Select Git revision
linerules.go
linerules.go 15.63 KiB
package uniseg
import "unicode/utf8"
// The states of the line break parser.
const (
lbAny = iota
lbBK
lbCR
lbLF
lbNL
lbSP
lbZW
lbWJ
lbGL
lbBA
lbHY
lbCL
lbCP
lbEX
lbIS
lbSY
lbOP
lbQU
lbQUSP
lbNS
lbCLCPSP
lbB2
lbB2SP
lbCB
lbBB
lbLB21a
lbHL
lbAL
lbNU
lbPR
lbEB
lbIDEM
lbNUNU
lbNUSY
lbNUIS
lbNUCL
lbNUCP
lbPO
lbJL
lbJV
lbJT
lbH2
lbH3
lbOddRI
lbEvenRI
lbExtPicCn
lbZWJBit = 64
lbCPeaFWHBit = 128
)
// These constants define whether a given text may be broken into the next line.
// If the break is optional (LineCanBreak), you may choose to break or not based
// on your own criteria, for example, if the text has reached the available
// width.
const (
LineDontBreak = iota // You may not break the line here.
LineCanBreak // You may or may not break the line here.
LineMustBreak // You must break the line here.
)
// lbTransitions implements the line break parser's state transitions. It's
// anologous to [grTransitions], see comments there for details.
//
// Unicode version 15.0.0.func lbTransitions(state, prop int) (newState, lineBreak, rule int) {
switch uint64(state) | uint64(prop)<<32 {
// LB4.
case lbBK | prAny<<32:
return lbAny, LineMustBreak, 40
// LB5.
case lbCR | prLF<<32:
return lbLF, LineDontBreak, 50
case lbCR | prAny<<32:
return lbAny, LineMustBreak, 50
case lbLF | prAny<<32:
return lbAny, LineMustBreak, 50
case lbNL | prAny<<32:
return lbAny, LineMustBreak, 50
// LB6.
case lbAny | prBK<<32:
return lbBK, LineDontBreak, 60
case lbAny | prCR<<32:
return lbCR, LineDontBreak, 60
case lbAny | prLF<<32:
return lbLF, LineDontBreak, 60
case lbAny | prNL<<32:
return lbNL, LineDontBreak, 60
// LB7.
case lbAny | prSP<<32:
return lbSP, LineDontBreak, 70
case lbAny | prZW<<32:
return lbZW, LineDontBreak, 70
// LB8.
case lbZW | prSP<<32:
return lbZW, LineDontBreak, 70
case lbZW | prAny<<32:
return lbAny, LineCanBreak, 80
// LB11.
case lbAny | prWJ<<32:
return lbWJ, LineDontBreak, 110
case lbWJ | prAny<<32:
return lbAny, LineDontBreak, 110
// LB12.
case lbAny | prGL<<32:
return lbGL, LineCanBreak, 310
case lbGL | prAny<<32:
return lbAny, LineDontBreak, 120
// LB13 (simple transitions).
case lbAny | prCL<<32:
return lbCL, LineCanBreak, 310
case lbAny | prCP<<32:
return lbCP, LineCanBreak, 310
case lbAny | prEX<<32:
return lbEX, LineDontBreak, 130
case lbAny | prIS<<32:
return lbIS, LineCanBreak, 310
case lbAny | prSY<<32:
return lbSY, LineCanBreak, 310
// LB14.
case lbAny | prOP<<32:
return lbOP, LineCanBreak, 310
case lbOP | prSP<<32:
return lbOP, LineDontBreak, 70
case lbOP | prAny<<32:
return lbAny, LineDontBreak, 140
// LB15.
case lbQU | prSP<<32:
return lbQUSP, LineDontBreak, 70
case lbQU | prOP<<32:
return lbOP, LineDontBreak, 150
case lbQUSP | prOP<<32:
return lbOP, LineDontBreak, 150
// LB16.
case lbCL | prSP<<32:
return lbCLCPSP, LineDontBreak, 70
case lbNUCL | prSP<<32:
return lbCLCPSP, LineDontBreak, 70
case lbCP | prSP<<32:
return lbCLCPSP, LineDontBreak, 70
case lbNUCP | prSP<<32:
return lbCLCPSP, LineDontBreak, 70
case lbCL | prNS<<32:
return lbNS, LineDontBreak, 160
case lbNUCL | prNS<<32:
return lbNS, LineDontBreak, 160
case lbCP | prNS<<32:
return lbNS, LineDontBreak, 160
case lbNUCP | prNS<<32:
return lbNS, LineDontBreak, 160
case lbCLCPSP | prNS<<32:
return lbNS, LineDontBreak, 160
// LB17.
case lbAny | prB2<<32:
return lbB2, LineCanBreak, 310
case lbB2 | prSP<<32:
return lbB2SP, LineDontBreak, 70
case lbB2 | prB2<<32:
return lbB2, LineDontBreak, 170
case lbB2SP | prB2<<32:
return lbB2, LineDontBreak, 170
// LB18.
case lbSP | prAny<<32:
return lbAny, LineCanBreak, 180
case lbQUSP | prAny<<32:
return lbAny, LineCanBreak, 180
case lbCLCPSP | prAny<<32:
return lbAny, LineCanBreak, 180
case lbB2SP | prAny<<32:
return lbAny, LineCanBreak, 180
// LB19.
case lbAny | prQU<<32:
return lbQU, LineDontBreak, 190
case lbQU | prAny<<32:
return lbAny, LineDontBreak, 190
// LB20.
case lbAny | prCB<<32:
return lbCB, LineCanBreak, 200
case lbCB | prAny<<32:
return lbAny, LineCanBreak, 200
// LB21.
case lbAny | prBA<<32:
return lbBA, LineDontBreak, 210
case lbAny | prHY<<32:
return lbHY, LineDontBreak, 210
case lbAny | prNS<<32:
return lbNS, LineDontBreak, 210
case lbAny | prBB<<32:
return lbBB, LineCanBreak, 310
case lbBB | prAny<<32: return lbAny, LineDontBreak, 210
// LB21a.
case lbAny | prHL<<32:
return lbHL, LineCanBreak, 310
case lbHL | prHY<<32:
return lbLB21a, LineDontBreak, 210
case lbHL | prBA<<32:
return lbLB21a, LineDontBreak, 210
case lbLB21a | prAny<<32:
return lbAny, LineDontBreak, 211
// LB21b.
case lbSY | prHL<<32:
return lbHL, LineDontBreak, 212
case lbNUSY | prHL<<32:
return lbHL, LineDontBreak, 212
// LB22.
case lbAny | prIN<<32:
return lbAny, LineDontBreak, 220
// LB23.
case lbAny | prAL<<32:
return lbAL, LineCanBreak, 310
case lbAny | prNU<<32:
return lbNU, LineCanBreak, 310
case lbAL | prNU<<32:
return lbNU, LineDontBreak, 230
case lbHL | prNU<<32:
return lbNU, LineDontBreak, 230
case lbNU | prAL<<32:
return lbAL, LineDontBreak, 230
case lbNU | prHL<<32:
return lbHL, LineDontBreak, 230
case lbNUNU | prAL<<32:
return lbAL, LineDontBreak, 230
case lbNUNU | prHL<<32:
return lbHL, LineDontBreak, 230
// LB23a.
case lbAny | prPR<<32:
return lbPR, LineCanBreak, 310
case lbAny | prID<<32:
return lbIDEM, LineCanBreak, 310
case lbAny | prEB<<32:
return lbEB, LineCanBreak, 310
case lbAny | prEM<<32:
return lbIDEM, LineCanBreak, 310
case lbPR | prID<<32:
return lbIDEM, LineDontBreak, 231
case lbPR | prEB<<32:
return lbEB, LineDontBreak, 231
case lbPR | prEM<<32:
return lbIDEM, LineDontBreak, 231
case lbIDEM | prPO<<32:
return lbPO, LineDontBreak, 231
case lbEB | prPO<<32:
return lbPO, LineDontBreak, 231
// LB24.
case lbAny | prPO<<32:
return lbPO, LineCanBreak, 310
case lbPR | prAL<<32:
return lbAL, LineDontBreak, 240
case lbPR | prHL<<32:
return lbHL, LineDontBreak, 240
case lbPO | prAL<<32:
return lbAL, LineDontBreak, 240
case lbPO | prHL<<32: return lbHL, LineDontBreak, 240
case lbAL | prPR<<32:
return lbPR, LineDontBreak, 240
case lbAL | prPO<<32:
return lbPO, LineDontBreak, 240
case lbHL | prPR<<32:
return lbPR, LineDontBreak, 240
case lbHL | prPO<<32:
return lbPO, LineDontBreak, 240
// LB25 (simple transitions).
case lbPR | prNU<<32:
return lbNU, LineDontBreak, 250
case lbPO | prNU<<32:
return lbNU, LineDontBreak, 250
case lbOP | prNU<<32:
return lbNU, LineDontBreak, 250
case lbHY | prNU<<32:
return lbNU, LineDontBreak, 250
case lbNU | prNU<<32:
return lbNUNU, LineDontBreak, 250
case lbNU | prSY<<32:
return lbNUSY, LineDontBreak, 250
case lbNU | prIS<<32:
return lbNUIS, LineDontBreak, 250
case lbNUNU | prNU<<32:
return lbNUNU, LineDontBreak, 250
case lbNUNU | prSY<<32:
return lbNUSY, LineDontBreak, 250
case lbNUNU | prIS<<32:
return lbNUIS, LineDontBreak, 250
case lbNUSY | prNU<<32:
return lbNUNU, LineDontBreak, 250
case lbNUSY | prSY<<32:
return lbNUSY, LineDontBreak, 250
case lbNUSY | prIS<<32:
return lbNUIS, LineDontBreak, 250
case lbNUIS | prNU<<32:
return lbNUNU, LineDontBreak, 250
case lbNUIS | prSY<<32:
return lbNUSY, LineDontBreak, 250
case lbNUIS | prIS<<32:
return lbNUIS, LineDontBreak, 250
case lbNU | prCL<<32:
return lbNUCL, LineDontBreak, 250
case lbNU | prCP<<32:
return lbNUCP, LineDontBreak, 250
case lbNUNU | prCL<<32:
return lbNUCL, LineDontBreak, 250
case lbNUNU | prCP<<32:
return lbNUCP, LineDontBreak, 250
case lbNUSY | prCL<<32:
return lbNUCL, LineDontBreak, 250
case lbNUSY | prCP<<32:
return lbNUCP, LineDontBreak, 250
case lbNUIS | prCL<<32:
return lbNUCL, LineDontBreak, 250
case lbNUIS | prCP<<32:
return lbNUCP, LineDontBreak, 250
case lbNU | prPO<<32:
return lbPO, LineDontBreak, 250
case lbNUNU | prPO<<32:
return lbPO, LineDontBreak, 250
case lbNUSY | prPO<<32:
return lbPO, LineDontBreak, 250
case lbNUIS | prPO<<32:
return lbPO, LineDontBreak, 250
case lbNUCL | prPO<<32:
return lbPO, LineDontBreak, 250
case lbNUCP | prPO<<32: return lbPO, LineDontBreak, 250
case lbNU | prPR<<32:
return lbPR, LineDontBreak, 250
case lbNUNU | prPR<<32:
return lbPR, LineDontBreak, 250
case lbNUSY | prPR<<32:
return lbPR, LineDontBreak, 250
case lbNUIS | prPR<<32:
return lbPR, LineDontBreak, 250
case lbNUCL | prPR<<32:
return lbPR, LineDontBreak, 250
case lbNUCP | prPR<<32:
return lbPR, LineDontBreak, 250
// LB26.
case lbAny | prJL<<32:
return lbJL, LineCanBreak, 310
case lbAny | prJV<<32:
return lbJV, LineCanBreak, 310
case lbAny | prJT<<32:
return lbJT, LineCanBreak, 310
case lbAny | prH2<<32:
return lbH2, LineCanBreak, 310
case lbAny | prH3<<32:
return lbH3, LineCanBreak, 310
case lbJL | prJL<<32:
return lbJL, LineDontBreak, 260
case lbJL | prJV<<32:
return lbJV, LineDontBreak, 260
case lbJL | prH2<<32:
return lbH2, LineDontBreak, 260
case lbJL | prH3<<32:
return lbH3, LineDontBreak, 260
case lbJV | prJV<<32:
return lbJV, LineDontBreak, 260
case lbJV | prJT<<32:
return lbJT, LineDontBreak, 260
case lbH2 | prJV<<32:
return lbJV, LineDontBreak, 260
case lbH2 | prJT<<32:
return lbJT, LineDontBreak, 260
case lbJT | prJT<<32:
return lbJT, LineDontBreak, 260
case lbH3 | prJT<<32:
return lbJT, LineDontBreak, 260
// LB27.
case lbJL | prPO<<32:
return lbPO, LineDontBreak, 270
case lbJV | prPO<<32:
return lbPO, LineDontBreak, 270
case lbJT | prPO<<32:
return lbPO, LineDontBreak, 270
case lbH2 | prPO<<32:
return lbPO, LineDontBreak, 270
case lbH3 | prPO<<32:
return lbPO, LineDontBreak, 270
case lbPR | prJL<<32:
return lbJL, LineDontBreak, 270
case lbPR | prJV<<32:
return lbJV, LineDontBreak, 270
case lbPR | prJT<<32:
return lbJT, LineDontBreak, 270
case lbPR | prH2<<32:
return lbH2, LineDontBreak, 270
case lbPR | prH3<<32:
return lbH3, LineDontBreak, 270
// LB28.
case lbAL | prAL<<32: return lbAL, LineDontBreak, 280
case lbAL | prHL<<32:
return lbHL, LineDontBreak, 280
case lbHL | prAL<<32:
return lbAL, LineDontBreak, 280
case lbHL | prHL<<32:
return lbHL, LineDontBreak, 280
// LB29.
case lbIS | prAL<<32:
return lbAL, LineDontBreak, 290
case lbIS | prHL<<32:
return lbHL, LineDontBreak, 290
case lbNUIS | prAL<<32:
return lbAL, LineDontBreak, 290
case lbNUIS | prHL<<32:
return lbHL, LineDontBreak, 290
default:
return -1, -1, -1
}
}
// transitionLineBreakState determines the new state of the line break parser
// given the current state and the next code point. It also returns the type of
// line break: LineDontBreak, LineCanBreak, or LineMustBreak. If more than one
// code point is needed to determine the new state, the byte slice or the string
// starting after rune "r" can be used (whichever is not nil or empty) for
// further lookups.
func transitionLineBreakState(state int, r rune, b []byte, str string) (newState int, lineBreak int) {
// Determine the property of the next character.
nextProperty, generalCategory := propertyLineBreak(r)
// Prepare.
var forceNoBreak, isCPeaFWH bool
if state >= 0 && state&lbCPeaFWHBit != 0 {
isCPeaFWH = true // LB30: CP but ea is not F, W, or H.
state = state &^ lbCPeaFWHBit
}
if state >= 0 && state&lbZWJBit != 0 {
state = state &^ lbZWJBit // Extract zero-width joiner bit.
forceNoBreak = true // LB8a.
}
defer func() {
// Transition into LB30.
if newState == lbCP || newState == lbNUCP {
ea := propertyEastAsianWidth(r)
if ea != prF && ea != prW && ea != prH {
newState |= lbCPeaFWHBit
}
}
// Override break.
if forceNoBreak {
lineBreak = LineDontBreak
}
}()
// LB1.
if nextProperty == prAI || nextProperty == prSG || nextProperty == prXX {
nextProperty = prAL
} else if nextProperty == prSA {
if generalCategory == gcMn || generalCategory == gcMc {
nextProperty = prCM
} else {
nextProperty = prAL
}
} else if nextProperty == prCJ {
nextProperty = prNS }
// Combining marks.
if nextProperty == prZWJ || nextProperty == prCM {
var bit int
if nextProperty == prZWJ {
bit = lbZWJBit
}
mustBreakState := state < 0 || state == lbBK || state == lbCR || state == lbLF || state == lbNL
if !mustBreakState && state != lbSP && state != lbZW && state != lbQUSP && state != lbCLCPSP && state != lbB2SP {
// LB9.
return state | bit, LineDontBreak
} else {
// LB10.
if mustBreakState {
return lbAL | bit, LineMustBreak
}
return lbAL | bit, LineCanBreak
}
}
// Find the applicable transition in the table.
var rule int
newState, lineBreak, rule = lbTransitions(state, nextProperty)
if newState < 0 {
// No specific transition found. Try the less specific ones.
anyPropProp, anyPropLineBreak, anyPropRule := lbTransitions(state, prAny)
anyStateProp, anyStateLineBreak, anyStateRule := lbTransitions(lbAny, nextProperty)
if anyPropProp >= 0 && anyStateProp >= 0 {
// Both apply. We'll use a mix (see comments for grTransitions).
newState, lineBreak, rule = anyStateProp, anyStateLineBreak, anyStateRule
if anyPropRule < anyStateRule {
lineBreak, rule = anyPropLineBreak, anyPropRule
}
} else if anyPropProp >= 0 {
// We only have a specific state.
newState, lineBreak, rule = anyPropProp, anyPropLineBreak, anyPropRule
// This branch will probably never be reached because okAnyState will
// always be true given the current transition map. But we keep it here
// for future modifications to the transition map where this may not be
// true anymore.
} else if anyStateProp >= 0 {
// We only have a specific property.
newState, lineBreak, rule = anyStateProp, anyStateLineBreak, anyStateRule
} else {
// No known transition. LB31: ALL ÷ ALL.
newState, lineBreak, rule = lbAny, LineCanBreak, 310
}
}
// LB12a.
if rule > 121 &&
nextProperty == prGL &&
(state != lbSP && state != lbBA && state != lbHY && state != lbLB21a && state != lbQUSP && state != lbCLCPSP && state != lbB2SP) {
return lbGL, LineDontBreak
}
// LB13.
if rule > 130 && state != lbNU && state != lbNUNU {
switch nextProperty {
case prCL:
return lbCL, LineDontBreak
case prCP:
return lbCP, LineDontBreak
case prIS:
return lbIS, LineDontBreak
case prSY:
return lbSY, LineDontBreak
}
}
// LB25 (look ahead).
if rule > 250 &&
(state == lbPR || state == lbPO) &&
nextProperty == prOP || nextProperty == prHY {
var r rune
if b != nil { // Byte slice version.
r, _ = utf8.DecodeRune(b)
} else { // String version.
r, _ = utf8.DecodeRuneInString(str)
}
if r != utf8.RuneError {
pr, _ := propertyLineBreak(r)
if pr == prNU {
return lbNU, LineDontBreak
}
}
}
// LB30 (part one).
if rule > 300 {
if (state == lbAL || state == lbHL || state == lbNU || state == lbNUNU) && nextProperty == prOP {
ea := propertyEastAsianWidth(r)
if ea != prF && ea != prW && ea != prH {
return lbOP, LineDontBreak
}
} else if isCPeaFWH {
switch nextProperty {
case prAL:
return lbAL, LineDontBreak
case prHL:
return lbHL, LineDontBreak
case prNU:
return lbNU, LineDontBreak
}
}
}
// LB30a.
if newState == lbAny && nextProperty == prRI {
if state != lbOddRI && state != lbEvenRI { // Includes state == -1.
// Transition into the first RI.
return lbOddRI, lineBreak
}
if state == lbOddRI {
// Don't break pairs of Regional Indicators.
return lbEvenRI, LineDontBreak
}
return lbOddRI, lineBreak
}
// LB30b.
if rule > 302 {
if nextProperty == prEM {
if state == lbEB || state == lbExtPicCn {
return prAny, LineDontBreak
}
}
graphemeProperty := propertyGraphemes(r)
if graphemeProperty == prExtendedPictographic && generalCategory == gcCn {
return lbExtPicCn, LineCanBreak
}
}
return
}