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