46 lines
1.1 KiB
JavaScript
46 lines
1.1 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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module.exports = function(babel) {
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const t = babel.types;
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// We can't construct an identifier with a type annotation all in 1 fell swoop
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// so we have to create & mutate, then pass along.
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const DEV_IDENTIFIER = t.identifier('__DEV__');
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DEV_IDENTIFIER.typeAnnotation = t.typeAnnotation(t.booleanTypeAnnotation());
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const DEV_DECLARATION = t.declareVariable(
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DEV_IDENTIFIER
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);
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return {
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pre() {
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this.usesDEV = false;
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},
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visitor: {
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Identifier: {
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enter(path, file) {
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this.usesDEV = this.usesDEV || path.isIdentifier({name: '__DEV__'});
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},
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},
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Program: {
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exit(path, file) {
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if (!this.usesDEV) {
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return;
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}
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// Add the declaration at the front of the body if we've used __DEV__.
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path.node.body.unshift(DEV_DECLARATION);
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},
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},
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},
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};
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};
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