Line data Source code
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 0 : if (list.length == 0) return -1;
15 0 : if (matches(list.first)) return 0;
16 0 : if (!matches(list.last)) return list.length;
17 :
18 : int min = 0;
19 0 : int max = list.length - 1;
20 0 : while (min < max) {
21 0 : var half = min + ((max - min) ~/ 2);
22 0 : if (matches(list[half])) {
23 : max = half;
24 : } else {
25 0 : min = half + 1;
26 : }
27 : }
28 : return max;
29 : }
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