diff --git a/include/llvm/ADT/Optional.h b/include/llvm/ADT/Optional.h new file mode 100644 index 00000000000..34e54a07a0e --- /dev/null +++ b/include/llvm/ADT/Optional.h @@ -0,0 +1,66 @@ +//===-- 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 + +namespace llvm { + +template +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 struct simplify_type; + +template +struct simplify_type > { + typedef const T* SimpleType; + static SimpleType getSimplifiedValue(const Optional &Val) { + return Val.getPointer(); + } +}; + +template +struct simplify_type > + : public simplify_type > {}; + +} // end llvm namespace + +#endif