angular-docs-cn/tools/source-map-test/parseMap.js

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#!/usr/bin/env node
/**
* @license
* Copyright Google LLC All Rights Reserved.
*
* Use of this source code is governed by an MIT-style license that can be
* found in the LICENSE file at https://angular.io/license
*/
const vlq = require('vlq');
const fs = require('fs');
const path = require('path');
module.exports = function getMappings(bundlePath) {
const sourceMap = JSON.parse(getFile(`${bundlePath}.map`));
const sourcesContent = sourceMap.sourcesContent.map(file => file.split('\n'));
const bundleLines = getFile(bundlePath).split('\n');
let sourceLines = sourcesContent[0];
let sourceFileIndex = 0;
let sourceLineIndex = 0;
let sourceColIndex = 0;
return decodeLines(sourceMap).reduce((matchData, mapLine, genLineIndex) => {
mapLine.forEach((segment, index) => {
if (segment.length) {
const [genColDiff, sourceFileDiff, sourceLineDiff, sourceColDiff] = segment;
// if source file changes, grab new file from sourcesContent
if (sourceFileDiff !== 0) {
sourceFileIndex += sourceFileDiff;
sourceLines = sourcesContent[sourceFileIndex];
}
const genText = bundleLines[genLineIndex].trim();
const sourceText = sourceLines[sourceLineIndex + sourceLineDiff].trim();
// only record mappings that are long enough to be meaningful
if (index === 0 && genText.length > 15 && sourceText.length > 15) {
matchData.push({
genLineIndex,
sourceLineIndex,
sourceFile: sourceMap.sources[sourceFileIndex],
genText,
sourceText
});
}
sourceLineIndex += sourceLineDiff;
sourceColIndex += sourceColDiff;
}
});
return matchData;
}, []);
};
function getFile(filePath) {
return fs.readFileSync(path.resolve(process.cwd(), filePath), 'UTF-8');
}
function decodeLines(sourceMap) {
return sourceMap.mappings.split(';').map(line => {
return line.split(',').map(seg => vlq.decode(seg));
});
}