57 lines
1.3 KiB
JavaScript
57 lines
1.3 KiB
JavaScript
/**
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* Copyright (c) 2013-present, Facebook, Inc.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*/
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'use strict';
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const MODULES = [
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// Local Promise implementation.
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'Promise',
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];
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/**
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* Automatically imports a module if its identifier is in the AST.
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*/
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module.exports = function autoImporter(babel) {
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const t = babel.types;
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function isAppropriateModule(name, scope, state) {
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const autoImported = state.autoImported;
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return MODULES.indexOf(name) !== -1
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&& !autoImported.hasOwnProperty(name)
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&& !scope.hasBinding(name, /*skip globals*/true);
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}
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return {
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pre: function() {
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// Cache per file to avoid calling `scope.hasBinding` several
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// times for the same module, which has already been auto-imported.
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this.autoImported = {};
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},
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visitor: {
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ReferencedIdentifier: function(path) {
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const node = path.node;
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const scope = path.scope;
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if (!isAppropriateModule(node.name, scope, this)) {
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return;
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}
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scope.getProgramParent().push({
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id: t.identifier(node.name),
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init: t.callExpression(
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t.identifier('require'),
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[t.stringLiteral(node.name)]
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),
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});
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this.autoImported[node.name] = true;
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},
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},
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};
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};
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