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