1//===--- StringSet.h - The LLVM Compiler Driver -----------------*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open
6// Source License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10//  StringSet - A set-like wrapper for the StringMap.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_ADT_STRINGSET_H
15#define LLVM_ADT_STRINGSET_H
16
17#include "llvm/ADT/StringMap.h"
18
19namespace llvm {
20
21  /// StringSet - A wrapper for StringMap that provides set-like functionality.
22  template <class AllocatorTy = llvm::MallocAllocator>
23  class StringSet : public llvm::StringMap<char, AllocatorTy> {
24    typedef llvm::StringMap<char, AllocatorTy> base;
25  public:
26
27    /// insert - Insert the specified key into the set.  If the key already
28    /// exists in the set, return false and ignore the request, otherwise insert
29    /// it and return true.
30    bool insert(StringRef Key) {
31      // Get or create the map entry for the key; if it doesn't exist the value
32      // type will be default constructed which we use to detect insert.
33      //
34      // We use '+' as the sentinel value in the map.
35      assert(!Key.empty());
36      StringMapEntry<char> &Entry = this->GetOrCreateValue(Key);
37      if (Entry.getValue() == '+')
38        return false;
39      Entry.setValue('+');
40      return true;
41    }
42  };
43}
44
45#endif // LLVM_ADT_STRINGSET_H
46