StringToOffsetTable.h revision 3c777947f4fdd94f061f8ac4a118a8db03da88a8 
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
18namespace 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.
24class StringToOffsetTable {
25  StringMap<unsigned> StringOffset;
26  std::string AggregateString;
27public:
28
29  unsigned GetOrAddStringOffset(StringRef Str, bool appendZero = true) {
30    StringMapEntry<unsigned> &Entry = StringOffset.GetOrCreateValue(Str, -1U);
31    if (Entry.getValue() == -1U) {
32      // Add the string to the aggregate if this is the first time found.
33      Entry.setValue(AggregateString.size());
34      AggregateString.append(Str.begin(), Str.end());
35      if (appendZero)
36        AggregateString += '\0';
37    }
38
39    return Entry.getValue();
40  }
41
42  void EmitString(raw_ostream &O) {
43    // Escape the string.
44    SmallString<256> Str;
45    raw_svector_ostream(Str).write_escaped(AggregateString);
46    AggregateString = Str.str();
47
48    O << "    \"";
49    unsigned CharsPrinted = 0;
50    for (unsigned i = 0, e = AggregateString.size(); i != e; ++i) {
51      if (CharsPrinted > 70) {
52        O << "\"\n    \"";
53        CharsPrinted = 0;
54      }
55      O << AggregateString[i];
56      ++CharsPrinted;
57
58      // Print escape sequences all together.
59      if (AggregateString[i] != '\\')
60        continue;
61
62      assert(i+1 < AggregateString.size() && "Incomplete escape sequence!");
63      if (isdigit(AggregateString[i+1])) {
64        assert(isdigit(AggregateString[i+2]) &&
65               isdigit(AggregateString[i+3]) &&
66               "Expected 3 digit octal escape!");
67        O << AggregateString[++i];
68        O << AggregateString[++i];
69        O << AggregateString[++i];
70        CharsPrinted += 3;
71      } else {
72        O << AggregateString[++i];
73        ++CharsPrinted;
74      }
75    }
76    O << "\"";
77  }
78};
79
80} // end namespace llvm
81
82#endif
83