SkNEW as default Create() for SkLazyPtr macros.

src/core/SkLazyPtr.h

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkLazyPtr_DEFINED
 #define SkLazyPtr_DEFINED
 
 /** Declare a lazily-chosen static pointer (or array of pointers) of type F.
  *
  *  Example usage:
  *
- *  Foo* CreateFoo() { return SkNEW(Foo); }
  *  Foo* GetSingletonFoo() {
- *      SK_DECLARE_STATIC_LAZY_PTR(Foo, singleton, CreateFoo);  // Clean up with SkDELETE.
+ *      SK_DECLARE_STATIC_LAZY_PTR(Foo, singleton);  // Created with SkNEW, destroyed with SkDELETE.
  *      return singleton.get();
  *  }
  *
- *  These macros take an optional void (*Destroy)(T*) at the end. If not given, we'll use SkDELETE.
- *  This option is most useful when T doesn't have a public destructor.
+ *  These macros take an optional T* (*Create)() and void (*Destroy)(T*) at the end.
+ *  If not given, we'll use SkNEW and SkDELETE.
+ *  These options are most useful when T doesn't have a public constructor or destructor.
+ *  Create comes first, so you may use a custom Create with a default Destroy, but not vice versa.
  *
- *  void CustomCleanup(Foo* ptr) { ... }
+ *  Foo* CustomCreate() { return ...; }
+ *  void CustomDestroy(Foo* ptr) { ... }
  *  Foo* GetSingletonFooWithCustomCleanup() {
- *      SK_DECLARE_STATIC_LAZY_PTR(Foo, singleton, CreateFoo, CustomCleanup);
+ *      SK_DECLARE_STATIC_LAZY_PTR(Foo, singleton, CustomCreate, CustomDestroy);
  *      return singleton.get();
  *  }
  *
  *  If you have a bunch of related static pointers of the same type, you can
- *  declare an array of lazy pointers together:
+ *  declare an array of lazy pointers together, and we'll pass the index to Create().
  *
  *  Foo* CreateFoo(int i) { return ...; }
  *  Foo* GetCachedFoo(Foo::Enum enumVal) {
  *      SK_DECLARE_STATIC_LAZY_PTR_ARRAY(Foo, Foo::kEnumCount, cachedFoos, CreateFoo);
  *      return cachedFoos[enumVal];
  *  }
  *
  *
  *  You can think of SK_DECLARE_STATIC_LAZY_PTR as a cheaper specialization of
  *  SkOnce.  There is no mutex or extra storage used past the pointer itself.
  *  In debug mode, each lazy pointer will be cleaned up at process exit so we
  *  can check that we've not leaked or freed them early.
  *
  *  We may call Create more than once, but all threads will see the same pointer
  *  returned from get().  Any extra calls to Create will be cleaned up.
  *
  *  These macros must be used in a global or function scope, not as a class member.
  */
 
-#define SK_DECLARE_STATIC_LAZY_PTR(T, name, Create, ...) \
-    static Private::SkLazyPtr<T, Create, ##__VA_ARGS__> name
+#define SK_DECLARE_STATIC_LAZY_PTR(T, name, ...) \
+    static Private::SkLazyPtr<T, ##__VA_ARGS__> name
 
-#define SK_DECLARE_STATIC_LAZY_PTR_ARRAY(T, name, N, Create, ...) \
-    static Private::SkLazyPtrArray<T, N, Create, ##__VA_ARGS__> name
+#define SK_DECLARE_STATIC_LAZY_PTR_ARRAY(T, name, N, ...) \
+    static Private::SkLazyPtrArray<T, N, ##__VA_ARGS__> name
 
 
 
 // Everything below here is private implementation details.  Don't touch, don't even look.
 
 #include "SkDynamicAnnotations.h"
 #include "SkThread.h"
 #include "SkThreadPriv.h"
 
 // See FIXME below.
-class SkFontConfigInterface;
+class SkFontConfigInterfaceDirect;
 
 namespace Private {
 
-template <typename T> void sk_delete(T* ptr) { SkDELETE(ptr); }
-
 // Set *dst to ptr if *dst is NULL.  Returns value of *dst, destroying ptr if not swapped in.
 // Issues the same memory barriers as sk_atomic_cas: acquire on failure, release on success.
 template <typename P, void (*Destroy)(P)>
 static P try_cas(void** dst, P ptr) {
     P prev = (P)sk_atomic_cas(dst, NULL, ptr);
 
     if (prev) {
         // We need an acquire barrier before returning prev, which sk_atomic_cas provided.
         Destroy(ptr);
         return prev;
     } else {
         // We need a release barrier before returning ptr, which sk_atomic_cas provided.
         return ptr;
     }
 }
 
+template <typename T> T* sk_new() { return SkNEW(T); }
+template <typename T> void sk_delete(T* ptr) { SkDELETE(ptr); }
+
 // This has no constructor and must be zero-initalized (the macro above does this).
-template <typename T, T* (*Create)(), void (*Destroy)(T*) = sk_delete<T> >
+template <typename T, T* (*Create)() = sk_new<T>, void (*Destroy)(T*) = sk_delete<T> >
 class SkLazyPtr {
 public:
     T* get() {
         // If fPtr has already been filled, we need an acquire barrier when loading it.
         // If not, we need a release barrier when setting it.  try_cas will do that.
         T* ptr = (T*)sk_acquire_load(&fPtr);
         return ptr ? ptr : try_cas<T*, Destroy>(&fPtr, Create());
     }
 
 #ifdef SK_DEVELOPER
     // FIXME: We know we leak refs on some classes.  For now, let them leak.
-    void cleanup(SkFontConfigInterface*) {}
+    void cleanup(SkFontConfigInterfaceDirect*) {}
     template <typename U> void cleanup(U* ptr) { Destroy(ptr); }
 
     ~SkLazyPtr() {
         this->cleanup((T*)fPtr);
         fPtr = NULL;
     }
 #endif
 
 private:
     void* fPtr;
 };
 
+template <typename T> T* sk_new_arg(int i) { return SkNEW_ARGS(T, (i)); }
+
 // This has no constructor and must be zero-initalized (the macro above does this).
-template <typename T, int N, T* (*Create)(int), void (*Destroy)(T*) = sk_delete<T> >
+template <typename T, int N, T* (*Create)(int) = sk_new_arg<T>, void (*Destroy)(T*) = sk_delete<T> >
 class SkLazyPtrArray {
 public:
     T* operator[](int i) {
         SkASSERT(i >= 0 && i < N);
         // If fPtr has already been filled, we need an acquire barrier when loading it.
         // If not, we need a release barrier when setting it.  try_cas will do that.
         T* ptr = (T*)sk_acquire_load(&fArray[i]);
         return ptr ? ptr : try_cas<T*, Destroy>(&fArray[i], Create(i));
     }
 
 #ifdef SK_DEVELOPER
     ~SkLazyPtrArray() {
         for (int i = 0; i < N; i++) {
             Destroy((T*)fArray[i]);
             fArray[i] = NULL;
         }
     }
 #endif
 
 private:
     void* fArray[N];
 };
 
 }  // namespace Private
 
 #endif//SkLazyPtr_DEFINED