angular-cn/packages/compiler-cli/test/ngtsc/sourcemap_utils.ts

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/**
* @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
*/
import {MappingItem, SourceMapConsumer} from 'source-map';
import {NgtscTestEnvironment} from './env';
class TestSourceFile {
private lineStarts: number[];
constructor(public url: string, public contents: string) {
this.lineStarts = this.getLineStarts();
}
getSegment(key: 'generated'|'original', start: MappingItem|any, end: MappingItem|any): string {
const startLine = start[key + 'Line'];
const startCol = start[key + 'Column'];
const endLine = end[key + 'Line'];
const endCol = end[key + 'Column'];
return this.contents.substring(
this.lineStarts[startLine - 1] + startCol, this.lineStarts[endLine - 1] + endCol);
}
getSourceMapFileName(generatedContents: string): string {
const match = /\/\/# sourceMappingURL=(.+)/.exec(generatedContents);
if (!match) {
throw new Error('Generated contents does not contain a sourceMappingURL');
}
return match[1];
}
private getLineStarts(): number[] {
const lineStarts = [0];
let currentPos = 0;
const lines = this.contents.split('\n');
lines.forEach(line => {
currentPos += line.length + 1;
lineStarts.push(currentPos);
});
return lineStarts;
}
}
/**
* A mapping of a segment of generated text to a segment of source text.
*/
export interface SegmentMapping {
/** The generated text in this segment. */
generated: string;
/** The source text in this segment. */
source: string;
/** The URL of the source file for this segment. */
sourceUrl: string;
}
/**
* Process a generated file to extract human understandable segment mappings.
* These mappings are easier to compare in unit tests that the raw SourceMap mappings.
* @param env the environment that holds the source and generated files.
* @param generatedFileName The name of the generated file to process.
* @returns An array of segment mappings for each mapped segment in the given generated file.
*/
export function getMappedSegments(
env: NgtscTestEnvironment, generatedFileName: string): SegmentMapping[] {
const generated = new TestSourceFile(generatedFileName, env.getContents(generatedFileName));
const sourceMapFileName = generated.getSourceMapFileName(generated.contents);
const sources = new Map<string, TestSourceFile>();
const mappings: MappingItem[] = [];
const mapContents = env.getContents(sourceMapFileName);
const sourceMapConsumer = new SourceMapConsumer(JSON.parse(mapContents));
sourceMapConsumer.eachMapping(item => {
if (!sources.has(item.source)) {
sources.set(item.source, new TestSourceFile(item.source, env.getContents(item.source)));
}
mappings.push(item);
});
const segments: SegmentMapping[] = [];
let currentMapping = mappings.shift();
while (currentMapping) {
const nextMapping = mappings.shift();
if (nextMapping) {
const source = sources.get(currentMapping.source)!;
const segment = {
generated: generated.getSegment('generated', currentMapping, nextMapping),
source: source.getSegment('original', currentMapping, nextMapping),
sourceUrl: source.url
};
if (segment.generated !== segment.source) {
segments.push(segment);
}
}
currentMapping = nextMapping;
}
return segments;
}