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1 // Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file | 1 // Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file |
2 // for details. All rights reserved. Use of this source code is governed by a | 2 // for details. All rights reserved. Use of this source code is governed by a |
3 // BSD-style license that can be found in the LICENSE file. | 3 // BSD-style license that can be found in the LICENSE file. |
4 | 4 |
5 part of dart.core; | 5 part of dart.core; |
6 | 6 |
7 /** | 7 /** |
8 * An integer or floating-point number. | 8 * An integer or floating-point number. |
9 * | 9 * |
10 * It is a compile-time error for any type other than [int] or [double] | 10 * It is a compile-time error for any type other than [int] or [double] |
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352 * 12.345e67.toString(); // 1.2345e+68 | 352 * 12.345e67.toString(); // 1.2345e+68 |
353 * | 353 * |
354 * Note: the conversion may round the output if the returned string | 354 * Note: the conversion may round the output if the returned string |
355 * is accurate enough to uniquely identify the input-number. | 355 * is accurate enough to uniquely identify the input-number. |
356 * For example the most precise representation of the [double] `9e59` equals | 356 * For example the most precise representation of the [double] `9e59` equals |
357 * `"899999999999999918767229449717619953810131273674690656206848"`, but | 357 * `"899999999999999918767229449717619953810131273674690656206848"`, but |
358 * this method returns the shorter (but still uniquely identifying) `"9e59"`. | 358 * this method returns the shorter (but still uniquely identifying) `"9e59"`. |
359 * | 359 * |
360 */ | 360 */ |
361 String toString(); | 361 String toString(); |
362 | |
363 /** | |
364 * Parses a string containing a number literal into a number. | |
365 * | |
366 * The method first tries to read the [input] as integer (similar to | |
367 * [int.parse] without a radix). | |
368 * If that fails, it tries to parse the [input] as a double (similar to | |
369 * [double.parse]). | |
370 * If that fails, too, it invokes [onError] with [input]. | |
371 * | |
372 * If no [onError] is supplied, it defaults to a function that throws a | |
373 * [FormatException]. | |
374 * | |
375 * For any number `n`, this function satisfies | |
376 * `identical(n, num.parse(n.toString()))`. | |
377 */ | |
378 static num parse(String input, [num onError(String input)]) { | |
379 String source = input.trim(); | |
380 // TODO(lrn): Optimize to detect format and result type in one check. | |
381 num result = int.parse(source, onError: _returnNull); | |
382 if (result != null) return result; | |
383 result = double.parse(source, _returnNull); | |
384 if (result != null) return result; | |
385 if (onError == null) throw new FormatException(input); | |
386 return onError(input); | |
387 } | |
388 | |
389 /** Helper function for [parse]. */ | |
390 static _returnNull(_) => null; | |
391 } | 362 } |
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