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esm: refactor dynamic modules

This is a change from the ecmascript-modules fork.
There is no change to behavior and we would like to
upstream to reduce the delta between our repos.

Refs: https://github.com/nodejs/ecmascript-modules#9

PR-URL: #24560
Refs: nodejs/ecmascript-modules#9
Reviewed-By: Guy Bedford <guybedford@gmail.com>
Reviewed-By: Gus Caplan <me@gus.host>
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MylesBorins authored and BridgeAR committed Nov 22, 2018
1 parent 8ffe04f commit 17435689759eb76308c791f9c5c4b1c90e9aa3eb
@@ -623,23 +623,24 @@ Module.prototype.load = function(filename) {
if (experimentalModules) {
if (asyncESM === undefined) lazyLoadESM();
const ESMLoader = asyncESM.ESMLoader;
const url = pathToFileURL(filename);
const urlString = `${url}`;
const url = `${pathToFileURL(filename)}`;
const module = ESMLoader.moduleMap.get(url);
// create module entry at load time to snapshot exports correctly
const exports = this.exports;
if (ESMLoader.moduleMap.has(urlString) !== true) {
if (module !== undefined) { // called from cjs translator
module.reflect.onReady((reflect) => {
reflect.exports.default.set(exports);
});
} else { // preemptively cache
ESMLoader.moduleMap.set(
urlString,
url,
new ModuleJob(ESMLoader, url, async () => {
const ctx = createDynamicModule(
['default'], url);
ctx.reflect.exports.default.set(exports);
return ctx;
return createDynamicModule(
['default'], url, (reflect) => {
reflect.exports.default.set(exports);
});
})
);
} else {
const job = ESMLoader.moduleMap.get(urlString);
if (job.reflect)
job.reflect.exports.default.set(exports);
}
}
};
@@ -1,6 +1,6 @@
'use strict';

const { ModuleWrap } = internalBinding('module_wrap');
const { ModuleWrap, callbackMap } = internalBinding('module_wrap');
const debug = require('util').debuglog('esm');
const ArrayJoin = Function.call.bind(Array.prototype.join);
const ArrayMap = Function.call.bind(Array.prototype.map);
@@ -10,50 +10,47 @@ const createDynamicModule = (exports, url = '', evaluate) => {
`creating ESM facade for ${url} with exports: ${ArrayJoin(exports, ', ')}`
);
const names = ArrayMap(exports, (name) => `${name}`);
// Create two modules: One whose exports are get- and set-able ('reflective'),
// and one which re-exports all of these but additionally may
// run an executor function once everything is set up.
const src = `
export let executor;
${ArrayJoin(ArrayMap(names, (name) => `export let $${name};`), '\n')}
/* This function is implicitly returned as the module's completion value */
(() => ({
setExecutor: fn => executor = fn,
reflect: {
exports: { ${
ArrayJoin(ArrayMap(names, (name) => `
${name}: {
get: () => $${name},
set: v => $${name} = v
}`), ', \n')}
}
}
}));`;
const reflectiveModule = new ModuleWrap(src, `cjs-facade:${url}`);
reflectiveModule.instantiate();
const { setExecutor, reflect } = reflectiveModule.evaluate(-1, false)();
// public exposed ESM
const reexports = `
import {
executor,
${ArrayMap(names, (name) => `$${name}`)}
} from "";
export {
${ArrayJoin(ArrayMap(names, (name) => `$${name} as ${name}`), ', ')}
}
if (typeof executor === "function") {
// add await to this later if top level await comes along
executor()
}`;
if (typeof evaluate === 'function') {
setExecutor(() => evaluate(reflect));
}
const module = new ModuleWrap(reexports, `${url}`);
module.link(async () => reflectiveModule);
module.instantiate();
reflect.namespace = module.namespace();

const source = `
${ArrayJoin(ArrayMap(names, (name) =>
`let $${name};
export { $${name} as ${name} };
import.meta.exports.${name} = {
get: () => $${name},
set: (v) => $${name} = v,
};`), '\n')
}
import.meta.done();
`;

const m = new ModuleWrap(source, `${url}`);
m.link(() => 0);
m.instantiate();

const readyfns = new Set();
const reflect = {
namespace: m.namespace(),
exports: {},
onReady: (cb) => { readyfns.add(cb); },
};

callbackMap.set(m, {
initializeImportMeta: (meta, wrap) => {
meta.exports = reflect.exports;
meta.done = () => {
evaluate(reflect);
reflect.onReady = (cb) => cb(reflect);
for (const fn of readyfns) {
readyfns.delete(fn);
fn(reflect);
}
};
},
});

return {
module,
module: m,
reflect,
};
};
@@ -60,9 +60,10 @@ translators.set('cjs', async (url, isMain) => {
const module = CJSModule._cache[
isWindows ? StringReplace(pathname, winSepRegEx, '\\') : pathname];
if (module && module.loaded) {
const ctx = createDynamicModule(['default'], url);
ctx.reflect.exports.default.set(module.exports);
return ctx;
const exports = module.exports;
return createDynamicModule(['default'], url, (reflect) => {
reflect.exports.default.set(exports);
});
}
return createDynamicModule(['default'], url, () => {
debug(`Loading CJSModule ${url}`);

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