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181 lines
5.2 KiB
181 lines
5.2 KiB
'use strict';
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//Const
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const NOAH_ARK_CAPACITY = 3;
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//List of formatting elements
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class FormattingElementList {
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constructor(treeAdapter) {
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this.length = 0;
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this.entries = [];
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this.treeAdapter = treeAdapter;
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this.bookmark = null;
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}
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//Noah Ark's condition
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//OPTIMIZATION: at first we try to find possible candidates for exclusion using
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//lightweight heuristics without thorough attributes check.
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_getNoahArkConditionCandidates(newElement) {
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const candidates = [];
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if (this.length >= NOAH_ARK_CAPACITY) {
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const neAttrsLength = this.treeAdapter.getAttrList(newElement).length;
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const neTagName = this.treeAdapter.getTagName(newElement);
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const neNamespaceURI = this.treeAdapter.getNamespaceURI(newElement);
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for (let i = this.length - 1; i >= 0; i--) {
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const entry = this.entries[i];
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if (entry.type === FormattingElementList.MARKER_ENTRY) {
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break;
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}
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const element = entry.element;
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const elementAttrs = this.treeAdapter.getAttrList(element);
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const isCandidate =
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this.treeAdapter.getTagName(element) === neTagName &&
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this.treeAdapter.getNamespaceURI(element) === neNamespaceURI &&
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elementAttrs.length === neAttrsLength;
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if (isCandidate) {
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candidates.push({ idx: i, attrs: elementAttrs });
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}
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}
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}
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return candidates.length < NOAH_ARK_CAPACITY ? [] : candidates;
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}
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_ensureNoahArkCondition(newElement) {
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const candidates = this._getNoahArkConditionCandidates(newElement);
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let cLength = candidates.length;
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if (cLength) {
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const neAttrs = this.treeAdapter.getAttrList(newElement);
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const neAttrsLength = neAttrs.length;
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const neAttrsMap = Object.create(null);
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//NOTE: build attrs map for the new element so we can perform fast lookups
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for (let i = 0; i < neAttrsLength; i++) {
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const neAttr = neAttrs[i];
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neAttrsMap[neAttr.name] = neAttr.value;
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}
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for (let i = 0; i < neAttrsLength; i++) {
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for (let j = 0; j < cLength; j++) {
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const cAttr = candidates[j].attrs[i];
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if (neAttrsMap[cAttr.name] !== cAttr.value) {
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candidates.splice(j, 1);
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cLength--;
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}
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if (candidates.length < NOAH_ARK_CAPACITY) {
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return;
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}
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}
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}
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//NOTE: remove bottommost candidates until Noah's Ark condition will not be met
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for (let i = cLength - 1; i >= NOAH_ARK_CAPACITY - 1; i--) {
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this.entries.splice(candidates[i].idx, 1);
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this.length--;
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}
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}
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}
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//Mutations
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insertMarker() {
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this.entries.push({ type: FormattingElementList.MARKER_ENTRY });
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this.length++;
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}
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pushElement(element, token) {
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this._ensureNoahArkCondition(element);
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this.entries.push({
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type: FormattingElementList.ELEMENT_ENTRY,
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element: element,
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token: token
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});
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this.length++;
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}
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insertElementAfterBookmark(element, token) {
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let bookmarkIdx = this.length - 1;
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for (; bookmarkIdx >= 0; bookmarkIdx--) {
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if (this.entries[bookmarkIdx] === this.bookmark) {
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break;
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}
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}
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this.entries.splice(bookmarkIdx + 1, 0, {
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type: FormattingElementList.ELEMENT_ENTRY,
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element: element,
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token: token
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});
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this.length++;
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}
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removeEntry(entry) {
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for (let i = this.length - 1; i >= 0; i--) {
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if (this.entries[i] === entry) {
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this.entries.splice(i, 1);
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this.length--;
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break;
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}
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}
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}
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clearToLastMarker() {
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while (this.length) {
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const entry = this.entries.pop();
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this.length--;
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if (entry.type === FormattingElementList.MARKER_ENTRY) {
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break;
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}
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}
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}
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//Search
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getElementEntryInScopeWithTagName(tagName) {
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for (let i = this.length - 1; i >= 0; i--) {
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const entry = this.entries[i];
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if (entry.type === FormattingElementList.MARKER_ENTRY) {
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return null;
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}
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if (this.treeAdapter.getTagName(entry.element) === tagName) {
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return entry;
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}
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}
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return null;
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}
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getElementEntry(element) {
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for (let i = this.length - 1; i >= 0; i--) {
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const entry = this.entries[i];
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if (entry.type === FormattingElementList.ELEMENT_ENTRY && entry.element === element) {
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return entry;
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}
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}
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return null;
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}
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}
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//Entry types
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FormattingElementList.MARKER_ENTRY = 'MARKER_ENTRY';
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FormattingElementList.ELEMENT_ENTRY = 'ELEMENT_ENTRY';
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module.exports = FormattingElementList;
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