1 //===-- Optional.h - Simple variant for passing optional values ---*- C++ -*-=//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
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.
14 //===----------------------------------------------------------------------===//
16 #ifndef LLVM_ADT_OPTIONAL
17 #define LLVM_ADT_OPTIONAL
28 explicit Optional() : x(), hasVal(false) {}
29 Optional(const T &y) : x(y), hasVal(true) {}
31 static inline Optional create(const T* y) {
32 return y ? Optional(*y) : Optional();
35 Optional &operator=(const T &y) {
41 const T* getPointer() const { assert(hasVal); return &x; }
42 const T& getValue() const { assert(hasVal); return x; }
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; }
50 template<typename T> struct simplify_type;
53 struct simplify_type<const Optional<T> > {
54 typedef const T* SimpleType;
55 static SimpleType getSimplifiedValue(const Optional<T> &Val) {
56 return Val.getPointer();
61 struct simplify_type<Optional<T> >
62 : public simplify_type<const Optional<T> > {};
64 } // end llvm namespace