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