Mario Romano 29df96a085 react app
2016-04-06 17:52:19 +01:00

81 lines
2.4 KiB
JavaScript

/**
* Copyright 2013 Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*jslint node:true*/
/**
* Desugars ES7 rest properties into ES5 object iteration.
*/
var Syntax = require('esprima-fb').Syntax;
// TODO: This is a pretty massive helper, it should only be defined once, in the
// transform's runtime environment. We don't currently have a runtime though.
var restFunction =
'(function(source, exclusion) {' +
'var rest = {};' +
'var hasOwn = Object.prototype.hasOwnProperty;' +
'if (source == null) {' +
'throw new TypeError();' +
'}' +
'for (var key in source) {' +
'if (hasOwn.call(source, key) && !hasOwn.call(exclusion, key)) {' +
'rest[key] = source[key];' +
'}' +
'}' +
'return rest;' +
'})';
function getPropertyNames(properties) {
var names = [];
for (var i = 0; i < properties.length; i++) {
var property = properties[i];
if (property.type === Syntax.SpreadProperty) {
continue;
}
if (property.type === Syntax.Identifier) {
names.push(property.name);
} else {
names.push(property.key.name);
}
}
return names;
}
function getRestFunctionCall(source, exclusion) {
return restFunction + '(' + source + ',' + exclusion + ')';
}
function getSimpleShallowCopy(accessorExpression) {
// This could be faster with 'Object.assign({}, ' + accessorExpression + ')'
// but to unify code paths and avoid a ES6 dependency we use the same
// helper as for the exclusion case.
return getRestFunctionCall(accessorExpression, '{}');
}
function renderRestExpression(accessorExpression, excludedProperties) {
var excludedNames = getPropertyNames(excludedProperties);
if (!excludedNames.length) {
return getSimpleShallowCopy(accessorExpression);
}
return getRestFunctionCall(
accessorExpression,
'{' + excludedNames.join(':1,') + ':1}'
);
}
exports.renderRestExpression = renderRestExpression;