1//===-- Optional.h - Simple variant for passing optional values ---*- C++ -*-=// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file provides Optional, a template class modeled in the spirit of 11// OCaml's 'opt' variant. The idea is to strongly type whether or not 12// a value can be optional. 13// 14//===----------------------------------------------------------------------===// 15 16#ifndef LLVM_ADT_OPTIONAL 17#define LLVM_ADT_OPTIONAL 18 19#include <cassert> 20 21namespace llvm { 22 23template<typename T> 24class Optional { 25 T x; 26 unsigned hasVal : 1; 27public: 28 explicit Optional() : x(), hasVal(false) {} 29 Optional(const T &y) : x(y), hasVal(true) {} 30 31 static inline Optional create(const T* y) { 32 return y ? Optional(*y) : Optional(); 33 } 34 35 Optional &operator=(const T &y) { 36 x = y; 37 hasVal = true; 38 return *this; 39 } 40 41 const T* getPointer() const { assert(hasVal); return &x; } 42 const T& getValue() const { assert(hasVal); return x; } 43 44 operator bool() const { return hasVal; } 45 bool hasValue() const { return hasVal; } 46 const T* operator->() const { return getPointer(); } 47 const T& operator*() const { assert(hasVal); return x; } 48}; 49 50template<typename T> struct simplify_type; 51 52template <typename T> 53struct simplify_type<const Optional<T> > { 54 typedef const T* SimpleType; 55 static SimpleType getSimplifiedValue(const Optional<T> &Val) { 56 return Val.getPointer(); 57 } 58}; 59 60template <typename T> 61struct simplify_type<Optional<T> > 62 : public simplify_type<const Optional<T> > {}; 63 64/// \brief Poison comparison between two \c Optional objects. Clients needs to 65/// explicitly compare the underlying values and account for empty \c Optional 66/// objects. 67/// 68/// This routine will never be defined. It returns \c void to help diagnose 69/// errors at compile time. 70template<typename T, typename U> 71void operator==(const Optional<T> &X, const Optional<U> &Y); 72 73/// \brief Poison comparison between two \c Optional objects. Clients needs to 74/// explicitly compare the underlying values and account for empty \c Optional 75/// objects. 76/// 77/// This routine will never be defined. It returns \c void to help diagnose 78/// errors at compile time. 79template<typename T, typename U> 80void operator!=(const Optional<T> &X, const Optional<U> &Y); 81 82/// \brief Poison comparison between two \c Optional objects. Clients needs to 83/// explicitly compare the underlying values and account for empty \c Optional 84/// objects. 85/// 86/// This routine will never be defined. It returns \c void to help diagnose 87/// errors at compile time. 88template<typename T, typename U> 89void operator<(const Optional<T> &X, const Optional<U> &Y); 90 91/// \brief Poison comparison between two \c Optional objects. Clients needs to 92/// explicitly compare the underlying values and account for empty \c Optional 93/// objects. 94/// 95/// This routine will never be defined. It returns \c void to help diagnose 96/// errors at compile time. 97template<typename T, typename U> 98void operator<=(const Optional<T> &X, const Optional<U> &Y); 99 100/// \brief Poison comparison between two \c Optional objects. Clients needs to 101/// explicitly compare the underlying values and account for empty \c Optional 102/// objects. 103/// 104/// This routine will never be defined. It returns \c void to help diagnose 105/// errors at compile time. 106template<typename T, typename U> 107void operator>=(const Optional<T> &X, const Optional<U> &Y); 108 109/// \brief Poison comparison between two \c Optional objects. Clients needs to 110/// explicitly compare the underlying values and account for empty \c Optional 111/// objects. 112/// 113/// This routine will never be defined. It returns \c void to help diagnose 114/// errors at compile time. 115template<typename T, typename U> 116void operator>(const Optional<T> &X, const Optional<U> &Y); 117 118} // end llvm namespace 119 120#endif 121