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-rw-r--r--include/llvm/ADT/Optional.h132
1 files changed, 98 insertions, 34 deletions
diff --git a/include/llvm/ADT/Optional.h b/include/llvm/ADT/Optional.h
index f43aeb1..194e53f 100644
--- a/include/llvm/ADT/Optional.h
+++ b/include/llvm/ADT/Optional.h
@@ -13,13 +13,15 @@
//
//===----------------------------------------------------------------------===//
-#ifndef LLVM_ADT_OPTIONAL
-#define LLVM_ADT_OPTIONAL
+#ifndef LLVM_ADT_OPTIONAL_H
+#define LLVM_ADT_OPTIONAL_H
+#include "llvm/ADT/None.h"
#include "llvm/Support/Compiler.h"
+#include "llvm/Support/AlignOf.h"
#include <cassert>
-#if LLVM_USE_RVALUE_REFERENCES
+#if LLVM_HAS_RVALUE_REFERENCES
#include <utility>
#endif
@@ -27,54 +29,116 @@ namespace llvm {
template<typename T>
class Optional {
- T x;
- unsigned hasVal : 1;
+ AlignedCharArrayUnion<T> storage;
+ bool hasVal;
public:
- explicit Optional() : x(), hasVal(false) {}
- Optional(const T &y) : x(y), hasVal(true) {}
+ Optional(NoneType) : hasVal(false) {}
+ explicit Optional() : hasVal(false) {}
+ Optional(const T &y) : hasVal(true) {
+ new (storage.buffer) T(y);
+ }
+ Optional(const Optional &O) : hasVal(O.hasVal) {
+ if (hasVal)
+ new (storage.buffer) T(*O);
+ }
-#if LLVM_USE_RVALUE_REFERENCES
- Optional(T &&y) : x(std::forward<T>(y)), hasVal(true) {}
+#if LLVM_HAS_RVALUE_REFERENCES
+ Optional(T &&y) : hasVal(true) {
+ new (storage.buffer) T(std::forward<T>(y));
+ }
+ Optional(Optional<T> &&O) : hasVal(O) {
+ if (O) {
+ new (storage.buffer) T(std::move(*O));
+ O.reset();
+ }
+ }
+ Optional &operator=(T &&y) {
+ if (hasVal)
+ **this = std::move(y);
+ else {
+ new (storage.buffer) T(std::move(y));
+ hasVal = true;
+ }
+ return *this;
+ }
+ Optional &operator=(Optional &&O) {
+ if (!O)
+ reset();
+ else {
+ *this = std::move(*O);
+ O.reset();
+ }
+ return *this;
+ }
#endif
static inline Optional create(const T* y) {
return y ? Optional(*y) : Optional();
}
+ // FIXME: these assignments (& the equivalent const T&/const Optional& ctors)
+ // could be made more efficient by passing by value, possibly unifying them
+ // with the rvalue versions above - but this could place a different set of
+ // requirements (notably: the existence of a default ctor) when implemented
+ // in that way. Careful SFINAE to avoid such pitfalls would be required.
Optional &operator=(const T &y) {
- x = y;
- hasVal = true;
+ if (hasVal)
+ **this = y;
+ else {
+ new (storage.buffer) T(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; }
-};
+ Optional &operator=(const Optional &O) {
+ if (!O)
+ reset();
+ else
+ *this = *O;
+ return *this;
+ }
-template<typename T> struct simplify_type;
+ void reset() {
+ if (hasVal) {
+ (**this).~T();
+ hasVal = false;
+ }
+ }
-template <typename T>
-struct simplify_type<const Optional<T> > {
- typedef const T* SimpleType;
- static SimpleType getSimplifiedValue(const Optional<T> &Val) {
- return Val.getPointer();
+ ~Optional() {
+ reset();
}
+
+ const T* getPointer() const { assert(hasVal); return reinterpret_cast<const T*>(storage.buffer); }
+ T* getPointer() { assert(hasVal); return reinterpret_cast<T*>(storage.buffer); }
+ const T& getValue() const LLVM_LVALUE_FUNCTION { assert(hasVal); return *getPointer(); }
+ T& getValue() LLVM_LVALUE_FUNCTION { assert(hasVal); return *getPointer(); }
+
+ LLVM_EXPLICIT operator bool() const { return hasVal; }
+ bool hasValue() const { return hasVal; }
+ const T* operator->() const { return getPointer(); }
+ T* operator->() { return getPointer(); }
+ const T& operator*() const LLVM_LVALUE_FUNCTION { assert(hasVal); return *getPointer(); }
+ T& operator*() LLVM_LVALUE_FUNCTION { assert(hasVal); return *getPointer(); }
+
+#if LLVM_HAS_RVALUE_REFERENCE_THIS
+ T&& getValue() && { assert(hasVal); return std::move(*getPointer()); }
+ T&& operator*() && { assert(hasVal); return std::move(*getPointer()); }
+#endif
};
-template <typename T>
-struct simplify_type<Optional<T> >
- : public simplify_type<const Optional<T> > {};
+template <typename T> struct isPodLike;
+template <typename T> struct isPodLike<Optional<T> > {
+ // An Optional<T> is pod-like if T is.
+ static const bool value = isPodLike<T>::value;
+};
/// \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
+/// 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);
@@ -83,7 +147,7 @@ void operator==(const Optional<T> &X, const Optional<U> &Y);
/// 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
+/// 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);
@@ -92,7 +156,7 @@ void operator!=(const Optional<T> &X, const Optional<U> &Y);
/// 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
+/// 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);
@@ -101,7 +165,7 @@ void operator<(const Optional<T> &X, const Optional<U> &Y);
/// 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
+/// 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);
@@ -110,7 +174,7 @@ void operator<=(const Optional<T> &X, const Optional<U> &Y);
/// 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
+/// 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);
@@ -119,7 +183,7 @@ void operator>=(const Optional<T> &X, const Optional<U> &Y);
/// 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
+/// 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);
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