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#include "llvm/Support/Unicode.h" 22 23namespace clang { 24namespace format { 25namespace encoding { 26 27enum Encoding { 28 Encoding_UTF8, 29 Encoding_Unknown // We treat all other encodings as 8-bit encodings. 30}; 31 32/// \brief Detects encoding of the Text. If the Text can be decoded using UTF-8, 33/// it is considered UTF8, otherwise we treat it as some 8-bit encoding. 34inline Encoding detectEncoding(StringRef Text) { 35 const UTF8 *Ptr = reinterpret_cast<const UTF8 *>(Text.begin()); 36 const UTF8 *BufEnd = reinterpret_cast<const UTF8 *>(Text.end()); 37 if (::isLegalUTF8String(&Ptr, BufEnd)) 38 return Encoding_UTF8; 39 return Encoding_Unknown; 40} 41 42inline unsigned getCodePointCountUTF8(StringRef Text) { 43 unsigned CodePoints = 0; 44 for (size_t i = 0, e = Text.size(); i < e; i += getNumBytesForUTF8(Text[i])) { 45 ++CodePoints; 46 } 47 return CodePoints; 48} 49 50/// \brief Gets the number of code points in the Text using the specified 51/// Encoding. 52inline unsigned getCodePointCount(StringRef Text, Encoding Encoding) { 53 switch (Encoding) { 54 case Encoding_UTF8: 55 return getCodePointCountUTF8(Text); 56 default: 57 return Text.size(); 58 } 59} 60 61/// \brief Returns the number of columns required to display the \p Text on a 62/// generic Unicode-capable terminal. Text is assumed to use the specified 63/// \p Encoding. 64inline unsigned columnWidth(StringRef Text, Encoding Encoding) { 65 if (Encoding == Encoding_UTF8) { 66 int ContentWidth = llvm::sys::unicode::columnWidthUTF8(Text); 67 // FIXME: Figure out the correct way to handle this in the presence of both 68 // printable and unprintable multi-byte UTF-8 characters. Falling back to 69 // returning the number of bytes may cause problems, as columnWidth suddenly 70 // becomes non-additive. 71 if (ContentWidth >= 0) 72 return ContentWidth; 73 } 74 return Text.size(); 75} 76 77/// \brief Returns the number of columns required to display the \p Text, 78/// starting from the \p StartColumn on a terminal with the \p TabWidth. The 79/// text is assumed to use the specified \p Encoding. 80inline unsigned columnWidthWithTabs(StringRef Text, unsigned StartColumn, 81 unsigned TabWidth, Encoding Encoding) { 82 unsigned TotalWidth = 0; 83 StringRef Tail = Text; 84 for (;;) { 85 StringRef::size_type TabPos = Tail.find('\t'); 86 if (TabPos == StringRef::npos) 87 return TotalWidth + columnWidth(Tail, Encoding); 88 TotalWidth += columnWidth(Tail.substr(0, TabPos), Encoding); 89 TotalWidth += TabWidth - (TotalWidth + StartColumn) % TabWidth; 90 Tail = Tail.substr(TabPos + 1); 91 } 92} 93 94/// \brief Gets the number of bytes in a sequence representing a single 95/// codepoint and starting with FirstChar in the specified Encoding. 96inline unsigned getCodePointNumBytes(char FirstChar, Encoding Encoding) { 97 switch (Encoding) { 98 case Encoding_UTF8: 99 return getNumBytesForUTF8(FirstChar); 100 default: 101 return 1; 102 } 103} 104 105inline bool isOctDigit(char c) { return '0' <= c && c <= '7'; } 106 107inline bool isHexDigit(char c) { 108 return ('0' <= c && c <= '9') || ('a' <= c && c <= 'f') || 109 ('A' <= c && c <= 'F'); 110} 111 112/// \brief Gets the length of an escape sequence inside a C++ string literal. 113/// Text should span from the beginning of the escape sequence (starting with a 114/// backslash) to the end of the string literal. 115inline unsigned getEscapeSequenceLength(StringRef Text) { 116 assert(Text[0] == '\\'); 117 if (Text.size() < 2) 118 return 1; 119 120 switch (Text[1]) { 121 case 'u': 122 return 6; 123 case 'U': 124 return 10; 125 case 'x': { 126 unsigned I = 2; // Point after '\x'. 127 while (I < Text.size() && isHexDigit(Text[I])) 128 ++I; 129 return I; 130 } 131 default: 132 if (isOctDigit(Text[1])) { 133 unsigned I = 1; 134 while (I < Text.size() && I < 4 && isOctDigit(Text[I])) 135 ++I; 136 return I; 137 } 138 return 2; 139 } 140} 141 142} // namespace encoding 143} // namespace format 144} // namespace clang 145 146#endif // LLVM_CLANG_FORMAT_ENCODING_H 147