Move GrTemplates.h to src

Review URL: http://codereview.appspot.com/6333053/


git-svn-id: http://skia.googlecode.com/svn/trunk@4300 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 70 insertions, 0 deletions

diff --git a/src/gpu/GrTemplates.h b/src/gpu/GrTemplates.h
new file mode 100644
index 0000000000..4378d70949
--- /dev/null
+++ b/src/gpu/GrTemplates.h
@@ -0,0 +1,70 @@
+
+/*
+ * Copyright 2010 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+
+#ifndef GrTemplates_DEFINED
+#define GrTemplates_DEFINED
+
+#include "GrNoncopyable.h"
+
+/**
+ *  Use to cast a ptr to a different type, and maintain strict-aliasing
+ */
+template <typename Dst, typename Src> Dst GrTCast(Src src) {
+    union {
+        Src src;
+        Dst dst;
+    } data;
+    data.src = src;
+    return data.dst;
+}
+
+/**
+ * takes a T*, saves the value it points to,  in and restores the value in the
+ * destructor
+ * e.g.:
+ * {
+ *      GrAutoTRestore<int*> autoCountRestore;
+ *      if (useExtra) {
+ *          autoCountRestore.reset(&fCount);
+ *          fCount += fExtraCount;
+ *      }
+ *      ...
+ * }  // fCount is restored
+ */
+template <typename T> class GrAutoTRestore : public GrNoncopyable {
+public:
+    GrAutoTRestore() : fPtr(NULL), fVal() {}
+    
+    GrAutoTRestore(T* ptr) {
+        fPtr = ptr;
+        if (NULL != ptr) {
+            fVal = *ptr;
+        }
+    }
+    
+    ~GrAutoTRestore() {
+        if (NULL != fPtr) {
+            *fPtr = fVal;
+        }
+    }
+    
+    // restores previously saved value (if any) and saves value for passed T*
+    void reset(T* ptr) {
+        if (NULL != fPtr) {
+            *fPtr = fVal;
+        }
+        fPtr = ptr;
+        fVal = *ptr;
+    }
+private:
+    T* fPtr;
+    T  fVal;
+};
+
+#endif