Add more set-like version constraint operations.

lib/src/utils.dart

Index: lib/src/utils.dart
diff --git a/lib/src/utils.dart b/lib/src/utils.dart
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+// Copyright (c) 2015, 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 pub_semver.src.utils;
+
+import 'version.dart';
+import 'version_constraint.dart';
+import 'version_range.dart';
+
+/// Returns whether [constraint1] is immediately next to, but not overlapping,
+/// [constraint2].
+///
+/// This assumes both constraints are either a [VersionRange] or a [Version].
+bool areAdjacent(VersionConstraint constraint1, VersionConstraint constraint2) {
+  if (_max(constraint1) != _min(constraint2)) return false;
+
+  var includeMax = _includeMax(constraint1);
+  var includeMin = _includeMin(constraint2);
+  return (includeMax && !includeMin) || (!includeMax && includeMin);
+}
+
+/// A [Comparator] that compares the maximum versions of [constraint1] and
+/// [constraint2].
+///
+/// This assumes both constraints are either a [VersionRange] or a [Version].
+int compareMax(VersionConstraint constraint1, VersionConstraint constraint2) {
+  var max1 = _max(constraint1);
+  var max2 = _max(constraint2);
+  if (max1 < max2) return -1;
+  if (max1 > max2) return 1;
+
+  var includeMax1 = _includeMax(constraint1);
+  var includeMax2 = _includeMax(constraint2);
+  if (!includeMax1 && includeMax2) return -1;
+  if (includeMax1 && !includeMax2) return 1;
+  return 0;
+}
+

[Bob Nystrom, 2015/05/05 20:49:09]

Instead of these functions, how about just making Version implement
VersionRange?

[nweiz, 2015/05/05 22:52:33]

Done.

+/// Returns the minimum version of [constraint], which may be a [VersionRange]
+/// or a [Version].
+Version _min(VersionConstraint constraint) =>
+    constraint is VersionRange ? constraint.min : (constraint as Version);
+
+/// Returns whether [constraint], which may be a [VersionRange] or a [Version],
+/// includes its minimum value.
+bool _includeMin(VersionConstraint constraint) =>

[Bob Nystrom, 2015/05/05 20:49:09]

How about "_includesMin"?

+    constraint is VersionRange ? constraint.includeMin : true;
+
+/// Returns the maximum version of [constraint], which may be a [VersionRange]
+/// or a [Version].
+Version _max(VersionConstraint constraint) =>
+    constraint is VersionRange ? constraint.max : (constraint as Version);
+
+/// Returns whether [constraint], which may be a [VersionRange] or a [Version],
+/// includes its maximum value.
+bool _includeMax(VersionConstraint constraint) =>

[Bob Nystrom, 2015/05/05 20:49:08]

Ditto.

+    constraint is VersionRange ? constraint.includeMax : true;