWrite};
-use crate::postings::TermInfo;
-
-use std::path::PathBuf;
-use std::str;
-
-const BLOCK_SIZE: usize = 1_500;
-
-fn make_term_info(term_ord: u64) -> TermInfo {
-    let offset = |term_ord: u64| term_ord * 100 + term_ord * term_ord;
-    TermInfo {
-        doc_freq: term_ord as u32,
-        postings_start_offset: offset(term_ord),
-        postings_stop_offset: offset(term_ord + 1),
-        positions_idx: offset(term_ord) * 2u64,
-    }
-}
-
-#[test]
-fn test_empty_term_dictionary() {
-    let empty = TermDictionary::empty();
-    assert!(empty.stream().unwrap().next().is_none());
-}
-
-#[test]
-fn test_term_ordinals() -> crate::Result<()> {
-    const COUNTRIES: [&'static str; 7] = [
-        "San Marino",
-        "Serbia",
-        "Slovakia",
-        "Slovenia",
-        "Spain",
-        "Sweden",
-        "Switzerland",
-    ];
-    let directory = RAMDirectory::create();
-    let path = PathBuf::from("TermDictionary");
-    {
-        let write = directory.open_write(&path)?;
-        let mut term_dictionary_builder = TermDictionaryBuilder::create(write)?;
-        for term in COUNTRIES.iter() {
-            term_dictionary_builder.insert(term.as_bytes(), &make_term_info(0u64))?;
-        }
-        term_dictionary_builder.finish()?.terminate()?;
-    }
-    let term_file = directory.open_read(&path)?;
-    let term_dict: TermDictionary = TermDictionary::open(term_file)?;
-    for (term_ord, term) in COUNTRIES.iter().enumerate() {
-        assert_eq!(term_dict.term_ord(term)?, Some(term_ord as u64));
-        let mut bytes = vec![];
-        assert!(term_dict.ord_to_term(term_ord as u64, &mut bytes)?);
-        assert_eq!(bytes, term.as_bytes());
-    }
-    Ok(())
-}
-
-#[test]
-fn test_term_dictionary_simple() -> crate::Result<()> {
-    let directory = RAMDirectory::create();
-    let path = PathBuf::from("TermDictionary");
-    {
-        let write = directory.open_write(&path)?;
-        let mut term_dictionary_builder = TermDictionaryBuilder::create(write)?;
-        term_dictionary_builder.insert("abc".as_bytes(), &make_term_info(34u64))?;
-        term_dictionary_builder.insert("abcd".as_bytes(), &make_term_info(346u64))?;
-        term_dictionary_builder.finish()?.terminate()?;
-    }
-    let file = directory.open_read(&path)?;
-    let term_dict: TermDictionary = TermDictionary::open(file)?;
-    assert_eq!(term_dict.get("abc")?.unwrap().doc_freq, 34u32);
-    assert_eq!(term_dict.get("abcd")?.unwrap().doc_freq, 346u32);
-    let mut stream = term_dict.stream()?;
-    {
-        {
-            let (k, v) = stream.next().unwrap();
-            assert_eq!(k.as_ref(), "abc".as_bytes());
-            assert_eq!(v.doc_freq, 34u32);
-        }
-        assert_eq!(stream.key(), "abc".as_bytes());
-        assert_eq!(stream.value().doc_freq, 34u32);
-    }
-    {
-        {
-            let (k, v) = stream.next().unwrap();
-            assert_eq!(k, "abcd".as_bytes());
-            assert_eq!(v.doc_freq, 346u32);
-        }
-        assert_eq!(stream.key(), "abcd".as_bytes());
-        assert_eq!(stream.value().doc_freq, 346u32);
-    }
-    assert!(!stream.advance());
-    Ok(())
-}
-
-#[test]
-fn test_term_dictionary_stream() -> crate::Result<()> {
-    let ids: Vec<_> = (0u32..10_000u32)
-        .map(|i| (format!("doc{:0>6}", i), i))
-        .collect();
-    let buffer: Vec<u8> = {
-        let mut term_dictionary_builder = TermDictionaryBuilder::create(vec![]).unwrap();
-        for &(ref id, ref i) in &ids {
-            term_dictionary_builder
-                .insert(id.as_bytes(), &make_term_info(*i as u64))
-                .unwrap();
-        }
-        term_dictionary_builder.finish()?
-    };
-    let term_file = FileSlice::from(buffer);
-    let term_dictionary: TermDictionary = TermDictionary::open(term_file)?;
-    {
-        let mut streamer = term_dictionary.stream()?;
-        let mut i = 0;
-        while let Some((streamer_k, streamer_v)) = streamer.next() {
-            let &(ref key, ref v) = &ids[i];
-            assert_eq!(streamer_k.as_ref(), key.as_bytes());
-            assert_eq!(streamer_v, &make_term_info(*v as u64));
-            i += 1;
-        }
-    }
-
-    let &(ref key, ref val) = &ids[2047];
-    assert_eq!(
-        term_dictionary.get(key.as_bytes())?,
-        Some(make_term_info(*val as u64))
-    );
-    Ok(())
-}
-
-#[test]
-fn test_stream_high_range_prefix_suffix() -> crate::Result<()> {
-    let buffer: Vec<u8> = {
-        let mut term_dictionary_builder = TermDictionaryBuilder::create(vec![]).unwrap();
-        // term requires more than 16bits
-        term_dictionary_builder.insert("abcdefghijklmnopqrstuvwxy", &make_term_info(1))?;
-        term_dictionary_builder.insert("abcdefghijklmnopqrstuvwxyz", &make_term_info(2))?;
-        term_dictionary_builder.insert("abr", &make_term_info(3))?;
-        term_dictionary_builder.finish()?
-    };
-    let term_dict_file = FileSlice::from(buffer);
-    let term_dictionary: TermDictionary = TermDictionary::open(term_dict_file)?;
-    let mut kv_stream = term_dictionary.stream()?;
-    assert!(kv_stream.advance());
-    assert_eq!(kv_stream.key(), "abcdefghijklmnopqrstuvwxy".as_bytes());
-    assert_eq!(kv_stream.value(), &make_term_info(1));
-    assert!(kv_stream.advance());
-    assert_eq!(kv_stream.key(), "abcdefghijklmnopqrstuvwxyz".as_bytes());
-    assert_eq!(kv_stream.value(), &make_term_info(2));
-    assert!(kv_stream.advance());
-    assert_eq!(kv_stream.key(), "abr".as_bytes());
-    assert_eq!(kv_stream.value(), &make_term_info(3));
-    assert!(!kv_stream.advance());
-    Ok(())
-}
-
-#[test]
-fn test_stream_range() -> crate::Result<()> {
-    let ids: Vec<_> = (0u32..10_000u32)
-        .map(|i| (format!("doc{:0>6}", i), i))
-        .collect();
-    let buffer: Vec<u8> = {
-        let mut term_dictionary_builder = TermDictionaryBuilder::create(vec![]).unwrap();
-        for &(ref id, ref i) in &ids {
-            term_dictionary_builder
-                .insert(id.as_bytes(), &make_term_info(*i as u64))
-                .unwrap();
-        }
-        term_dictionary_builder.finish()?
-    };
-
-    let file = FileSlice::from(buffer);
-
-    let term_dictionary: TermDictionary = TermDictionary::open(file)?;
-    {
-        for i in (0..20).chain(6000..8_000) {
-            let &(ref target_key, _) = &ids[i];
-            let mut streamer = term_dictionary
-                .range()
-                .ge(target_key.as_bytes())
-                .into_stream()?;
-            for j in 0..3 {
-                let (streamer_k, streamer_v) = streamer.next().unwrap();
-                let &(ref key, ref v) = &ids[i + j];
-                assert_eq!(str::from_utf8(streamer_k.as_ref()).unwrap(), key);
-                assert_eq!(streamer_v.doc_freq, *v);
-                assert_eq!(streamer_v, &make_term_info(*v as u64));
-            }
-        }
-    }
-
-    {
-        for i in (0..20).chain(BLOCK_SIZE - 10..BLOCK_SIZE + 10) {
-            let &(ref target_key, _) = &ids[i];
-            let mut streamer = term_dictionary
-                .range()
-                .gt(target_key.as_bytes())
-                .into_stream()?;
-            for j in 0..3 {
-                let (streamer_k, streamer_v) = streamer.next().unwrap();
-                let &(ref key, ref v) = &ids[i + j + 1];
-                assert_eq!(streamer_k.as_ref(), key.as_bytes());
-                assert_eq!(streamer_v.doc_freq, *v);
-            }
-        }
-    }
-
-    {
-        for i in (0..20).chain(BLOCK_SIZE - 10..BLOCK_SIZE + 10) {
-            for j in 0..3 {
-                let &(ref fst_key, _) = &ids[i];
-                let &(ref last_key, _) = &ids[i + j];
-                let mut streamer = term_dictionary
-                    .range()
-                    .ge(fst_key.as_bytes())
-                    .lt(last_key.as_bytes())
-                    .into_stream()?;
-                for _ in 0..j {
-                    assert!(streamer.next().is_some());
-                }
-                assert!(streamer.next().is_none());
-            }
-        }
-    }
-    Ok(())
-}
-
-#[test]
-fn test_empty_string() -> crate::Result<()> {
-    let buffer: Vec<u8> = {
-        let mut term_dictionary_builder = TermDictionaryBuilder::create(vec![]).unwrap();
-        term_dictionary_builder
-            .insert(&[], &make_term_info(1 as u64))
-            .unwrap();
-        term_dictionary_builder
-            .insert(&[1u8], &make_term_info(2 as u64))
-            .unwrap();
-        term_dictionary_builder.finish()?
-    };
-    let file = FileSlice::from(buffer);
-    let term_dictionary: TermDictionary = TermDictionary::open(file)?;
-    let mut stream = term_dictionary.stream()?;
-    assert!(stream.advance());
-    assert!(stream.key().is_empty());
-    assert!(stream.advance());
-    assert_eq!(stream.key(), &[1u8]);
-    assert!(!stream.advance());
-    Ok(())
-}
-
-#[test]
-fn test_stream_range_boundaries() -> crate::Result<()> {
-    let buffer: Vec<u8> = {
-        let mut term_dictionary_builder = TermDictionaryBuilder::create(Vec::new())?;
-        for i in 0u8..10u8 {
-            let number_arr = [i; 1];
-            term_dictionary_builder.insert(&number_arr, &make_term_info(i as u64))?;
-        }
-        term_dictionary_builder.finish()?
-    };
-    let file = FileSlice::from(buffer);
-    let term_dictionary: TermDictionary = TermDictionary::open(file)?;
-
-    let value_list = |mut streamer: TermStreamer<'_>, backwards: bool| {
-        let mut res: Vec<u32> = vec![];
-        while let Some((_, ref v)) = streamer.next() {
-            res.push(v.doc_freq);
-        }
-        if backwards {
-            res.reverse();
-        }
-        res
-    };
-    {
-        let range = term_dictionary.range().backward().into_stream()?;
-        assert_eq!(
-            value_list(range, true),
-            vec![0u32, 1u32, 2u32, 3u32, 4u32, 5u32, 6u32, 7u32, 8u32, 9u32]
-        );
-    }
-    {
-        let range = term_dictionary.range().ge([2u8]).into_stream()?;
-        assert_eq!(
-            value_list(range, false),
-            vec![2u32, 3u32, 4u32, 5u32, 6u32, 7u32, 8u32, 9u32]
-        );
-    }
-    {
-        let range = term_dictionary.range().ge([2u8]).backward().into_stream()?;
-        assert_eq!(
-            value_list(range, true),
-            vec![2u32, 3u32, 4u32, 5u32, 6u32, 7u32, 8u32, 9u32]
-        );
-    }
-    {
-        let range = term_dictionary.range().gt([2u8]).into_stream()?;
-        assert_eq!(
-            value_list(range, false),
-            vec![3u32, 4u32, 5u32, 6u32, 7u32, 8u32, 9u32]
-        );
-    }
-    {
-        let range = term_dictionary.range().gt([2u8]).backward().into_stream()?;
-        assert_eq!(
-            value_list(range, true),
-            vec![3u32, 4u32, 5u32, 6u32, 7u32, 8u32, 9u32]
-        );
-    }
-    {
-        let range = term_dictionary.range().lt([6u8]).into_stream()?;
-        assert_eq!(
-            value_list(range, false),
-            vec![0u32, 1u32, 2u32, 3u32, 4u32, 5u32]
-        );
-    }
-    {
-        let range = term_dictionary.range().lt([6u8]).backward().into_stream()?;
-        assert_eq!(
-            value_list(range, true),
-            vec![0u32, 1u32, 2u32, 3u32, 4u32, 5u32]
-        );
-    }
-    {
-        let range = term_dictionary.range().le([6u8]).into_stream()?;
-        assert_eq!(
-            value_list(range, false),
-            vec![0u32, 1u32, 2u32, 3u32, 4u32, 5u32, 6u32]
-        );
-    }
-    {
-        let range = term_dictionary.range().le([6u8]).backward().into_stream()?;
-        assert_eq!(
-            value_list(range, true),
-            vec![0u32, 1u32, 2u32, 3u32, 4u32, 5u32, 6u32]
-        );
-    }
-    {
-        let range = term_dictionary.range().ge([0u8]).lt([5u8]).into_stream()?;
-        assert_eq!(value_list(range, false), vec![0u32, 1u32, 2u32, 3u32, 4u32]);
-    }
-    {
-        let range = term_dictionary
-            .range()
-            .ge([0u8])
-            .lt([5u8])
-            .backward()
-            .into_stream()?;
-        assert_eq!(value_list(range, true), vec![0u32, 1u32, 2u32, 3u32, 4u32]);
-    }
-    Ok(())
-}
-
-#[test]
-fn test_automaton_search() -> crate::Result<()> {
-    use crate::query::DFAWrapper;
-    use levenshtein_automata::LevenshteinAutomatonBuilder;
-
-    const COUNTRIES: [&'static str; 7] = [
-        "San Marino",
-        "Serbia",
-        "Slovakia",
-        "Slovenia",
-        "Spain",
-        "Sweden",
-        "Switzerland",
-    ];
-
-    let directory = RAMDirectory::create();
-    let path = PathBuf::from("TermDictionary");
-    {
-        let write = directory.open_write(&path)?;
-        let mut term_dictionary_builder = TermDictionaryBuilder::create(write)?;
-        for term in COUNTRIES.iter() {
-            term_dictionary_builder.insert(term.as_bytes(), &make_term_info(0u64))?;
-        }
-        term_dictionary_builder.finish()?.terminate()?;
-    }
-    let file = directory.open_read(&path)?;
-    let term_dict: TermDictionary = TermDictionary::open(file)?;
-
-    // We can now build an entire dfa.
-    let lev_automaton_builder = LevenshteinAutomatonBuilder::new(2, true);
-    let automaton = DFAWrapper(lev_automaton_builder.build_dfa("Spaen"));
-
-    let mut range = term_dict.search(automaton).into_stream()?;
-
-    // get the first finding
-    assert!(range.advance());
-    assert_eq!("Spain".as_bytes(), range.key());
-    assert!(!range.advance());
-    Ok(())
-}