utils/TableGen/StringToOffsetTable.h

   1 //===- StringToOffsetTable.h - Emit a big concatenated string ---*- C++ -*-===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9
  10 #ifndef TBLGEN_STRING_TO_OFFSET_TABLE_H
  11 #define TBLGEN_STRING_TO_OFFSET_TABLE_H
  12
  13 #include "llvm/ADT/SmallString.h"
  14 #include "llvm/ADT/StringMap.h"
  15 #include "llvm/ADT/StringExtras.h"
  16 #include "llvm/Support/raw_ostream.h"
  17
  18 namespace llvm {
  19
  20 /// StringToOffsetTable - This class uniques a bunch of nul-terminated strings
  21 /// and keeps track of their offset in a massive contiguous string allocation.
  22 /// It can then output this string blob and use indexes into the string to
  23 /// reference each piece.
  24 class StringToOffsetTable {
  25   StringMap<unsigned> StringOffset;
  26   std::string AggregateString;
  27 public:
  28
  29   unsigned GetOrAddStringOffset(StringRef Str) {
  30     unsigned &Entry = StringOffset[Str];
  31     if (Entry == 0) {
  32       // Add the string to the aggregate if this is the first time found.
  33       Entry = AggregateString.size();
  34       AggregateString.append(Str.begin(), Str.end());
  35       AggregateString += '\0';
  36     }
  37
  38     return Entry;
  39   }
  40
  41   void EmitString(raw_ostream &O) {
  42     // Escape the string.
  43     SmallString<256> Str;
  44     raw_svector_ostream(Str).write_escaped(AggregateString);
  45     AggregateString = Str.str();
  46
  47     O << "    \"";
  48     unsigned CharsPrinted = 0;
  49     for (unsigned i = 0, e = AggregateString.size(); i != e; ++i) {
  50       if (CharsPrinted > 70) {
  51         O << "\"\n    \"";
  52         CharsPrinted = 0;
  53       }
  54       O << AggregateString[i];
  55       ++CharsPrinted;
  56
  57       // Print escape sequences all together.
  58       if (AggregateString[i] != '\\')
  59         continue;
  60
  61       assert(i+1 < AggregateString.size() && "Incomplete escape sequence!");
  62       if (isdigit(AggregateString[i+1])) {
  63         assert(isdigit(AggregateString[i+2]) &&
  64                isdigit(AggregateString[i+3]) &&
  65                "Expected 3 digit octal escape!");
  66         O << AggregateString[++i];
  67         O << AggregateString[++i];
  68         O << AggregateString[++i];
  69         CharsPrinted += 3;
  70       } else {
  71         O << AggregateString[++i];
  72         ++CharsPrinted;
  73       }
  74     }
  75     O << "\"";
  76   }
  77 };
  78
  79 } // end namespace llvm
  80
  81 #endif