Add a class to allocate small objects w/o extra calls to new.

tests/StackAllocatorTest.cpp

+/*
+ * Copyright 2014 Google, Inc
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "Test.h"

[tfarina, 2014/02/27 17:33:15]

could you keep this sorted?

[scroggo, 2014/03/05 20:25:52]

Done.

+#include "SkStackAllocator.h"
+#include "SkTypes.h"
+
+class CountingClass {
+public:
+    CountingClass() {
+        kCount++;
+    }
+
+    ~CountingClass() {
+        kCount--;
+    }
+
+    static int GetCount() { return kCount; }
+
+private:
+    static int kCount;
+};
+
+int CountingClass::kCount;
+
+template<size_t size> void test_allocator(skiatest::Reporter* reporter) {
+    {
+        SkStackAllocator<size> alloc;
+        for (int i = 0; i < 99; ++i) {
+            void* buf = alloc.template reserveT<CountingClass>();
+            SkNEW_PLACEMENT(buf, CountingClass);
+            CountingClass* c = static_cast<CountingClass*>(buf);
+            REPORTER_ASSERT(reporter, c != NULL);
+            REPORTER_ASSERT(reporter, CountingClass::GetCount() == i+1);
+        }
+    }
+    REPORTER_ASSERT(reporter, CountingClass::GetCount() == 0);
+}
+
+DEF_TEST(StackAllocator, reporter) {
+    test_allocator<0>(reporter);
+    test_allocator<5>(reporter);
+    test_allocator<50>(reporter);
+    test_allocator<100>(reporter);
+}