From 5aaa3e93c1ef035b0760e5c1b678b4f168f5d8de Mon Sep 17 00:00:00 2001 From: greatroar <61184462+greatroar@users.noreply.github.com> Date: Sun, 29 Aug 2021 14:54:15 +0200 Subject: [PATCH] internal/ui/termstatus: Optimize and publish Truncate MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit name old time/op new time/op delta TruncateASCII-8 347ns ± 1% 69ns ± 1% -80.02% (p=0.000 n=9+10) TruncateUnicode-8 447ns ± 3% 348ns ± 1% -22.04% (p=0.000 n=10+10) --- internal/ui/termstatus/status.go | 24 ++++++++++++--------- internal/ui/termstatus/status_test.go | 30 ++++++++++++++++++++++++--- 2 files changed, 41 insertions(+), 13 deletions(-) diff --git a/internal/ui/termstatus/status.go b/internal/ui/termstatus/status.go index e275f5b7d..ce6593f37 100644 --- a/internal/ui/termstatus/status.go +++ b/internal/ui/termstatus/status.go @@ -8,6 +8,7 @@ import ( "io" "os" "strings" + "unicode" "golang.org/x/crypto/ssh/terminal" "golang.org/x/text/width" @@ -280,7 +281,7 @@ func (t *Terminal) Errorf(msg string, args ...interface{}) { // Truncate s to fit in width (number of terminal cells) w. // If w is negative, returns the empty string. -func truncate(s string, w int) string { +func Truncate(s string, w int) string { if len(s) < w { // Since the display width of a character is at most 2 // and all of ASCII (single byte per rune) has width 1, @@ -289,16 +290,11 @@ func truncate(s string, w int) string { } for i, r := range s { - // Determine width of the rune. This cannot be determined without - // knowing the terminal font, so let's just be careful and treat - // all ambigous characters as full-width, i.e., two cells. - wr := 2 - switch width.LookupRune(r).Kind() { - case width.Neutral, width.EastAsianNarrow: - wr = 1 + w-- + if r > unicode.MaxASCII && wideRune(r) { + w-- } - w -= wr if w < 0 { return s[:i] } @@ -307,6 +303,14 @@ func truncate(s string, w int) string { return s } +// Guess whether r would occupy two terminal cells instead of one. +// This cannot be determined exactly without knowing the terminal font, +// so we treat all ambigous runes as full-width, i.e., two cells. +func wideRune(r rune) bool { + kind := width.LookupRune(r).Kind() + return kind != width.Neutral && kind != width.EastAsianNarrow +} + // SetStatus updates the status lines. func (t *Terminal) SetStatus(lines []string) { if len(lines) == 0 { @@ -328,7 +332,7 @@ func (t *Terminal) SetStatus(lines []string) { for i, line := range lines { line = strings.TrimRight(line, "\n") if width > 0 { - line = truncate(line, width-2) + line = Truncate(line, width-2) } lines[i] = line + "\n" } diff --git a/internal/ui/termstatus/status_test.go b/internal/ui/termstatus/status_test.go index d22605e31..ce18f42e6 100644 --- a/internal/ui/termstatus/status_test.go +++ b/internal/ui/termstatus/status_test.go @@ -19,13 +19,14 @@ func TestTruncate(t *testing.T) { {"foo", 0, ""}, {"foo", -1, ""}, {"Löwen", 4, "Löwe"}, - {"あああああああああ/data", 10, "あああああ"}, - {"あああああああああ/data", 11, "あああああ"}, + {"あああああ/data", 7, "あああ"}, + {"あああああ/data", 10, "あああああ"}, + {"あああああ/data", 11, "あああああ/"}, } for _, test := range tests { t.Run("", func(t *testing.T) { - out := truncate(test.input, test.width) + out := Truncate(test.input, test.width) if out != test.output { t.Fatalf("wrong output for input %v, width %d: want %q, got %q", test.input, test.width, test.output, out) @@ -33,3 +34,26 @@ func TestTruncate(t *testing.T) { }) } } + +func benchmarkTruncate(b *testing.B, s string, w int) { + for i := 0; i < b.N; i++ { + Truncate(s, w) + } +} + +func BenchmarkTruncateASCII(b *testing.B) { + s := "This is an ASCII-only status message...\r\n" + benchmarkTruncate(b, s, len(s)-1) +} + +func BenchmarkTruncateUnicode(b *testing.B) { + s := "Hello World or Καλημέρα κόσμε or こんにちは 世界" + w := 0 + for _, r := range s { + w++ + if wideRune(r) { + w++ + } + } + benchmarkTruncate(b, s, w-1) +}