1//===--- Encoding.h - Format C++ code -------------------------------------===//
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/// \file
11/// \brief Contains functions for text encoding manipulation. Supports UTF-8,
12/// 8-bit encodings and escape sequences in C++ string literals.
13///
14//===----------------------------------------------------------------------===//
15
16#ifndef LLVM_CLANG_FORMAT_ENCODING_H
17#define LLVM_CLANG_FORMAT_ENCODING_H
18
19#include "clang/Basic/LLVM.h"
20#include "llvm/Support/ConvertUTF.h"
21
22namespace clang {
23namespace format {
24namespace encoding {
25
26enum Encoding {
27  Encoding_UTF8,
28  Encoding_Unknown // We treat all other encodings as 8-bit encodings.
29};
30
31/// \brief Detects encoding of the Text. If the Text can be decoded using UTF-8,
32/// it is considered UTF8, otherwise we treat it as some 8-bit encoding.
33inline Encoding detectEncoding(StringRef Text) {
34  const UTF8 *Ptr = reinterpret_cast<const UTF8 *>(Text.begin());
35  const UTF8 *BufEnd = reinterpret_cast<const UTF8 *>(Text.end());
36  if (::isLegalUTF8String(&Ptr, BufEnd))
37    return Encoding_UTF8;
38  return Encoding_Unknown;
39}
40
41inline unsigned getCodePointCountUTF8(StringRef Text) {
42  unsigned CodePoints = 0;
43  for (size_t i = 0, e = Text.size(); i < e; i += getNumBytesForUTF8(Text[i])) {
44    ++CodePoints;
45  }
46  return CodePoints;
47}
48
49/// \brief Gets the number of code points in the Text using the specified
50/// Encoding.
51inline unsigned getCodePointCount(StringRef Text, Encoding Encoding) {
52  switch (Encoding) {
53  case Encoding_UTF8:
54    return getCodePointCountUTF8(Text);
55  default:
56    return Text.size();
57  }
58}
59
60/// \brief Gets the number of bytes in a sequence representing a single
61/// codepoint and starting with FirstChar in the specified Encoding.
62inline unsigned getCodePointNumBytes(char FirstChar, Encoding Encoding) {
63  switch (Encoding) {
64  case Encoding_UTF8:
65    return getNumBytesForUTF8(FirstChar);
66  default:
67    return 1;
68  }
69}
70
71inline bool isOctDigit(char c) { return '0' <= c && c <= '7'; }
72
73inline bool isHexDigit(char c) {
74  return ('0' <= c && c <= '9') || ('a' <= c && c <= 'f') ||
75         ('A' <= c && c <= 'F');
76}
77
78/// \brief Gets the length of an escape sequence inside a C++ string literal.
79/// Text should span from the beginning of the escape sequence (starting with a
80/// backslash) to the end of the string literal.
81inline unsigned getEscapeSequenceLength(StringRef Text) {
82  assert(Text[0] == '\\');
83  if (Text.size() < 2)
84    return 1;
85
86  switch (Text[1]) {
87  case 'u':
88    return 6;
89  case 'U':
90    return 10;
91  case 'x': {
92    unsigned I = 2; // Point after '\x'.
93    while (I < Text.size() && isHexDigit(Text[I]))
94      ++I;
95    return I;
96  }
97  default:
98    if (isOctDigit(Text[1])) {
99      unsigned I = 1;
100      while (I < Text.size() && I < 4 && isOctDigit(Text[I]))
101        ++I;
102      return I;
103    }
104    return 2;
105  }
106}
107
108} // namespace encoding
109} // namespace format
110} // namespace clang
111
112#endif // LLVM_CLANG_FORMAT_ENCODING_H
113