1 //===--- Encoding.h - Format C++ code ---------------------------*- C++ -*-===//
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //===----------------------------------------------------------------------===//
10 /// Contains functions for text encoding manipulation. Supports UTF-8,
11 /// 8-bit encodings and escape sequences in C++ string literals.
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_CLANG_LIB_FORMAT_ENCODING_H
16 #define LLVM_CLANG_LIB_FORMAT_ENCODING_H
18 #include "clang/Basic/LLVM.h"
19 #include "llvm/ADT/StringRef.h"
20 #include "llvm/Support/ConvertUTF.h"
21 #include "llvm/Support/Unicode.h"
29 Encoding_Unknown // We treat all other encodings as 8-bit encodings.
32 /// 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.
34 inline Encoding detectEncoding(StringRef Text) {
35 const llvm::UTF8 *Ptr = reinterpret_cast<const llvm::UTF8 *>(Text.begin());
36 const llvm::UTF8 *BufEnd = reinterpret_cast<const llvm::UTF8 *>(Text.end());
37 if (llvm::isLegalUTF8String(&Ptr, BufEnd))
39 return Encoding_Unknown;
42 /// Returns the number of columns required to display the \p Text on a
43 /// generic Unicode-capable terminal. Text is assumed to use the specified
45 inline unsigned columnWidth(StringRef Text, Encoding Encoding) {
46 if (Encoding == Encoding_UTF8) {
47 int ContentWidth = llvm::sys::unicode::columnWidthUTF8(Text);
48 // FIXME: Figure out the correct way to handle this in the presence of both
49 // printable and unprintable multi-byte UTF-8 characters. Falling back to
50 // returning the number of bytes may cause problems, as columnWidth suddenly
51 // becomes non-additive.
52 if (ContentWidth >= 0)
58 /// Returns the number of columns required to display the \p Text,
59 /// starting from the \p StartColumn on a terminal with the \p TabWidth. The
60 /// text is assumed to use the specified \p Encoding.
61 inline unsigned columnWidthWithTabs(StringRef Text, unsigned StartColumn,
62 unsigned TabWidth, Encoding Encoding) {
63 unsigned TotalWidth = 0;
64 StringRef Tail = Text;
66 StringRef::size_type TabPos = Tail.find('\t');
67 if (TabPos == StringRef::npos)
68 return TotalWidth + columnWidth(Tail, Encoding);
69 TotalWidth += columnWidth(Tail.substr(0, TabPos), Encoding);
70 TotalWidth += TabWidth - (TotalWidth + StartColumn) % TabWidth;
71 Tail = Tail.substr(TabPos + 1);
75 /// Gets the number of bytes in a sequence representing a single
76 /// codepoint and starting with FirstChar in the specified Encoding.
77 inline unsigned getCodePointNumBytes(char FirstChar, Encoding Encoding) {
80 return llvm::getNumBytesForUTF8(FirstChar);
86 inline bool isOctDigit(char c) { return '0' <= c && c <= '7'; }
88 inline bool isHexDigit(char c) {
89 return ('0' <= c && c <= '9') || ('a' <= c && c <= 'f') ||
90 ('A' <= c && c <= 'F');
93 /// Gets the length of an escape sequence inside a C++ string literal.
94 /// Text should span from the beginning of the escape sequence (starting with a
95 /// backslash) to the end of the string literal.
96 inline unsigned getEscapeSequenceLength(StringRef Text) {
97 assert(Text[0] == '\\');
107 unsigned I = 2; // Point after '\x'.
108 while (I < Text.size() && isHexDigit(Text[I]))
113 if (isOctDigit(Text[1])) {
115 while (I < Text.size() && I < 4 && isOctDigit(Text[I]))
119 return 1 + llvm::getNumBytesForUTF8(Text[1]);
123 } // namespace encoding
124 } // namespace format