include/llvm/Support/Unicode.h

   1 //===- llvm/Support/Unicode.h - Unicode character properties  -*- C++ -*-=====//
   2 //
   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
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file defines functions that allow querying certain properties of Unicode
  10 // characters.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #ifndef LLVM_SUPPORT_UNICODE_H
  15 #define LLVM_SUPPORT_UNICODE_H
  16
  17 namespace llvm {
  18 class StringRef;
  19
  20 namespace sys {
  21 namespace unicode {
  22
  23 enum ColumnWidthErrors {
  24   ErrorInvalidUTF8 = -2,
  25   ErrorNonPrintableCharacter = -1
  26 };
  27
  28 /// Determines if a character is likely to be displayed correctly on the
  29 /// terminal. Exact implementation would have to depend on the specific
  30 /// terminal, so we define the semantic that should be suitable for generic case
  31 /// of a terminal capable to output Unicode characters.
  32 ///
  33 /// All characters from the Unicode code point range are considered printable
  34 /// except for:
  35 ///   * C0 and C1 control character ranges;
  36 ///   * default ignorable code points as per 5.21 of
  37 ///     http://www.unicode.org/versions/Unicode6.2.0/UnicodeStandard-6.2.pdf
  38 ///     except for U+00AD SOFT HYPHEN, as it's actually displayed on most
  39 ///     terminals;
  40 ///   * format characters (category = Cf);
  41 ///   * surrogates (category = Cs);
  42 ///   * unassigned characters (category = Cn).
  43 /// \return true if the character is considered printable.
  44 bool isPrintable(int UCS);
  45
  46 /// Gets the number of positions the UTF8-encoded \p Text is likely to occupy
  47 /// when output on a terminal ("character width"). This depends on the
  48 /// implementation of the terminal, and there's no standard definition of
  49 /// character width.
  50 ///
  51 /// The implementation defines it in a way that is expected to be compatible
  52 /// with a generic Unicode-capable terminal.
  53 ///
  54 /// \return Character width:
  55 ///   * ErrorNonPrintableCharacter (-1) if \p Text contains non-printable
  56 ///     characters (as identified by isPrintable);
  57 ///   * 0 for each non-spacing and enclosing combining mark;
  58 ///   * 2 for each CJK character excluding halfwidth forms;
  59 ///   * 1 for each of the remaining characters.
  60 int columnWidthUTF8(StringRef Text);
  61
  62 /// Fold input unicode character according the Simple unicode case folding
  63 /// rules.
  64 int foldCharSimple(int C);
  65
  66 } // namespace unicode
  67 } // namespace sys
  68 } // namespace llvm
  69
  70 #endif