Bug 1449094 - Implement constexpr mozilla::AllOf. r=froydnj

MozReview-Commit-ID: KvKY9CMqfww

--HG--
extra : rebase_source : 5e548884d3a331b5dc8704a690ccbd532ac2534a

mfbt/Algorithm.h

@@ -0,0 +1,29 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* A polyfill for `<algorithm>`. */
+
+#ifndef mozilla_Algorithm_h
+#define mozilla_Algorithm_h
+
+namespace mozilla {
+
+// Returns true if all elements in the range [aFirst, aLast)
+// satisfy the predicate aPred.
+template <class Iter, class Pred>
+constexpr bool AllOf(Iter aFirst, Iter aLast, Pred aPred)
+{
+  for (; aFirst != aLast; ++aFirst) {
+    if (!aPred(*aFirst)) {
+      return false;
+    }
+  }
+  return true;
+}
+
+} // namespace mozilla
+
+#endif // mozilla_Algorithm_h

mfbt/moz.build

@@ -12,6 +12,7 @@ TEST_DIRS += ['tests']
 Library('mfbt')
 
 EXPORTS.mozilla = [
+    'Algorithm.h',
     'Alignment.h',
     'AllocPolicy.h',
     'AlreadyAddRefed.h',

mfbt/tests/TestAlgorithm.cpp

@@ -0,0 +1,44 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/Algorithm.h"
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/Assertions.h"
+#include <iterator>
+
+static constexpr bool even(int32_t n) { return !(n & 1); }
+static constexpr bool odd(int32_t n) { return (n & 1); }
+
+void TestAllOf()
+{
+  using namespace mozilla;
+  using namespace std;
+
+  constexpr static int32_t arr1[3] = {1, 2, 3};
+  MOZ_RELEASE_ASSERT(!AllOf(begin(arr1), end(arr1), even));
+  MOZ_RELEASE_ASSERT(!AllOf(begin(arr1), end(arr1), odd));
+  static_assert(!AllOf(arr1, arr1 + ArrayLength(arr1), even), "1-1");
+  static_assert(!AllOf(arr1, arr1 + ArrayLength(arr1), odd), "1-2");
+
+  constexpr static int32_t arr2[3] = {1, 3, 5};
+  MOZ_RELEASE_ASSERT(!AllOf(begin(arr2), end(arr2), even));
+  MOZ_RELEASE_ASSERT(AllOf(begin(arr2), end(arr2), odd));
+  static_assert(!AllOf(arr2, arr2 + ArrayLength(arr2), even), "2-1");
+  static_assert(AllOf(arr2, arr2 + ArrayLength(arr2), odd), "2-2");
+
+  constexpr static int32_t arr3[3] = {2, 4, 6};
+  MOZ_RELEASE_ASSERT(AllOf(begin(arr3), end(arr3), even));
+  MOZ_RELEASE_ASSERT(!AllOf(begin(arr3), end(arr3), odd));
+  static_assert(AllOf(arr3, arr3 + ArrayLength(arr3), even), "3-1");
+  static_assert(!AllOf(arr3, arr3 + ArrayLength(arr3), odd), "3-2");
+}
+
+int
+main()
+{
+  TestAllOf();
+  return 0;
+}

mfbt/tests/moz.build

@@ -10,6 +10,7 @@ if CONFIG['MOZ_WIDGET_TOOLKIT']:
     ]
 
 CppUnitTests([
+    'TestAlgorithm',
     'TestArray',
     'TestArrayUtils',
     'TestAtomics',