From c30e486b648c1540a660802a5015aeca208274fa Mon Sep 17 00:00:00 2001
From: Junegunn Choi <junegunn.c@gmail.com>
Date: Tue, 2 Apr 2024 08:43:08 +0900
Subject: [PATCH] Further performance improvements by removing unnecessary
 copies

---
 CHANGELOG.md      |  5 ++++-
 src/ansi.go       |  2 +-
 src/core.go       | 10 +++++++---
 src/tokenizer.go  |  4 ++--
 src/util/chars.go |  2 +-
 5 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index d5f66a6..a91d7b0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,7 +3,10 @@ CHANGELOG
 
 0.49.0
 ------
-- Ingestion performance improved by around 40%
+- Performance improvements
+    - Ingestion performance improved by 40%
+    - `--ansi` performance improved by 50%
+    - `--with-nth` performance improved by 30%
 - Added two environment variables exported to the child processes
     - `FZF_PREVIEW_LABEL`
     - `FZF_BORDER_LABEL`
diff --git a/src/ansi.go b/src/ansi.go
index e917a4f..53fae95 100644
--- a/src/ansi.go
+++ b/src/ansi.go
@@ -312,7 +312,7 @@ func parseAnsiCode(s string, delimiter byte) (int, byte, string) {
 		// Inlined version of strconv.Atoi() that only handles positive
 		// integers and does not allocate on error.
 		code := 0
-		for _, ch := range []byte(s) {
+		for _, ch := range sbytes(s) {
 			ch -= '0'
 			if ch > 9 {
 				return -1, delimiter, remaining
diff --git a/src/core.go b/src/core.go
index 1006109..ae5e58b 100644
--- a/src/core.go
+++ b/src/core.go
@@ -23,6 +23,10 @@ func ustring(data []byte) string {
 	return unsafe.String(unsafe.SliceData(data), len(data))
 }
 
+func sbytes(data string) []byte {
+	return unsafe.Slice(unsafe.StringData(data), len(data))
+}
+
 // Run starts fzf
 func Run(opts *Options, version string, revision string) {
 	sort := opts.Sort > 0
@@ -52,14 +56,14 @@ func Run(opts *Options, version string, revision string) {
 				prevLineAnsiState = lineAnsiState
 				trimmed, offsets, newState := extractColor(ustring(data), lineAnsiState, nil)
 				lineAnsiState = newState
-				return util.ToChars([]byte(trimmed)), offsets
+				return util.ToChars(sbytes(trimmed)), offsets
 			}
 		} else {
 			// When color is disabled but ansi option is given,
 			// we simply strip out ANSI codes from the input
 			ansiProcessor = func(data []byte) (util.Chars, *[]ansiOffset) {
 				trimmed, _, _ := extractColor(ustring(data), nil, nil)
-				return util.ToChars([]byte(trimmed)), nil
+				return util.ToChars(sbytes(trimmed)), nil
 			}
 		}
 	}
@@ -106,7 +110,7 @@ func Run(opts *Options, version string, revision string) {
 				eventBox.Set(EvtHeader, header)
 				return false
 			}
-			item.text, item.colors = ansiProcessor([]byte(transformed))
+			item.text, item.colors = ansiProcessor(sbytes(transformed))
 			item.text.TrimTrailingWhitespaces()
 			item.text.Index = itemIndex
 			item.origText = &data
diff --git a/src/tokenizer.go b/src/tokenizer.go
index 9f9e2c1..defe8cc 100644
--- a/src/tokenizer.go
+++ b/src/tokenizer.go
@@ -91,7 +91,7 @@ func withPrefixLengths(tokens []string, begin int) []Token {
 
 	prefixLength := begin
 	for idx := range tokens {
-		chars := util.ToChars([]byte(tokens[idx]))
+		chars := util.ToChars(sbytes(tokens[idx]))
 		ret[idx] = Token{&chars, int32(prefixLength)}
 		prefixLength += chars.Length()
 	}
@@ -187,7 +187,7 @@ func Transform(tokens []Token, withNth []Range) []Token {
 		if r.begin == r.end {
 			idx := r.begin
 			if idx == rangeEllipsis {
-				chars := util.ToChars([]byte(joinTokens(tokens)))
+				chars := util.ToChars(sbytes(joinTokens(tokens)))
 				parts = append(parts, &chars)
 			} else {
 				if idx < 0 {
diff --git a/src/util/chars.go b/src/util/chars.go
index 41de924..f946da8 100644
--- a/src/util/chars.go
+++ b/src/util/chars.go
@@ -163,7 +163,7 @@ func (chars *Chars) ToString() string {
 	if runes := chars.optionalRunes(); runes != nil {
 		return string(runes)
 	}
-	return string(chars.slice)
+	return unsafe.String(unsafe.SliceData(chars.slice), len(chars.slice))
 }
 
 func (chars *Chars) ToRunes() []rune {