Merge pull request #145 from mum4k/runewidth

Fixing the width of characters whose context is known.

CHANGELOG.md

@@ -48,6 +48,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   series are provided.
 - Lint issues in the codebase, and updated Travis configuration so that golint
   is executed on every run.
+- Termdash now correctly starts in locales like zh_CN.UTF-8 where some of the
+  characters it uses internally can have ambiguous width.
 
 ## [0.6.1] - 12-Feb-2019
 

align/align.go

@@ -20,7 +20,7 @@ import (
 	"image"
 	"strings"
 
-	runewidth "github.com/mattn/go-runewidth"
+	"github.com/mum4k/termdash/cell/runewidth"
 )
 
 // Horizontal indicates the type of horizontal alignment.

cell/cell.go

@@ -23,8 +23,8 @@ import (
 	"fmt"
 	"image"
 
-	runewidth "github.com/mattn/go-runewidth"
 	"github.com/mum4k/termdash/area"
+	"github.com/mum4k/termdash/cell/runewidth"
 )
 
 // Option is used to provide options for cells on a 2-D terminal.

cell/runewidth/runewidth.go

@@ -0,0 +1,98 @@
+// Copyright 2019 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package runewidth is a wrapper over github.com/mattn/go-runewidth which
+// gives different treatment to certain runes with ambiguous width.
+package runewidth
+
+import runewidth "github.com/mattn/go-runewidth"
+
+// RuneWidth returns the number of cells needed to draw r.
+// Background in http://www.unicode.org/reports/tr11/.
+//
+// Treats runes used internally by termdash as single-cell (half-width) runes
+// regardless of the locale. I.e. runes that are used to draw lines, boxes,
+// indicate resize or text trimming was needed and runes used by the braille
+// canvas.
+//
+// This should be safe, since even in locales where these runes have ambiguous
+// width, we still place all the character content around them so they should
+// have be half-width.
+func RuneWidth(r rune) int {
+	if inTable(r, exceptions) {
+		return 1
+	}
+	return runewidth.RuneWidth(r)
+}
+
+// StringWidth is like RuneWidth, but returns the number of cells occupied by
+// all the runes in the string.
+func StringWidth(s string) int {
+	var width int
+	for _, r := range []rune(s) {
+		width += RuneWidth(r)
+	}
+	return width
+}
+
+// inTable determines if the rune falls within the table.
+// Copied from github.com/mattn/go-runewidth/blob/master/runewidth.go.
+func inTable(r rune, t table) bool {
+	// func (t table) IncludesRune(r rune) bool {
+	if r < t[0].first {
+		return false
+	}
+
+	bot := 0
+	top := len(t) - 1
+	for top >= bot {
+		mid := (bot + top) >> 1
+
+		switch {
+		case t[mid].last < r:
+			bot = mid + 1
+		case t[mid].first > r:
+			top = mid - 1
+		default:
+			return true
+		}
+	}
+
+	return false
+}
+
+type interval struct {
+	first rune
+	last  rune
+}
+
+type table []interval
+
+// exceptions runes defined here are always considered to be half-width even if
+// they might be ambiguous in some contexts.
+var exceptions = table{
+	// Characters used by termdash to indicate text trim or scroll.
+	{0x2026, 0x2026},
+	{0x21c4, 0x21c4},
+	{0x21e7, 0x21e7},
+	{0x21e9, 0x21e9},
+
+	// Box drawing, used as line-styles.
+	// https://en.wikipedia.org/wiki/Box-drawing_character
+	{0x2500, 0x257F},
+
+	// Block elements used as sparks.
+	// https://en.wikipedia.org/wiki/Box-drawing_character
+	{0x2580, 0x258F},
+}

cell/runewidth/runewidth_test.go

@@ -0,0 +1,166 @@
+// Copyright 2019 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package runewidth
+
+import (
+	"testing"
+
+	runewidth "github.com/mattn/go-runewidth"
+)
+
+func TestRuneWidth(t *testing.T) {
+	tests := []struct {
+		desc      string
+		runes     []rune
+		eastAsian bool
+		want      int
+	}{
+		{
+			desc:  "ascii characters",
+			runes: []rune{'a', 'f', '#'},
+			want:  1,
+		},
+		{
+			desc:  "non-printable characters from mattn/runewidth/runewidth_test",
+			runes: []rune{'\x00', '\x01', '\u0300', '\u2028', '\u2029'},
+			want:  0,
+		},
+		{
+			desc:  "half-width runes from mattn/runewidth/runewidth_test",
+			runes: []rune{'ｾ', 'ｶ', 'ｲ', '☆'},
+			want:  1,
+		},
+		{
+			desc:  "full-width runes from mattn/runewidth/runewidth_test",
+			runes: []rune{'世', '界'},
+			want:  2,
+		},
+		{
+			desc:      "ambiguous so double-width in eastAsian from mattn/runewidth/runewidth_test",
+			runes:     []rune{'☆'},
+			eastAsian: true,
+			want:      2,
+		},
+		{
+			desc:  "braille runes",
+			runes: []rune{'⠀', '⠴', '⠷', '⣿'},
+			want:  1,
+		},
+		{
+			desc:      "braille runes in eastAsian",
+			runes:     []rune{'⠀', '⠴', '⠷', '⣿'},
+			eastAsian: true,
+			want:      1,
+		},
+		{
+			desc:  "termdash special runes",
+			runes: []rune{'⇄', '…', '⇧', '⇩'},
+			want:  1,
+		},
+		{
+			desc:      "termdash special runes in eastAsian",
+			runes:     []rune{'⇄', '…', '⇧', '⇩'},
+			eastAsian: true,
+			want:      1,
+		},
+		{
+			desc:  "termdash sparks",
+			runes: []rune{'▁', '▂', '▃', '▄', '▅', '▆', '▇', '█'},
+			want:  1,
+		},
+		{
+			desc:      "termdash sparks in eastAsian",
+			runes:     []rune{'▁', '▂', '▃', '▄', '▅', '▆', '▇', '█'},
+			eastAsian: true,
+			want:      1,
+		},
+		{
+			desc:  "termdash line styles",
+			runes: []rune{'─', '═', '─', '┼', '╬', '┼'},
+			want:  1,
+		},
+		{
+			desc:      "termdash line styles in eastAsian",
+			runes:     []rune{'─', '═', '─', '┼', '╬', '┼'},
+			eastAsian: true,
+			want:      1,
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.desc, func(t *testing.T) {
+			runewidth.DefaultCondition.EastAsianWidth = tc.eastAsian
+			defer func() {
+				runewidth.DefaultCondition.EastAsianWidth = false
+			}()
+
+			for _, r := range tc.runes {
+				if got := RuneWidth(r); got != tc.want {
+					t.Errorf("RuneWidth(%c, %#x) => %v, want %v", r, r, got, tc.want)
+				}
+			}
+		})
+	}
+}
+
+func TestStringWidth(t *testing.T) {
+	tests := []struct {
+		desc      string
+		str       string
+		eastAsian bool
+		want      int
+	}{
+		{
+			desc: "ascii characters",
+			str:  "hello",
+			want: 5,
+		},
+		{
+			desc: "string from mattn/runewidth/runewidth_test",
+			str:  "■㈱の世界①",
+			want: 10,
+		},
+		{
+			desc:      "string in eastAsian from mattn/runewidth/runewidth_test",
+			str:       "■㈱の世界①",
+			eastAsian: true,
+			want:      12,
+		},
+		{
+			desc: "string using termdash characters",
+			str:  "⇄…⇧⇩",
+			want: 4,
+		},
+		{
+			desc:      "string in eastAsien using termdash characters",
+			str:       "⇄…⇧⇩",
+			eastAsian: true,
+			want:      4,
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.desc, func(t *testing.T) {
+			runewidth.DefaultCondition.EastAsianWidth = tc.eastAsian
+			defer func() {
+				runewidth.DefaultCondition.EastAsianWidth = false
+			}()
+
+			if got := StringWidth(tc.str); got != tc.want {
+				t.Errorf("StringWidth(%q) => %v, want %v", tc.str, got, tc.want)
+			}
+		})
+	}
+}

draw/line_style.go

@@ -17,7 +17,7 @@ package draw
 import (
 	"fmt"
 
-	runewidth "github.com/mattn/go-runewidth"
+	"github.com/mum4k/termdash/cell/runewidth"
 )
 
 // line_style.go contains the Unicode characters used for drawing lines of

draw/text.go

@@ -21,9 +21,9 @@ import (
 	"fmt"
 	"image"
 
-	runewidth "github.com/mattn/go-runewidth"
 	"github.com/mum4k/termdash/canvas"
 	"github.com/mum4k/termdash/cell"
+	"github.com/mum4k/termdash/cell/runewidth"
 )
 
 // OverrunMode represents

widgets/donut/donut.go

@@ -22,10 +22,10 @@ import (
 	"image"
 	"sync"
 
-	runewidth "github.com/mattn/go-runewidth"
 	"github.com/mum4k/termdash/align"
 	"github.com/mum4k/termdash/canvas"
 	"github.com/mum4k/termdash/canvas/braille"
+	"github.com/mum4k/termdash/cell/runewidth"
 	"github.com/mum4k/termdash/draw"
 	"github.com/mum4k/termdash/numbers"
 	"github.com/mum4k/termdash/terminalapi"

widgets/gauge/gauge.go

@@ -22,11 +22,11 @@ import (
 	"image"
 	"sync"
 
-	runewidth "github.com/mattn/go-runewidth"
 	"github.com/mum4k/termdash/align"
 	"github.com/mum4k/termdash/area"
 	"github.com/mum4k/termdash/canvas"
 	"github.com/mum4k/termdash/cell"
+	"github.com/mum4k/termdash/cell/runewidth"
 	"github.com/mum4k/termdash/draw"
 	"github.com/mum4k/termdash/terminalapi"
 	"github.com/mum4k/termdash/widgetapi"

widgets/sparkline/sparks.go

@@ -20,7 +20,7 @@ package sparkline
 import (
 	"fmt"
 
-	runewidth "github.com/mattn/go-runewidth"
+	"github.com/mum4k/termdash/cell/runewidth"
 	"github.com/mum4k/termdash/numbers"
 )
 

widgets/text/line_scanner.go

@@ -20,7 +20,7 @@ import (
 	"strings"
 	"text/scanner"
 
-	runewidth "github.com/mattn/go-runewidth"
+	"github.com/mum4k/termdash/cell/runewidth"
 )
 
 // wrapNeeded returns true if wrapping is needed for the rune at the horizontal

widgets/text/line_trim.go

@@ -18,8 +18,8 @@ import (
 	"fmt"
 	"image"
 
-	runewidth "github.com/mattn/go-runewidth"
 	"github.com/mum4k/termdash/canvas"
+	"github.com/mum4k/termdash/cell/runewidth"
 )
 
 // line_trim.go contains code that trims lines that are too long.