Merge pull request #1 from katbyte/sergi/pull/125

copy of sergi#125 to solve sergi#123 for katbyte/terrafmt

diffmatchpatch/diff.go

@@ -34,7 +34,7 @@ const (
 	DiffInsert Operation = 1
 	// DiffEqual item represents an equal diff.
 	DiffEqual Operation = 0
-	//IndexSeparator is used to seperate the array indexes in an index string
+	// IndexSeparator is used to seperate the array indexes in an index string
 	IndexSeparator = ","
 )
 
@@ -1168,7 +1168,7 @@ func (dmp *DiffMatchPatch) DiffPrettyText(diffs []Diff) string {
 
 // DiffText1 computes and returns the source text (all equalities and deletions).
 func (dmp *DiffMatchPatch) DiffText1(diffs []Diff) string {
-	//StringBuilder text = new StringBuilder()
+	// StringBuilder text = new StringBuilder()
 	var text bytes.Buffer
 
 	for _, aDiff := range diffs {
@@ -1312,18 +1312,19 @@ func (dmp *DiffMatchPatch) DiffFromDelta(text1 string, delta string) (diffs []Di
 func (dmp *DiffMatchPatch) diffLinesToStrings(text1, text2 string) (string, string, []string) {
 	// '\x00' is a valid character, but various debuggers don't like it. So we'll insert a junk entry to avoid generating a null character.
 	lineArray := []string{""} // e.g. lineArray[4] == 'Hello\n'
+	lineHash := make(map[string]int)
+	lineHash[""] = 0
 
-	//Each string has the index of lineArray which it points to
-	strIndexArray1 := dmp.diffLinesToStringsMunge(text1, &lineArray)
-	strIndexArray2 := dmp.diffLinesToStringsMunge(text2, &lineArray)
+	// Each string has the index of lineArray which it points to
+	strIndexArray1 := dmp.diffLinesToStringsMunge(text1, &lineArray, lineHash)
+	strIndexArray2 := dmp.diffLinesToStringsMunge(text2, &lineArray, lineHash)
 
 	return intArrayToString(strIndexArray1), intArrayToString(strIndexArray2), lineArray
 }
 
 // diffLinesToStringsMunge splits a text into an array of strings, and reduces the texts to a []string.
-func (dmp *DiffMatchPatch) diffLinesToStringsMunge(text string, lineArray *[]string) []uint32 {
+func (dmp *DiffMatchPatch) diffLinesToStringsMunge(text string, lineArray *[]string, lineHash map[string]int) []uint32 {
 	// Walk the text, pulling out a substring for each line. text.split('\n') would would temporarily double our memory footprint. Modifying text would create many large strings to garbage collect.
-	lineHash := map[string]int{} // e.g. lineHash['Hello\n'] == 4
 	lineStart := 0
 	lineEnd := -1
 	strs := []uint32{}