99 lines
3.0 KiB
JavaScript
99 lines
3.0 KiB
JavaScript
/**
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* Copyright 2013 Facebook, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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'use strict';
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var assert = require('assert');
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var recast = require('recast');
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var types = recast.types;
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var namedTypes = types.namedTypes;
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var builders = types.builders;
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var hasOwn = Object.prototype.hasOwnProperty;
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function propagate(constants, source) {
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return recast.print(transform(recast.parse(source), constants));
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}
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var DEV_EXPRESSION = builders.binaryExpression(
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'!==',
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builders.literal('production'),
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builders.memberExpression(
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builders.memberExpression(
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builders.identifier('process'),
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builders.identifier('env'),
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false
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),
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builders.identifier('NODE_ENV'),
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false
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)
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);
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function transform(ast, constants) {
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constants = constants || {};
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return types.traverse(ast, function(node, traverse) {
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if (namedTypes.Identifier.check(node)) {
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// If the identifier is the property of a member expression
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// (e.g. object.property), then it definitely is not a constant
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// expression that we want to replace.
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if (namedTypes.MemberExpression.check(this.parent.node) &&
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this.name === 'property' &&
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!this.parent.node.computed) {
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return false;
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}
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// There could in principle be a constant called "hasOwnProperty",
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// so be careful always to use Object.prototype.hasOwnProperty.
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if (node.name === '__DEV__') {
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// replace __DEV__ with process.env.NODE_ENV !== 'production'
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this.replace(DEV_EXPRESSION);
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return false;
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} else if (hasOwn.call(constants, node.name)) {
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this.replace(builders.literal(constants[node.name]));
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return false;
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}
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} else if (namedTypes.CallExpression.check(node)) {
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if (namedTypes.Identifier.check(node.callee) &&
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node.callee.name === 'invariant') {
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// Truncate the arguments of invariant(condition, ...)
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// statements to just the condition based on NODE_ENV
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// (dead code removal will remove the extra bytes).
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this.replace(
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builders.conditionalExpression(
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DEV_EXPRESSION,
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node,
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builders.callExpression(
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node.callee,
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[node.arguments[0]]
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)
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)
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);
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return false;
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}
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}
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});
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}
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if (!module.parent) {
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var constants = JSON.parse(process.argv[3]);
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recast.run(function(ast, callback) {
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callback(transform(ast, constants));
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});
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}
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exports.propagate = propagate;
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exports.transform = transform;
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