61 lines
1.6 KiB
Go
61 lines
1.6 KiB
Go
package uniseg
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// EastAsianAmbiguousWidth specifies the monospace width for East Asian
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// characters classified as Ambiguous. The default is 1 but some rare fonts
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// render them with a width of 2.
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var EastAsianAmbiguousWidth = 1
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// runeWidth returns the monospace width for the given rune. The provided
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// grapheme property is a value mapped by the [graphemeCodePoints] table.
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//
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// Every rune has a width of 1, except for runes with the following properties
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// (evaluated in this order):
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//
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// - Control, CR, LF, Extend, ZWJ: Width of 0
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// - \u2e3a, TWO-EM DASH: Width of 3
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// - \u2e3b, THREE-EM DASH: Width of 4
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// - East-Asian width Fullwidth and Wide: Width of 2 (Ambiguous and Neutral
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// have a width of 1)
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// - Regional Indicator: Width of 2
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// - Extended Pictographic: Width of 2, unless Emoji Presentation is "No".
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func runeWidth(r rune, graphemeProperty int) int {
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switch graphemeProperty {
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case prControl, prCR, prLF, prExtend, prZWJ:
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return 0
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case prRegionalIndicator:
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return 2
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case prExtendedPictographic:
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if property(emojiPresentation, r) == prEmojiPresentation {
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return 2
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}
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return 1
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}
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switch r {
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case 0x2e3a:
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return 3
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case 0x2e3b:
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return 4
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}
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switch propertyEastAsianWidth(r) {
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case prW, prF:
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return 2
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case prA:
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return EastAsianAmbiguousWidth
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}
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return 1
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}
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// StringWidth returns the monospace width for the given string, that is, the
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// number of same-size cells to be occupied by the string.
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func StringWidth(s string) (width int) {
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state := -1
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for len(s) > 0 {
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var w int
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_, s, w, state = FirstGraphemeClusterInString(s, state)
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width += w
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}
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return
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}
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