Godeps/_workspace/src/github.com/peterh/liner/width.go


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package liner

import "unicode"

// These character classes are mostly zero width (when combined).
// A few might not be, depending on the user's font. Fixing this
// is non-trivial, given that some terminals don't support
// ANSI DSR/CPR
var zeroWidth = []*unicode.RangeTable{
    unicode.Mn,
    unicode.Me,
    unicode.Cc,
    unicode.Cf,
}

func countGlyphs(s []rune) int {
    n := 0
    for _, r := range s {
        if !unicode.IsOneOf(zeroWidth, r) {
            n++
        }
    }
    return n
}

func getPrefixGlyphs(s []rune, num int) []rune {
    p := 0
    for n := 0; n < num && p < len(s); p++ {
        if !unicode.IsOneOf(zeroWidth, s[p]) {
            n++
        }
    }
    for p < len(s) && unicode.IsOneOf(zeroWidth, s[p]) {
        p++
    }
    return s[:p]
}

func getSuffixGlyphs(s []rune, num int) []rune {
    p := len(s)
    for n := 0; n < num && p > 0; p-- {
        if !unicode.IsOneOf(zeroWidth, s[p-1]) {
            n++
        }
    }
    return s[p:]
}