1 files changed, 128 insertions, 0 deletions
diff --git a/clang/lib/Format/Encoding.h b/clang/lib/Format/Encoding.h
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+++ b/clang/lib/Format/Encoding.h
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+//===--- Encoding.h - Format C++ code ---------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// Contains functions for text encoding manipulation. Supports UTF-8,
+/// 8-bit encodings and escape sequences in C++ string literals.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_LIB_FORMAT_ENCODING_H
+#define LLVM_CLANG_LIB_FORMAT_ENCODING_H
+
+#include "clang/Basic/LLVM.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Support/ConvertUTF.h"
+#include "llvm/Support/Unicode.h"
+
+namespace clang {
+namespace format {
+namespace encoding {
+
+enum Encoding {
+  Encoding_UTF8,
+  Encoding_Unknown // We treat all other encodings as 8-bit encodings.
+};
+
+/// Detects encoding of the Text. If the Text can be decoded using UTF-8,
+/// it is considered UTF8, otherwise we treat it as some 8-bit encoding.
+inline Encoding detectEncoding(StringRef Text) {
+  const llvm::UTF8 *Ptr = reinterpret_cast<const llvm::UTF8 *>(Text.begin());
+  const llvm::UTF8 *BufEnd = reinterpret_cast<const llvm::UTF8 *>(Text.end());
+  if (llvm::isLegalUTF8String(&Ptr, BufEnd))
+    return Encoding_UTF8;
+  return Encoding_Unknown;
+}
+
+/// Returns the number of columns required to display the \p Text on a
+/// generic Unicode-capable terminal. Text is assumed to use the specified
+/// \p Encoding.
+inline unsigned columnWidth(StringRef Text, Encoding Encoding) {
+  if (Encoding == Encoding_UTF8) {
+    int ContentWidth = llvm::sys::unicode::columnWidthUTF8(Text);
+    // FIXME: Figure out the correct way to handle this in the presence of both
+    // printable and unprintable multi-byte UTF-8 characters. Falling back to
+    // returning the number of bytes may cause problems, as columnWidth suddenly
+    // becomes non-additive.
+    if (ContentWidth >= 0)
+      return ContentWidth;
+  }
+  return Text.size();
+}
+
+/// Returns the number of columns required to display the \p Text,
+/// starting from the \p StartColumn on a terminal with the \p TabWidth. The
+/// text is assumed to use the specified \p Encoding.
+inline unsigned columnWidthWithTabs(StringRef Text, unsigned StartColumn,
+                                    unsigned TabWidth, Encoding Encoding) {
+  unsigned TotalWidth = 0;
+  StringRef Tail = Text;
+  for (;;) {
+    StringRef::size_type TabPos = Tail.find('\t');
+    if (TabPos == StringRef::npos)
+      return TotalWidth + columnWidth(Tail, Encoding);
+    TotalWidth += columnWidth(Tail.substr(0, TabPos), Encoding);
+    if (TabWidth)
+      TotalWidth += TabWidth - (TotalWidth + StartColumn) % TabWidth;
+    Tail = Tail.substr(TabPos + 1);
+  }
+}
+
+/// Gets the number of bytes in a sequence representing a single
+/// codepoint and starting with FirstChar in the specified Encoding.
+inline unsigned getCodePointNumBytes(char FirstChar, Encoding Encoding) {
+  switch (Encoding) {
+  case Encoding_UTF8:
+    return llvm::getNumBytesForUTF8(FirstChar);
+  default:
+    return 1;
+  }
+}
+
+inline bool isOctDigit(char c) { return '0' <= c && c <= '7'; }
+
+inline bool isHexDigit(char c) {
+  return ('0' <= c && c <= '9') || ('a' <= c && c <= 'f') ||
+         ('A' <= c && c <= 'F');
+}
+
+/// Gets the length of an escape sequence inside a C++ string literal.
+/// Text should span from the beginning of the escape sequence (starting with a
+/// backslash) to the end of the string literal.
+inline unsigned getEscapeSequenceLength(StringRef Text) {
+  assert(Text[0] == '\\');
+  if (Text.size() < 2)
+    return 1;
+
+  switch (Text[1]) {
+  case 'u':
+    return 6;
+  case 'U':
+    return 10;
+  case 'x': {
+    unsigned I = 2; // Point after '\x'.
+    while (I < Text.size() && isHexDigit(Text[I]))
+      ++I;
+    return I;
+  }
+  default:
+    if (isOctDigit(Text[1])) {
+      unsigned I = 1;
+      while (I < Text.size() && I < 4 && isOctDigit(Text[I]))
+        ++I;
+      return I;
+    }
+    return 1 + llvm::getNumBytesForUTF8(Text[1]);
+  }
+}
+
+} // namespace encoding
+} // namespace format
+} // namespace clang
+
+#endif