move phrase search logic into phrase searcher

the logic of how a phrase search works should be an internal
detail of the phrase searcher.  further, these changes will
allow proper scoring of phrase matches, which require access
to the underlying searcher objects, which were hidden in the
previous approach.

search/query/phrase.go

@@ -25,10 +25,9 @@ import (
 )
 
 type PhraseQuery struct {
-	Terms       []string `json:"terms"`
-	Field       string   `json:"field,omitempty"`
-	BoostVal    *Boost   `json:"boost,omitempty"`
-	termQueries []Query
+	Terms    []string `json:"terms"`
+	Field    string   `json:"field,omitempty"`
+	BoostVal *Boost   `json:"boost,omitempty"`
 }
 
 // NewPhraseQuery creates a new Query for finding
@@ -38,18 +37,9 @@ type PhraseQuery struct {
 // specified field. Queried field must have been indexed with
 // IncludeTermVectors set to true.
 func NewPhraseQuery(terms []string, field string) *PhraseQuery {
-	termQueries := make([]Query, 0)
-	for _, term := range terms {
-		if term != "" {
-			tq := NewTermQuery(term)
-			tq.SetField(field)
-			termQueries = append(termQueries, tq)
-		}
-	}
 	return &PhraseQuery{
-		Terms:       terms,
-		Field:       field,
-		termQueries: termQueries,
+		Terms: terms,
+		Field: field,
 	}
 }
 
@@ -63,18 +53,11 @@ func (q *PhraseQuery) Boost() float64 {
 }
 
 func (q *PhraseQuery) Searcher(i index.IndexReader, m mapping.IndexMapping, options search.SearcherOptions) (search.Searcher, error) {
-	options.IncludeTermVectors = true
-
-	conjunctionQuery := NewConjunctionQuery(q.termQueries)
-	conjunctionSearcher, err := conjunctionQuery.Searcher(i, m, options)
-	if err != nil {
-		return nil, err
-	}
-	return searcher.NewPhraseSearcher(i, conjunctionSearcher.(*searcher.ConjunctionSearcher), q.Terms)
+	return searcher.NewPhraseSearcher(i, q.Terms, q.Field, options)
 }
 
 func (q *PhraseQuery) Validate() error {
-	if len(q.termQueries) < 1 {
+	if len(q.Terms) < 1 {
 		return fmt.Errorf("phrase query must contain at least one term")
 	}
 	return nil
@@ -90,9 +73,5 @@ func (q *PhraseQuery) UnmarshalJSON(data []byte) error {
 	q.Terms = tmp.Terms
 	q.Field = tmp.Field
 	q.BoostVal = tmp.BoostVal
-	q.termQueries = make([]Query, len(q.Terms))
-	for i, term := range q.Terms {
-		q.termQueries[i] = &TermQuery{Term: term, FieldVal: q.Field, BoostVal: q.BoostVal}
-	}
 	return nil
 }

search/query/query.go

@@ -301,14 +301,6 @@ func expandQuery(m mapping.IndexMapping, query Query) (Query, error) {
 				return nil, err
 			}
 			return &q, nil
-		case *PhraseQuery:
-			q := *query.(*PhraseQuery)
-			children, err := expandSlice(q.termQueries)
-			if err != nil {
-				return nil, err
-			}
-			q.termQueries = children
-			return &q, nil
 		default:
 			return query, nil
 		}

search/searcher/search_phrase.go

@@ -15,6 +15,7 @@
 package searcher
 
 import (
+	"fmt"
 	"math"
 
 	"github.com/blevesearch/bleve/index"
@@ -31,7 +32,24 @@ type PhraseSearcher struct {
 	initialized  bool
 }
 
-func NewPhraseSearcher(indexReader index.IndexReader, mustSearcher *ConjunctionSearcher, terms []string) (*PhraseSearcher, error) {
+func NewPhraseSearcher(indexReader index.IndexReader, terms []string, field string, options search.SearcherOptions) (*PhraseSearcher, error) {
+	options.IncludeTermVectors = true
+	termSearchers := make([]search.Searcher, 0)
+	for _, term := range terms {
+		if term != "" {
+			ts, err := NewTermSearcher(indexReader, term, field, 1.0, options)
+			if err != nil {
+				return nil, fmt.Errorf("phrase searcher error building term searcher: %v", err)
+			}
+			termSearchers = append(termSearchers, ts)
+		}
+	}
+
+	mustSearcher, err := NewConjunctionSearcher(indexReader, termSearchers, options)
+	if err != nil {
+		return nil, fmt.Errorf("phrase searcher error building conjunction searcher: %v", err)
+	}
+
 	// build our searcher
 	rv := PhraseSearcher{
 		indexReader:  indexReader,

search/searcher/search_phrase_test.go

@@ -36,20 +36,7 @@ func TestPhraseSearch(t *testing.T) {
 	}()
 
 	soptions := search.SearcherOptions{Explain: true, IncludeTermVectors: true}
-
-	angstTermSearcher, err := NewTermSearcher(twoDocIndexReader, "angst", "desc", 1.0, soptions)
-	if err != nil {
-		t.Fatal(err)
-	}
-	beerTermSearcher, err := NewTermSearcher(twoDocIndexReader, "beer", "desc", 1.0, soptions)
-	if err != nil {
-		t.Fatal(err)
-	}
-	mustSearcher, err := NewConjunctionSearcher(twoDocIndexReader, []search.Searcher{angstTermSearcher, beerTermSearcher}, soptions)
-	if err != nil {
-		t.Fatal(err)
-	}
-	phraseSearcher, err := NewPhraseSearcher(twoDocIndexReader, mustSearcher, []string{"angst", "beer"})
+	phraseSearcher, err := NewPhraseSearcher(twoDocIndexReader, []string{"angst", "beer"}, "desc", soptions)
 	if err != nil {
 		t.Fatal(err)
 	}