Adding package:smoke. This CL includes the intial APIs, a mirror-based

pkg/smoke/lib/src/common.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.
+
+/// Some common utilities used by other libraries in this package.
+library smoke.src.common;
+
+/// Returns [input] adjusted to be within [min] and [max] length. Truncating it
+/// if it's longer, or padding it with nulls if it's shorter. The returned list
+/// is a new copy if any modification is needed, otherwise [input] is returned.
+List adjustList(List input, int min, int max) {
+  if (input.length < min) {
+    return new List(min)..setRange(0, input.length, input);
+  }
+
+  if (input.length > max) {
+    return new List(max)..setRange(0, max, input);
+  }
+  return input;
+}
+
+/// Returns whether [metadata] contains any annotation that is either equal to
+/// an annotation in [queryAnnotations] or whose type is listed in
+/// [queryAnnotations].
+bool matchesAnnotation(Iterable metadata, Iterable queryAnnotations) {
+  return metadata.any((m) => queryAnnotations.contains(m) ||
+      queryAnnotations.contains(m.runtimeType));
+}
+
+/// Number of arguments supported by [minArgs] and [maxArgs].
+const SUPPORTED_ARGS = 3;
+
+typedef _Func0();
+typedef _Func1(a);
+typedef _Func2(a, b);
+typedef _Func3(a, b, c);
+
+/// Returns the minimum number of arguments that [f] takes as input, in other
+/// words, the total number of required arguments of [f]. If [f] expects more
+/// than [SUPPORTED_ARGS], this function returns `SUPPORTED_ARGS + 1`.
+/// 
+/// For instance, the current implementation only supports calculating the
+/// number of arguments between `0` and `3`. If the function takes `4` or more,
+/// this function automatically returns `4`.
+int minArgs(Function f) {
+  if (f is _Func0) return 0;
+  if (f is _Func1) return 1;
+  if (f is _Func2) return 2;
+  if (f is _Func3) return 3;
+  return SUPPORTED_ARGS + 1;
+}
+
+/// Returns the maximum number of arguments that [f] takes as input, which is
+/// the total number of required and optional arguments of [f]. If
+/// [f] may take more than [SUPPORTED_ARGS] required arguments, this function
+/// returns `-1`. However, if it takes less required arguments, but more than
+/// [SUPPORTED_ARGS] arguments including optional arguments, the result will be
+/// [SUPPORTED_ARGS].
+///
+/// For instance, the current implementation only supports calculating the
+/// number of arguments between `0` and `3`.  If the function takes `4`
+/// mandatory arguments, this function returns `-1`, but if the funtion takes
+/// `2` mandatory arguments and 10 optional arguments, this function returns
+/// `3`.
+int maxArgs(Function f) {
+  if (f is _Func3) return 3;
+  if (f is _Func2) return 2;
+  if (f is _Func1) return 1;
+  if (f is _Func0) return 0;
+  return -1;
+}