added TitlePositions and BodyPositions to the posting struct to prepare for proximity scoring

3 files changed, 21 insertions, 13 deletions

diff --git a/index/index.go b/index/index.go
index cceabeb..60c3d9f 100644
--- a/index/index.go
+++ b/index/index.go
@@ -6,9 +6,11 @@ import (
 )
 
 type Posting struct {
-	DocId      int
-	Count      int
-	TitleCount int
+	DocId          int
+	BodyCount      int
+	TitleCount     int
+	BodyPositions  []int
+	TitlePositions []int
 }
 type InvertedIndex struct {
 	Mu       sync.RWMutex
@@ -27,20 +29,24 @@ func (idx *InvertedIndex) Add(docID int, title string, bodyTokens []string) {
 	titleTokens := analyzer.ProcessText(title)
 
 	type fieldStats struct {
-		body  int
-		title int
+		body           int
+		bodyPositions  []int
+		title          int
+		titlePositions []int
 	}
 	docStats := make(map[string]fieldStats)
 
-	for _, token := range titleTokens {
+	for position, token := range titleTokens {
 		stats := docStats[token]
 		stats.title++
+		stats.titlePositions = append(stats.titlePositions, position)
 		docStats[token] = stats
 	}
 
-	for _, token := range bodyTokens {
+	for position, token := range bodyTokens {
 		stats := docStats[token]
 		stats.body++
+		stats.bodyPositions = append(stats.bodyPositions, position)
 		docStats[token] = stats
 	}
 
@@ -51,9 +57,11 @@ func (idx *InvertedIndex) Add(docID int, title string, bodyTokens []string) {
 
 	for token, stats := range docStats {
 		idx.Data[token] = append(idx.Data[token], Posting{
-			DocId:      docID,
-			Count:      stats.body,
-			TitleCount: stats.title,
+			DocId:          docID,
+			BodyCount:      stats.body,
+			TitleCount:     stats.title,
+			BodyPositions:  stats.bodyPositions,
+			TitlePositions: stats.titlePositions,
 		})
 	}
 }
diff --git a/scoring/field.go b/scoring/field.go
index 9637950..d84ab3b 100644
--- a/scoring/field.go
+++ b/scoring/field.go
@@ -6,5 +6,5 @@ var TitleWeight = 5.0
 var BodyWeight = 1.0
 
 func FieldScore(p index.Posting) float64 {
-	return (float64(p.TitleCount) * TitleWeight) + (float64(p.Count) * BodyWeight)
+	return (float64(p.TitleCount) * TitleWeight) + (float64(p.BodyCount) * BodyWeight)
 }
diff --git a/search/search.go b/search/search.go
index 5fb96f3..061c99c 100644
--- a/search/search.go
+++ b/search/search.go
@@ -28,7 +28,7 @@ func Search(idx *index.InvertedIndex, query string) []string {
 
 	scores := make(map[int]int)
 	for _, p := range basePostings {
-		scores[p.DocId] = p.Count
+		scores[p.DocId] = p.BodyCount
 	}
 
 	for i := 1; i < len(tokenizedQuery); i++ {
@@ -40,7 +40,7 @@ func Search(idx *index.InvertedIndex, query string) []string {
 
 		lookup := make(map[int]int)
 		for _, p := range nextPostings {
-			lookup[p.DocId] = p.Count
+			lookup[p.DocId] = p.BodyCount
 		}
 
 		newScores := make(map[int]int)