forked from mirror/ledisdb
61 lines
1.2 KiB
Go
61 lines
1.2 KiB
Go
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package liner
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import "unicode"
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// These character classes are mostly zero width (when combined).
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// A few might not be, depending on the user's font. Fixing this
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// is non-trivial, given that some terminals don't support
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// ANSI DSR/CPR
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var zeroWidth = []*unicode.RangeTable{
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unicode.Mn,
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unicode.Me,
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unicode.Cc,
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unicode.Cf,
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}
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var doubleWidth = []*unicode.RangeTable{
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unicode.Han,
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unicode.Hangul,
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unicode.Hiragana,
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unicode.Katakana,
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}
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// countGlyphs considers zero-width characters to be zero glyphs wide,
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// and members of Chinese, Japanese, and Korean scripts to be 2 glyphs wide.
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func countGlyphs(s []rune) int {
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n := 0
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for _, r := range s {
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switch {
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case unicode.IsOneOf(zeroWidth, r):
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case unicode.IsOneOf(doubleWidth, r):
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n += 2
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default:
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n++
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}
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}
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return n
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}
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func getPrefixGlyphs(s []rune, num int) []rune {
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p := 0
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for n := 0; n < num && p < len(s); p++ {
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if !unicode.IsOneOf(zeroWidth, s[p]) {
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n++
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}
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}
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for p < len(s) && unicode.IsOneOf(zeroWidth, s[p]) {
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p++
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}
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return s[:p]
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}
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func getSuffixGlyphs(s []rune, num int) []rune {
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p := len(s)
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for n := 0; n < num && p > 0; p-- {
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if !unicode.IsOneOf(zeroWidth, s[p-1]) {
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n++
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}
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}
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return s[p:]
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}
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