691 lines
26 KiB
JavaScript
691 lines
26 KiB
JavaScript
import {
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BN_LIKE_TYPES,
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getBidiCharType,
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ISOLATE_INIT_TYPES,
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NEUTRAL_ISOLATE_TYPES,
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STRONG_TYPES,
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TRAILING_TYPES,
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TYPES
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} from './charTypes.js'
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import { closingToOpeningBracket, getCanonicalBracket, openingToClosingBracket } from './brackets.js'
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// Local type aliases
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const {
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L: TYPE_L,
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R: TYPE_R,
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EN: TYPE_EN,
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ES: TYPE_ES,
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ET: TYPE_ET,
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AN: TYPE_AN,
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CS: TYPE_CS,
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B: TYPE_B,
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S: TYPE_S,
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ON: TYPE_ON,
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BN: TYPE_BN,
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NSM: TYPE_NSM,
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AL: TYPE_AL,
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LRO: TYPE_LRO,
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RLO: TYPE_RLO,
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LRE: TYPE_LRE,
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RLE: TYPE_RLE,
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PDF: TYPE_PDF,
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LRI: TYPE_LRI,
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RLI: TYPE_RLI,
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FSI: TYPE_FSI,
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PDI: TYPE_PDI
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} = TYPES
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/**
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* @typedef {object} GetEmbeddingLevelsResult
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* @property {{start, end, level}[]} paragraphs
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* @property {Uint8Array} levels
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*/
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/**
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* This function applies the Bidirectional Algorithm to a string, returning the resolved embedding levels
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* in a single Uint8Array plus a list of objects holding each paragraph's start and end indices and resolved
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* base embedding level.
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*
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* @param {string} string - The input string
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* @param {"ltr"|"rtl"|"auto"} [baseDirection] - Use "ltr" or "rtl" to force a base paragraph direction,
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* otherwise a direction will be chosen automatically from each paragraph's contents.
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* @return {GetEmbeddingLevelsResult}
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*/
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export function getEmbeddingLevels (string, baseDirection) {
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const MAX_DEPTH = 125
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// Start by mapping all characters to their unicode type, as a bitmask integer
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const charTypes = new Uint32Array(string.length)
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for (let i = 0; i < string.length; i++) {
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charTypes[i] = getBidiCharType(string[i])
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}
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const charTypeCounts = new Map() //will be cleared at start of each paragraph
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function changeCharType(i, type) {
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const oldType = charTypes[i]
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charTypes[i] = type
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charTypeCounts.set(oldType, charTypeCounts.get(oldType) - 1)
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if (oldType & NEUTRAL_ISOLATE_TYPES) {
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charTypeCounts.set(NEUTRAL_ISOLATE_TYPES, charTypeCounts.get(NEUTRAL_ISOLATE_TYPES) - 1)
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}
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charTypeCounts.set(type, (charTypeCounts.get(type) || 0) + 1)
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if (type & NEUTRAL_ISOLATE_TYPES) {
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charTypeCounts.set(NEUTRAL_ISOLATE_TYPES, (charTypeCounts.get(NEUTRAL_ISOLATE_TYPES) || 0) + 1)
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}
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}
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const embedLevels = new Uint8Array(string.length)
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const isolationPairs = new Map() //init->pdi and pdi->init
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// === 3.3.1 The Paragraph Level ===
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// 3.3.1 P1: Split the text into paragraphs
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const paragraphs = [] // [{start, end, level}, ...]
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let paragraph = null
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for (let i = 0; i < string.length; i++) {
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if (!paragraph) {
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paragraphs.push(paragraph = {
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start: i,
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end: string.length - 1,
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// 3.3.1 P2-P3: Determine the paragraph level
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level: baseDirection === 'rtl' ? 1 : baseDirection === 'ltr' ? 0 : determineAutoEmbedLevel(i, false)
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})
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}
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if (charTypes[i] & TYPE_B) {
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paragraph.end = i
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paragraph = null
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}
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}
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const FORMATTING_TYPES = TYPE_RLE | TYPE_LRE | TYPE_RLO | TYPE_LRO | ISOLATE_INIT_TYPES | TYPE_PDI | TYPE_PDF | TYPE_B
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const nextEven = n => n + ((n & 1) ? 1 : 2)
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const nextOdd = n => n + ((n & 1) ? 2 : 1)
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// Everything from here on will operate per paragraph.
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for (let paraIdx = 0; paraIdx < paragraphs.length; paraIdx++) {
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paragraph = paragraphs[paraIdx]
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const statusStack = [{
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_level: paragraph.level,
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_override: 0, //0=neutral, 1=L, 2=R
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_isolate: 0 //bool
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}]
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let stackTop
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let overflowIsolateCount = 0
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let overflowEmbeddingCount = 0
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let validIsolateCount = 0
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charTypeCounts.clear()
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// === 3.3.2 Explicit Levels and Directions ===
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for (let i = paragraph.start; i <= paragraph.end; i++) {
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let charType = charTypes[i]
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stackTop = statusStack[statusStack.length - 1]
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// Set initial counts
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charTypeCounts.set(charType, (charTypeCounts.get(charType) || 0) + 1)
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if (charType & NEUTRAL_ISOLATE_TYPES) {
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charTypeCounts.set(NEUTRAL_ISOLATE_TYPES, (charTypeCounts.get(NEUTRAL_ISOLATE_TYPES) || 0) + 1)
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}
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// Explicit Embeddings: 3.3.2 X2 - X3
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if (charType & FORMATTING_TYPES) { //prefilter all formatters
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if (charType & (TYPE_RLE | TYPE_LRE)) {
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embedLevels[i] = stackTop._level // 5.2
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const level = (charType === TYPE_RLE ? nextOdd : nextEven)(stackTop._level)
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if (level <= MAX_DEPTH && !overflowIsolateCount && !overflowEmbeddingCount) {
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statusStack.push({
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_level: level,
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_override: 0,
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_isolate: 0
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})
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} else if (!overflowIsolateCount) {
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overflowEmbeddingCount++
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}
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}
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// Explicit Overrides: 3.3.2 X4 - X5
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else if (charType & (TYPE_RLO | TYPE_LRO)) {
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embedLevels[i] = stackTop._level // 5.2
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const level = (charType === TYPE_RLO ? nextOdd : nextEven)(stackTop._level)
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if (level <= MAX_DEPTH && !overflowIsolateCount && !overflowEmbeddingCount) {
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statusStack.push({
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_level: level,
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_override: (charType & TYPE_RLO) ? TYPE_R : TYPE_L,
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_isolate: 0
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})
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} else if (!overflowIsolateCount) {
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overflowEmbeddingCount++
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}
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}
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// Isolates: 3.3.2 X5a - X5c
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else if (charType & ISOLATE_INIT_TYPES) {
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// X5c - FSI becomes either RLI or LRI
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if (charType & TYPE_FSI) {
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charType = determineAutoEmbedLevel(i + 1, true) === 1 ? TYPE_RLI : TYPE_LRI
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}
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embedLevels[i] = stackTop._level
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if (stackTop._override) {
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changeCharType(i, stackTop._override)
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}
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const level = (charType === TYPE_RLI ? nextOdd : nextEven)(stackTop._level)
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if (level <= MAX_DEPTH && overflowIsolateCount === 0 && overflowEmbeddingCount === 0) {
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validIsolateCount++
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statusStack.push({
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_level: level,
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_override: 0,
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_isolate: 1,
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_isolInitIndex: i
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})
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} else {
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overflowIsolateCount++
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}
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}
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// Terminating Isolates: 3.3.2 X6a
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else if (charType & TYPE_PDI) {
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if (overflowIsolateCount > 0) {
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overflowIsolateCount--
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} else if (validIsolateCount > 0) {
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overflowEmbeddingCount = 0
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while (!statusStack[statusStack.length - 1]._isolate) {
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statusStack.pop()
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}
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// Add to isolation pairs bidirectional mapping:
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const isolInitIndex = statusStack[statusStack.length - 1]._isolInitIndex
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if (isolInitIndex != null) {
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isolationPairs.set(isolInitIndex, i)
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isolationPairs.set(i, isolInitIndex)
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}
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statusStack.pop()
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validIsolateCount--
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}
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stackTop = statusStack[statusStack.length - 1]
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embedLevels[i] = stackTop._level
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if (stackTop._override) {
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changeCharType(i, stackTop._override)
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}
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}
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// Terminating Embeddings and Overrides: 3.3.2 X7
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else if (charType & TYPE_PDF) {
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if (overflowIsolateCount === 0) {
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if (overflowEmbeddingCount > 0) {
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overflowEmbeddingCount--
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} else if (!stackTop._isolate && statusStack.length > 1) {
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statusStack.pop()
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stackTop = statusStack[statusStack.length - 1]
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}
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}
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embedLevels[i] = stackTop._level // 5.2
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}
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// End of Paragraph: 3.3.2 X8
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else if (charType & TYPE_B) {
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embedLevels[i] = paragraph.level
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}
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}
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// Non-formatting characters: 3.3.2 X6
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else {
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embedLevels[i] = stackTop._level
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// NOTE: This exclusion of BN seems to go against what section 5.2 says, but is required for test passage
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if (stackTop._override && charType !== TYPE_BN) {
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changeCharType(i, stackTop._override)
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}
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}
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}
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// === 3.3.3 Preparations for Implicit Processing ===
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// Remove all RLE, LRE, RLO, LRO, PDF, and BN characters: 3.3.3 X9
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// Note: Due to section 5.2, we won't remove them, but we'll use the BN_LIKE_TYPES bitset to
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// easily ignore them all from here on out.
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// 3.3.3 X10
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// Compute the set of isolating run sequences as specified by BD13
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const levelRuns = []
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let currentRun = null
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let isolationLevel = 0
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for (let i = paragraph.start; i <= paragraph.end; i++) {
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const charType = charTypes[i]
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if (!(charType & BN_LIKE_TYPES)) {
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const lvl = embedLevels[i]
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const isIsolInit = charType & ISOLATE_INIT_TYPES
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const isPDI = charType === TYPE_PDI
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if (isIsolInit) {
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isolationLevel++
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}
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if (currentRun && lvl === currentRun._level) {
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currentRun._end = i
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currentRun._endsWithIsolInit = isIsolInit
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} else {
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levelRuns.push(currentRun = {
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_start: i,
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_end: i,
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_level: lvl,
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_startsWithPDI: isPDI,
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_endsWithIsolInit: isIsolInit
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})
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}
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if (isPDI) {
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isolationLevel--
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}
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}
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}
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const isolatingRunSeqs = [] // [{seqIndices: [], sosType: L|R, eosType: L|R}]
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for (let runIdx = 0; runIdx < levelRuns.length; runIdx++) {
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const run = levelRuns[runIdx]
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if (!run._startsWithPDI || (run._startsWithPDI && !isolationPairs.has(run._start))) {
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const seqRuns = [currentRun = run]
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for (let pdiIndex; currentRun && currentRun._endsWithIsolInit && (pdiIndex = isolationPairs.get(currentRun._end)) != null;) {
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for (let i = runIdx + 1; i < levelRuns.length; i++) {
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if (levelRuns[i]._start === pdiIndex) {
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seqRuns.push(currentRun = levelRuns[i])
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break
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}
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}
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}
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// build flat list of indices across all runs:
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const seqIndices = []
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for (let i = 0; i < seqRuns.length; i++) {
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const run = seqRuns[i]
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for (let j = run._start; j <= run._end; j++) {
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seqIndices.push(j)
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}
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}
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// determine the sos/eos types:
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let firstLevel = embedLevels[seqIndices[0]]
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let prevLevel = paragraph.level
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for (let i = seqIndices[0] - 1; i >= 0; i--) {
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if (!(charTypes[i] & BN_LIKE_TYPES)) { //5.2
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prevLevel = embedLevels[i]
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break
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}
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}
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const lastIndex = seqIndices[seqIndices.length - 1]
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let lastLevel = embedLevels[lastIndex]
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let nextLevel = paragraph.level
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if (!(charTypes[lastIndex] & ISOLATE_INIT_TYPES)) {
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for (let i = lastIndex + 1; i <= paragraph.end; i++) {
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if (!(charTypes[i] & BN_LIKE_TYPES)) { //5.2
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nextLevel = embedLevels[i]
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break
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}
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}
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}
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isolatingRunSeqs.push({
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_seqIndices: seqIndices,
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_sosType: Math.max(prevLevel, firstLevel) % 2 ? TYPE_R : TYPE_L,
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_eosType: Math.max(nextLevel, lastLevel) % 2 ? TYPE_R : TYPE_L
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})
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}
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}
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// The next steps are done per isolating run sequence
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for (let seqIdx = 0; seqIdx < isolatingRunSeqs.length; seqIdx++) {
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const { _seqIndices: seqIndices, _sosType: sosType, _eosType: eosType } = isolatingRunSeqs[seqIdx]
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/**
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* All the level runs in an isolating run sequence have the same embedding level.
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*
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* DO NOT change any `embedLevels[i]` within the current scope.
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*/
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const embedDirection = ((embedLevels[seqIndices[0]]) & 1) ? TYPE_R : TYPE_L;
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// === 3.3.4 Resolving Weak Types ===
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// W1 + 5.2. Search backward from each NSM to the first character in the isolating run sequence whose
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// bidirectional type is not BN, and set the NSM to ON if it is an isolate initiator or PDI, and to its
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// type otherwise. If the NSM is the first non-BN character, change the NSM to the type of sos.
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if (charTypeCounts.get(TYPE_NSM)) {
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for (let si = 0; si < seqIndices.length; si++) {
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const i = seqIndices[si]
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if (charTypes[i] & TYPE_NSM) {
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let prevType = sosType
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for (let sj = si - 1; sj >= 0; sj--) {
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if (!(charTypes[seqIndices[sj]] & BN_LIKE_TYPES)) { //5.2 scan back to first non-BN
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prevType = charTypes[seqIndices[sj]]
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break
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}
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}
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changeCharType(i, (prevType & (ISOLATE_INIT_TYPES | TYPE_PDI)) ? TYPE_ON : prevType)
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}
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}
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}
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// W2. Search backward from each instance of a European number until the first strong type (R, L, AL, or sos)
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// is found. If an AL is found, change the type of the European number to Arabic number.
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if (charTypeCounts.get(TYPE_EN)) {
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for (let si = 0; si < seqIndices.length; si++) {
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const i = seqIndices[si]
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if (charTypes[i] & TYPE_EN) {
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for (let sj = si - 1; sj >= -1; sj--) {
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const prevCharType = sj === -1 ? sosType : charTypes[seqIndices[sj]]
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if (prevCharType & STRONG_TYPES) {
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if (prevCharType === TYPE_AL) {
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changeCharType(i, TYPE_AN)
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}
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break
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}
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}
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}
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}
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}
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// W3. Change all ALs to R
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if (charTypeCounts.get(TYPE_AL)) {
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for (let si = 0; si < seqIndices.length; si++) {
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const i = seqIndices[si]
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if (charTypes[i] & TYPE_AL) {
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changeCharType(i, TYPE_R)
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}
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}
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}
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// W4. A single European separator between two European numbers changes to a European number. A single common
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// separator between two numbers of the same type changes to that type.
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if (charTypeCounts.get(TYPE_ES) || charTypeCounts.get(TYPE_CS)) {
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for (let si = 1; si < seqIndices.length - 1; si++) {
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const i = seqIndices[si]
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if (charTypes[i] & (TYPE_ES | TYPE_CS)) {
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let prevType = 0, nextType = 0
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for (let sj = si - 1; sj >= 0; sj--) {
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prevType = charTypes[seqIndices[sj]]
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if (!(prevType & BN_LIKE_TYPES)) { //5.2
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break
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}
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}
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for (let sj = si + 1; sj < seqIndices.length; sj++) {
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nextType = charTypes[seqIndices[sj]]
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if (!(nextType & BN_LIKE_TYPES)) { //5.2
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break
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}
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}
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if (prevType === nextType && (charTypes[i] === TYPE_ES ? prevType === TYPE_EN : (prevType & (TYPE_EN | TYPE_AN)))) {
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changeCharType(i, prevType)
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}
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}
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}
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}
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// W5. A sequence of European terminators adjacent to European numbers changes to all European numbers.
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if (charTypeCounts.get(TYPE_EN)) {
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for (let si = 0; si < seqIndices.length; si++) {
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const i = seqIndices[si]
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if (charTypes[i] & TYPE_EN) {
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for (let sj = si - 1; sj >= 0 && (charTypes[seqIndices[sj]] & (TYPE_ET | BN_LIKE_TYPES)); sj--) {
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changeCharType(seqIndices[sj], TYPE_EN)
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}
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for (si++; si < seqIndices.length && (charTypes[seqIndices[si]] & (TYPE_ET | BN_LIKE_TYPES | TYPE_EN)); si++) {
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if (charTypes[seqIndices[si]] !== TYPE_EN) {
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changeCharType(seqIndices[si], TYPE_EN)
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}
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}
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}
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}
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}
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// W6. Otherwise, separators and terminators change to Other Neutral.
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if (charTypeCounts.get(TYPE_ET) || charTypeCounts.get(TYPE_ES) || charTypeCounts.get(TYPE_CS)) {
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for (let si = 0; si < seqIndices.length; si++) {
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const i = seqIndices[si]
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if (charTypes[i] & (TYPE_ET | TYPE_ES | TYPE_CS)) {
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changeCharType(i, TYPE_ON)
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// 5.2 transform adjacent BNs too:
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for (let sj = si - 1; sj >= 0 && (charTypes[seqIndices[sj]] & BN_LIKE_TYPES); sj--) {
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changeCharType(seqIndices[sj], TYPE_ON)
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}
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for (let sj = si + 1; sj < seqIndices.length && (charTypes[seqIndices[sj]] & BN_LIKE_TYPES); sj++) {
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changeCharType(seqIndices[sj], TYPE_ON)
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}
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}
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}
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}
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// W7. Search backward from each instance of a European number until the first strong type (R, L, or sos)
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// is found. If an L is found, then change the type of the European number to L.
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// NOTE: implemented in single forward pass for efficiency
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if (charTypeCounts.get(TYPE_EN)) {
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for (let si = 0, prevStrongType = sosType; si < seqIndices.length; si++) {
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const i = seqIndices[si]
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const type = charTypes[i]
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if (type & TYPE_EN) {
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if (prevStrongType === TYPE_L) {
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changeCharType(i, TYPE_L)
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}
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} else if (type & STRONG_TYPES) {
|
|
prevStrongType = type
|
|
}
|
|
}
|
|
}
|
|
|
|
// === 3.3.5 Resolving Neutral and Isolate Formatting Types ===
|
|
|
|
if (charTypeCounts.get(NEUTRAL_ISOLATE_TYPES)) {
|
|
// N0. Process bracket pairs in an isolating run sequence sequentially in the logical order of the text
|
|
// positions of the opening paired brackets using the logic given below. Within this scope, bidirectional
|
|
// types EN and AN are treated as R.
|
|
const R_TYPES_FOR_N_STEPS = (TYPE_R | TYPE_EN | TYPE_AN)
|
|
const STRONG_TYPES_FOR_N_STEPS = R_TYPES_FOR_N_STEPS | TYPE_L
|
|
|
|
// * Identify the bracket pairs in the current isolating run sequence according to BD16.
|
|
const bracketPairs = []
|
|
{
|
|
const openerStack = []
|
|
for (let si = 0; si < seqIndices.length; si++) {
|
|
// NOTE: for any potential bracket character we also test that it still carries a NI
|
|
// type, as that may have been changed earlier. This doesn't seem to be explicitly
|
|
// called out in the spec, but is required for passage of certain tests.
|
|
if (charTypes[seqIndices[si]] & NEUTRAL_ISOLATE_TYPES) {
|
|
const char = string[seqIndices[si]]
|
|
let oppositeBracket
|
|
// Opening bracket
|
|
if (openingToClosingBracket(char) !== null) {
|
|
if (openerStack.length < 63) {
|
|
openerStack.push({ char, seqIndex: si })
|
|
} else {
|
|
break
|
|
}
|
|
}
|
|
// Closing bracket
|
|
else if ((oppositeBracket = closingToOpeningBracket(char)) !== null) {
|
|
for (let stackIdx = openerStack.length - 1; stackIdx >= 0; stackIdx--) {
|
|
const stackChar = openerStack[stackIdx].char
|
|
if (stackChar === oppositeBracket ||
|
|
stackChar === closingToOpeningBracket(getCanonicalBracket(char)) ||
|
|
openingToClosingBracket(getCanonicalBracket(stackChar)) === char
|
|
) {
|
|
bracketPairs.push([openerStack[stackIdx].seqIndex, si])
|
|
openerStack.length = stackIdx //pop the matching bracket and all following
|
|
break
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
bracketPairs.sort((a, b) => a[0] - b[0])
|
|
}
|
|
// * For each bracket-pair element in the list of pairs of text positions
|
|
for (let pairIdx = 0; pairIdx < bracketPairs.length; pairIdx++) {
|
|
const [openSeqIdx, closeSeqIdx] = bracketPairs[pairIdx]
|
|
// a. Inspect the bidirectional types of the characters enclosed within the bracket pair.
|
|
// b. If any strong type (either L or R) matching the embedding direction is found, set the type for both
|
|
// brackets in the pair to match the embedding direction.
|
|
let foundStrongType = false
|
|
let useStrongType = 0
|
|
for (let si = openSeqIdx + 1; si < closeSeqIdx; si++) {
|
|
const i = seqIndices[si]
|
|
if (charTypes[i] & STRONG_TYPES_FOR_N_STEPS) {
|
|
foundStrongType = true
|
|
const lr = (charTypes[i] & R_TYPES_FOR_N_STEPS) ? TYPE_R : TYPE_L
|
|
if (lr === embedDirection) {
|
|
useStrongType = lr
|
|
break
|
|
}
|
|
}
|
|
}
|
|
// c. Otherwise, if there is a strong type it must be opposite the embedding direction. Therefore, test
|
|
// for an established context with a preceding strong type by checking backwards before the opening paired
|
|
// bracket until the first strong type (L, R, or sos) is found.
|
|
// 1. If the preceding strong type is also opposite the embedding direction, context is established, so
|
|
// set the type for both brackets in the pair to that direction.
|
|
// 2. Otherwise set the type for both brackets in the pair to the embedding direction.
|
|
if (foundStrongType && !useStrongType) {
|
|
useStrongType = sosType
|
|
for (let si = openSeqIdx - 1; si >= 0; si--) {
|
|
const i = seqIndices[si]
|
|
if (charTypes[i] & STRONG_TYPES_FOR_N_STEPS) {
|
|
const lr = (charTypes[i] & R_TYPES_FOR_N_STEPS) ? TYPE_R : TYPE_L
|
|
if (lr !== embedDirection) {
|
|
useStrongType = lr
|
|
} else {
|
|
useStrongType = embedDirection
|
|
}
|
|
break
|
|
}
|
|
}
|
|
}
|
|
if (useStrongType) {
|
|
charTypes[seqIndices[openSeqIdx]] = charTypes[seqIndices[closeSeqIdx]] = useStrongType
|
|
// * Any number of characters that had original bidirectional character type NSM prior to the application
|
|
// of W1 that immediately follow a paired bracket which changed to L or R under N0 should change to match
|
|
// the type of their preceding bracket.
|
|
if (useStrongType !== embedDirection) {
|
|
for (let si = openSeqIdx + 1; si < seqIndices.length; si++) {
|
|
if (!(charTypes[seqIndices[si]] & BN_LIKE_TYPES)) {
|
|
if (getBidiCharType(string[seqIndices[si]]) & TYPE_NSM) {
|
|
charTypes[seqIndices[si]] = useStrongType
|
|
}
|
|
break
|
|
}
|
|
}
|
|
}
|
|
if (useStrongType !== embedDirection) {
|
|
for (let si = closeSeqIdx + 1; si < seqIndices.length; si++) {
|
|
if (!(charTypes[seqIndices[si]] & BN_LIKE_TYPES)) {
|
|
if (getBidiCharType(string[seqIndices[si]]) & TYPE_NSM) {
|
|
charTypes[seqIndices[si]] = useStrongType
|
|
}
|
|
break
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// N1. A sequence of NIs takes the direction of the surrounding strong text if the text on both sides has the
|
|
// same direction.
|
|
// N2. Any remaining NIs take the embedding direction.
|
|
for (let si = 0; si < seqIndices.length; si++) {
|
|
if (charTypes[seqIndices[si]] & NEUTRAL_ISOLATE_TYPES) {
|
|
let niRunStart = si, niRunEnd = si
|
|
let prevType = sosType //si === 0 ? sosType : (charTypes[seqIndices[si - 1]] & R_TYPES_FOR_N_STEPS) ? TYPE_R : TYPE_L
|
|
for (let si2 = si - 1; si2 >= 0; si2--) {
|
|
if (charTypes[seqIndices[si2]] & BN_LIKE_TYPES) {
|
|
niRunStart = si2 //5.2 treat BNs adjacent to NIs as NIs
|
|
} else {
|
|
prevType = (charTypes[seqIndices[si2]] & R_TYPES_FOR_N_STEPS) ? TYPE_R : TYPE_L
|
|
break
|
|
}
|
|
}
|
|
let nextType = eosType
|
|
for (let si2 = si + 1; si2 < seqIndices.length; si2++) {
|
|
if (charTypes[seqIndices[si2]] & (NEUTRAL_ISOLATE_TYPES | BN_LIKE_TYPES)) {
|
|
niRunEnd = si2
|
|
} else {
|
|
nextType = (charTypes[seqIndices[si2]] & R_TYPES_FOR_N_STEPS) ? TYPE_R : TYPE_L
|
|
break
|
|
}
|
|
}
|
|
for (let sj = niRunStart; sj <= niRunEnd; sj++) {
|
|
charTypes[seqIndices[sj]] = prevType === nextType ? prevType : embedDirection
|
|
}
|
|
si = niRunEnd
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// === 3.3.6 Resolving Implicit Levels ===
|
|
|
|
for (let i = paragraph.start; i <= paragraph.end; i++) {
|
|
const level = embedLevels[i]
|
|
const type = charTypes[i]
|
|
// I2. For all characters with an odd (right-to-left) embedding level, those of type L, EN or AN go up one level.
|
|
if (level & 1) {
|
|
if (type & (TYPE_L | TYPE_EN | TYPE_AN)) {
|
|
embedLevels[i]++
|
|
}
|
|
}
|
|
// I1. For all characters with an even (left-to-right) embedding level, those of type R go up one level
|
|
// and those of type AN or EN go up two levels.
|
|
else {
|
|
if (type & TYPE_R) {
|
|
embedLevels[i]++
|
|
} else if (type & (TYPE_AN | TYPE_EN)) {
|
|
embedLevels[i] += 2
|
|
}
|
|
}
|
|
|
|
// 5.2: Resolve any LRE, RLE, LRO, RLO, PDF, or BN to the level of the preceding character if there is one,
|
|
// and otherwise to the base level.
|
|
if (type & BN_LIKE_TYPES) {
|
|
embedLevels[i] = i === 0 ? paragraph.level : embedLevels[i - 1]
|
|
}
|
|
|
|
// 3.4 L1.1-4: Reset the embedding level of segment/paragraph separators, and any sequence of whitespace or
|
|
// isolate formatting characters preceding them or the end of the paragraph, to the paragraph level.
|
|
// NOTE: this will also need to be applied to each individual line ending after line wrapping occurs.
|
|
if (i === paragraph.end || getBidiCharType(string[i]) & (TYPE_S | TYPE_B)) {
|
|
for (let j = i; j >= 0 && (getBidiCharType(string[j]) & TRAILING_TYPES); j--) {
|
|
embedLevels[j] = paragraph.level
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// DONE! The resolved levels can then be used, after line wrapping, to flip runs of characters
|
|
// according to section 3.4 Reordering Resolved Levels
|
|
return {
|
|
levels: embedLevels,
|
|
paragraphs
|
|
}
|
|
|
|
function determineAutoEmbedLevel (start, isFSI) {
|
|
// 3.3.1 P2 - P3
|
|
for (let i = start; i < string.length; i++) {
|
|
const charType = charTypes[i]
|
|
if (charType & (TYPE_R | TYPE_AL)) {
|
|
return 1
|
|
}
|
|
if ((charType & (TYPE_B | TYPE_L)) || (isFSI && charType === TYPE_PDI)) {
|
|
return 0
|
|
}
|
|
if (charType & ISOLATE_INIT_TYPES) {
|
|
const pdi = indexOfMatchingPDI(i)
|
|
i = pdi === -1 ? string.length : pdi
|
|
}
|
|
}
|
|
return 0
|
|
}
|
|
|
|
function indexOfMatchingPDI (isolateStart) {
|
|
// 3.1.2 BD9
|
|
let isolationLevel = 1
|
|
for (let i = isolateStart + 1; i < string.length; i++) {
|
|
const charType = charTypes[i]
|
|
if (charType & TYPE_B) {
|
|
break
|
|
}
|
|
if (charType & TYPE_PDI) {
|
|
if (--isolationLevel === 0) {
|
|
return i
|
|
}
|
|
} else if (charType & ISOLATE_INIT_TYPES) {
|
|
isolationLevel++
|
|
}
|
|
}
|
|
return -1
|
|
}
|
|
}
|