Optimize successive calls SourceFile.getLine().

lib/src/utils.dart

 // 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;
 }