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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;