129 lines
4.1 KiB
C++
129 lines
4.1 KiB
C++
//===--- Encoding.h - Format C++ code ---------------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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///
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/// \file
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/// Contains functions for text encoding manipulation. Supports UTF-8,
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/// 8-bit encodings and escape sequences in C++ string literals.
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///
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CLANG_LIB_FORMAT_ENCODING_H
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#define LLVM_CLANG_LIB_FORMAT_ENCODING_H
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#include "clang/Basic/LLVM.h"
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#include "llvm/ADT/StringRef.h"
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#include "llvm/Support/ConvertUTF.h"
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#include "llvm/Support/Unicode.h"
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namespace clang {
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namespace format {
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namespace encoding {
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enum Encoding {
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Encoding_UTF8,
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Encoding_Unknown // We treat all other encodings as 8-bit encodings.
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};
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/// Detects encoding of the Text. If the Text can be decoded using UTF-8,
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/// it is considered UTF8, otherwise we treat it as some 8-bit encoding.
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inline Encoding detectEncoding(StringRef Text) {
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const llvm::UTF8 *Ptr = reinterpret_cast<const llvm::UTF8 *>(Text.begin());
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const llvm::UTF8 *BufEnd = reinterpret_cast<const llvm::UTF8 *>(Text.end());
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if (llvm::isLegalUTF8String(&Ptr, BufEnd))
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return Encoding_UTF8;
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return Encoding_Unknown;
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}
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/// Returns the number of columns required to display the \p Text on a
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/// generic Unicode-capable terminal. Text is assumed to use the specified
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/// \p Encoding.
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inline unsigned columnWidth(StringRef Text, Encoding Encoding) {
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if (Encoding == Encoding_UTF8) {
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int ContentWidth = llvm::sys::unicode::columnWidthUTF8(Text);
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// FIXME: Figure out the correct way to handle this in the presence of both
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// printable and unprintable multi-byte UTF-8 characters. Falling back to
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// returning the number of bytes may cause problems, as columnWidth suddenly
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// becomes non-additive.
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if (ContentWidth >= 0)
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return ContentWidth;
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}
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return Text.size();
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}
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/// Returns the number of columns required to display the \p Text,
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/// starting from the \p StartColumn on a terminal with the \p TabWidth. The
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/// text is assumed to use the specified \p Encoding.
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inline unsigned columnWidthWithTabs(StringRef Text, unsigned StartColumn,
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unsigned TabWidth, Encoding Encoding) {
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unsigned TotalWidth = 0;
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StringRef Tail = Text;
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for (;;) {
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StringRef::size_type TabPos = Tail.find('\t');
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if (TabPos == StringRef::npos)
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return TotalWidth + columnWidth(Tail, Encoding);
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TotalWidth += columnWidth(Tail.substr(0, TabPos), Encoding);
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if (TabWidth)
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TotalWidth += TabWidth - (TotalWidth + StartColumn) % TabWidth;
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Tail = Tail.substr(TabPos + 1);
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}
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}
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/// Gets the number of bytes in a sequence representing a single
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/// codepoint and starting with FirstChar in the specified Encoding.
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inline unsigned getCodePointNumBytes(char FirstChar, Encoding Encoding) {
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switch (Encoding) {
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case Encoding_UTF8:
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return llvm::getNumBytesForUTF8(FirstChar);
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default:
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return 1;
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}
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}
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inline bool isOctDigit(char c) { return '0' <= c && c <= '7'; }
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inline bool isHexDigit(char c) {
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return ('0' <= c && c <= '9') || ('a' <= c && c <= 'f') ||
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('A' <= c && c <= 'F');
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}
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/// Gets the length of an escape sequence inside a C++ string literal.
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/// Text should span from the beginning of the escape sequence (starting with a
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/// backslash) to the end of the string literal.
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inline unsigned getEscapeSequenceLength(StringRef Text) {
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assert(Text[0] == '\\');
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if (Text.size() < 2)
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return 1;
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switch (Text[1]) {
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case 'u':
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return 6;
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case 'U':
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return 10;
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case 'x': {
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unsigned I = 2; // Point after '\x'.
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while (I < Text.size() && isHexDigit(Text[I]))
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++I;
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return I;
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}
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default:
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if (isOctDigit(Text[1])) {
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unsigned I = 1;
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while (I < Text.size() && I < 4 && isOctDigit(Text[I]))
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++I;
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return I;
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}
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return 1 + llvm::getNumBytesForUTF8(Text[1]);
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}
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}
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} // namespace encoding
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} // namespace format
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} // namespace clang
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#endif
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