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.
)
// The line break parser's state transitions. It's anologous to grTransitions,
// see comments there for details. Unicode version 14.0.0.
var lbTransitions = map[[2]int][3]int{
// LB4.
{lbAny, prBK}: {lbBK, LineCanBreak, 310},
{lbBK, prAny}: {lbAny, LineMustBreak, 40},
// LB5.
{lbAny, prCR}: {lbCR, LineCanBreak, 310},
{lbAny, prLF}: {lbLF, LineCanBreak, 310},
{lbAny, prNL}: {lbNL, LineCanBreak, 310},
{lbCR, prLF}: {lbLF, LineDontBreak, 50},
{lbCR, prAny}: {lbAny, LineMustBreak, 50},
{lbLF, prAny}: {lbAny, LineMustBreak, 50},
{lbNL, prAny}: {lbAny, LineMustBreak, 50},
// LB6.
{lbAny, prBK}: {lbBK, LineDontBreak, 60},
{lbAny, prCR}: {lbCR, LineDontBreak, 60},
{lbAny, prLF}: {lbLF, LineDontBreak, 60},
{lbAny, prNL}: {lbNL, LineDontBreak, 60},
// LB7.
{lbAny, prSP}: {lbSP, LineDontBreak, 70},
{lbAny, prZW}: {lbZW, LineDontBreak, 70},
// LB8.
{lbZW, prSP}: {lbZW, LineDontBreak, 70},
{lbZW, prAny}: {lbAny, LineCanBreak, 80},
// LB11.
{lbAny, prWJ}: {lbWJ, LineDontBreak, 110},
{lbWJ, prAny}: {lbAny, LineDontBreak, 110},
// LB12.
{lbAny, prGL}: {lbGL, LineCanBreak, 310},
{lbGL, prAny}: {lbAny, LineDontBreak, 120},
// LB13 (simple transitions).
{lbAny, prCL}: {lbCL, LineCanBreak, 310},
{lbAny, prCP}: {lbCP, LineCanBreak, 310},
{lbAny, prEX}: {lbEX, LineDontBreak, 130},
{lbAny, prIS}: {lbIS, LineCanBreak, 310},
{lbAny, prSY}: {lbSY, LineCanBreak, 310},
// LB14.
{lbAny, prOP}: {lbOP, LineCanBreak, 310},
{lbOP, prSP}: {lbOP, LineDontBreak, 70},
{lbOP, prAny}: {lbAny, LineDontBreak, 140},
// LB15.
{lbQU, prSP}: {lbQUSP, LineDontBreak, 70},
{lbQU, prOP}: {lbOP, LineDontBreak, 150},
{lbQUSP, prOP}: {lbOP, LineDontBreak, 150},
// LB16.
{lbCL, prSP}: {lbCLCPSP, LineDontBreak, 70},
{lbNUCL, prSP}: {lbCLCPSP, LineDontBreak, 70},
{lbCP, prSP}: {lbCLCPSP, LineDontBreak, 70},
{lbNUCP, prSP}: {lbCLCPSP, LineDontBreak, 70},
{lbCL, prNS}: {lbNS, LineDontBreak, 160},
{lbNUCL, prNS}: {lbNS, LineDontBreak, 160},
{lbCP, prNS}: {lbNS, LineDontBreak, 160},
{lbNUCP, prNS}: {lbNS, LineDontBreak, 160},
{lbCLCPSP, prNS}: {lbNS, LineDontBreak, 160},
// LB17.
{lbAny, prB2}: {lbB2, LineCanBreak, 310},
{lbB2, prSP}: {lbB2SP, LineDontBreak, 70},
{lbB2, prB2}: {lbB2, LineDontBreak, 170},
{lbB2SP, prB2}: {lbB2, LineDontBreak, 170},
// LB18.
{lbSP, prAny}: {lbAny, LineCanBreak, 180},
{lbQUSP, prAny}: {lbAny, LineCanBreak, 180},
{lbCLCPSP, prAny}: {lbAny, LineCanBreak, 180},
{lbB2SP, prAny}: {lbAny, LineCanBreak, 180},
// LB19.
{lbAny, prQU}: {lbQU, LineDontBreak, 190},
{lbQU, prAny}: {lbAny, LineDontBreak, 190},
// LB20.
{lbAny, prCB}: {lbCB, LineCanBreak, 200},
{lbCB, prAny}: {lbAny, LineCanBreak, 200},
// LB21.
{lbAny, prBA}: {lbBA, LineDontBreak, 210},
{lbAny, prHY}: {lbHY, LineDontBreak, 210},
{lbAny, prNS}: {lbNS, LineDontBreak, 210},
{lbAny, prBB}: {lbBB, LineCanBreak, 310},
{lbBB, prAny}: {lbAny, LineDontBreak, 210},
// LB21a.
{lbAny, prHL}: {lbHL, LineCanBreak, 310},
{lbHL, prHY}: {lbLB21a, LineDontBreak, 210},
{lbHL, prBA}: {lbLB21a, LineDontBreak, 210},
{lbLB21a, prAny}: {lbAny, LineDontBreak, 211},
// LB21b.
{lbSY, prHL}: {lbHL, LineDontBreak, 212},
{lbNUSY, prHL}: {lbHL, LineDontBreak, 212},
// LB22.
{lbAny, prIN}: {lbAny, LineDontBreak, 220},
// LB23.
{lbAny, prAL}: {lbAL, LineCanBreak, 310},
{lbAny, prNU}: {lbNU, LineCanBreak, 310},
{lbAL, prNU}: {lbNU, LineDontBreak, 230},
{lbHL, prNU}: {lbNU, LineDontBreak, 230},
{lbNU, prAL}: {lbAL, LineDontBreak, 230},
{lbNU, prHL}: {lbHL, LineDontBreak, 230},
{lbNUNU, prAL}: {lbAL, LineDontBreak, 230},
{lbNUNU, prHL}: {lbHL, LineDontBreak, 230},
// LB23a.
{lbAny, prPR}: {lbPR, LineCanBreak, 310},
{lbAny, prID}: {lbIDEM, LineCanBreak, 310},
{lbAny, prEB}: {lbEB, LineCanBreak, 310},
{lbAny, prEM}: {lbIDEM, LineCanBreak, 310},
{lbPR, prID}: {lbIDEM, LineDontBreak, 231},
{lbPR, prEB}: {lbEB, LineDontBreak, 231},
{lbPR, prEM}: {lbIDEM, LineDontBreak, 231},
{lbIDEM, prPO}: {lbPO, LineDontBreak, 231},
{lbEB, prPO}: {lbPO, LineDontBreak, 231},
// LB24.
{lbAny, prPO}: {lbPO, LineCanBreak, 310},
{lbPR, prAL}: {lbAL, LineDontBreak, 240},
{lbPR, prHL}: {lbHL, LineDontBreak, 240},
{lbPO, prAL}: {lbAL, LineDontBreak, 240},
{lbPO, prHL}: {lbHL, LineDontBreak, 240},
{lbAL, prPR}: {lbPR, LineDontBreak, 240},
{lbAL, prPO}: {lbPO, LineDontBreak, 240},
{lbHL, prPR}: {lbPR, LineDontBreak, 240},
{lbHL, prPO}: {lbPO, LineDontBreak, 240},
// LB25 (simple transitions).
{lbPR, prNU}: {lbNU, LineDontBreak, 250},
{lbPO, prNU}: {lbNU, LineDontBreak, 250},
{lbOP, prNU}: {lbNU, LineDontBreak, 250},
{lbHY, prNU}: {lbNU, LineDontBreak, 250},
{lbNU, prNU}: {lbNUNU, LineDontBreak, 250},
{lbNU, prSY}: {lbNUSY, LineDontBreak, 250},
{lbNU, prIS}: {lbNUIS, LineDontBreak, 250},
{lbNUNU, prNU}: {lbNUNU, LineDontBreak, 250},
{lbNUNU, prSY}: {lbNUSY, LineDontBreak, 250},
{lbNUNU, prIS}: {lbNUIS, LineDontBreak, 250},
{lbNUSY, prNU}: {lbNUNU, LineDontBreak, 250},
{lbNUSY, prSY}: {lbNUSY, LineDontBreak, 250},
{lbNUSY, prIS}: {lbNUIS, LineDontBreak, 250},
{lbNUIS, prNU}: {lbNUNU, LineDontBreak, 250},
{lbNUIS, prSY}: {lbNUSY, LineDontBreak, 250},
{lbNUIS, prIS}: {lbNUIS, LineDontBreak, 250},
{lbNU, prCL}: {lbNUCL, LineDontBreak, 250},
{lbNU, prCP}: {lbNUCP, LineDontBreak, 250},
{lbNUNU, prCL}: {lbNUCL, LineDontBreak, 250},
{lbNUNU, prCP}: {lbNUCP, LineDontBreak, 250},
{lbNUSY, prCL}: {lbNUCL, LineDontBreak, 250},
{lbNUSY, prCP}: {lbNUCP, LineDontBreak, 250},
{lbNUIS, prCL}: {lbNUCL, LineDontBreak, 250},
{lbNUIS, prCP}: {lbNUCP, LineDontBreak, 250},
{lbNU, prPO}: {lbPO, LineDontBreak, 250},
{lbNUNU, prPO}: {lbPO, LineDontBreak, 250},
{lbNUSY, prPO}: {lbPO, LineDontBreak, 250},
{lbNUIS, prPO}: {lbPO, LineDontBreak, 250},
{lbNUCL, prPO}: {lbPO, LineDontBreak, 250},
{lbNUCP, prPO}: {lbPO, LineDontBreak, 250},
{lbNU, prPR}: {lbPR, LineDontBreak, 250},
{lbNUNU, prPR}: {lbPR, LineDontBreak, 250},
{lbNUSY, prPR}: {lbPR, LineDontBreak, 250},
{lbNUIS, prPR}: {lbPR, LineDontBreak, 250},
{lbNUCL, prPR}: {lbPR, LineDontBreak, 250},
{lbNUCP, prPR}: {lbPR, LineDontBreak, 250},
// LB26.
{lbAny, prJL}: {lbJL, LineCanBreak, 310},
{lbAny, prJV}: {lbJV, LineCanBreak, 310},
{lbAny, prJT}: {lbJT, LineCanBreak, 310},
{lbAny, prH2}: {lbH2, LineCanBreak, 310},
{lbAny, prH3}: {lbH3, LineCanBreak, 310},
{lbJL, prJL}: {lbJL, LineDontBreak, 260},
{lbJL, prJV}: {lbJV, LineDontBreak, 260},
{lbJL, prH2}: {lbH2, LineDontBreak, 260},
{lbJL, prH3}: {lbH3, LineDontBreak, 260},
{lbJV, prJV}: {lbJV, LineDontBreak, 260},
{lbJV, prJT}: {lbJT, LineDontBreak, 260},
{lbH2, prJV}: {lbJV, LineDontBreak, 260},
{lbH2, prJT}: {lbJT, LineDontBreak, 260},
{lbJT, prJT}: {lbJT, LineDontBreak, 260},
{lbH3, prJT}: {lbJT, LineDontBreak, 260},
// LB27.
{lbJL, prPO}: {lbPO, LineDontBreak, 270},
{lbJV, prPO}: {lbPO, LineDontBreak, 270},
{lbJT, prPO}: {lbPO, LineDontBreak, 270},
{lbH2, prPO}: {lbPO, LineDontBreak, 270},
{lbH3, prPO}: {lbPO, LineDontBreak, 270},
{lbPR, prJL}: {lbJL, LineDontBreak, 270},
{lbPR, prJV}: {lbJV, LineDontBreak, 270},
{lbPR, prJT}: {lbJT, LineDontBreak, 270},
{lbPR, prH2}: {lbH2, LineDontBreak, 270},
{lbPR, prH3}: {lbH3, LineDontBreak, 270},
// LB28.
{lbAL, prAL}: {lbAL, LineDontBreak, 280},
{lbAL, prHL}: {lbHL, LineDontBreak, 280},
{lbHL, prAL}: {lbAL, LineDontBreak, 280},
{lbHL, prHL}: {lbHL, LineDontBreak, 280},
// LB29.
{lbIS, prAL}: {lbAL, LineDontBreak, 290},
{lbIS, prHL}: {lbHL, LineDontBreak, 290},
{lbNUIS, prAL}: {lbAL, LineDontBreak, 290},
{lbNUIS, prHL}: {lbHL, LineDontBreak, 290},
}
// 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 := propertyWithGenCat(lineBreakCodePoints, 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 := property(eastAsianWidth, 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
transition, ok := lbTransitions[[2]int{state, nextProperty}]
if ok {
// We have a specific transition. We'll use it.
newState, lineBreak, rule = transition[0], transition[1], transition[2]
} else {
// No specific transition found. Try the less specific ones.
transAnyProp, okAnyProp := lbTransitions[[2]int{state, prAny}]
transAnyState, okAnyState := lbTransitions[[2]int{lbAny, nextProperty}]
if okAnyProp && okAnyState {
// Both apply. We'll use a mix (see comments for grTransitions).
newState, lineBreak, rule = transAnyState[0], transAnyState[1], transAnyState[2]
if transAnyProp[2] < transAnyState[2] {
lineBreak, rule = transAnyProp[1], transAnyProp[2]
}
} else if okAnyProp {
// We only have a specific state.
newState, lineBreak, rule = transAnyProp[0], transAnyProp[1], transAnyProp[2]
// 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 okAnyState {
// We only have a specific property.
newState, lineBreak, rule = transAnyState[0], transAnyState[1], transAnyState[2]
} else {
// No known transition. LB31: ALL รท 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, _ := propertyWithGenCat(lineBreakCodePoints, 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 := property(eastAsianWidth, 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 := property(graphemeCodePoints, r)
if graphemeProperty == prExtendedPictographic && generalCategory == gcCn {
return lbExtPicCn, LineCanBreak
}
}
return
}