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/* eslint-disable no-underscore-dangle */
import { Transform } from 'node:stream';
import postcss from 'postcss';
import sourcemap from 'source-map';
import DoIUse from '../DoIUse.js';
/** @typedef {import('../../data/features.js').FeatureKeys} FeatureKeys */
/** @typedef {import('./SourceMapTransform.js').SourceMapTransformation} SourceMapTransformation */
export default class RuleUsageTransform extends Transform {
/** @type {import("postcss").Processor} */
#processor;
#skipErrors;
#filename;
/**
* @param {Object} options
* @param {string} options.browsers
* @param {FeatureKeys[]} [options.ignore]
* @param {boolean} [options.skipErrors]
* @param {string} [filename] Filename for outputting source code locations.
*/
constructor(options, filename = '<streaming css input>') {
super({
objectMode: true,
});
this.#processor = postcss([new DoIUse({
browsers: options.browsers,
ignore: options.ignore,
onFeatureUsage: (usage) => {
this.push(usage);
},
})]);
this.#filename = filename;
this.#skipErrors = options.skipErrors;
}
/**
* @param {SourceMapTransformation} rule
* @param {any} encoding
* @param {Function} callback
*/
async _transform(rule, encoding, callback) {
let caughtError;
try {
const mapper = new sourcemap.SourceMapGenerator();
const lines = rule.content.split('\n');
let oline = rule.line;
let ocol = rule.column;
for (const [lineNumber, content] of lines.entries()) {
mapper.addMapping({
generated: { line: lineNumber + 1, column: 1 },
original: { line: oline, column: ocol },
source: this.#filename,
});
mapper.addMapping({
generated: { line: lineNumber + 1, column: content.length },
original: { line: oline, column: ocol + content.length },
source: this.#filename,
});
oline += 1;
ocol = 1;
}
await this.#processor.process(rule.content, {
from: this.#filename, map: { prev: mapper.toString() },
});
} catch (error) {
if (this.#skipErrors) {
this.emit('warning', error);
} else {
caughtError = error;
}
}
callback(caughtError);
}
}
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