uPDF with buttons

git-svn-id: svn://kolibrios.org@4680 a494cfbc-eb01-0410-851d-a64ba20cac60

contrib/media/updf/include/lispcleanupstack.h

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+
+/** \file lispcleanupstack.h
+ * Implementation of a cleanup stack for exception handling on platforms
+ *  that don't clean up the stack automatically after an exception
+ *  occurs. The macro's SAFEPUSH and SAFEPOP as defined in
+ *  plat/<plat>/lisptype.h define which cleanup handler
+ *  to use, so it can be configured differently for different platforms.
+ *
+ */
+
+#ifndef __lispcleanupstack_h__
+#define __lispcleanupstack_h__
+
+#include "yacasbase.h"
+#include "grower.h"
+
+/** Base class that specifies one pure abstract method Delete.
+ *  Only classes derived from this one can be pushed onto
+ *  a cleanup stack. This in order to assure the cleanup code
+ *  knows where to find the destructor.
+ *
+ *  Typical candidates for cleanup include places in the code that
+ *  have temporal global side effects that need to be finalized on,
+ *  Like opening a file for reading, reading and then closing. If
+ *  reading prematurely finishes through an exception, the file
+ *  should be closed.
+ */
+class LispBase : public YacasBase
+{
+public:
+    virtual void Delete()=0;
+    virtual ~LispBase(){};
+};
+
+/** Clean up stack that doesn't actually delete objects itself.
+ *  Use this clean up stack if the compiler generates
+ *  cleanup code itself (particularly for newer c++ compilers).
+ *  Alternatively SAFEPUSH and SAFEPOP can then be defined to do nothing.
+ */
+class LispCleanup : public YacasBase
+{
+public:
+   inline LispCleanup() : iObjects() {}
+    virtual ~LispCleanup();
+    /// Push an object onto the cleanup stack for guarding
+    virtual void Push(LispBase& aObject);
+    /// Pop an object from the cleanup stack (the system is finished using it)
+    virtual void Pop();
+    /// Exception occurred: delete all objects on the stack, back to front.
+    virtual void Delete();
+    /** For testing purposes, verify that all places that pushed an object
+     *  popped it too.
+     */
+    void CheckStackEmpty();
+
+protected:
+    CArrayGrower<LispBase*, ArrOpsCustomPtr<LispBase> > iObjects;
+};
+
+/** Clean up stack that deletes objects itself when needed.
+ *  Use this clean up stack if the compiler doesn't generate
+ *  cleanup code itself (particularly for older c++ compilers).
+ */
+class DeletingLispCleanup : public LispCleanup
+{
+public:
+    virtual ~DeletingLispCleanup();
+    virtual void Push(LispBase& aObject);
+    virtual void Pop();
+    virtual void Delete();
+};
+
+
+#endif
+
+