195 lines
No EOL
6.8 KiB
JavaScript
Executable file
195 lines
No EOL
6.8 KiB
JavaScript
Executable file
import { CODE_POINTS as $, getSurrogatePairCodePoint, isControlCodePoint, isSurrogate, isSurrogatePair, isUndefinedCodePoint, } from '../common/unicode.js';
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import { ERR } from '../common/error-codes.js';
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//Const
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const DEFAULT_BUFFER_WATERLINE = 1 << 16;
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//Preprocessor
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//NOTE: HTML input preprocessing
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//(see: http://www.whatwg.org/specs/web-apps/current-work/multipage/parsing.html#preprocessing-the-input-stream)
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export class Preprocessor {
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constructor(handler) {
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this.handler = handler;
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this.html = '';
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this.pos = -1;
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// NOTE: Initial `lastGapPos` is -2, to ensure `col` on initialisation is 0
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this.lastGapPos = -2;
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this.gapStack = [];
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this.skipNextNewLine = false;
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this.lastChunkWritten = false;
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this.endOfChunkHit = false;
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this.bufferWaterline = DEFAULT_BUFFER_WATERLINE;
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this.isEol = false;
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this.lineStartPos = 0;
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this.droppedBufferSize = 0;
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this.line = 1;
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//NOTE: avoid reporting errors twice on advance/retreat
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this.lastErrOffset = -1;
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}
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/** The column on the current line. If we just saw a gap (eg. a surrogate pair), return the index before. */
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get col() {
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return this.pos - this.lineStartPos + Number(this.lastGapPos !== this.pos);
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}
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get offset() {
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return this.droppedBufferSize + this.pos;
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}
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getError(code) {
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const { line, col, offset } = this;
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return {
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code,
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startLine: line,
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endLine: line,
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startCol: col,
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endCol: col,
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startOffset: offset,
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endOffset: offset,
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};
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}
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_err(code) {
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if (this.handler.onParseError && this.lastErrOffset !== this.offset) {
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this.lastErrOffset = this.offset;
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this.handler.onParseError(this.getError(code));
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}
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}
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_addGap() {
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this.gapStack.push(this.lastGapPos);
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this.lastGapPos = this.pos;
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}
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_processSurrogate(cp) {
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//NOTE: try to peek a surrogate pair
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if (this.pos !== this.html.length - 1) {
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const nextCp = this.html.charCodeAt(this.pos + 1);
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if (isSurrogatePair(nextCp)) {
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//NOTE: we have a surrogate pair. Peek pair character and recalculate code point.
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this.pos++;
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//NOTE: add a gap that should be avoided during retreat
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this._addGap();
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return getSurrogatePairCodePoint(cp, nextCp);
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}
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}
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//NOTE: we are at the end of a chunk, therefore we can't infer the surrogate pair yet.
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else if (!this.lastChunkWritten) {
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this.endOfChunkHit = true;
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return $.EOF;
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}
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//NOTE: isolated surrogate
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this._err(ERR.surrogateInInputStream);
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return cp;
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}
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willDropParsedChunk() {
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return this.pos > this.bufferWaterline;
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}
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dropParsedChunk() {
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if (this.willDropParsedChunk()) {
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this.html = this.html.substring(this.pos);
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this.lineStartPos -= this.pos;
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this.droppedBufferSize += this.pos;
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this.pos = 0;
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this.lastGapPos = -2;
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this.gapStack.length = 0;
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}
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}
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write(chunk, isLastChunk) {
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if (this.html.length > 0) {
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this.html += chunk;
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}
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else {
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this.html = chunk;
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}
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this.endOfChunkHit = false;
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this.lastChunkWritten = isLastChunk;
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}
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insertHtmlAtCurrentPos(chunk) {
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this.html = this.html.substring(0, this.pos + 1) + chunk + this.html.substring(this.pos + 1);
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this.endOfChunkHit = false;
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}
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startsWith(pattern, caseSensitive) {
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// Check if our buffer has enough characters
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if (this.pos + pattern.length > this.html.length) {
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this.endOfChunkHit = !this.lastChunkWritten;
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return false;
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}
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if (caseSensitive) {
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return this.html.startsWith(pattern, this.pos);
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}
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for (let i = 0; i < pattern.length; i++) {
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const cp = this.html.charCodeAt(this.pos + i) | 0x20;
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if (cp !== pattern.charCodeAt(i)) {
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return false;
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}
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}
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return true;
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}
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peek(offset) {
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const pos = this.pos + offset;
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if (pos >= this.html.length) {
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this.endOfChunkHit = !this.lastChunkWritten;
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return $.EOF;
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}
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const code = this.html.charCodeAt(pos);
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return code === $.CARRIAGE_RETURN ? $.LINE_FEED : code;
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}
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advance() {
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this.pos++;
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//NOTE: LF should be in the last column of the line
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if (this.isEol) {
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this.isEol = false;
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this.line++;
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this.lineStartPos = this.pos;
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}
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if (this.pos >= this.html.length) {
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this.endOfChunkHit = !this.lastChunkWritten;
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return $.EOF;
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}
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let cp = this.html.charCodeAt(this.pos);
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//NOTE: all U+000D CARRIAGE RETURN (CR) characters must be converted to U+000A LINE FEED (LF) characters
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if (cp === $.CARRIAGE_RETURN) {
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this.isEol = true;
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this.skipNextNewLine = true;
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return $.LINE_FEED;
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}
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//NOTE: any U+000A LINE FEED (LF) characters that immediately follow a U+000D CARRIAGE RETURN (CR) character
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//must be ignored.
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if (cp === $.LINE_FEED) {
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this.isEol = true;
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if (this.skipNextNewLine) {
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// `line` will be bumped again in the recursive call.
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this.line--;
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this.skipNextNewLine = false;
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this._addGap();
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return this.advance();
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}
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}
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this.skipNextNewLine = false;
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if (isSurrogate(cp)) {
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cp = this._processSurrogate(cp);
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}
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//OPTIMIZATION: first check if code point is in the common allowed
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//range (ASCII alphanumeric, whitespaces, big chunk of BMP)
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//before going into detailed performance cost validation.
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const isCommonValidRange = this.handler.onParseError === null ||
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(cp > 0x1f && cp < 0x7f) ||
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cp === $.LINE_FEED ||
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cp === $.CARRIAGE_RETURN ||
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(cp > 0x9f && cp < 64976);
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if (!isCommonValidRange) {
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this._checkForProblematicCharacters(cp);
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}
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return cp;
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}
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_checkForProblematicCharacters(cp) {
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if (isControlCodePoint(cp)) {
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this._err(ERR.controlCharacterInInputStream);
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}
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else if (isUndefinedCodePoint(cp)) {
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this._err(ERR.noncharacterInInputStream);
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}
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}
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retreat(count) {
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this.pos -= count;
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while (this.pos < this.lastGapPos) {
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this.lastGapPos = this.gapStack.pop();
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this.pos--;
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}
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this.isEol = false;
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}
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}
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//# sourceMappingURL=preprocessor.js.map
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