-//===-- StringPool.h - Interned string pool -------------------------------===//
+//===-- StringPool.h - Interned string pool ---------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
//
// This file declares an interned string pool, which helps reduce the cost of
// strings by using the same storage for identical strings.
-//
+//
// To intern a string:
-//
+//
// StringPool Pool;
// PooledStringPtr Str = Pool.intern("wakka wakka");
-//
+//
// To use the value of an interned string, use operator bool and operator*:
-//
+//
// if (Str)
// cerr << "the string is" << *Str << "\n";
-//
+//
// Pooled strings are immutable, but you can change a PooledStringPtr to point
// to another instance. So that interned strings can eventually be freed,
// strings in the string pool are reference-counted (automatically).
-//
+//
//===----------------------------------------------------------------------===//
#ifndef LLVM_SUPPORT_STRINGPOOL_H
#define LLVM_SUPPORT_STRINGPOOL_H
+#include "llvm/Support/Compiler.h"
#include "llvm/ADT/StringMap.h"
-#include <new>
#include <cassert>
+#include <new>
namespace llvm {
struct PooledString {
StringPool *Pool; ///< So the string can remove itself.
unsigned Refcount; ///< Number of referencing PooledStringPtrs.
-
+
public:
- PooledString() : Pool(0), Refcount(0) { }
+ PooledString() : Pool(nullptr), Refcount(0) { }
};
-
+
friend class PooledStringPtr;
-
+
typedef StringMap<PooledString> table_t;
typedef StringMapEntry<PooledString> entry_t;
table_t InternTable;
-
+
public:
StringPool();
~StringPool();
-
+
/// intern - Adds a string to the pool and returns a reference-counted
/// pointer to it. No additional memory is allocated if the string already
/// exists in the pool.
- PooledStringPtr intern(const char *Begin, const char *End);
-
- /// intern - Adds a null-terminated string to the pool and returns a
- /// reference-counted pointer to it. No additional memory is allocated if
- /// the string already exists in the pool.
- inline PooledStringPtr intern(const char *Str);
-
+ PooledStringPtr intern(StringRef Str);
+
/// empty - Checks whether the pool is empty. Returns true if so.
- ///
+ ///
inline bool empty() const { return InternTable.empty(); }
};
-
+
/// PooledStringPtr - A pointer to an interned string. Use operator bool to
/// test whether the pointer is valid, and operator * to get the string if so.
/// This is a lightweight value class with storage requirements equivalent to
class PooledStringPtr {
typedef StringPool::entry_t entry_t;
entry_t *S;
-
+
public:
- PooledStringPtr() : S(0) {}
-
+ PooledStringPtr() : S(nullptr) {}
+
explicit PooledStringPtr(entry_t *E) : S(E) {
if (S) ++S->getValue().Refcount;
}
-
+
PooledStringPtr(const PooledStringPtr &That) : S(That.S) {
if (S) ++S->getValue().Refcount;
}
-
+
PooledStringPtr &operator=(const PooledStringPtr &That) {
if (S != That.S) {
clear();
}
return *this;
}
-
+
void clear() {
if (!S)
return;
S->getValue().Pool->InternTable.remove(S);
S->Destroy();
}
- S = 0;
+ S = nullptr;
}
-
+
~PooledStringPtr() { clear(); }
-
+
inline const char *begin() const {
assert(*this && "Attempt to dereference empty PooledStringPtr!");
return S->getKeyData();
}
-
+
inline const char *end() const {
assert(*this && "Attempt to dereference empty PooledStringPtr!");
return S->getKeyData() + S->getKeyLength();
}
-
+
inline unsigned size() const {
assert(*this && "Attempt to dereference empty PooledStringPtr!");
return S->getKeyLength();
}
-
+
inline const char *operator*() const { return begin(); }
- inline operator bool() const { return S != 0; }
-
- inline bool operator==(const PooledStringPtr &That) { return S == That.S; }
- inline bool operator!=(const PooledStringPtr &That) { return S != That.S; }
+ inline LLVM_EXPLICIT operator bool() const { return S != nullptr; }
+
+ inline bool operator==(const PooledStringPtr &That) const { return S == That.S; }
+ inline bool operator!=(const PooledStringPtr &That) const { return S != That.S; }
};
-
- PooledStringPtr StringPool::intern(const char *Str) {
- return intern(Str, Str + strlen(Str));
- }
} // End llvm namespace