fix incorrect results returned by phrase search

previously phrase searcher would not validate that consecutive
terms were actually occurring in the same array position

fixes #292

search/search.go

@@ -16,6 +16,20 @@ type Location struct {
 	ArrayPositions []float64 `json:"array_positions"`
 }
 
+// SameArrayElement returns true if two locations are point to
+// the same array element
+func (l *Location) SameArrayElement(other *Location) bool {
+	if len(l.ArrayPositions) != len(other.ArrayPositions) {
+		return false
+	}
+	for i, elem := range l.ArrayPositions {
+		if other.ArrayPositions[i] != elem {
+			return false
+		}
+	}
+	return true
+}
+
 type Locations []*Location
 
 type TermLocationMap map[string]Locations

search/searchers/search_phrase.go

@@ -119,7 +119,7 @@ func (s *PhraseSearcher) Next() (*search.DocumentMatch, error) {
 							nextLocations, ok := termLocMap[nextTerm]
 							if ok {
 								for _, nextLocation := range nextLocations {
-									if nextLocation.Pos == location.Pos+float64(i) {
+									if nextLocation.Pos == location.Pos+float64(i) && nextLocation.SameArrayElement(location) {
 										// found a location match for this term
 										crvtlm.AddLocation(nextTerm, nextLocation)
 										continue INNER

test/tests/phrase/data/b.json

@@ -0,0 +1,3 @@
+{
+	"body": ["bad call", "defenseless receiver"]
+}

test/tests/phrase/searches.json

@@ -322,5 +322,55 @@
 				}
 			]
 		}
+	},
+	{
+		"search": {
+			"from": 0,
+			"size": 10,
+			"query": {
+				"field": "body",
+				"match_phrase": "bad call"
+			}
+		},
+		"result": {
+			"total_hits": 1,
+			"hits": [
+				{
+					"id": "b"
+				}
+			]
+		}
+	},
+	{
+		"search": {
+			"from": 0,
+			"size": 10,
+			"query": {
+				"field": "body",
+				"match_phrase": "defenseless receiver"
+			}
+		},
+		"result": {
+			"total_hits": 1,
+			"hits": [
+				{
+					"id": "b"
+				}
+			]
+		}
+	},
+	{
+		"search": {
+			"from": 0,
+			"size": 10,
+			"query": {
+				"field": "body",
+				"match_phrase": "bad receiver"
+			}
+		},
+		"result": {
+			"total_hits": 0,
+			"hits": []
+		}
 	}
 ]