Lu Yifei
d5ebe6cb47
Build offline specialized players from the matching Scratch VM, with audited linking, pruning and scheduling-property renaming across browser, Node and standalone outputs.
40 lines
1.8 KiB
JavaScript
40 lines
1.8 KiB
JavaScript
import {createHash} from 'node:crypto';
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import {parse} from '@babel/parser';
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import traverseModule from '@babel/traverse';
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import generateModule from '@babel/generator';
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import * as t from '@babel/types';
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const traverse = traverseModule.default;
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const generate = generateModule.default;
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// twgl 4.4.0's npm package only ships a webpack bundle. Its 15 modules have
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// an acyclic static graph; the webpack cache/factories add no required ordering.
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// Fail closed when upstream changes instead of guessing another bundle format.
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export function unbundleTWGL(code) {
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if (createHash('sha256').update(code).digest('hex') !==
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'60a924fb69acaba30567e9bd349890aa27b74664e4015c44634838c016191e8c') {
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throw new Error('TWGL source changed; review its module graph before updating the source pack');
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}
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let functions;
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traverse(parse(code), {CallExpression(p) {
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const array = p.node.arguments[0];
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if (t.isArrayExpression(array) && array.elements.length === 15 &&
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array.elements.every(item => t.isFunctionExpression(item))) functions = array.elements;
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}});
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if (!functions) throw new Error('Missing audited TWGL module table');
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return functions.map(fn => {
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const tree = t.file(t.program(fn.body.body));
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traverse(tree, {CallExpression(p) {
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if (!t.isIdentifier(p.node.callee, {name: '__webpack_require__'})) return;
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const [id] = p.node.arguments;
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if (p.node.arguments.length !== 1 || !t.isNumericLiteral(id) || id.value < 0 || id.value >= 15) {
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throw new Error('Non-static TWGL dependency');
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}
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p.replaceWith(t.callExpression(t.identifier('require'), [t.stringLiteral(`\0specialized-twgl:${id.value}.js`)]));
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}});
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const result = generate(tree, {comments: false}).code;
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if (result.includes('__webpack_require__')) throw new Error('Unconverted TWGL bootstrap reference');
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return result;
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});
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}
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