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[ADT] Fix StringSet::insert() to not allocate on every lookup.

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- The previous implementation always constructed the StringMap entry, even if
   the key was present in the set.

llvm-svn: 177178
This commit is contained in:
Daniel Dunbar 2013-03-15 20:16:59 +00:00
parent 59e25a6e11
commit 3835c43762
1 changed files with 14 additions and 12 deletions
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26
include/llvm/ADT/StringSet.h
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@ -18,23 +18,25 @@
namespace llvm {
/// StringSet - A wrapper for StringMap that provides set-like
/// functionality. Only insert() and count() methods are used by my
/// code.
/// StringSet - A wrapper for StringMap that provides set-like functionality.
template <class AllocatorTy = llvm::MallocAllocator>
class StringSet : public llvm::StringMap<char, AllocatorTy> {
typedef llvm::StringMap<char, AllocatorTy> base;
public:
bool insert(StringRef InLang) {
assert(!InLang.empty());
const char *KeyStart = InLang.data();
const char *KeyEnd = KeyStart + InLang.size();
llvm::StringMapEntry<char> *Entry = llvm::StringMapEntry<char>::
Create(KeyStart, KeyEnd, base::getAllocator(), '+');
if (!base::insert(Entry)) {
Entry->Destroy(base::getAllocator());
/// insert - Insert the specified key into the set. If the key already
/// exists in the set, return false and ignore the request, otherwise insert
/// it and return true.
bool insert(StringRef Key) {
// Get or create the map entry for the key; if it doesn't exist the value
// type will be default constructed which we use to detect insert.
//
// We use '+' as the sentinel value in the map.
assert(!Key.empty());
StringMapEntry<char> &Entry = this->GetOrCreateValue(Key);
if (Entry.getValue() == '+')
return false;
}
Entry.setValue('+');
return true;
}
};