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1 // Copyright (c) 2013, the Dart project authors. Please see the AUTHORS file | |
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. | |
4 | |
5 /// Utilities that shouldn't be in this package. | |
6 library source_maps.utils; | |
7 | |
8 /// Find the first entry in a sorted [list] that matches a monotonic predicate. | |
9 /// Given a result `n`, that all items before `n` will not match, `n` matches, | |
10 /// and all items after `n` match too. The result is -1 when there are no | |
11 /// items, 0 when all items match, and list.length when none does. | |
12 // TODO(sigmund): remove this function after dartbug.com/5624 is fixed. | |
13 int binarySearch(List list, bool matches(item)) { | |
14 if (list.length == 0) return -1; | |
15 if (matches(list.first)) return 0; | |
16 if (!matches(list.last)) return list.length; | |
17 | |
18 int min = 0; | |
19 int max = list.length - 1; | |
20 while (min < max) { | |
21 var half = min + ((max - min) ~/ 2); | |
22 if (matches(list[half])) { | |
23 max = half; | |
24 } else { | |
25 min = half + 1; | |
26 } | |
27 } | |
28 return max; | |
29 } | |
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