1//===- llvm/Support/Unicode.h - Unicode character properties  -*- C++ -*-=====//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file defines functions that allow querying certain properties of Unicode
11// characters.
12//
13//===----------------------------------------------------------------------===//
14
15#ifndef LLVM_SUPPORT_UNICODE_H
16#define LLVM_SUPPORT_UNICODE_H
17
18#include "llvm/ADT/StringRef.h"
19
20namespace llvm {
21namespace sys {
22namespace unicode {
23
24enum ColumnWidthErrors {
25  ErrorInvalidUTF8 = -2,
26  ErrorNonPrintableCharacter = -1
27};
28
29/// Determines if a character is likely to be displayed correctly on the
30/// terminal. Exact implementation would have to depend on the specific
31/// terminal, so we define the semantic that should be suitable for generic case
32/// of a terminal capable to output Unicode characters.
33///
34/// All characters from the Unicode code point range are considered printable
35/// except for:
36///   * C0 and C1 control character ranges;
37///   * default ignorable code points as per 5.21 of
38///     http://www.unicode.org/versions/Unicode6.2.0/UnicodeStandard-6.2.pdf
39///     except for U+00AD SOFT HYPHEN, as it's actually displayed on most
40///     terminals;
41///   * format characters (category = Cf);
42///   * surrogates (category = Cs);
43///   * unassigned characters (category = Cn).
44/// \return true if the character is considered printable.
45bool isPrintable(int UCS);
46
47/// Gets the number of positions the UTF8-encoded \p Text is likely to occupy
48/// when output on a terminal ("character width"). This depends on the
49/// implementation of the terminal, and there's no standard definition of
50/// character width.
51///
52/// The implementation defines it in a way that is expected to be compatible
53/// with a generic Unicode-capable terminal.
54///
55/// \return Character width:
56///   * ErrorNonPrintableCharacter (-1) if \p Text contains non-printable
57///     characters (as identified by isPrintable);
58///   * 0 for each non-spacing and enclosing combining mark;
59///   * 2 for each CJK character excluding halfwidth forms;
60///   * 1 for each of the remaining characters.
61int columnWidthUTF8(StringRef Text);
62
63} // namespace unicode
64} // namespace sys
65} // namespace llvm
66
67#endif
68