168 lines
4.9 KiB
JavaScript
168 lines
4.9 KiB
JavaScript
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'use strict';
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//Const
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var NOAH_ARK_CAPACITY = 3;
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//List of formatting elements
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var FormattingElementList = module.exports = function (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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//Entry types
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FormattingElementList.MARKER_ENTRY = 'MARKER_ENTRY';
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FormattingElementList.ELEMENT_ENTRY = 'ELEMENT_ENTRY';
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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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FormattingElementList.prototype._getNoahArkConditionCandidates = function (newElement) {
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var candidates = [];
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if (this.length >= NOAH_ARK_CAPACITY) {
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var neAttrsLength = this.treeAdapter.getAttrList(newElement).length,
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neTagName = this.treeAdapter.getTagName(newElement),
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neNamespaceURI = this.treeAdapter.getNamespaceURI(newElement);
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for (var i = this.length - 1; i >= 0; i--) {
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var entry = this.entries[i];
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if (entry.type === FormattingElementList.MARKER_ENTRY)
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break;
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var element = entry.element,
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elementAttrs = this.treeAdapter.getAttrList(element),
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isCandidate = 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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return candidates.length < NOAH_ARK_CAPACITY ? [] : candidates;
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};
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FormattingElementList.prototype._ensureNoahArkCondition = function (newElement) {
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var candidates = this._getNoahArkConditionCandidates(newElement),
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cLength = candidates.length;
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if (cLength) {
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var neAttrs = this.treeAdapter.getAttrList(newElement),
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neAttrsLength = neAttrs.length,
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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 (var i = 0; i < neAttrsLength; i++) {
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var neAttr = neAttrs[i];
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neAttrsMap[neAttr.name] = neAttr.value;
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}
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for (i = 0; i < neAttrsLength; i++) {
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for (var j = 0; j < cLength; j++) {
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var 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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//NOTE: remove bottommost candidates until Noah's Ark condition will not be met
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for (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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FormattingElementList.prototype.insertMarker = function () {
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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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FormattingElementList.prototype.pushElement = function (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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FormattingElementList.prototype.insertElementAfterBookmark = function (element, token) {
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var 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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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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FormattingElementList.prototype.removeEntry = function (entry) {
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for (var 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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FormattingElementList.prototype.clearToLastMarker = function () {
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while (this.length) {
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var 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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//Search
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FormattingElementList.prototype.getElementEntryInScopeWithTagName = function (tagName) {
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for (var i = this.length - 1; i >= 0; i--) {
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var entry = this.entries[i];
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if (entry.type === FormattingElementList.MARKER_ENTRY)
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return null;
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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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return null;
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};
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FormattingElementList.prototype.getElementEntry = function (element) {
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for (var i = this.length - 1; i >= 0; i--) {
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var 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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return null;
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};
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