Performance tuning - eager rune array conversion

> wc -l /tmp/list2
     2594098 /tmp/list2

    > time cat /tmp/list2 | fzf-0.10.1-darwin_amd64 -fqwerty > /dev/null

    real    0m5.418s
    user    0m10.990s
    sys     0m1.302s

    > time cat /tmp/list2 | fzf-head -fqwerty > /dev/null

    real    0m4.862s
    user    0m6.619s
    sys     0m0.982s

src/algo/algo.go

@@ -16,7 +16,7 @@ import (
  */
 
 // FuzzyMatch performs fuzzy-match
-func FuzzyMatch(caseSensitive bool, runes *[]rune, pattern []rune) (int, int) {
+func FuzzyMatch(caseSensitive bool, runes []rune, pattern []rune) (int, int) {
 	if len(pattern) == 0 {
 		return 0, 0
 	}
@@ -34,7 +34,7 @@ func FuzzyMatch(caseSensitive bool, runes *[]rune, pattern []rune) (int, int) {
 	sidx := -1
 	eidx := -1
 
-	for index, char := range *runes {
+	for index, char := range runes {
 		// This is considerably faster than blindly applying strings.ToLower to the
 		// whole string
 		if !caseSensitive {
@@ -61,7 +61,7 @@ func FuzzyMatch(caseSensitive bool, runes *[]rune, pattern []rune) (int, int) {
 	if sidx >= 0 && eidx >= 0 {
 		pidx--
 		for index := eidx - 1; index >= sidx; index-- {
-			char := (*runes)[index]
+			char := runes[index]
 			if !caseSensitive {
 				if char >= 'A' && char <= 'Z' {
 					char += 32
@@ -88,12 +88,12 @@ func FuzzyMatch(caseSensitive bool, runes *[]rune, pattern []rune) (int, int) {
 //
 // We might try to implement better algorithms in the future:
 // http://en.wikipedia.org/wiki/String_searching_algorithm
-func ExactMatchNaive(caseSensitive bool, runes *[]rune, pattern []rune) (int, int) {
+func ExactMatchNaive(caseSensitive bool, runes []rune, pattern []rune) (int, int) {
 	if len(pattern) == 0 {
 		return 0, 0
 	}
 
-	numRunes := len(*runes)
+	numRunes := len(runes)
 	plen := len(pattern)
 	if numRunes < plen {
 		return -1, -1
@@ -101,7 +101,7 @@ func ExactMatchNaive(caseSensitive bool, runes *[]rune, pattern []rune) (int, in
 
 	pidx := 0
 	for index := 0; index < numRunes; index++ {
-		char := (*runes)[index]
+		char := runes[index]
 		if !caseSensitive {
 			if char >= 'A' && char <= 'Z' {
 				char += 32
@@ -123,13 +123,13 @@ func ExactMatchNaive(caseSensitive bool, runes *[]rune, pattern []rune) (int, in
 }
 
 // PrefixMatch performs prefix-match
-func PrefixMatch(caseSensitive bool, runes *[]rune, pattern []rune) (int, int) {
-	if len(*runes) < len(pattern) {
+func PrefixMatch(caseSensitive bool, runes []rune, pattern []rune) (int, int) {
+	if len(runes) < len(pattern) {
 		return -1, -1
 	}
 
 	for index, r := range pattern {
-		char := (*runes)[index]
+		char := runes[index]
 		if !caseSensitive {
 			char = unicode.ToLower(char)
 		}
@@ -141,7 +141,7 @@ func PrefixMatch(caseSensitive bool, runes *[]rune, pattern []rune) (int, int) {
 }
 
 // SuffixMatch performs suffix-match
-func SuffixMatch(caseSensitive bool, input *[]rune, pattern []rune) (int, int) {
+func SuffixMatch(caseSensitive bool, input []rune, pattern []rune) (int, int) {
 	runes := util.TrimRight(input)
 	trimmedLen := len(runes)
 	diff := trimmedLen - len(pattern)
@@ -161,11 +161,11 @@ func SuffixMatch(caseSensitive bool, input *[]rune, pattern []rune) (int, int) {
 	return trimmedLen - len(pattern), trimmedLen
 }
 
-func EqualMatch(caseSensitive bool, runes *[]rune, pattern []rune) (int, int) {
-	if len(*runes) != len(pattern) {
+func EqualMatch(caseSensitive bool, runes []rune, pattern []rune) (int, int) {
+	if len(runes) != len(pattern) {
 		return -1, -1
 	}
-	runesStr := string(*runes)
+	runesStr := string(runes)
 	if !caseSensitive {
 		runesStr = strings.ToLower(runesStr)
 	}

src/algo/algo_test.go

@@ -5,12 +5,11 @@ import (
 	"testing"
 )
 
-func assertMatch(t *testing.T, fun func(bool, *[]rune, []rune) (int, int), caseSensitive bool, input string, pattern string, sidx int, eidx int) {
+func assertMatch(t *testing.T, fun func(bool, []rune, []rune) (int, int), caseSensitive bool, input string, pattern string, sidx int, eidx int) {
 	if !caseSensitive {
 		pattern = strings.ToLower(pattern)
 	}
-	runes := []rune(input)
-	s, e := fun(caseSensitive, &runes, []rune(pattern))
+	s, e := fun(caseSensitive, []rune(input), []rune(pattern))
 	if s != sidx {
 		t.Errorf("Invalid start index: %d (expected: %d, %s / %s)", s, sidx, input, pattern)
 	}

src/ansi.go

@@ -36,7 +36,7 @@ func init() {
 	ansiRegex = regexp.MustCompile("\x1b\\[[0-9;]*[mK]")
 }
 
-func extractColor(str *string, state *ansiState) (*string, []ansiOffset, *ansiState) {
+func extractColor(str string, state *ansiState) (string, []ansiOffset, *ansiState) {
 	var offsets []ansiOffset
 	var output bytes.Buffer
 
@@ -45,9 +45,9 @@ func extractColor(str *string, state *ansiState) (*string, []ansiOffset, *ansiSt
 	}
 
 	idx := 0
-	for _, offset := range ansiRegex.FindAllStringIndex(*str, -1) {
-		output.WriteString((*str)[idx:offset[0]])
-		newState := interpretCode((*str)[offset[0]:offset[1]], state)
+	for _, offset := range ansiRegex.FindAllStringIndex(str, -1) {
+		output.WriteString(str[idx:offset[0]])
+		newState := interpretCode(str[offset[0]:offset[1]], state)
 
 		if !newState.equals(state) {
 			if state != nil {
@@ -69,7 +69,7 @@ func extractColor(str *string, state *ansiState) (*string, []ansiOffset, *ansiSt
 		idx = offset[1]
 	}
 
-	rest := (*str)[idx:]
+	rest := str[idx:]
 	if len(rest) > 0 {
 		output.WriteString(rest)
 		if state != nil {
@@ -77,8 +77,7 @@ func extractColor(str *string, state *ansiState) (*string, []ansiOffset, *ansiSt
 			(&offsets[len(offsets)-1]).offset[1] = int32(utf8.RuneCount(output.Bytes()))
 		}
 	}
-	outputStr := output.String()
-	return &outputStr, offsets, state
+	return output.String(), offsets, state
 }
 
 func interpretCode(ansiCode string, prevState *ansiState) *ansiState {

src/ansi_test.go

@@ -17,9 +17,9 @@ func TestExtractColor(t *testing.T) {
 	var state *ansiState
 	clean := "\x1b[0m"
 	check := func(assertion func(ansiOffsets []ansiOffset, state *ansiState)) {
-		output, ansiOffsets, newState := extractColor(&src, state)
+		output, ansiOffsets, newState := extractColor(src, state)
 		state = newState
-		if *output != "hello world" {
+		if output != "hello world" {
 			t.Errorf("Invalid output: {}", output)
 		}
 		fmt.Println(src, ansiOffsets, clean)

src/chunklist.go

@@ -7,7 +7,7 @@ type Chunk []*Item // >>> []Item
 
 // ItemBuilder is a closure type that builds Item object from a pointer to a
 // string and an integer
-type ItemBuilder func(*string, int) *Item
+type ItemBuilder func([]rune, int) *Item
 
 // ChunkList is a list of Chunks
 type ChunkList struct {
@@ -26,7 +26,7 @@ func NewChunkList(trans ItemBuilder) *ChunkList {
 		trans:  trans}
 }
 
-func (c *Chunk) push(trans ItemBuilder, data *string, index int) bool {
+func (c *Chunk) push(trans ItemBuilder, data []rune, index int) bool {
 	item := trans(data, index)
 	if item != nil {
 		*c = append(*c, item)
@@ -53,7 +53,7 @@ func CountItems(cs []*Chunk) int {
 }
 
 // Push adds the item to the list
-func (cl *ChunkList) Push(data string) bool {
+func (cl *ChunkList) Push(data []rune) bool {
 	cl.mutex.Lock()
 	defer cl.mutex.Unlock()
 
@@ -62,7 +62,7 @@ func (cl *ChunkList) Push(data string) bool {
 		cl.chunks = append(cl.chunks, &newChunk)
 	}
 
-	if cl.lastChunk().push(cl.trans, &data, cl.count) {
+	if cl.lastChunk().push(cl.trans, data, cl.count) {
 		cl.count++
 		return true
 	}

src/chunklist_test.go

@@ -6,7 +6,7 @@ import (
 )
 
 func TestChunkList(t *testing.T) {
-	cl := NewChunkList(func(s *string, i int) *Item {
+	cl := NewChunkList(func(s []rune, i int) *Item {
 		return &Item{text: s, rank: Rank{0, 0, uint32(i * 2)}}
 	})
 
@@ -17,8 +17,8 @@ func TestChunkList(t *testing.T) {
 	}
 
 	// Add some data
-	cl.Push("hello")
-	cl.Push("world")
+	cl.Push([]rune("hello"))
+	cl.Push([]rune("world"))
 
 	// Previously created snapshot should remain the same
 	if len(snapshot) > 0 {
@@ -36,8 +36,8 @@ func TestChunkList(t *testing.T) {
 	if len(*chunk1) != 2 {
 		t.Error("Snapshot should contain only two items")
 	}
-	if *(*chunk1)[0].text != "hello" || (*chunk1)[0].rank.index != 0 ||
-		*(*chunk1)[1].text != "world" || (*chunk1)[1].rank.index != 2 {
+	if string((*chunk1)[0].text) != "hello" || (*chunk1)[0].rank.index != 0 ||
+		string((*chunk1)[1].text) != "world" || (*chunk1)[1].rank.index != 2 {
 		t.Error("Invalid data")
 	}
 	if chunk1.IsFull() {
@@ -46,7 +46,7 @@ func TestChunkList(t *testing.T) {
 
 	// Add more data
 	for i := 0; i < chunkSize*2; i++ {
-		cl.Push(fmt.Sprintf("item %d", i))
+		cl.Push([]rune(fmt.Sprintf("item %d", i)))
 	}
 
 	// Previous snapshot should remain the same
@@ -64,8 +64,8 @@ func TestChunkList(t *testing.T) {
 		t.Error("Unexpected number of items")
 	}
 
-	cl.Push("hello")
-	cl.Push("world")
+	cl.Push([]rune("hello"))
+	cl.Push([]rune("world"))
 
 	lastChunkCount := len(*snapshot[len(snapshot)-1])
 	if lastChunkCount != 2 {

src/core.go

@@ -63,24 +63,24 @@ func Run(opts *Options) {
 	eventBox := util.NewEventBox()
 
 	// ANSI code processor
-	ansiProcessor := func(data *string) (*string, []ansiOffset) {
+	ansiProcessor := func(runes []rune) ([]rune, []ansiOffset) {
 		// By default, we do nothing
-		return data, nil
+		return runes, nil
 	}
 	if opts.Ansi {
 		if opts.Theme != nil {
 			var state *ansiState
-			ansiProcessor = func(data *string) (*string, []ansiOffset) {
-				trimmed, offsets, newState := extractColor(data, state)
+			ansiProcessor = func(runes []rune) ([]rune, []ansiOffset) {
+				trimmed, offsets, newState := extractColor(string(runes), state)
 				state = newState
-				return trimmed, offsets
+				return []rune(trimmed), offsets
 			}
 		} else {
 			// When color is disabled but ansi option is given,
 			// we simply strip out ANSI codes from the input
-			ansiProcessor = func(data *string) (*string, []ansiOffset) {
-				trimmed, _, _ := extractColor(data, nil)
-				return trimmed, nil
+			ansiProcessor = func(runes []rune) ([]rune, []ansiOffset) {
+				trimmed, _, _ := extractColor(string(runes), nil)
+				return []rune(trimmed), nil
 			}
 		}
 	}
@@ -89,9 +89,9 @@ func Run(opts *Options) {
 	var chunkList *ChunkList
 	header := make([]string, 0, opts.HeaderLines)
 	if len(opts.WithNth) == 0 {
-		chunkList = NewChunkList(func(data *string, index int) *Item {
+		chunkList = NewChunkList(func(data []rune, index int) *Item {
 			if len(header) < opts.HeaderLines {
-				header = append(header, *data)
+				header = append(header, string(data))
 				eventBox.Set(EvtHeader, header)
 				return nil
 			}
@@ -103,17 +103,17 @@ func Run(opts *Options) {
 				rank:   Rank{0, 0, uint32(index)}}
 		})
 	} else {
-		chunkList = NewChunkList(func(data *string, index int) *Item {
+		chunkList = NewChunkList(func(data []rune, index int) *Item {
 			tokens := Tokenize(data, opts.Delimiter)
 			trans := Transform(tokens, opts.WithNth)
 			if len(header) < opts.HeaderLines {
-				header = append(header, *joinTokens(trans))
+				header = append(header, string(joinTokens(trans)))
 				eventBox.Set(EvtHeader, header)
 				return nil
 			}
 			item := Item{
 				text:     joinTokens(trans),
-				origText: data,
+				origText: &data,
 				index:    uint32(index),
 				colors:   nil,
 				rank:     Rank{0, 0, uint32(index)}}
@@ -128,8 +128,8 @@ func Run(opts *Options) {
 	// Reader
 	streamingFilter := opts.Filter != nil && !sort && !opts.Tac && !opts.Sync
 	if !streamingFilter {
-		reader := Reader{func(str string) bool {
-			return chunkList.Push(str)
+		reader := Reader{func(data []rune) bool {
+			return chunkList.Push(data)
 		}, eventBox, opts.ReadZero}
 		go reader.ReadSource()
 	}
@@ -151,10 +151,10 @@ func Run(opts *Options) {
 
 		if streamingFilter {
 			reader := Reader{
-				func(str string) bool {
-					item := chunkList.trans(&str, 0)
+				func(runes []rune) bool {
+					item := chunkList.trans(runes, 0)
 					if item != nil && pattern.MatchItem(item) {
-						fmt.Println(*item.text)
+						fmt.Println(string(item.text))
 					}
 					return false
 				}, eventBox, opts.ReadZero}

src/item.go

@@ -17,9 +17,9 @@ type colorOffset struct {
 
 // Item represents each input line
 type Item struct {
-	text        *string
-	origText    *string
-	transformed *[]Token
+	text        []rune
+	origText    *[]rune
+	transformed []Token
 	index       uint32
 	offsets     []Offset
 	colors      []ansiOffset
@@ -66,19 +66,19 @@ func (i *Item) Rank(cache bool) Rank {
 		// It is guaranteed that .transformed in not null in normal execution
 		if i.transformed != nil {
 			lenSum := 0
-			for _, token := range *i.transformed {
-				lenSum += len(*token.text)
+			for _, token := range i.transformed {
+				lenSum += len(token.text)
 			}
 			tiebreak = uint16(lenSum)
 		} else {
-			tiebreak = uint16(len(*i.text))
+			tiebreak = uint16(len(i.text))
 		}
 	case byBegin:
 		// We can't just look at i.offsets[0][0] because it can be an inverse term
 		tiebreak = uint16(minBegin)
 	case byEnd:
 		if prevEnd > 0 {
-			tiebreak = uint16(1 + len(*i.text) - prevEnd)
+			tiebreak = uint16(1 + len(i.text) - prevEnd)
 		} else {
 			// Empty offsets due to inverse terms.
 			tiebreak = 1
@@ -100,10 +100,12 @@ func (i *Item) AsString() string {
 
 // StringPtr returns the pointer to the original string
 func (i *Item) StringPtr() *string {
+	runes := i.text
 	if i.origText != nil {
-		return i.origText
+		runes = *i.origText
 	}
-	return i.text
+	str := string(runes)
+	return &str
 }
 
 func (item *Item) colorOffsets(color int, bold bool, current bool) []colorOffset {

src/item_test.go

@@ -39,14 +39,14 @@ func TestRankComparison(t *testing.T) {
 
 // Match length, string length, index
 func TestItemRank(t *testing.T) {
-	strs := []string{"foo", "foobar", "bar", "baz"}
-	item1 := Item{text: &strs[0], index: 1, offsets: []Offset{}}
+	strs := [][]rune{[]rune("foo"), []rune("foobar"), []rune("bar"), []rune("baz")}
+	item1 := Item{text: strs[0], index: 1, offsets: []Offset{}}
 	rank1 := item1.Rank(true)
 	if rank1.matchlen != 0 || rank1.tiebreak != 3 || rank1.index != 1 {
 		t.Error(item1.Rank(true))
 	}
 	// Only differ in index
-	item2 := Item{text: &strs[0], index: 0, offsets: []Offset{}}
+	item2 := Item{text: strs[0], index: 0, offsets: []Offset{}}
 
 	items := []*Item{&item1, &item2}
 	sort.Sort(ByRelevance(items))
@@ -62,10 +62,10 @@ func TestItemRank(t *testing.T) {
 	}
 
 	// Sort by relevance
-	item3 := Item{text: &strs[1], rank: Rank{0, 0, 2}, offsets: []Offset{Offset{1, 3}, Offset{5, 7}}}
-	item4 := Item{text: &strs[1], rank: Rank{0, 0, 2}, offsets: []Offset{Offset{1, 2}, Offset{6, 7}}}
-	item5 := Item{text: &strs[2], rank: Rank{0, 0, 2}, offsets: []Offset{Offset{1, 3}, Offset{5, 7}}}
-	item6 := Item{text: &strs[2], rank: Rank{0, 0, 2}, offsets: []Offset{Offset{1, 2}, Offset{6, 7}}}
+	item3 := Item{text: strs[1], rank: Rank{0, 0, 2}, offsets: []Offset{Offset{1, 3}, Offset{5, 7}}}
+	item4 := Item{text: strs[1], rank: Rank{0, 0, 2}, offsets: []Offset{Offset{1, 2}, Offset{6, 7}}}
+	item5 := Item{text: strs[2], rank: Rank{0, 0, 2}, offsets: []Offset{Offset{1, 3}, Offset{5, 7}}}
+	item6 := Item{text: strs[2], rank: Rank{0, 0, 2}, offsets: []Offset{Offset{1, 2}, Offset{6, 7}}}
 	items = []*Item{&item1, &item2, &item3, &item4, &item5, &item6}
 	sort.Sort(ByRelevance(items))
 	if items[0] != &item2 || items[1] != &item1 ||

src/merger_test.go

@@ -22,7 +22,7 @@ func randItem() *Item {
 		offsets[idx] = Offset{sidx, eidx}
 	}
 	return &Item{
-		text:    &str,
+		text:    []rune(str),
 		index:   rand.Uint32(),
 		offsets: offsets}
 }

src/pattern.go

@@ -44,7 +44,7 @@ type Pattern struct {
 	hasInvTerm    bool
 	delimiter     *regexp.Regexp
 	nth           []Range
-	procFun       map[termType]func(bool, *[]rune, []rune) (int, int)
+	procFun       map[termType]func(bool, []rune, []rune) (int, int)
 }
 
 var (
@@ -114,7 +114,7 @@ func BuildPattern(mode Mode, caseMode Case,
 		hasInvTerm:    hasInvTerm,
 		nth:           nth,
 		delimiter:     delimiter,
-		procFun:       make(map[termType]func(bool, *[]rune, []rune) (int, int))}
+		procFun:       make(map[termType]func(bool, []rune, []rune) (int, int))}
 
 	ptr.procFun[termFuzzy] = algo.FuzzyMatch
 	ptr.procFun[termEqual] = algo.EqualMatch
@@ -305,27 +305,25 @@ func (p *Pattern) extendedMatch(item *Item) []Offset {
 	return offsets
 }
 
-func (p *Pattern) prepareInput(item *Item) *[]Token {
+func (p *Pattern) prepareInput(item *Item) []Token {
 	if item.transformed != nil {
 		return item.transformed
 	}
 
-	var ret *[]Token
+	var ret []Token
 	if len(p.nth) > 0 {
 		tokens := Tokenize(item.text, p.delimiter)
 		ret = Transform(tokens, p.nth)
 	} else {
-		runes := []rune(*item.text)
-		trans := []Token{Token{text: &runes, prefixLength: 0}}
-		ret = &trans
+		ret = []Token{Token{text: item.text, prefixLength: 0}}
 	}
 	item.transformed = ret
 	return ret
 }
 
-func (p *Pattern) iter(pfun func(bool, *[]rune, []rune) (int, int),
-	tokens *[]Token, caseSensitive bool, pattern []rune) (int, int) {
-	for _, part := range *tokens {
+func (p *Pattern) iter(pfun func(bool, []rune, []rune) (int, int),
+	tokens []Token, caseSensitive bool, pattern []rune) (int, int) {
+	for _, part := range tokens {
 		prefixLength := part.prefixLength
 		if sidx, eidx := pfun(caseSensitive, part.text, pattern); sidx >= 0 {
 			return sidx + prefixLength, eidx + prefixLength

src/pattern_test.go

@@ -1,6 +1,7 @@
 package fzf
 
 import (
+	"reflect"
 	"testing"
 
 	"github.com/junegunn/fzf/src/algo"
@@ -59,8 +60,8 @@ func TestExact(t *testing.T) {
 	clearPatternCache()
 	pattern := BuildPattern(ModeExtended, CaseSmart,
 		[]Range{}, nil, []rune("'abc"))
-	runes := []rune("aabbcc abc")
-	sidx, eidx := algo.ExactMatchNaive(pattern.caseSensitive, &runes, pattern.terms[0].text)
+	sidx, eidx := algo.ExactMatchNaive(
+		pattern.caseSensitive, []rune("aabbcc abc"), pattern.terms[0].text)
 	if sidx != 7 || eidx != 10 {
 		t.Errorf("%s / %d / %d", pattern.terms, sidx, eidx)
 	}
@@ -72,8 +73,8 @@ func TestEqual(t *testing.T) {
 	pattern := BuildPattern(ModeExtended, CaseSmart, []Range{}, nil, []rune("^AbC$"))
 
 	match := func(str string, sidxExpected int, eidxExpected int) {
-		runes := []rune(str)
-		sidx, eidx := algo.EqualMatch(pattern.caseSensitive, &runes, pattern.terms[0].text)
+		sidx, eidx := algo.EqualMatch(
+			pattern.caseSensitive, []rune(str), pattern.terms[0].text)
 		if sidx != sidxExpected || eidx != eidxExpected {
 			t.Errorf("%s / %d / %d", pattern.terms, sidx, eidx)
 		}
@@ -108,25 +109,23 @@ func TestCaseSensitivity(t *testing.T) {
 }
 
 func TestOrigTextAndTransformed(t *testing.T) {
-	strptr := func(str string) *string {
-		return &str
-	}
 	pattern := BuildPattern(ModeExtended, CaseSmart, []Range{}, nil, []rune("jg"))
-	tokens := Tokenize(strptr("junegunn"), nil)
+	tokens := Tokenize([]rune("junegunn"), nil)
 	trans := Transform(tokens, []Range{Range{1, 1}})
 
+	origRunes := []rune("junegunn.choi")
 	for _, mode := range []Mode{ModeFuzzy, ModeExtended} {
 		chunk := Chunk{
 			&Item{
-				text:        strptr("junegunn"),
-				origText:    strptr("junegunn.choi"),
+				text:        []rune("junegunn"),
+				origText:    &origRunes,
 				transformed: trans},
 		}
 		pattern.mode = mode
 		matches := pattern.matchChunk(&chunk)
-		if *matches[0].text != "junegunn" || *matches[0].origText != "junegunn.choi" ||
+		if string(matches[0].text) != "junegunn" || string(*matches[0].origText) != "junegunn.choi" ||
 			matches[0].offsets[0][0] != 0 || matches[0].offsets[0][1] != 5 ||
-			matches[0].transformed != trans {
+			!reflect.DeepEqual(matches[0].transformed, trans) {
 			t.Error("Invalid match result", matches)
 		}
 	}

src/reader.go

@@ -5,13 +5,14 @@ import (
 	"io"
 	"os"
 	"os/exec"
+	"unicode/utf8"
 
 	"github.com/junegunn/fzf/src/util"
 )
 
 // Reader reads from command or standard input
 type Reader struct {
-	pusher   func(string) bool
+	pusher   func([]rune) bool
 	eventBox *util.EventBox
 	delimNil bool
 }
@@ -37,13 +38,25 @@ func (r *Reader) feed(src io.Reader) {
 	}
 	reader := bufio.NewReader(src)
 	for {
-		line, err := reader.ReadString(delim)
-		if line != "" {
-			// "ReadString returns err != nil if and only if the returned data does not end in delim."
+		// ReadBytes returns err != nil if and only if the returned data does not
+		// end in delim.
+		bytea, err := reader.ReadBytes(delim)
+		if len(bytea) > 0 {
+			runes := make([]rune, 0, len(bytea))
+			for i := 0; i < len(bytea); {
+				if bytea[i] < utf8.RuneSelf {
+					runes = append(runes, rune(bytea[i]))
+					i++
+				} else {
+					r, sz := utf8.DecodeRune(bytea[i:])
+					i += sz
+					runes = append(runes, r)
+				}
+			}
 			if err == nil {
-				line = line[:len(line)-1]
+				runes = runes[:len(runes)-1]
 			}
-			if r.pusher(line) {
+			if r.pusher(runes) {
 				r.eventBox.Set(EvtReadNew, nil)
 			}
 		}

src/reader_test.go

@@ -10,7 +10,7 @@ func TestReadFromCommand(t *testing.T) {
 	strs := []string{}
 	eb := util.NewEventBox()
 	reader := Reader{
-		pusher:   func(s string) bool { strs = append(strs, s); return true },
+		pusher:   func(s []rune) bool { strs = append(strs, string(s)); return true },
 		eventBox: eb}
 
 	// Check EventBox

src/terminal.go

@@ -441,10 +441,10 @@ func (t *Terminal) printHeader() {
 		if line >= max {
 			continue
 		}
-		trimmed, colors, newState := extractColor(&lineStr, state)
+		trimmed, colors, newState := extractColor(lineStr, state)
 		state = newState
 		item := &Item{
-			text:   trimmed,
+			text:   []rune(trimmed),
 			index:  0,
 			colors: colors,
 			rank:   Rank{0, 0, 0}}
@@ -537,7 +537,7 @@ func (t *Terminal) printHighlighted(item *Item, bold bool, col1 int, col2 int, c
 	}
 
 	// Overflow
-	text := []rune(*item.text)
+	text := item.text
 	offsets := item.colorOffsets(col2, bold, current)
 	maxWidth := C.MaxX() - 3 - t.marginInt[1] - t.marginInt[3]
 	fullWidth := displayWidth(text)

src/tokenizer.go

@@ -18,7 +18,7 @@ type Range struct {
 
 // Token contains the tokenized part of the strings and its prefix length
 type Token struct {
-	text         *[]rune
+	text         []rune
 	prefixLength int
 }
 
@@ -75,8 +75,7 @@ func withPrefixLengths(tokens []string, begin int) []Token {
 	for idx, token := range tokens {
 		// Need to define a new local variable instead of the reused token to take
 		// the pointer to it
-		runes := []rune(token)
-		ret[idx] = Token{text: &runes, prefixLength: prefixLength}
+		ret[idx] = Token{text: []rune(token), prefixLength: prefixLength}
 		prefixLength += len([]rune(token))
 	}
 	return ret
@@ -88,13 +87,13 @@ const (
 	awkWhite
 )
 
-func awkTokenizer(input *string) ([]string, int) {
+func awkTokenizer(input []rune) ([]string, int) {
 	// 9, 32
 	ret := []string{}
 	str := []rune{}
 	prefixLength := 0
 	state := awkNil
-	for _, r := range []rune(*input) {
+	for _, r := range input {
 		white := r == 9 || r == 32
 		switch state {
 		case awkNil:
@@ -126,34 +125,34 @@ func awkTokenizer(input *string) ([]string, int) {
 }
 
 // Tokenize tokenizes the given string with the delimiter
-func Tokenize(str *string, delimiter *regexp.Regexp) []Token {
+func Tokenize(runes []rune, delimiter *regexp.Regexp) []Token {
 	if delimiter == nil {
 		// AWK-style (\S+\s*)
-		tokens, prefixLength := awkTokenizer(str)
+		tokens, prefixLength := awkTokenizer(runes)
 		return withPrefixLengths(tokens, prefixLength)
 	}
-	tokens := delimiter.FindAllString(*str, -1)
+	tokens := delimiter.FindAllString(string(runes), -1)
 	return withPrefixLengths(tokens, 0)
 }
 
-func joinTokens(tokens *[]Token) *string {
-	ret := ""
-	for _, token := range *tokens {
-		ret += string(*token.text)
+func joinTokens(tokens []Token) []rune {
+	ret := []rune{}
+	for _, token := range tokens {
+		ret = append(ret, token.text...)
 	}
-	return &ret
+	return ret
 }
 
-func joinTokensAsRunes(tokens *[]Token) *[]rune {
+func joinTokensAsRunes(tokens []Token) []rune {
 	ret := []rune{}
-	for _, token := range *tokens {
-		ret = append(ret, *token.text...)
+	for _, token := range tokens {
+		ret = append(ret, token.text...)
 	}
-	return &ret
+	return ret
 }
 
 // Transform is used to transform the input when --with-nth option is given
-func Transform(tokens []Token, withNth []Range) *[]Token {
+func Transform(tokens []Token, withNth []Range) []Token {
 	transTokens := make([]Token, len(withNth))
 	numTokens := len(tokens)
 	for idx, r := range withNth {
@@ -162,14 +161,14 @@ func Transform(tokens []Token, withNth []Range) *[]Token {
 		if r.begin == r.end {
 			idx := r.begin
 			if idx == rangeEllipsis {
-				part = append(part, *joinTokensAsRunes(&tokens)...)
+				part = append(part, joinTokensAsRunes(tokens)...)
 			} else {
 				if idx < 0 {
 					idx += numTokens + 1
 				}
 				if idx >= 1 && idx <= numTokens {
 					minIdx = idx - 1
-					part = append(part, *tokens[idx-1].text...)
+					part = append(part, tokens[idx-1].text...)
 				}
 			}
 		} else {
@@ -196,7 +195,7 @@ func Transform(tokens []Token, withNth []Range) *[]Token {
 			minIdx = util.Max(0, begin-1)
 			for idx := begin; idx <= end; idx++ {
 				if idx >= 1 && idx <= numTokens {
-					part = append(part, *tokens[idx-1].text...)
+					part = append(part, tokens[idx-1].text...)
 				}
 			}
 		}
@@ -206,7 +205,7 @@ func Transform(tokens []Token, withNth []Range) *[]Token {
 		} else {
 			prefixLength = 0
 		}
-		transTokens[idx] = Token{&part, prefixLength}
+		transTokens[idx] = Token{part, prefixLength}
 	}
-	return &transTokens
+	return transTokens
 }

src/tokenizer_test.go

@@ -43,14 +43,14 @@ func TestParseRange(t *testing.T) {
 func TestTokenize(t *testing.T) {
 	// AWK-style
 	input := "  abc:  def:  ghi  "
-	tokens := Tokenize(&input, nil)
-	if string(*tokens[0].text) != "abc:  " || tokens[0].prefixLength != 2 {
+	tokens := Tokenize([]rune(input), nil)
+	if string(tokens[0].text) != "abc:  " || tokens[0].prefixLength != 2 {
 		t.Errorf("%s", tokens)
 	}
 
 	// With delimiter
-	tokens = Tokenize(&input, delimiterRegexp(":"))
-	if string(*tokens[0].text) != "  abc:" || tokens[0].prefixLength != 0 {
+	tokens = Tokenize([]rune(input), delimiterRegexp(":"))
+	if string(tokens[0].text) != "  abc:" || tokens[0].prefixLength != 0 {
 		t.Errorf("%s", tokens)
 	}
 }
@@ -58,39 +58,39 @@ func TestTokenize(t *testing.T) {
 func TestTransform(t *testing.T) {
 	input := "  abc:  def:  ghi:  jkl"
 	{
-		tokens := Tokenize(&input, nil)
+		tokens := Tokenize([]rune(input), nil)
 		{
 			ranges := splitNth("1,2,3")
 			tx := Transform(tokens, ranges)
-			if *joinTokens(tx) != "abc:  def:  ghi:  " {
-				t.Errorf("%s", *tx)
+			if string(joinTokens(tx)) != "abc:  def:  ghi:  " {
+				t.Errorf("%s", tx)
 			}
 		}
 		{
 			ranges := splitNth("1..2,3,2..,1")
 			tx := Transform(tokens, ranges)
-			if *joinTokens(tx) != "abc:  def:  ghi:  def:  ghi:  jklabc:  " ||
-				len(*tx) != 4 ||
-				string(*(*tx)[0].text) != "abc:  def:  " || (*tx)[0].prefixLength != 2 ||
-				string(*(*tx)[1].text) != "ghi:  " || (*tx)[1].prefixLength != 14 ||
-				string(*(*tx)[2].text) != "def:  ghi:  jkl" || (*tx)[2].prefixLength != 8 ||
-				string(*(*tx)[3].text) != "abc:  " || (*tx)[3].prefixLength != 2 {
-				t.Errorf("%s", *tx)
+			if string(joinTokens(tx)) != "abc:  def:  ghi:  def:  ghi:  jklabc:  " ||
+				len(tx) != 4 ||
+				string(tx[0].text) != "abc:  def:  " || tx[0].prefixLength != 2 ||
+				string(tx[1].text) != "ghi:  " || tx[1].prefixLength != 14 ||
+				string(tx[2].text) != "def:  ghi:  jkl" || tx[2].prefixLength != 8 ||
+				string(tx[3].text) != "abc:  " || tx[3].prefixLength != 2 {
+				t.Errorf("%s", tx)
 			}
 		}
 	}
 	{
-		tokens := Tokenize(&input, delimiterRegexp(":"))
+		tokens := Tokenize([]rune(input), delimiterRegexp(":"))
 		{
 			ranges := splitNth("1..2,3,2..,1")
 			tx := Transform(tokens, ranges)
-			if *joinTokens(tx) != "  abc:  def:  ghi:  def:  ghi:  jkl  abc:" ||
-				len(*tx) != 4 ||
-				string(*(*tx)[0].text) != "  abc:  def:" || (*tx)[0].prefixLength != 0 ||
-				string(*(*tx)[1].text) != "  ghi:" || (*tx)[1].prefixLength != 12 ||
-				string(*(*tx)[2].text) != "  def:  ghi:  jkl" || (*tx)[2].prefixLength != 6 ||
-				string(*(*tx)[3].text) != "  abc:" || (*tx)[3].prefixLength != 0 {
-				t.Errorf("%s", *tx)
+			if string(joinTokens(tx)) != "  abc:  def:  ghi:  def:  ghi:  jkl  abc:" ||
+				len(tx) != 4 ||
+				string(tx[0].text) != "  abc:  def:" || tx[0].prefixLength != 0 ||
+				string(tx[1].text) != "  ghi:" || tx[1].prefixLength != 12 ||
+				string(tx[2].text) != "  def:  ghi:  jkl" || tx[2].prefixLength != 6 ||
+				string(tx[3].text) != "  abc:" || tx[3].prefixLength != 0 {
+				t.Errorf("%s", tx)
 			}
 		}
 	}

src/util/util.go

@@ -78,13 +78,13 @@ func IsTty() bool {
 	return int(C.isatty(C.int(os.Stdin.Fd()))) != 0
 }
 
-func TrimRight(runes *[]rune) []rune {
+func TrimRight(runes []rune) []rune {
 	var i int
-	for i = len(*runes) - 1; i >= 0; i-- {
-		char := (*runes)[i]
+	for i = len(runes) - 1; i >= 0; i-- {
+		char := runes[i]
 		if char != ' ' && char != '\t' {
 			break
 		}
 	}
-	return (*runes)[0 : i+1]
+	return runes[0 : i+1]
 }