| '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; |