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      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/StringExtras.h"
     15 #include "llvm/ADT/StringMap.h"
     16 #include "llvm/Support/raw_ostream.h"
     17 #include <cctype>
     18 
     19 namespace llvm {
     20 
     21 /// StringToOffsetTable - This class uniques a bunch of nul-terminated strings
     22 /// and keeps track of their offset in a massive contiguous string allocation.
     23 /// It can then output this string blob and use indexes into the string to
     24 /// reference each piece.
     25 class StringToOffsetTable {
     26   StringMap<unsigned> StringOffset;
     27   std::string AggregateString;
     28 public:
     29 
     30   unsigned GetOrAddStringOffset(StringRef Str, bool appendZero = true) {
     31     StringMapEntry<unsigned> &Entry = StringOffset.GetOrCreateValue(Str, -1U);
     32     if (Entry.getValue() == -1U) {
     33       // Add the string to the aggregate if this is the first time found.
     34       Entry.setValue(AggregateString.size());
     35       AggregateString.append(Str.begin(), Str.end());
     36       if (appendZero)
     37         AggregateString += '\0';
     38     }
     39 
     40     return Entry.getValue();
     41   }
     42 
     43   void EmitString(raw_ostream &O) {
     44     // Escape the string.
     45     SmallString<256> Str;
     46     raw_svector_ostream(Str).write_escaped(AggregateString);
     47     AggregateString = Str.str();
     48 
     49     O << "    \"";
     50     unsigned CharsPrinted = 0;
     51     for (unsigned i = 0, e = AggregateString.size(); i != e; ++i) {
     52       if (CharsPrinted > 70) {
     53         O << "\"\n    \"";
     54         CharsPrinted = 0;
     55       }
     56       O << AggregateString[i];
     57       ++CharsPrinted;
     58 
     59       // Print escape sequences all together.
     60       if (AggregateString[i] != '\\')
     61         continue;
     62 
     63       assert(i+1 < AggregateString.size() && "Incomplete escape sequence!");
     64       if (isdigit(AggregateString[i+1])) {
     65         assert(isdigit(AggregateString[i+2]) &&
     66                isdigit(AggregateString[i+3]) &&
     67                "Expected 3 digit octal escape!");
     68         O << AggregateString[++i];
     69         O << AggregateString[++i];
     70         O << AggregateString[++i];
     71         CharsPrinted += 3;
     72       } else {
     73         O << AggregateString[++i];
     74         ++CharsPrinted;
     75       }
     76     }
     77     O << "\"";
     78   }
     79 };
     80 
     81 } // end namespace llvm
     82 
     83 #endif
     84