include/llvm/Support/StringSaver.h

   1 //===- llvm/Support/StringSaver.h -------------------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #ifndef LLVM_SUPPORT_STRINGSAVER_H
  10 #define LLVM_SUPPORT_STRINGSAVER_H
  11
  12 #include "llvm/ADT/DenseSet.h"
  13 #include "llvm/ADT/StringRef.h"
  14 #include "llvm/ADT/Twine.h"
  15 #include "llvm/Support/Allocator.h"
  16
  17 namespace llvm {
  18
  19 /// Saves strings in the provided stable storage and returns a
  20 /// StringRef with a stable character pointer.
  21 class StringSaver final {
  22   BumpPtrAllocator &Alloc;
  23
  24 public:
  25   StringSaver(BumpPtrAllocator &Alloc) : Alloc(Alloc) {}
  26
  27   // All returned strings are null-terminated: *save(S).end() == 0.
  28   StringRef save(const char *S) { return save(StringRef(S)); }
  29   StringRef save(StringRef S);
  30   StringRef save(const Twine &S) { return save(StringRef(S.str())); }
  31   StringRef save(const std::string &S) { return save(StringRef(S)); }
  32 };
  33
  34 /// Saves strings in the provided stable storage and returns a StringRef with a
  35 /// stable character pointer. Saving the same string yields the same StringRef.
  36 ///
  37 /// Compared to StringSaver, it does more work but avoids saving the same string
  38 /// multiple times.
  39 ///
  40 /// Compared to StringPool, it performs fewer allocations but doesn't support
  41 /// refcounting/deletion.
  42 class UniqueStringSaver final {
  43   StringSaver Strings;
  44   llvm::DenseSet<llvm::StringRef> Unique;
  45
  46 public:
  47   UniqueStringSaver(BumpPtrAllocator &Alloc) : Strings(Alloc) {}
  48
  49   // All returned strings are null-terminated: *save(S).end() == 0.
  50   StringRef save(const char *S) { return save(StringRef(S)); }
  51   StringRef save(StringRef S);
  52   StringRef save(const Twine &S) { return save(StringRef(S.str())); }
  53   StringRef save(const std::string &S) { return save(StringRef(S)); }
  54 };
  55
  56 }
  57 #endif