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283 lines
8.2 KiB
Go
283 lines
8.2 KiB
Go
package uniseg
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import "unicode/utf8"
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// The states of the word break parser.
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const (
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wbAny = iota
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wbCR
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wbLF
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wbNewline
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wbWSegSpace
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wbHebrewLetter
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wbALetter
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wbWB7
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wbWB7c
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wbNumeric
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wbWB11
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wbKatakana
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wbExtendNumLet
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wbOddRI
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wbEvenRI
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wbZWJBit = 16 // This bit is set for any states followed by at least one zero-width joiner (see WB4 and WB3c).
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)
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// wbTransitions implements the word break parser's state transitions. It's
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// anologous to [grTransitions], see comments there for details.
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//
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// Unicode version 15.0.0.
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func wbTransitions(state, prop int) (newState int, wordBreak bool, rule int) {
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switch uint64(state) | uint64(prop)<<32 {
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// WB3b.
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case wbAny | prNewline<<32:
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return wbNewline, true, 32
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case wbAny | prCR<<32:
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return wbCR, true, 32
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case wbAny | prLF<<32:
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return wbLF, true, 32
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// WB3a.
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case wbNewline | prAny<<32:
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return wbAny, true, 31
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case wbCR | prAny<<32:
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return wbAny, true, 31
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case wbLF | prAny<<32:
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return wbAny, true, 31
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// WB3.
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case wbCR | prLF<<32:
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return wbLF, false, 30
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// WB3d.
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case wbAny | prWSegSpace<<32:
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return wbWSegSpace, true, 9990
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case wbWSegSpace | prWSegSpace<<32:
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return wbWSegSpace, false, 34
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// WB5.
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case wbAny | prALetter<<32:
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return wbALetter, true, 9990
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case wbAny | prHebrewLetter<<32:
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return wbHebrewLetter, true, 9990
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case wbALetter | prALetter<<32:
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return wbALetter, false, 50
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case wbALetter | prHebrewLetter<<32:
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return wbHebrewLetter, false, 50
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case wbHebrewLetter | prALetter<<32:
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return wbALetter, false, 50
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case wbHebrewLetter | prHebrewLetter<<32:
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return wbHebrewLetter, false, 50
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// WB7. Transitions to wbWB7 handled by transitionWordBreakState().
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case wbWB7 | prALetter<<32:
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return wbALetter, false, 70
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case wbWB7 | prHebrewLetter<<32:
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return wbHebrewLetter, false, 70
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// WB7a.
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case wbHebrewLetter | prSingleQuote<<32:
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return wbAny, false, 71
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// WB7c. Transitions to wbWB7c handled by transitionWordBreakState().
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case wbWB7c | prHebrewLetter<<32:
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return wbHebrewLetter, false, 73
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// WB8.
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case wbAny | prNumeric<<32:
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return wbNumeric, true, 9990
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case wbNumeric | prNumeric<<32:
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return wbNumeric, false, 80
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// WB9.
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case wbALetter | prNumeric<<32:
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return wbNumeric, false, 90
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case wbHebrewLetter | prNumeric<<32:
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return wbNumeric, false, 90
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// WB10.
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case wbNumeric | prALetter<<32:
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return wbALetter, false, 100
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case wbNumeric | prHebrewLetter<<32:
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return wbHebrewLetter, false, 100
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// WB11. Transitions to wbWB11 handled by transitionWordBreakState().
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case wbWB11 | prNumeric<<32:
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return wbNumeric, false, 110
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// WB13.
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case wbAny | prKatakana<<32:
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return wbKatakana, true, 9990
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case wbKatakana | prKatakana<<32:
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return wbKatakana, false, 130
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// WB13a.
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case wbAny | prExtendNumLet<<32:
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return wbExtendNumLet, true, 9990
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case wbALetter | prExtendNumLet<<32:
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return wbExtendNumLet, false, 131
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case wbHebrewLetter | prExtendNumLet<<32:
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return wbExtendNumLet, false, 131
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case wbNumeric | prExtendNumLet<<32:
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return wbExtendNumLet, false, 131
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case wbKatakana | prExtendNumLet<<32:
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return wbExtendNumLet, false, 131
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case wbExtendNumLet | prExtendNumLet<<32:
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return wbExtendNumLet, false, 131
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// WB13b.
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case wbExtendNumLet | prALetter<<32:
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return wbALetter, false, 132
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case wbExtendNumLet | prHebrewLetter<<32:
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return wbHebrewLetter, false, 132
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case wbExtendNumLet | prNumeric<<32:
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return wbNumeric, false, 132
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case wbExtendNumLet | prKatakana<<32:
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return wbKatakana, false, 132
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default:
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return -1, false, -1
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}
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}
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// transitionWordBreakState determines the new state of the word break parser
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// given the current state and the next code point. It also returns whether a
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// word boundary was detected. If more than one code point is needed to
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// determine the new state, the byte slice or the string starting after rune "r"
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// can be used (whichever is not nil or empty) for further lookups.
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func transitionWordBreakState(state int, r rune, b []byte, str string) (newState int, wordBreak bool) {
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// Determine the property of the next character.
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nextProperty := property(workBreakCodePoints, r)
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// "Replacing Ignore Rules".
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if nextProperty == prZWJ {
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// WB4 (for zero-width joiners).
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if state == wbNewline || state == wbCR || state == wbLF {
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return wbAny | wbZWJBit, true // Make sure we don't apply WB4 to WB3a.
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}
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if state < 0 {
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return wbAny | wbZWJBit, false
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}
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return state | wbZWJBit, false
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} else if nextProperty == prExtend || nextProperty == prFormat {
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// WB4 (for Extend and Format).
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if state == wbNewline || state == wbCR || state == wbLF {
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return wbAny, true // Make sure we don't apply WB4 to WB3a.
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}
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if state == wbWSegSpace || state == wbAny|wbZWJBit {
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return wbAny, false // We don't break but this is also not WB3d or WB3c.
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}
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if state < 0 {
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return wbAny, false
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}
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return state, false
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} else if nextProperty == prExtendedPictographic && state >= 0 && state&wbZWJBit != 0 {
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// WB3c.
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return wbAny, false
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}
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if state >= 0 {
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state = state &^ wbZWJBit
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}
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// Find the applicable transition in the table.
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var rule int
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newState, wordBreak, rule = wbTransitions(state, nextProperty)
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if newState < 0 {
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// No specific transition found. Try the less specific ones.
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anyPropState, anyPropWordBreak, anyPropRule := wbTransitions(state, prAny)
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anyStateState, anyStateWordBreak, anyStateRule := wbTransitions(wbAny, nextProperty)
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if anyPropState >= 0 && anyStateState >= 0 {
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// Both apply. We'll use a mix (see comments for grTransitions).
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newState, wordBreak, rule = anyStateState, anyStateWordBreak, anyStateRule
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if anyPropRule < anyStateRule {
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wordBreak, rule = anyPropWordBreak, anyPropRule
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}
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} else if anyPropState >= 0 {
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// We only have a specific state.
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newState, wordBreak, rule = anyPropState, anyPropWordBreak, anyPropRule
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// This branch will probably never be reached because okAnyState will
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// always be true given the current transition map. But we keep it here
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// for future modifications to the transition map where this may not be
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// true anymore.
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} else if anyStateState >= 0 {
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// We only have a specific property.
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newState, wordBreak, rule = anyStateState, anyStateWordBreak, anyStateRule
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} else {
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// No known transition. WB999: Any ÷ Any.
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newState, wordBreak, rule = wbAny, true, 9990
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}
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}
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// For those rules that need to look up runes further in the string, we
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// determine the property after nextProperty, skipping over Format, Extend,
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// and ZWJ (according to WB4). It's -1 if not needed, if such a rune cannot
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// be determined (because the text ends or the rune is faulty).
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farProperty := -1
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if rule > 60 &&
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(state == wbALetter || state == wbHebrewLetter || state == wbNumeric) &&
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(nextProperty == prMidLetter || nextProperty == prMidNumLet || nextProperty == prSingleQuote || // WB6.
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nextProperty == prDoubleQuote || // WB7b.
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nextProperty == prMidNum) { // WB12.
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for {
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var (
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r rune
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length int
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)
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if b != nil { // Byte slice version.
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r, length = utf8.DecodeRune(b)
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b = b[length:]
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} else { // String version.
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r, length = utf8.DecodeRuneInString(str)
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str = str[length:]
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}
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if r == utf8.RuneError {
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break
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}
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prop := property(workBreakCodePoints, r)
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if prop == prExtend || prop == prFormat || prop == prZWJ {
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continue
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}
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farProperty = prop
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break
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}
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}
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// WB6.
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if rule > 60 &&
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(state == wbALetter || state == wbHebrewLetter) &&
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(nextProperty == prMidLetter || nextProperty == prMidNumLet || nextProperty == prSingleQuote) &&
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(farProperty == prALetter || farProperty == prHebrewLetter) {
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return wbWB7, false
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}
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// WB7b.
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if rule > 72 &&
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state == wbHebrewLetter &&
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nextProperty == prDoubleQuote &&
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farProperty == prHebrewLetter {
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return wbWB7c, false
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}
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// WB12.
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if rule > 120 &&
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state == wbNumeric &&
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(nextProperty == prMidNum || nextProperty == prMidNumLet || nextProperty == prSingleQuote) &&
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farProperty == prNumeric {
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return wbWB11, false
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}
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// WB15 and WB16.
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if newState == wbAny && nextProperty == prRegionalIndicator {
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if state != wbOddRI && state != wbEvenRI { // Includes state == -1.
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// Transition into the first RI.
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return wbOddRI, true
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}
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if state == wbOddRI {
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// Don't break pairs of Regional Indicators.
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return wbEvenRI, false
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}
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return wbOddRI, true // We can break after a pair.
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}
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return
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}
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