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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 "llvm/Support/Compiler.h"
#include <cassert>
#if LLVM_USE_RVALUE_REFERENCES
#include <utility>
#endif
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) {}
#if LLVM_USE_RVALUE_REFERENCES
Optional(T &&y) : x(std::forward<T>(y)), hasVal(true) {}
#endif
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> > {};
/// \brief Poison comparison between two \c Optional objects. Clients needs to
/// explicitly compare the underlying values and account for empty \c Optional
/// objects.
///
/// This routine will never be defined. It returns \c void to help diagnose
/// errors at compile time.
template<typename T, typename U>
void operator==(const Optional<T> &X, const Optional<U> &Y);
/// \brief Poison comparison between two \c Optional objects. Clients needs to
/// explicitly compare the underlying values and account for empty \c Optional
/// objects.
///
/// This routine will never be defined. It returns \c void to help diagnose
/// errors at compile time.
template<typename T, typename U>
void operator!=(const Optional<T> &X, const Optional<U> &Y);
/// \brief Poison comparison between two \c Optional objects. Clients needs to
/// explicitly compare the underlying values and account for empty \c Optional
/// objects.
///
/// This routine will never be defined. It returns \c void to help diagnose
/// errors at compile time.
template<typename T, typename U>
void operator<(const Optional<T> &X, const Optional<U> &Y);
/// \brief Poison comparison between two \c Optional objects. Clients needs to
/// explicitly compare the underlying values and account for empty \c Optional
/// objects.
///
/// This routine will never be defined. It returns \c void to help diagnose
/// errors at compile time.
template<typename T, typename U>
void operator<=(const Optional<T> &X, const Optional<U> &Y);
/// \brief Poison comparison between two \c Optional objects. Clients needs to
/// explicitly compare the underlying values and account for empty \c Optional
/// objects.
///
/// This routine will never be defined. It returns \c void to help diagnose
/// errors at compile time.
template<typename T, typename U>
void operator>=(const Optional<T> &X, const Optional<U> &Y);
/// \brief Poison comparison between two \c Optional objects. Clients needs to
/// explicitly compare the underlying values and account for empty \c Optional
/// objects.
///
/// This routine will never be defined. It returns \c void to help diagnose
/// errors at compile time.
template<typename T, typename U>
void operator>(const Optional<T> &X, const Optional<U> &Y);
} // end llvm namespace
#endif
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