121 lines
3.0 KiB
JavaScript
121 lines
3.0 KiB
JavaScript
/*
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MIT License http://www.opensource.org/licenses/mit-license.php
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Author Tobias Koppers @sokra
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*/
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"use strict";
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const ALPHABET =
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"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
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const CONTINUATION_BIT = 0x20;
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const END_SEGMENT_BIT = 0x40;
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const NEXT_LINE = END_SEGMENT_BIT | 0x01;
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const INVALID = END_SEGMENT_BIT | 0x02;
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const DATA_MASK = 0x1f;
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const ccToValue = new Uint8Array("z".charCodeAt(0) + 1);
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ccToValue.fill(INVALID);
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for (let i = 0; i < ALPHABET.length; i++) {
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ccToValue[ALPHABET.charCodeAt(i)] = i;
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}
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ccToValue[",".charCodeAt(0)] = END_SEGMENT_BIT;
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ccToValue[";".charCodeAt(0)] = NEXT_LINE;
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const ccMax = ccToValue.length - 1;
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/** @typedef {(generatedLine: number, generatedColumn: number, sourceIndex: number, originalLine: number, originalColumn: number, nameIndex: number) => void} OnMapping */
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/**
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* @param {string} mappings the mappings string
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* @param {OnMapping} onMapping called for each mapping
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* @returns {void}
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*/
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const readMappings = (mappings, onMapping) => {
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// generatedColumn, [sourceIndex, originalLine, orignalColumn, [nameIndex]]
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const currentData = new Uint32Array([0, 0, 1, 0, 0]);
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let currentDataPos = 0;
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// currentValue will include a sign bit at bit 0
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let currentValue = 0;
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let currentValuePos = 0;
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let generatedLine = 1;
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let generatedColumn = -1;
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for (let i = 0; i < mappings.length; i++) {
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const cc = mappings.charCodeAt(i);
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if (cc > ccMax) continue;
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const value = ccToValue[cc];
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if ((value & END_SEGMENT_BIT) !== 0) {
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// End current segment
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if (currentData[0] > generatedColumn) {
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if (currentDataPos === 1) {
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onMapping(generatedLine, currentData[0], -1, -1, -1, -1);
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} else if (currentDataPos === 4) {
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onMapping(
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generatedLine,
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currentData[0],
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currentData[1],
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currentData[2],
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currentData[3],
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-1,
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);
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} else if (currentDataPos === 5) {
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onMapping(
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generatedLine,
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currentData[0],
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currentData[1],
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currentData[2],
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currentData[3],
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currentData[4],
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);
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}
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[generatedColumn] = currentData;
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}
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currentDataPos = 0;
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if (value === NEXT_LINE) {
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// Start new line
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generatedLine++;
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currentData[0] = 0;
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generatedColumn = -1;
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}
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} else if ((value & CONTINUATION_BIT) === 0) {
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// last sextet
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currentValue |= value << currentValuePos;
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const finalValue =
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currentValue & 1 ? -(currentValue >> 1) : currentValue >> 1;
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currentData[currentDataPos++] += finalValue;
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currentValuePos = 0;
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currentValue = 0;
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} else {
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currentValue |= (value & DATA_MASK) << currentValuePos;
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currentValuePos += 5;
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}
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}
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// End current segment
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if (currentDataPos === 1) {
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onMapping(generatedLine, currentData[0], -1, -1, -1, -1);
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} else if (currentDataPos === 4) {
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onMapping(
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generatedLine,
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currentData[0],
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currentData[1],
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currentData[2],
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currentData[3],
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-1,
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);
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} else if (currentDataPos === 5) {
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onMapping(
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generatedLine,
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currentData[0],
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currentData[1],
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currentData[2],
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currentData[3],
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currentData[4],
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);
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}
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};
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module.exports = readMappings;
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