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- import { lst } from "./misc.js"
- // BIDI HELPERS
- export function iterateBidiSections(order, from, to, f) {
- if (!order) return f(from, to, "ltr", 0)
- let found = false
- for (let i = 0; i < order.length; ++i) {
- let part = order[i]
- if (part.from < to && part.to > from || from == to && part.to == from) {
- f(Math.max(part.from, from), Math.min(part.to, to), part.level == 1 ? "rtl" : "ltr", i)
- found = true
- }
- }
- if (!found) f(from, to, "ltr")
- }
- export let bidiOther = null
- export function getBidiPartAt(order, ch, sticky) {
- let found
- bidiOther = null
- for (let i = 0; i < order.length; ++i) {
- let cur = order[i]
- if (cur.from < ch && cur.to > ch) return i
- if (cur.to == ch) {
- if (cur.from != cur.to && sticky == "before") found = i
- else bidiOther = i
- }
- if (cur.from == ch) {
- if (cur.from != cur.to && sticky != "before") found = i
- else bidiOther = i
- }
- }
- return found != null ? found : bidiOther
- }
- // Bidirectional ordering algorithm
- // See http://unicode.org/reports/tr9/tr9-13.html for the algorithm
- // that this (partially) implements.
- // One-char codes used for character types:
- // L (L): Left-to-Right
- // R (R): Right-to-Left
- // r (AL): Right-to-Left Arabic
- // 1 (EN): European Number
- // + (ES): European Number Separator
- // % (ET): European Number Terminator
- // n (AN): Arabic Number
- // , (CS): Common Number Separator
- // m (NSM): Non-Spacing Mark
- // b (BN): Boundary Neutral
- // s (B): Paragraph Separator
- // t (S): Segment Separator
- // w (WS): Whitespace
- // N (ON): Other Neutrals
- // Returns null if characters are ordered as they appear
- // (left-to-right), or an array of sections ({from, to, level}
- // objects) in the order in which they occur visually.
- let bidiOrdering = (function() {
- // Character types for codepoints 0 to 0xff
- let lowTypes = "bbbbbbbbbtstwsbbbbbbbbbbbbbbssstwNN%%%NNNNNN,N,N1111111111NNNNNNNLLLLLLLLLLLLLLLLLLLLLLLLLLNNNNNNLLLLLLLLLLLLLLLLLLLLLLLLLLNNNNbbbbbbsbbbbbbbbbbbbbbbbbbbbbbbbbb,N%%%%NNNNLNNNNN%%11NLNNN1LNNNNNLLLLLLLLLLLLLLLLLLLLLLLNLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLN"
- // Character types for codepoints 0x600 to 0x6f9
- let arabicTypes = "nnnnnnNNr%%r,rNNmmmmmmmmmmmrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrmmmmmmmmmmmmmmmmmmmmmnnnnnnnnnn%nnrrrmrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrmmmmmmmnNmmmmmmrrmmNmmmmrr1111111111"
- function charType(code) {
- if (code <= 0xf7) return lowTypes.charAt(code)
- else if (0x590 <= code && code <= 0x5f4) return "R"
- else if (0x600 <= code && code <= 0x6f9) return arabicTypes.charAt(code - 0x600)
- else if (0x6ee <= code && code <= 0x8ac) return "r"
- else if (0x2000 <= code && code <= 0x200b) return "w"
- else if (code == 0x200c) return "b"
- else return "L"
- }
- let bidiRE = /[\u0590-\u05f4\u0600-\u06ff\u0700-\u08ac]/
- let isNeutral = /[stwN]/, isStrong = /[LRr]/, countsAsLeft = /[Lb1n]/, countsAsNum = /[1n]/
- function BidiSpan(level, from, to) {
- this.level = level
- this.from = from; this.to = to
- }
- return function(str, direction) {
- let outerType = direction == "ltr" ? "L" : "R"
- if (str.length == 0 || direction == "ltr" && !bidiRE.test(str)) return false
- let len = str.length, types = []
- for (let i = 0; i < len; ++i)
- types.push(charType(str.charCodeAt(i)))
- // W1. Examine each non-spacing mark (NSM) in the level run, and
- // change the type of the NSM to the type of the previous
- // character. If the NSM is at the start of the level run, it will
- // get the type of sor.
- for (let i = 0, prev = outerType; i < len; ++i) {
- let type = types[i]
- if (type == "m") types[i] = prev
- else prev = type
- }
- // W2. Search backwards from each instance of a European number
- // until the first strong type (R, L, AL, or sor) is found. If an
- // AL is found, change the type of the European number to Arabic
- // number.
- // W3. Change all ALs to R.
- for (let i = 0, cur = outerType; i < len; ++i) {
- let type = types[i]
- if (type == "1" && cur == "r") types[i] = "n"
- else if (isStrong.test(type)) { cur = type; if (type == "r") types[i] = "R" }
- }
- // W4. A single European separator between two European numbers
- // changes to a European number. A single common separator between
- // two numbers of the same type changes to that type.
- for (let i = 1, prev = types[0]; i < len - 1; ++i) {
- let type = types[i]
- if (type == "+" && prev == "1" && types[i+1] == "1") types[i] = "1"
- else if (type == "," && prev == types[i+1] &&
- (prev == "1" || prev == "n")) types[i] = prev
- prev = type
- }
- // W5. A sequence of European terminators adjacent to European
- // numbers changes to all European numbers.
- // W6. Otherwise, separators and terminators change to Other
- // Neutral.
- for (let i = 0; i < len; ++i) {
- let type = types[i]
- if (type == ",") types[i] = "N"
- else if (type == "%") {
- let end
- for (end = i + 1; end < len && types[end] == "%"; ++end) {}
- let replace = (i && types[i-1] == "!") || (end < len && types[end] == "1") ? "1" : "N"
- for (let j = i; j < end; ++j) types[j] = replace
- i = end - 1
- }
- }
- // W7. Search backwards from each instance of a European number
- // until the first strong type (R, L, or sor) is found. If an L is
- // found, then change the type of the European number to L.
- for (let i = 0, cur = outerType; i < len; ++i) {
- let type = types[i]
- if (cur == "L" && type == "1") types[i] = "L"
- else if (isStrong.test(type)) cur = type
- }
- // N1. A sequence of neutrals takes the direction of the
- // surrounding strong text if the text on both sides has the same
- // direction. European and Arabic numbers act as if they were R in
- // terms of their influence on neutrals. Start-of-level-run (sor)
- // and end-of-level-run (eor) are used at level run boundaries.
- // N2. Any remaining neutrals take the embedding direction.
- for (let i = 0; i < len; ++i) {
- if (isNeutral.test(types[i])) {
- let end
- for (end = i + 1; end < len && isNeutral.test(types[end]); ++end) {}
- let before = (i ? types[i-1] : outerType) == "L"
- let after = (end < len ? types[end] : outerType) == "L"
- let replace = before == after ? (before ? "L" : "R") : outerType
- for (let j = i; j < end; ++j) types[j] = replace
- i = end - 1
- }
- }
- // Here we depart from the documented algorithm, in order to avoid
- // building up an actual levels array. Since there are only three
- // levels (0, 1, 2) in an implementation that doesn't take
- // explicit embedding into account, we can build up the order on
- // the fly, without following the level-based algorithm.
- let order = [], m
- for (let i = 0; i < len;) {
- if (countsAsLeft.test(types[i])) {
- let start = i
- for (++i; i < len && countsAsLeft.test(types[i]); ++i) {}
- order.push(new BidiSpan(0, start, i))
- } else {
- let pos = i, at = order.length, isRTL = direction == "rtl" ? 1 : 0
- for (++i; i < len && types[i] != "L"; ++i) {}
- for (let j = pos; j < i;) {
- if (countsAsNum.test(types[j])) {
- if (pos < j) { order.splice(at, 0, new BidiSpan(1, pos, j)); at += isRTL }
- let nstart = j
- for (++j; j < i && countsAsNum.test(types[j]); ++j) {}
- order.splice(at, 0, new BidiSpan(2, nstart, j))
- at += isRTL
- pos = j
- } else ++j
- }
- if (pos < i) order.splice(at, 0, new BidiSpan(1, pos, i))
- }
- }
- if (direction == "ltr") {
- if (order[0].level == 1 && (m = str.match(/^\s+/))) {
- order[0].from = m[0].length
- order.unshift(new BidiSpan(0, 0, m[0].length))
- }
- if (lst(order).level == 1 && (m = str.match(/\s+$/))) {
- lst(order).to -= m[0].length
- order.push(new BidiSpan(0, len - m[0].length, len))
- }
- }
- return direction == "rtl" ? order.reverse() : order
- }
- })()
- // Get the bidi ordering for the given line (and cache it). Returns
- // false for lines that are fully left-to-right, and an array of
- // BidiSpan objects otherwise.
- export function getOrder(line, direction) {
- let order = line.order
- if (order == null) order = line.order = bidiOrdering(line.text, direction)
- return order
- }
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