1 files changed, 75 insertions, 0 deletions
diff --git a/src/core/SkFunction.h b/src/core/SkFunction.h
new file mode 100644
index 0000000000..8e41cba929
--- /dev/null
+++ b/src/core/SkFunction.h
@@ -0,0 +1,75 @@
+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkFunction_DEFINED
+#define SkFunction_DEFINED
+
+// TODO: document, more pervasive move support in constructors, small-Fn optimization
+
+#include "SkTemplates.h"
+#include "SkTypes.h"
+
+template <typename> class SkFunction;
+
+template <typename R, typename... Args>
+class SkFunction<R(Args...)> {
+public:
+    SkFunction() {}
+
+    template <typename Fn>
+    SkFunction(const Fn& fn) : fFunction(SkNEW_ARGS(LambdaImpl<Fn>, (fn))) {}
+
+    SkFunction(R (*fn)(Args...)) : fFunction(SkNEW_ARGS(FnPtrImpl, (fn))) {}
+
+    SkFunction(const SkFunction& other) { *this = other; }
+    SkFunction& operator=(const SkFunction& other) {
+        if (this != &other) {
+            fFunction.reset(other.fFunction ? other.fFunction->clone() : nullptr);
+        }
+        return *this;
+    }
+
+    R operator()(Args... args) const {
+        SkASSERT(fFunction.get());
+        return fFunction->call(Forward(args)...);
+    }
+
+private:
+    // ~= std::forward.  This moves its argument if possible, falling back to a copy if not.
+    template <typename T> static T&& Forward(T& v) { return (T&&)v; }
+
+    struct Interface {
+        virtual ~Interface() {}
+        virtual R call(Args...) const = 0;
+        virtual Interface* clone() const = 0;
+    };
+
+    template <typename Fn>
+    class LambdaImpl final : public Interface {
+    public:
+        LambdaImpl(const Fn& fn) : fFn(fn) {}
+
+        R call(Args... args) const override { return fFn(Forward(args)...); }
+        Interface* clone() const override { return SkNEW_ARGS(LambdaImpl<Fn>, (fFn)); }
+    private:
+        Fn fFn;
+    };
+
+    class FnPtrImpl final : public Interface {
+    public:
+        FnPtrImpl(R (*fn)(Args...)) : fFn(fn) {}
+
+        R call(Args... args) const override { return fFn(Forward(args)...); }
+        Interface* clone() const override { return SkNEW_ARGS(FnPtrImpl, (fFn)); }
+    private:
+        R (*fFn)(Args...);
+    };
+
+    SkAutoTDelete<Interface> fFunction;
+};
+
+#endif//SkFunction_DEFINED