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// Copyright 2015 Huan Du. All rights reserved.
// Licensed under the MIT license that can be found in the LICENSE file.
package xstrings
import (
"unicode"
"unicode/utf8"
)
// Len returns str's utf8 rune length.
func Len(str string) int {
return utf8.RuneCountInString(str)
}
// WordCount returns number of words in a string.
//
// Word is defined as a locale dependent string containing alphabetic characters,
// which may also contain but not start with `'` and `-` characters.
func WordCount(str string) int {
var r rune
var size, n int
inWord := false
for len(str) > 0 {
r, size = utf8.DecodeRuneInString(str)
switch {
case isAlphabet(r):
if !inWord {
inWord = true
n++
}
case inWord && (r == '\'' || r == '-'):
// Still in word.
default:
inWord = false
}
str = str[size:]
}
return n
}
const minCJKCharacter = '\u3400'
// Checks r is a letter but not CJK character.
func isAlphabet(r rune) bool {
if !unicode.IsLetter(r) {
return false
}
switch {
// Quick check for non-CJK character.
case r < minCJKCharacter:
return true
// Common CJK characters.
case r >= '\u4E00' && r <= '\u9FCC':
return false
// Rare CJK characters.
case r >= '\u3400' && r <= '\u4D85':
return false
// Rare and historic CJK characters.
case r >= '\U00020000' && r <= '\U0002B81D':
return false
}
return true
}
// Width returns string width in monotype font.
// Multi-byte characters are usually twice the width of single byte characters.
//
// Algorithm comes from `mb_strwidth` in PHP.
// http://php.net/manual/en/function.mb-strwidth.php
func Width(str string) int {
var r rune
var size, n int
for len(str) > 0 {
r, size = utf8.DecodeRuneInString(str)
n += RuneWidth(r)
str = str[size:]
}
return n
}
// RuneWidth returns character width in monotype font.
// Multi-byte characters are usually twice the width of single byte characters.
//
// Algorithm comes from `mb_strwidth` in PHP.
// http://php.net/manual/en/function.mb-strwidth.php
func RuneWidth(r rune) int {
switch {
case r == utf8.RuneError || r < '\x20':
return 0
case '\x20' <= r && r < '\u2000':
return 1
case '\u2000' <= r && r < '\uFF61':
return 2
case '\uFF61' <= r && r < '\uFFA0':
return 1
case '\uFFA0' <= r:
return 2
}
return 0
}
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