| 'use strict'; |
| |
| var UNICODE = require('../common/unicode'); |
| |
| //Aliases |
| var $ = UNICODE.CODE_POINTS; |
| |
| //Utils |
| |
| //OPTIMIZATION: these utility functions should not be moved out of this module. V8 Crankshaft will not inline |
| //this functions if they will be situated in another module due to context switch. |
| //Always perform inlining check before modifying this functions ('node --trace-inlining'). |
| function isReservedCodePoint(cp) { |
| return cp >= 0xD800 && cp <= 0xDFFF || cp > 0x10FFFF; |
| } |
| |
| function isSurrogatePair(cp1, cp2) { |
| return cp1 >= 0xD800 && cp1 <= 0xDBFF && cp2 >= 0xDC00 && cp2 <= 0xDFFF; |
| } |
| |
| function getSurrogatePairCodePoint(cp1, cp2) { |
| return (cp1 - 0xD800) * 0x400 + 0x2400 + cp2; |
| } |
| |
| //Preprocessor |
| //NOTE: HTML input preprocessing |
| //(see: http://www.whatwg.org/specs/web-apps/current-work/multipage/parsing.html#preprocessing-the-input-stream) |
| var Preprocessor = module.exports = function (html) { |
| this.write(html); |
| |
| //NOTE: one leading U+FEFF BYTE ORDER MARK character must be ignored if any are present in the input stream. |
| this.pos = this.html.charCodeAt(0) === $.BOM ? 0 : -1; |
| |
| this.gapStack = []; |
| this.lastGapPos = -1; |
| this.skipNextNewLine = false; |
| }; |
| |
| Preprocessor.prototype.write = function (html) { |
| if (this.html) { |
| this.html = this.html.substring(0, this.pos + 1) + |
| html + |
| this.html.substring(this.pos + 1, this.html.length); |
| |
| } |
| else |
| this.html = html; |
| |
| |
| this.lastCharPos = this.html.length - 1; |
| }; |
| |
| Preprocessor.prototype.advanceAndPeekCodePoint = function () { |
| this.pos++; |
| |
| if (this.pos > this.lastCharPos) |
| return $.EOF; |
| |
| var cp = this.html.charCodeAt(this.pos); |
| |
| //NOTE: any U+000A LINE FEED (LF) characters that immediately follow a U+000D CARRIAGE RETURN (CR) character |
| //must be ignored. |
| if (this.skipNextNewLine && cp === $.LINE_FEED) { |
| this.skipNextNewLine = false; |
| this._addGap(); |
| return this.advanceAndPeekCodePoint(); |
| } |
| |
| //NOTE: all U+000D CARRIAGE RETURN (CR) characters must be converted to U+000A LINE FEED (LF) characters |
| if (cp === $.CARRIAGE_RETURN) { |
| this.skipNextNewLine = true; |
| return $.LINE_FEED; |
| } |
| |
| this.skipNextNewLine = false; |
| |
| //OPTIMIZATION: first perform check if the code point in the allowed range that covers most common |
| //HTML input (e.g. ASCII codes) to avoid performance-cost operations for high-range code points. |
| return cp >= 0xD800 ? this._processHighRangeCodePoint(cp) : cp; |
| }; |
| |
| Preprocessor.prototype._processHighRangeCodePoint = function (cp) { |
| //NOTE: try to peek a surrogate pair |
| if (this.pos !== this.lastCharPos) { |
| var nextCp = this.html.charCodeAt(this.pos + 1); |
| |
| if (isSurrogatePair(cp, nextCp)) { |
| //NOTE: we have a surrogate pair. Peek pair character and recalculate code point. |
| this.pos++; |
| cp = getSurrogatePairCodePoint(cp, nextCp); |
| |
| //NOTE: add gap that should be avoided during retreat |
| this._addGap(); |
| } |
| } |
| |
| if (isReservedCodePoint(cp)) |
| cp = $.REPLACEMENT_CHARACTER; |
| |
| return cp; |
| }; |
| |
| Preprocessor.prototype._addGap = function () { |
| this.gapStack.push(this.lastGapPos); |
| this.lastGapPos = this.pos; |
| }; |
| |
| Preprocessor.prototype.retreat = function () { |
| if (this.pos === this.lastGapPos) { |
| this.lastGapPos = this.gapStack.pop(); |
| this.pos--; |
| } |
| |
| this.pos--; |
| }; |