blob: 2d3386542dceb182631363fe3e4041deacb92bee [file] [log] [blame]
 // Copyright (c) 2014, the Dart project authors. Please see the AUTHORS file // for details. All rights reserved. Use of this source code is governed by a // BSD-style license that can be found in the LICENSE file. library source_span.utils; /// Returns the minimum of [obj1] and [obj2] according to /// [Comparable.compareTo]. Comparable min(Comparable obj1, Comparable obj2) => obj1.compareTo(obj2) > 0 ? obj2 : obj1; /// Returns the maximum of [obj1] and [obj2] according to /// [Comparable.compareTo]. Comparable max(Comparable obj1, Comparable obj2) => obj1.compareTo(obj2) > 0 ? obj1 : obj2; /// Find the first entry in a sorted [list] that matches a monotonic predicate. /// /// Given a result `n`, that all items before `n` will not match, `n` matches, /// and all items after `n` match too. The result is -1 when there are no /// items, 0 when all items match, and list.length when none does. int binarySearch(List list, bool matches(item)) { if (list.length == 0) return -1; if (matches(list.first)) return 0; if (!matches(list.last)) return list.length; int min = 0; int max = list.length - 1; while (min < max) { var half = min + ((max - min) ~/ 2); if (matches(list[half])) { max = half; } else { min = half + 1; } } return max; } /// Finds a line in [context] containing [text] at the specified [column]. /// /// Returns the index in [context] where that line begins, or null if none /// exists. int findLineStart(String context, String text, int column) { var isEmpty = text == ''; var index = context.indexOf(text); while (index != -1) { var lineStart = context.lastIndexOf('\n', index) + 1; var textColumn = index - lineStart; if (column == textColumn || (isEmpty && column == textColumn + 1)) { return lineStart; } index = context.indexOf(text, index + 1); } return null; }