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Move 'Optional' class from Clang to LLVM/ADT.
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@100889 91177308-0d34-0410-b5e6-96231b3b80d8
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tkremenek committed Apr 9, 2010
1 parent e0c74fb commit 76e94e5
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66 changes: 66 additions & 0 deletions include/llvm/ADT/Optional.h
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//===-- Optional.h - Simple variant for passing optional values ---*- C++ -*-=//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file provides Optional, a template class modeled in the spirit of
// OCaml's 'opt' variant. The idea is to strongly type whether or not
// a value can be optional.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_ADT_OPTIONAL
#define LLVM_ADT_OPTIONAL

#include <cassert>

namespace llvm {

template<typename T>
class Optional {
T x;
unsigned hasVal : 1;
public:
explicit Optional() : x(), hasVal(false) {}
Optional(const T &y) : x(y), hasVal(true) {}

static inline Optional create(const T* y) {
return y ? Optional(*y) : Optional();
}

Optional &operator=(const T &y) {
x = y;
hasVal = true;
return *this;
}

const T* getPointer() const { assert(hasVal); return &x; }
const T& getValue() const { assert(hasVal); return x; }

operator bool() const { return hasVal; }
bool hasValue() const { return hasVal; }
const T* operator->() const { return getPointer(); }
const T& operator*() const { assert(hasVal); return x; }
};

template<typename T> struct simplify_type;

template <typename T>
struct simplify_type<const Optional<T> > {
typedef const T* SimpleType;
static SimpleType getSimplifiedValue(const Optional<T> &Val) {
return Val.getPointer();
}
};

template <typename T>
struct simplify_type<Optional<T> >
: public simplify_type<const Optional<T> > {};

} // end llvm namespace

#endif

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