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package runewidth
import (
"os"
"github.com/rivo/uniseg"
)
//go:generate go run script/generate.go
var (
// EastAsianWidth will be set true if the current locale is CJK
EastAsianWidth bool
// DefaultCondition is a condition in current locale
DefaultCondition = &Condition{}
)
func init() {
handleEnv()
}
func handleEnv() {
env := os.Getenv("RUNEWIDTH_EASTASIAN")
if env == "" {
EastAsianWidth = IsEastAsian()
} else {
EastAsianWidth = env == "1"
}
// update DefaultCondition
DefaultCondition.EastAsianWidth = EastAsianWidth
}
type interval struct {
first rune
last rune
}
type table []interval
func inTables(r rune, ts ...table) bool {
for _, t := range ts {
if inTable(r, t) {
return true
}
}
return false
}
func inTable(r rune, t table) 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
}
var private = table{
{0x00E000, 0x00F8FF}, {0x0F0000, 0x0FFFFD}, {0x100000, 0x10FFFD},
}
var nonprint = table{
{0x0000, 0x001F}, {0x007F, 0x009F}, {0x00AD, 0x00AD},
{0x070F, 0x070F}, {0x180B, 0x180E}, {0x200B, 0x200F},
{0x2028, 0x202E}, {0x206A, 0x206F}, {0xD800, 0xDFFF},
{0xFEFF, 0xFEFF}, {0xFFF9, 0xFFFB}, {0xFFFE, 0xFFFF},
}
// Condition have flag EastAsianWidth whether the current locale is CJK or not.
type Condition struct {
EastAsianWidth bool
}
// NewCondition return new instance of Condition which is current locale.
func NewCondition() *Condition {
return &Condition{
EastAsianWidth: EastAsianWidth,
}
}
// RuneWidth returns the number of cells in r.
// See http://www.unicode.org/reports/tr11/
func (c *Condition) RuneWidth(r rune) int {
switch {
case r < 0 || r > 0x10FFFF || inTables(r, nonprint, combining, notassigned):
return 0
case (c.EastAsianWidth && IsAmbiguousWidth(r)) || inTables(r, doublewidth):
return 2
default:
return 1
}
}
// StringWidth return width as you can see
func (c *Condition) StringWidth(s string) (width int) {
g := uniseg.NewGraphemes(s)
for g.Next() {
var chWidth int
for _, r := range g.Runes() {
chWidth = c.RuneWidth(r)
if chWidth > 0 {
break // Our best guess at this point is to use the width of the first non-zero-width rune.
}
}
width += chWidth
}
return
}
// Truncate return string truncated with w cells
func (c *Condition) Truncate(s string, w int, tail string) string {
if c.StringWidth(s) <= w {
return s
}
w -= c.StringWidth(tail)
var width int
pos := len(s)
g := uniseg.NewGraphemes(s)
for g.Next() {
var chWidth int
for _, r := range g.Runes() {
chWidth = c.RuneWidth(r)
if chWidth > 0 {
break // See StringWidth() for details.
}
}
if width+chWidth > w {
pos, _ = g.Positions()
break
}
width += chWidth
}
return s[:pos] + tail
}
// Wrap return string wrapped with w cells
func (c *Condition) Wrap(s string, w int) string {
width := 0
out := ""
for _, r := range []rune(s) {
cw := c.RuneWidth(r)
if r == '\n' {
out += string(r)
width = 0
continue
} else if width+cw > w {
out += "\n"
width = 0
out += string(r)
width += cw
continue
}
out += string(r)
width += cw
}
return out
}
// FillLeft return string filled in left by spaces in w cells
func (c *Condition) FillLeft(s string, w int) string {
width := c.StringWidth(s)
count := w - width
if count > 0 {
b := make([]byte, count)
for i := range b {
b[i] = ' '
}
return string(b) + s
}
return s
}
// FillRight return string filled in left by spaces in w cells
func (c *Condition) FillRight(s string, w int) string {
width := c.StringWidth(s)
count := w - width
if count > 0 {
b := make([]byte, count)
for i := range b {
b[i] = ' '
}
return s + string(b)
}
return s
}
// RuneWidth returns the number of cells in r.
// See http://www.unicode.org/reports/tr11/
func RuneWidth(r rune) int {
return DefaultCondition.RuneWidth(r)
}
// IsAmbiguousWidth returns whether is ambiguous width or not.
func IsAmbiguousWidth(r rune) bool {
return inTables(r, private, ambiguous)
}
// IsNeutralWidth returns whether is neutral width or not.
func IsNeutralWidth(r rune) bool {
return inTable(r, neutral)
}
// StringWidth return width as you can see
func StringWidth(s string) (width int) {
return DefaultCondition.StringWidth(s)
}
// Truncate return string truncated with w cells
func Truncate(s string, w int, tail string) string {
return DefaultCondition.Truncate(s, w, tail)
}
// Wrap return string wrapped with w cells
func Wrap(s string, w int) string {
return DefaultCondition.Wrap(s, w)
}
// FillLeft return string filled in left by spaces in w cells
func FillLeft(s string, w int) string {
return DefaultCondition.FillLeft(s, w)
}
// FillRight return string filled in left by spaces in w cells
func FillRight(s string, w int) string {
return DefaultCondition.FillRight(s, w)
}
|
