add query support for multi-phrase

when parsing json, when we encounter the key "terms", we first
try to parse as traditional phrase query, then if that fails,
we also try parsing it as multi-phrase

search/query/multi_phrase.go

@@ -0,0 +1,80 @@
+//  Copyright (c) 2014 Couchbase, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// 		http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package query
+
+import (
+	"encoding/json"
+	"fmt"
+
+	"github.com/blevesearch/bleve/index"
+	"github.com/blevesearch/bleve/mapping"
+	"github.com/blevesearch/bleve/search"
+	"github.com/blevesearch/bleve/search/searcher"
+)
+
+type MultiPhraseQuery struct {
+	Terms    [][]string `json:"terms"`
+	Field    string     `json:"field,omitempty"`
+	BoostVal *Boost     `json:"boost,omitempty"`
+}
+
+// NewMultiPhraseQuery creates a new Query for finding
+// term phrases in the index.
+// It is like PhraseQuery, but each position in the
+// phrase may be satisfied by a list of terms
+// as opposed to just one.
+// At least one of the terms must exist in the correct
+// order, at the correct index offsets, in the
+// specified field. Queried field must have been indexed with
+// IncludeTermVectors set to true.
+func NewMultiPhraseQuery(terms [][]string, field string) *MultiPhraseQuery {
+	return &MultiPhraseQuery{
+		Terms: terms,
+		Field: field,
+	}
+}
+
+func (q *MultiPhraseQuery) SetBoost(b float64) {
+	boost := Boost(b)
+	q.BoostVal = &boost
+}
+
+func (q *MultiPhraseQuery) Boost() float64 {
+	return q.BoostVal.Value()
+}
+
+func (q *MultiPhraseQuery) Searcher(i index.IndexReader, m mapping.IndexMapping, options search.SearcherOptions) (search.Searcher, error) {
+	return searcher.NewMultiPhraseSearcher(i, q.Terms, q.Field, options)
+}
+
+func (q *MultiPhraseQuery) Validate() error {
+	if len(q.Terms) < 1 {
+		return fmt.Errorf("phrase query must contain at least one term")
+	}
+	return nil
+}
+
+func (q *MultiPhraseQuery) UnmarshalJSON(data []byte) error {
+	type _mphraseQuery MultiPhraseQuery
+	tmp := _mphraseQuery{}
+	err := json.Unmarshal(data, &tmp)
+	if err != nil {
+		return err
+	}
+	q.Terms = tmp.Terms
+	q.Field = tmp.Field
+	q.BoostVal = tmp.BoostVal
+	return nil
+}

search/query/query.go

@@ -123,7 +123,13 @@ func ParseQuery(input []byte) (Query, error) {
 		var rv PhraseQuery
 		err := json.Unmarshal(input, &rv)
 		if err != nil {
-			return nil, err
+			// now try multi-phrase
+			var rv2 MultiPhraseQuery
+			err = json.Unmarshal(input, &rv2)
+			if err != nil {
+				return nil, err
+			}
+			return &rv2, nil
 		}
 		return &rv, nil
 	}

test/tests/phrase/searches.json

@@ -372,5 +372,24 @@
 			"total_hits": 0,
 			"hits": []
 		}
+	},
+  {
+    "comment": "multi-phrase terms",
+		"search": {
+			"from": 0,
+			"size": 10,
+			"query": {
+				"field": "body",
+				"terms": [["twenti","thirti"],["thousand"]]
+			}
+		},
+		"result": {
+			"total_hits": 1,
+			"hits": [
+				{
+					"id": "a"
+				}
+			]
+		}
 	}
-]
+]