1 | // Copyright 2008 The Closure Library Authors. All Rights Reserved. |
2 | // |
3 | // Licensed under the Apache License, Version 2.0 (the "License"); |
4 | // you may not use this file except in compliance with the License. |
5 | // You may obtain a copy of the License at |
6 | // |
7 | // http://www.apache.org/licenses/LICENSE-2.0 |
8 | // |
9 | // Unless required by applicable law or agreed to in writing, software |
10 | // distributed under the License is distributed on an "AS-IS" BASIS, |
11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
12 | // See the License for the specific language governing permissions and |
13 | // limitations under the License. |
14 | |
15 | /** |
16 | * @fileoverview Utilities to check the preconditions, postconditions and |
17 | * invariants runtime. |
18 | * |
19 | * Methods in this package should be given special treatment by the compiler |
20 | * for type-inference. For example, <code>goog.asserts.assert(foo)</code> |
21 | * will restrict <code>foo</code> to a truthy value. |
22 | * |
23 | * The compiler has an option to disable asserts. So code like: |
24 | * <code> |
25 | * var x = goog.asserts.assert(foo()); goog.asserts.assert(bar()); |
26 | * </code> |
27 | * will be transformed into: |
28 | * <code> |
29 | * var x = foo(); |
30 | * </code> |
31 | * The compiler will leave in foo() (because its return value is used), |
32 | * but it will remove bar() because it assumes it does not have side-effects. |
33 | * |
34 | */ |
35 | |
36 | goog.provide('goog.asserts'); |
37 | goog.provide('goog.asserts.AssertionError'); |
38 | |
39 | goog.require('goog.debug.Error'); |
40 | goog.require('goog.dom.NodeType'); |
41 | goog.require('goog.string'); |
42 | |
43 | |
44 | /** |
45 | * @define {boolean} Whether to strip out asserts or to leave them in. |
46 | */ |
47 | goog.define('goog.asserts.ENABLE_ASSERTS', goog.DEBUG); |
48 | |
49 | |
50 | |
51 | /** |
52 | * Error object for failed assertions. |
53 | * @param {string} messagePattern The pattern that was used to form message. |
54 | * @param {!Array.<*>} messageArgs The items to substitute into the pattern. |
55 | * @constructor |
56 | * @extends {goog.debug.Error} |
57 | * @final |
58 | */ |
59 | goog.asserts.AssertionError = function(messagePattern, messageArgs) { |
60 | messageArgs.unshift(messagePattern); |
61 | goog.debug.Error.call(this, goog.string.subs.apply(null, messageArgs)); |
62 | // Remove the messagePattern afterwards to avoid permenantly modifying the |
63 | // passed in array. |
64 | messageArgs.shift(); |
65 | |
66 | /** |
67 | * The message pattern used to format the error message. Error handlers can |
68 | * use this to uniquely identify the assertion. |
69 | * @type {string} |
70 | */ |
71 | this.messagePattern = messagePattern; |
72 | }; |
73 | goog.inherits(goog.asserts.AssertionError, goog.debug.Error); |
74 | |
75 | |
76 | /** @override */ |
77 | goog.asserts.AssertionError.prototype.name = 'AssertionError'; |
78 | |
79 | |
80 | /** |
81 | * Throws an exception with the given message and "Assertion failed" prefixed |
82 | * onto it. |
83 | * @param {string} defaultMessage The message to use if givenMessage is empty. |
84 | * @param {Array.<*>} defaultArgs The substitution arguments for defaultMessage. |
85 | * @param {string|undefined} givenMessage Message supplied by the caller. |
86 | * @param {Array.<*>} givenArgs The substitution arguments for givenMessage. |
87 | * @throws {goog.asserts.AssertionError} When the value is not a number. |
88 | * @private |
89 | */ |
90 | goog.asserts.doAssertFailure_ = |
91 | function(defaultMessage, defaultArgs, givenMessage, givenArgs) { |
92 | var message = 'Assertion failed'; |
93 | if (givenMessage) { |
94 | message += ': ' + givenMessage; |
95 | var args = givenArgs; |
96 | } else if (defaultMessage) { |
97 | message += ': ' + defaultMessage; |
98 | args = defaultArgs; |
99 | } |
100 | // The '' + works around an Opera 10 bug in the unit tests. Without it, |
101 | // a stack trace is added to var message above. With this, a stack trace is |
102 | // not added until this line (it causes the extra garbage to be added after |
103 | // the assertion message instead of in the middle of it). |
104 | throw new goog.asserts.AssertionError('' + message, args || []); |
105 | }; |
106 | |
107 | |
108 | /** |
109 | * Checks if the condition evaluates to true if goog.asserts.ENABLE_ASSERTS is |
110 | * true. |
111 | * @template T |
112 | * @param {T} condition The condition to check. |
113 | * @param {string=} opt_message Error message in case of failure. |
114 | * @param {...*} var_args The items to substitute into the failure message. |
115 | * @return {T} The value of the condition. |
116 | * @throws {goog.asserts.AssertionError} When the condition evaluates to false. |
117 | */ |
118 | goog.asserts.assert = function(condition, opt_message, var_args) { |
119 | if (goog.asserts.ENABLE_ASSERTS && !condition) { |
120 | goog.asserts.doAssertFailure_('', null, opt_message, |
121 | Array.prototype.slice.call(arguments, 2)); |
122 | } |
123 | return condition; |
124 | }; |
125 | |
126 | |
127 | /** |
128 | * Fails if goog.asserts.ENABLE_ASSERTS is true. This function is useful in case |
129 | * when we want to add a check in the unreachable area like switch-case |
130 | * statement: |
131 | * |
132 | * <pre> |
133 | * switch(type) { |
134 | * case FOO: doSomething(); break; |
135 | * case BAR: doSomethingElse(); break; |
136 | * default: goog.assert.fail('Unrecognized type: ' + type); |
137 | * // We have only 2 types - "default:" section is unreachable code. |
138 | * } |
139 | * </pre> |
140 | * |
141 | * @param {string=} opt_message Error message in case of failure. |
142 | * @param {...*} var_args The items to substitute into the failure message. |
143 | * @throws {goog.asserts.AssertionError} Failure. |
144 | */ |
145 | goog.asserts.fail = function(opt_message, var_args) { |
146 | if (goog.asserts.ENABLE_ASSERTS) { |
147 | throw new goog.asserts.AssertionError( |
148 | 'Failure' + (opt_message ? ': ' + opt_message : ''), |
149 | Array.prototype.slice.call(arguments, 1)); |
150 | } |
151 | }; |
152 | |
153 | |
154 | /** |
155 | * Checks if the value is a number if goog.asserts.ENABLE_ASSERTS is true. |
156 | * @param {*} value The value to check. |
157 | * @param {string=} opt_message Error message in case of failure. |
158 | * @param {...*} var_args The items to substitute into the failure message. |
159 | * @return {number} The value, guaranteed to be a number when asserts enabled. |
160 | * @throws {goog.asserts.AssertionError} When the value is not a number. |
161 | */ |
162 | goog.asserts.assertNumber = function(value, opt_message, var_args) { |
163 | if (goog.asserts.ENABLE_ASSERTS && !goog.isNumber(value)) { |
164 | goog.asserts.doAssertFailure_('Expected number but got %s: %s.', |
165 | [goog.typeOf(value), value], opt_message, |
166 | Array.prototype.slice.call(arguments, 2)); |
167 | } |
168 | return /** @type {number} */ (value); |
169 | }; |
170 | |
171 | |
172 | /** |
173 | * Checks if the value is a string if goog.asserts.ENABLE_ASSERTS is true. |
174 | * @param {*} value The value to check. |
175 | * @param {string=} opt_message Error message in case of failure. |
176 | * @param {...*} var_args The items to substitute into the failure message. |
177 | * @return {string} The value, guaranteed to be a string when asserts enabled. |
178 | * @throws {goog.asserts.AssertionError} When the value is not a string. |
179 | */ |
180 | goog.asserts.assertString = function(value, opt_message, var_args) { |
181 | if (goog.asserts.ENABLE_ASSERTS && !goog.isString(value)) { |
182 | goog.asserts.doAssertFailure_('Expected string but got %s: %s.', |
183 | [goog.typeOf(value), value], opt_message, |
184 | Array.prototype.slice.call(arguments, 2)); |
185 | } |
186 | return /** @type {string} */ (value); |
187 | }; |
188 | |
189 | |
190 | /** |
191 | * Checks if the value is a function if goog.asserts.ENABLE_ASSERTS is true. |
192 | * @param {*} value The value to check. |
193 | * @param {string=} opt_message Error message in case of failure. |
194 | * @param {...*} var_args The items to substitute into the failure message. |
195 | * @return {!Function} The value, guaranteed to be a function when asserts |
196 | * enabled. |
197 | * @throws {goog.asserts.AssertionError} When the value is not a function. |
198 | */ |
199 | goog.asserts.assertFunction = function(value, opt_message, var_args) { |
200 | if (goog.asserts.ENABLE_ASSERTS && !goog.isFunction(value)) { |
201 | goog.asserts.doAssertFailure_('Expected function but got %s: %s.', |
202 | [goog.typeOf(value), value], opt_message, |
203 | Array.prototype.slice.call(arguments, 2)); |
204 | } |
205 | return /** @type {!Function} */ (value); |
206 | }; |
207 | |
208 | |
209 | /** |
210 | * Checks if the value is an Object if goog.asserts.ENABLE_ASSERTS is true. |
211 | * @param {*} value The value to check. |
212 | * @param {string=} opt_message Error message in case of failure. |
213 | * @param {...*} var_args The items to substitute into the failure message. |
214 | * @return {!Object} The value, guaranteed to be a non-null object. |
215 | * @throws {goog.asserts.AssertionError} When the value is not an object. |
216 | */ |
217 | goog.asserts.assertObject = function(value, opt_message, var_args) { |
218 | if (goog.asserts.ENABLE_ASSERTS && !goog.isObject(value)) { |
219 | goog.asserts.doAssertFailure_('Expected object but got %s: %s.', |
220 | [goog.typeOf(value), value], |
221 | opt_message, Array.prototype.slice.call(arguments, 2)); |
222 | } |
223 | return /** @type {!Object} */ (value); |
224 | }; |
225 | |
226 | |
227 | /** |
228 | * Checks if the value is an Array if goog.asserts.ENABLE_ASSERTS is true. |
229 | * @param {*} value The value to check. |
230 | * @param {string=} opt_message Error message in case of failure. |
231 | * @param {...*} var_args The items to substitute into the failure message. |
232 | * @return {!Array} The value, guaranteed to be a non-null array. |
233 | * @throws {goog.asserts.AssertionError} When the value is not an array. |
234 | */ |
235 | goog.asserts.assertArray = function(value, opt_message, var_args) { |
236 | if (goog.asserts.ENABLE_ASSERTS && !goog.isArray(value)) { |
237 | goog.asserts.doAssertFailure_('Expected array but got %s: %s.', |
238 | [goog.typeOf(value), value], opt_message, |
239 | Array.prototype.slice.call(arguments, 2)); |
240 | } |
241 | return /** @type {!Array} */ (value); |
242 | }; |
243 | |
244 | |
245 | /** |
246 | * Checks if the value is a boolean if goog.asserts.ENABLE_ASSERTS is true. |
247 | * @param {*} value The value to check. |
248 | * @param {string=} opt_message Error message in case of failure. |
249 | * @param {...*} var_args The items to substitute into the failure message. |
250 | * @return {boolean} The value, guaranteed to be a boolean when asserts are |
251 | * enabled. |
252 | * @throws {goog.asserts.AssertionError} When the value is not a boolean. |
253 | */ |
254 | goog.asserts.assertBoolean = function(value, opt_message, var_args) { |
255 | if (goog.asserts.ENABLE_ASSERTS && !goog.isBoolean(value)) { |
256 | goog.asserts.doAssertFailure_('Expected boolean but got %s: %s.', |
257 | [goog.typeOf(value), value], opt_message, |
258 | Array.prototype.slice.call(arguments, 2)); |
259 | } |
260 | return /** @type {boolean} */ (value); |
261 | }; |
262 | |
263 | |
264 | /** |
265 | * Checks if the value is a DOM Element if goog.asserts.ENABLE_ASSERTS is true. |
266 | * @param {*} value The value to check. |
267 | * @param {string=} opt_message Error message in case of failure. |
268 | * @param {...*} var_args The items to substitute into the failure message. |
269 | * @return {!Element} The value, likely to be a DOM Element when asserts are |
270 | * enabled. |
271 | * @throws {goog.asserts.AssertionError} When the value is not a boolean. |
272 | */ |
273 | goog.asserts.assertElement = function(value, opt_message, var_args) { |
274 | if (goog.asserts.ENABLE_ASSERTS && (!goog.isObject(value) || |
275 | value.nodeType != goog.dom.NodeType.ELEMENT)) { |
276 | goog.asserts.doAssertFailure_('Expected Element but got %s: %s.', |
277 | [goog.typeOf(value), value], opt_message, |
278 | Array.prototype.slice.call(arguments, 2)); |
279 | } |
280 | return /** @type {!Element} */ (value); |
281 | }; |
282 | |
283 | |
284 | /** |
285 | * Checks if the value is an instance of the user-defined type if |
286 | * goog.asserts.ENABLE_ASSERTS is true. |
287 | * |
288 | * The compiler may tighten the type returned by this function. |
289 | * |
290 | * @param {*} value The value to check. |
291 | * @param {function(new: T, ...)} type A user-defined constructor. |
292 | * @param {string=} opt_message Error message in case of failure. |
293 | * @param {...*} var_args The items to substitute into the failure message. |
294 | * @throws {goog.asserts.AssertionError} When the value is not an instance of |
295 | * type. |
296 | * @return {!T} |
297 | * @template T |
298 | */ |
299 | goog.asserts.assertInstanceof = function(value, type, opt_message, var_args) { |
300 | if (goog.asserts.ENABLE_ASSERTS && !(value instanceof type)) { |
301 | goog.asserts.doAssertFailure_('instanceof check failed.', null, |
302 | opt_message, Array.prototype.slice.call(arguments, 3)); |
303 | } |
304 | return value; |
305 | }; |
306 | |
307 | |
308 | /** |
309 | * Checks that no enumerable keys are present in Object.prototype. Such keys |
310 | * would break most code that use {@code for (var ... in ...)} loops. |
311 | */ |
312 | goog.asserts.assertObjectPrototypeIsIntact = function() { |
313 | for (var key in Object.prototype) { |
314 | goog.asserts.fail(key + ' should not be enumerable in Object.prototype.'); |
315 | } |
316 | }; |