Add box_clone() and downcast::Any to Query (#303)

src/query/all_query.rs

@@ -9,7 +9,7 @@ use Score;
 /// Query that matches all of the documents.
 ///
 /// All of the document get the score 1f32.
-#[derive(Debug)]
+#[derive(Clone, Debug)]
 pub struct AllQuery;
 
 impl Query for AllQuery {

src/query/boolean_query/boolean_query.rs

@@ -23,6 +23,16 @@ pub struct BooleanQuery {
     subqueries: Vec<(Occur, Box<Query>)>,
 }
 
+impl Clone for BooleanQuery {
+    fn clone(&self) -> Self {
+        self.subqueries
+            .iter()
+            .map(|(x, y)| (x.clone(), y.box_clone()))
+            .collect::<Vec<_>>()
+            .into()
+    }
+}
+
 impl From<Vec<(Occur, Box<Query>)>> for BooleanQuery {
     fn from(subqueries: Vec<(Occur, Box<Query>)>) -> BooleanQuery {
         BooleanQuery { subqueries }
@@ -55,4 +65,8 @@ impl BooleanQuery {
             .collect();
         BooleanQuery::from(occur_term_queries)
     }
+
+    pub fn clauses(&self) -> &[(Occur, Box<Query>)] {
+        &self.subqueries[..]
+    }
 }

src/query/phrase_query/phrase_query.rs

@@ -21,7 +21,7 @@ use Result;
 /// Using a `PhraseQuery` on a field requires positions
 /// to be indexed for this field.
 ///
-#[derive(Debug)]
+#[derive(Clone, Debug)]
 pub struct PhraseQuery {
     field: Field,
     phrase_terms: Vec<Term>,
@@ -47,6 +47,14 @@ impl PhraseQuery {
             phrase_terms: terms,
         }
     }
+
+    pub fn field(&self) -> Field {
+        self.field
+    }
+
+    pub fn phrase_terms(&self) -> &[Term] {
+        &self.phrase_terms[..]
+    }
 }
 
 impl Query for PhraseQuery {

src/query/query.rs

@@ -1,6 +1,7 @@
 use super::Weight;
 use collector::Collector;
 use core::searcher::Searcher;
+use downcast;
 use std::fmt;
 use Result;
 use SegmentLocalId;
@@ -38,7 +39,7 @@ use SegmentLocalId;
 ///
 /// When implementing a new type of `Query`, it is normal to implement a
 /// dedicated `Query`, `Weight` and `Scorer`.
-pub trait Query: fmt::Debug {
+pub trait Query: QueryClone + downcast::Any + fmt::Debug {
     /// Create the weight associated to a query.
     ///
     /// If scoring is not required, setting `scoring_enabled` to `false`
@@ -77,3 +78,20 @@ pub trait Query: fmt::Debug {
         Ok(())
     }
 }
+
+pub trait QueryClone {
+    fn box_clone(&self) -> Box<Query>;
+}
+
+impl<T> QueryClone for T
+where T: 'static + Query + Clone
+{
+    fn box_clone(&self) -> Box<Query> {
+        Box::new(self.clone())
+    }
+}
+
+#[allow(missing_docs)]
+mod downcast_impl {
+    downcast!(super::Query);
+}

src/query/range_query.rs

@@ -80,7 +80,7 @@ fn map_bound<TFrom, Transform: Fn(TFrom) -> Vec<u8>>(
 /// #   run().unwrap()
 /// # }
 /// ```
-#[derive(Debug)]
+#[derive(Clone, Debug)]
 pub struct RangeQuery {
     field: Field,
     value_type: Type,

src/query/term_query/term_query.rs

@@ -16,7 +16,7 @@ use Term;
 /// * `idf`        - inverse document frequency.
 /// * `term_freq`  - number of occurrences of the term in the field
 /// * `field norm` - number of tokens in the field.
-#[derive(Debug)]
+#[derive(Clone, Debug)]
 pub struct TermQuery {
     term: Term,
     index_record_option: IndexRecordOption,
@@ -31,6 +31,10 @@ impl TermQuery {
         }
     }
 
+    pub fn term(&self) -> &Term {
+        &self.term
+    }
+
     /// Returns a weight object.
     ///
     /// While `.weight(...)` returns a boxed trait object,