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;

import 'package:smoke/smoke.dart' as smoke show isSubclassOf;

/// 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) {
  for (var meta in metadata) {
    for (var queryMeta in queryAnnotations) {
      if (meta == queryMeta) return true;
      if (queryMeta is Type &&
          smoke.isSubclassOf(meta.runtimeType, queryMeta)) return true;
    }
  }
  return false;
}

/// 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;
}

/// Shallow comparison of two lists.
bool compareLists(List a, List b, {bool unordered: false}) {
  if (a == null && b != null) return false;
  if (a != null && b == null) return false;
  if (a.length != b.length) return false;
  if (unordered) {
    var bSet = new Set()..addAll(b);
    for (int i = 0; i < a.length; i++) {
      if (!bSet.contains(a[i])) return false;
    }
  } else {
    for (int i = 0; i < a.length; i++) {
      if (a[i] != b[i]) return false;
    }
  }
  return true;
}

/// Shallow comparison of two maps.
bool compareMaps(Map a, Map b) {
  if (a == null && b != null) return false;
  if (a != null && b == null) return false;
  if (a.length != b.length) return false;
  for (var k in a.keys) {
    if (!b.containsKey(k) || a[k] != b[k]) return false;
  }
  return true;
}