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feat: reuse postcss ast from other loaders (i.e postcss-loader) (#840)
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evilebottnawi committed Dec 3, 2018
1 parent fe94ebc commit 1dad1fb
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Showing 3 changed files with 18 additions and 6 deletions.
13 changes: 12 additions & 1 deletion lib/loader.js
Expand Up @@ -3,6 +3,7 @@
Author Tobias Koppers @sokra
*/
const postcss = require('postcss');
const postcssPkg = require('postcss/package.json');
const localByDefault = require('postcss-modules-local-by-default');
const extractImports = require('postcss-modules-extract-imports');
const modulesScope = require('postcss-modules-scope');
Expand All @@ -26,7 +27,7 @@ const {
const Warning = require('./Warning');
const CssSyntaxError = require('./CssSyntaxError');

module.exports = function loader(content, map) {
module.exports = function loader(content, map, meta) {
const callback = this.async();
const options = getOptions(this) || {};
const sourceMap = options.sourceMap || false;
Expand All @@ -49,6 +50,16 @@ module.exports = function loader(content, map) {
}
/* eslint-enable no-param-reassign */

// Reuse CSS AST (PostCSS AST e.g 'postcss-loader') to avoid reparsing
if (meta) {
const { ast } = meta;

if (ast && ast.type === 'postcss' && ast.version === postcssPkg.version) {
// eslint-disable-next-line no-param-reassign
content = ast.root;
}
}

const resolveImport = options.import !== false;
const resolveUrl = options.url !== false;
const loaderContext = this;
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8 changes: 4 additions & 4 deletions test/__snapshots__/loader.test.js.snap
Expand Up @@ -444,9 +444,9 @@ You may need an appropriate loader to handle this file type.

exports[`loader should throws error when no loader for assets: warnings 1`] = `Array []`;

exports[`loader using together with "postcss-loader": errors 1`] = `Array []`;
exports[`loader using together with "postcss-loader" and reuse \`ast\`: errors 1`] = `Array []`;

exports[`loader using together with "postcss-loader": module (evaluated) 1`] = `
exports[`loader using together with "postcss-loader" and reuse \`ast\`: module (evaluated) 1`] = `
Array [
Array [
1,
Expand Down Expand Up @@ -513,7 +513,7 @@ a:hover {
]
`;

exports[`loader using together with "postcss-loader": module 1`] = `
exports[`loader using together with "postcss-loader" and reuse \`ast\`: module 1`] = `
"var escape = require(\\"../../../lib/runtime/escape.js\\");
exports = module.exports = require(\\"../../../lib/runtime/api.js\\")(false);
// imports
Expand All @@ -526,7 +526,7 @@ exports.push([module.id, \\":root {\\\\n --fontSize: 1rem;\\\\n --mainColor: r
"
`;

exports[`loader using together with "postcss-loader": warnings 1`] = `Array []`;
exports[`loader using together with "postcss-loader" and reuse \`ast\`: warnings 1`] = `Array []`;

exports[`loader using together with "sass-loader": errors 1`] = `Array []`;

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3 changes: 2 additions & 1 deletion test/loader.test.js
Expand Up @@ -90,7 +90,8 @@ describe('loader', () => {
expect(normalizeErrors(stats.compilation.errors)).toMatchSnapshot('errors');
});

it('using together with "postcss-loader"', async () => {
it('using together with "postcss-loader" and reuse `ast`', async () => {
// It is hard to test `postcss` on reuse `ast`, please look on coverage before merging
const config = {
postcssLoader: true,
postcssLoaderOptions: {
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