Unicode.h

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//===- llvm/Support/Unicode.h - Unicode character properties  -*- C++ -*-=====//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines functions that allow querying certain properties of Unicode
// characters.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_SUPPORT_UNICODE_H
#define LLVM_SUPPORT_UNICODE_H

#include "llvm/ADT/StringRef.h"

namespace llvm {
namespace sys {
namespace unicode {

enum ColumnWidthErrors {
  ErrorInvalidUTF8 = -2,
  ErrorNonPrintableCharacter = -1
};

/// Determines if a character is likely to be displayed correctly on the
/// terminal. Exact implementation would have to depend on the specific
/// terminal, so we define the semantic that should be suitable for generic case
/// of a terminal capable to output Unicode characters.
///
/// All characters from the Unicode code point range are considered printable
/// except for:
///   * C0 and C1 control character ranges;
///   * default ignorable code points as per 5.21 of
///     http://www.unicode.org/versions/Unicode6.2.0/UnicodeStandard-6.2.pdf
///     except for U+00AD SOFT HYPHEN, as it's actually displayed on most
///     terminals;
///   * format characters (category = Cf);
///   * surrogates (category = Cs);
///   * unassigned characters (category = Cn).
/// \return true if the character is considered printable.
bool isPrintable(int UCS);

/// Gets the number of positions the UTF8-encoded \p Text is likely to occupy
/// when output on a terminal ("character width"). This depends on the
/// implementation of the terminal, and there's no standard definition of
/// character width.
///
/// The implementation defines it in a way that is expected to be compatible
/// with a generic Unicode-capable terminal.
///
/// \return Character width:
///   * ErrorNonPrintableCharacter (-1) if \p Text contains non-printable
///     characters (as identified by isPrintable);
///   * 0 for each non-spacing and enclosing combining mark;
///   * 2 for each CJK character excluding halfwidth forms;
///   * 1 for each of the remaining characters.
int columnWidthUTF8(StringRef Text);

} // namespace unicode
} // namespace sys
} // namespace llvm

#endif