91 lines
1.6 KiB
Go
91 lines
1.6 KiB
Go
package liner
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import (
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"unicode"
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"github.com/mattn/go-runewidth"
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)
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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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// 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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// speed up the common case
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if r < 127 {
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n++
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continue
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}
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n += runewidth.RuneWidth(r)
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}
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return n
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}
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func countMultiLineGlyphs(s []rune, columns int, start int) int {
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n := start
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for _, r := range s {
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if r < 127 {
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n++
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continue
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}
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switch runewidth.RuneWidth(r) {
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case 0:
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case 1:
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n++
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case 2:
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n += 2
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// no room for a 2-glyphs-wide char in the ending
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// so skip a column and display it at the beginning
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if n%columns == 1 {
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n++
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}
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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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// speed up the common case
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if s[p] < 127 {
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n++
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continue
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}
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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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// speed up the common case
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if s[p-1] < 127 {
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n++
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continue
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}
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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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