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 #include "llvm/ADT/SmallString.h"
18 #include <optional>
19 #include <string>
20 
21 namespace llvm {
22 class StringRef;
23 
24 namespace sys {
25 namespace unicode {
26 
27 enum ColumnWidthErrors {
28   ErrorInvalidUTF8 = -2,
29   ErrorNonPrintableCharacter = -1
30 };
31 
32 /// Determines if a character is likely to be displayed correctly on the
33 /// terminal. Exact implementation would have to depend on the specific
34 /// terminal, so we define the semantic that should be suitable for generic case
35 /// of a terminal capable to output Unicode characters.
36 ///
37 /// Printable codepoints are those in the categories L, M, N, P, S and Zs
38 /// \return true if the character is considered printable.
39 bool isPrintable(int UCS);
40 
41 // Formatting codepoints are codepoints in the Cf category.
42 bool isFormatting(int UCS);
43 
44 /// Gets the number of positions the UTF8-encoded \p Text is likely to occupy
45 /// when output on a terminal ("character width"). This depends on the
46 /// implementation of the terminal, and there's no standard definition of
47 /// character width.
48 ///
49 /// The implementation defines it in a way that is expected to be compatible
50 /// with a generic Unicode-capable terminal.
51 ///
52 /// \return Character width:
53 ///   * ErrorNonPrintableCharacter (-1) if \p Text contains non-printable
54 ///     characters (as identified by isPrintable);
55 ///   * 0 for each non-spacing and enclosing combining mark;
56 ///   * 2 for each CJK character excluding halfwidth forms;
57 ///   * 1 for each of the remaining characters.
58 int columnWidthUTF8(StringRef Text);
59 
60 /// Fold input unicode character according the Simple unicode case folding
61 /// rules.
62 int foldCharSimple(int C);
63 
64 /// Maps the name or the alias of a Unicode character to its associated
65 /// codepoints.
66 /// The names and aliases are derived from UnicodeData.txt and NameAliases.txt
67 /// For compatibility with the semantics of named character escape sequences in
68 /// C++, this mapping does an exact match sensitive to casing and spacing.
69 /// \return The codepoint of the corresponding character, if any.
70 std::optional<char32_t> nameToCodepointStrict(StringRef Name);
71 
72 struct LooseMatchingResult {
73   char32_t CodePoint;
74   SmallString<64> Name;
75 };
76 
77 std::optional<LooseMatchingResult> nameToCodepointLooseMatching(StringRef Name);
78 
79 struct MatchForCodepointName {
80   std::string Name;
81   uint32_t Distance = 0;
82   char32_t Value = 0;
83 };
84 
85 SmallVector<MatchForCodepointName>
86 nearestMatchesForCodepointName(StringRef Pattern, std::size_t MaxMatchesCount);
87 
88 } // namespace unicode
89 } // namespace sys
90 } // namespace llvm
91 
92 #endif
93