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'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 isSurrogatePair(cp1, cp2) {
return cp1 >= 0xD800 && cp1 <= 0xDBFF && cp2 >= 0xDC00 && cp2 <= 0xDFFF;
}
function getSurrogatePairCodePoint(cp1, cp2) {
return (cp1 - 0xD800) * 0x400 + 0x2400 + cp2;
}
//Const
var DEFAULT_BUFFER_WATERLINE = 1 << 16;
//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 () {
this.html = null;
this.pos = -1;
this.lastGapPos = -1;
this.lastCharPos = -1;
this.gapStack = [];
this.skipNextNewLine = false;
this.lastChunkWritten = false;
this.endOfChunkHit = false;
this.bufferWaterline = DEFAULT_BUFFER_WATERLINE;
};
Preprocessor.prototype.dropParsedChunk = function () {
if (this.pos > this.bufferWaterline) {
this.lastCharPos -= this.pos;
this.html = this.html.substring(this.pos);
this.pos = 0;
this.lastGapPos = -1;
this.gapStack = [];
}
};
Preprocessor.prototype._addGap = function () {
this.gapStack.push(this.lastGapPos);
this.lastGapPos = this.pos;
};
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();
}
}
// NOTE: we've hit the end of chunk, stop processing at this point
else if (!this.lastChunkWritten) {
this.endOfChunkHit = true;
return $.EOF;
}
return cp;
};
Preprocessor.prototype.write = function (chunk, isLastChunk) {
if (this.html)
this.html += chunk;
else
this.html = chunk;
this.lastCharPos = this.html.length - 1;
this.endOfChunkHit = false;
this.lastChunkWritten = isLastChunk;
};
Preprocessor.prototype.insertHtmlAtCurrentPos = function (chunk) {
this.html = this.html.substring(0, this.pos + 1) +
chunk +
this.html.substring(this.pos + 1, this.html.length);
this.lastCharPos = this.html.length - 1;
this.endOfChunkHit = false;
};
Preprocessor.prototype.advance = function () {
this.pos++;
if (this.pos > this.lastCharPos) {
if (!this.lastChunkWritten)
this.endOfChunkHit = true;
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.advance();
}
//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.retreat = function () {
if (this.pos === this.lastGapPos) {
this.lastGapPos = this.gapStack.pop();
this.pos--;
}
this.pos--;
};
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