react/vendor/constants.js

113 lines
3.4 KiB
JavaScript

/**
* Copyright 2013-2015, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under the BSD-style license found in the
* LICENSE file in the root directory of this source tree. An additional grant
* of patent rights can be found in the PATENTS file in the same directory.
*/
'use strict';
module.exports = function(babel) {
var t = babel.types;
var DEV_EXPRESSION = t.binaryExpression(
'!==',
t.literal('production'),
t.memberExpression(
t.memberExpression(
t.identifier('process'),
t.identifier('env'),
false
),
t.identifier('NODE_ENV'),
false
)
);
return new babel.Transformer('react.constants', {
Identifier: {
enter: function(node, parent) {
// replace __DEV__ with process.env.NODE_ENV !== 'production'
if (this.isIdentifier({name: '__DEV__'})) {
return DEV_EXPRESSION;
}
},
},
CallExpression: {
exit: function(node, parent) {
if (this.get('callee').isIdentifier({name: 'invariant'})) {
// Turns this code:
//
// invariant(condition, argument, argument);
//
// into this:
//
// if (!condition) {
// if ("production" !== process.env.NODE_ENV) {
// invariant(false, argument, argument);
// } else {
// invariant(false);
// }
// }
//
// Specifically this does 2 things:
// 1. Checks the condition first, preventing an extra function call.
// 2. Adds an environment check so that verbose error messages aren't
// shipped to production.
// The generated code is longer than the original code but will dead
// code removal in a minifier will strip that out.
var condition = node.arguments[0];
return t.ifStatement(
t.unaryExpression('!', condition),
t.blockStatement([
t.ifStatement(
DEV_EXPRESSION,
t.blockStatement([
t.expressionStatement(
t.callExpression(
node.callee,
[t.literal(false)].concat(node.arguments.slice(1))
)
),
]),
t.blockStatement([
t.expressionStatement(
t.callExpression(
node.callee,
[t.literal(false)]
)
),
])
),
])
);
} else if (this.get('callee').isIdentifier({name: 'warning'})) {
// Turns this code:
//
// warning(condition, argument, argument);
//
// into this:
//
// if ("production" !== process.env.NODE_ENV) {
// warning(condition, argument, argument);
// }
//
// The goal is to strip out warning calls entirely in production. We
// don't need the same optimizations for conditions that we use for
// invariant because we don't care about an extra call in __DEV__
return t.ifStatement(
DEV_EXPRESSION,
t.blockStatement([
t.expressionStatement(
node
),
])
);
}
},
},
});
};