diff options
Diffstat (limited to 'vendor/github.com/peterh/liner/width.go')
-rw-r--r-- | vendor/github.com/peterh/liner/width.go | 79 |
1 files changed, 79 insertions, 0 deletions
diff --git a/vendor/github.com/peterh/liner/width.go b/vendor/github.com/peterh/liner/width.go new file mode 100644 index 000000000..d8984aae9 --- /dev/null +++ b/vendor/github.com/peterh/liner/width.go @@ -0,0 +1,79 @@ +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, +} + +var doubleWidth = []*unicode.RangeTable{ + unicode.Han, + unicode.Hangul, + unicode.Hiragana, + unicode.Katakana, +} + +// countGlyphs considers zero-width characters to be zero glyphs wide, +// and members of Chinese, Japanese, and Korean scripts to be 2 glyphs wide. +func countGlyphs(s []rune) int { + n := 0 + for _, r := range s { + switch { + case unicode.IsOneOf(zeroWidth, r): + case unicode.IsOneOf(doubleWidth, r): + n += 2 + default: + n++ + } + } + return n +} + +func countMultiLineGlyphs(s []rune, columns int, start int) int { + n := start + for _, r := range s { + switch { + case unicode.IsOneOf(zeroWidth, r): + case unicode.IsOneOf(doubleWidth, r): + n += 2 + // no room for a 2-glyphs-wide char in the ending + // so skip a column and display it at the beginning + if n%columns == 1 { + n++ + } + default: + 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:] +} |