Make life a little more sparkly.

lib/src/utils.dart

 // Copyright (c) 2012, 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.
 
 /// Generic utility functions. Stuff that should possibly be in core.
 import 'dart:async';
 import "dart:convert";
 import 'dart:io';
+import 'dart:math' as math;
 
 import "package:crypto/crypto.dart";
 import 'package:path/path.dart' as path;
 import "package:stack_trace/stack_trace.dart";
 
 import 'exceptions.dart';
 import 'io.dart';
 import 'log.dart' as log;
 
 export 'asset/dart/utils.dart';
 
 /// A regular expression matching a Dart identifier.
 ///
 /// This also matches a package name, since they must be Dart identifiers.
 final identifierRegExp = new RegExp(r"[a-zA-Z_]\w*");
 
 /// Like [identifierRegExp], but anchored so that it only matches strings that
 /// are *just* Dart identifiers.
 final onlyIdentifierRegExp = new RegExp("^${identifierRegExp.pattern}\$");
 
 /// Dart reserved words, from the Dart spec.
 const reservedWords = const [
   "assert", "break", "case", "catch", "class", "const", "continue", "default",
   "do", "else", "extends", "false", "final", "finally", "for", "if", "in", "is",
   "new", "null", "return", "super", "switch", "this", "throw", "true", "try",
   "var", "void", "while", "with"
 ];
 
+/// An cryptographically secure instance of [math.Random].
+final random = new math.Random.secure();
+
 /// A pair of values.
 class Pair<E, F> {
   E first;
   F last;
 
   Pair(this.first, this.last);
 
   String toString() => '($first, $last)';
 
   bool operator==(other) {
@@ skipping 233 matching lines @@
         helper(element);
       } else {
         result.add(element);
       }
     }
   }
   helper(nested);
   return result;
 }
 
+/// Randomly chooses a single element in [elements].
+choose(List elements) => elements[random.nextInt(elements.length)];

[Bob Nystrom, 2016/04/01 20:35:27]

Make this a generic method. :)

[nweiz, 2016/04/01 20:38:16]

Done.

+
 /// Returns a set containing all elements in [minuend] that are not in
 /// [subtrahend].
 Set setMinus(Iterable minuend, Iterable subtrahend) {
   var minuendSet = new Set.from(minuend);
   minuendSet.removeAll(subtrahend);
   return minuendSet;
 }
 
 /// Returns whether there's any overlap between [set1] and [set2].
 bool overlaps(Set set1, Set set2) {
@@ skipping 640 matching lines @@
   } else {
     throw new ApplicationException(message);
   }
 }
 
 /// Throw a [DataException] with [message] to indicate that the command has
 /// failed because of invalid input data.
 ///
 /// This will report the error and cause pub to exit with [exit_codes.DATA].
 void dataError(String message) => throw new DataException(message);