Fixes build for no-default-features

src/core/index.rs

@@ -24,8 +24,10 @@ use crate::IndexWriter;
 use std::borrow::BorrowMut;
 use std::collections::HashSet;
 use std::fmt;
+
 #[cfg(feature = "mmap")]
-use std::path::{Path, PathBuf};
+use std::path::Path;
+use std::path::PathBuf;
 use std::sync::Arc;
 
 fn load_metas(

src/core/segment_reader.rs

@@ -295,8 +295,8 @@ impl SegmentReader {
     }
 
     /// Returns an iterator that will iterate over the alive document ids
-    pub fn doc_ids_alive<'a>(&'a self) -> impl Iterator<Item = DocId> + 'a {
-        (0u32..self.max_doc).filter(move |doc| !self.is_deleted(*doc))
+    pub fn doc_ids_alive(&self) -> SegmentReaderAliveDocsIterator<'_> {
+        SegmentReaderAliveDocsIterator::new(&self)
     }
 
     /// Summarize total space usage of this segment.
@@ -324,6 +324,52 @@ impl fmt::Debug for SegmentReader {
     }
 }
 
+/// Implements the iterator trait to allow easy iteration
+/// over non-deleted ("alive") DocIds in a SegmentReader
+pub struct SegmentReaderAliveDocsIterator<'a> {
+    reader: &'a SegmentReader,
+    max_doc: DocId,
+    current: DocId,
+}
+
+impl<'a> SegmentReaderAliveDocsIterator<'a> {
+    pub fn new(reader: &'a SegmentReader) -> SegmentReaderAliveDocsIterator<'a> {
+        SegmentReaderAliveDocsIterator {
+            reader,
+            max_doc: reader.max_doc(),
+            current: 0,
+        }
+    }
+}
+
+impl<'a> Iterator for SegmentReaderAliveDocsIterator<'a> {
+    type Item = DocId;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        // TODO: Use TinySet (like in BitSetDocSet) to speed this process up
+        if self.current >= self.max_doc {
+            return None;
+        }
+
+        // find the next alive doc id
+        while self.reader.is_deleted(self.current) {
+            self.current += 1;
+
+            if self.current >= self.max_doc {
+                return None;
+            }
+        }
+
+        // capture the current alive DocId
+        let result = Some(self.current);
+
+        // move down the chain
+        self.current += 1;
+
+        result
+    }
+}
+
 #[cfg(test)]
 mod test {
     use crate::core::Index;

src/indexer/merger.rs

@@ -589,7 +589,9 @@ impl IndexMerger {
             // of all of the segments containing the given term.
             //
             // These segments are non-empty and advance has already been called.
-            if !segment_postings.is_empty() {
+            if segment_postings.is_empty() {
+                continue;
+            }
             // If not, the `term` will be entirely removed.
 
             // We know that there is at least one document containing
@@ -617,11 +619,7 @@ impl IndexMerger {
                         segment_postings.positions(&mut positions_buffer);
 
                         let delta_positions = delta_computer.compute_delta(&positions_buffer);
-                            field_serializer.write_doc(
-                                remapped_doc_id,
-                                term_freq,
-                                delta_positions,
-                            )?;
+                        field_serializer.write_doc(remapped_doc_id, term_freq, delta_positions)?;
                     }
 
                     doc = segment_postings.advance();
@@ -631,7 +629,6 @@ impl IndexMerger {
             // closing the term.
             field_serializer.close_term()?;
         }
-        }
         field_serializer.close()?;
         Ok(term_ord_mapping_opt)
     }