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situations where on the common path an API can return a pointer to some direct memory, but which on an exceptional path may need to return a pointer to a temporary struct. llvm-svn: 120201
78 lines
2.1 KiB
C++
78 lines
2.1 KiB
C++
//===- InMemoryStruct.h - Indirect Struct Access Smart Pointer --*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ADT_INMEMORYSTRUCT_H
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#define LLVM_ADT_INMEMORYSTRUCT_H
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#include <cassert>
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namespace llvm {
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/// \brief Helper object for abstracting access to an in-memory structure which
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/// may require some kind of temporary storage.
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///
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/// This class is designed to be used for accessing file data structures which
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/// in the common case can be accessed from a direct pointer to a memory mapped
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/// object, but which in some cases may require indirect access to a temporary
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/// structure (which, for example, may have undergone endianness translation).
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template<typename T>
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class InMemoryStruct {
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typedef T value_type;
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typedef value_type &reference;
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typedef value_type *pointer;
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typedef const value_type &const_reference;
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typedef const value_type *const_pointer;
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/// \brief The smart pointer target.
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value_type *Target;
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/// \brief A temporary object which can be used as a target of the smart
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/// pointer.
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value_type Contents;
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private:
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public:
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InMemoryStruct() : Target(0) {}
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InMemoryStruct(reference Value) : Target(&Contents), Contents(Value) {}
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InMemoryStruct(pointer Value) : Target(Value) {}
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InMemoryStruct(const InMemoryStruct<T> &Value) { *this = Value; }
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void operator=(const InMemoryStruct<T> &Value) {
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if (Value.Target != &Value.Contents) {
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Target = Value.Target;
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} else {
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Target = &Contents;
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Contents = Value.Contents;
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}
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}
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const_reference operator*() const {
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assert(Target && "Cannot dereference null pointer");
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return *Target;
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}
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reference operator*() {
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assert(Target && "Cannot dereference null pointer");
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return *Target;
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}
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const_pointer operator->() const {
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return Target;
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}
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pointer operator->() {
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return Target;
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}
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operator bool() const { return Target != 0; }
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};
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}
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#endif
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