UniConversion.h

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// Scintilla source code edit control
/** @file UniConversion.h
 ** Functions to handle UTF-8 and UTF-16 strings.
 **/
// Copyright 1998-2001 by Neil Hodgson <neilh@scintilla.org>
// The License.txt file describes the conditions under which this software may be distributed.
 
#ifndef UNICONVERSION_H
#define UNICONVERSION_H
 
namespace Scintilla {
 
constexpr int UTF8MaxBytes = 4;
 
constexpr int unicodeReplacementChar = 0xFFFD;
 
size_t UTF8Length(const wchar_t *uptr, size_t tlen) noexcept;
void UTF8FromUTF16(const wchar_t *uptr, size_t tlen, char *putf, size_t len) noexcept;
void UTF8FromUTF32Character(int uch, char *putf) noexcept;
size_t UTF16Length(const char *s, size_t len) noexcept;
size_t UTF16FromUTF8(const char *s, size_t len, wchar_t *tbuf, size_t tlen);
size_t UTF32Length(const char *s, size_t len) noexcept;
size_t UTF32FromUTF8(const char *s, size_t len, unsigned int *tbuf, size_t tlen);
// WStringFromUTF8 does the right thing when wchar_t is 2 or 4 bytes so
// works on both Windows and Unix.
std::wstring WStringFromUTF8(const char *s, size_t len);
unsigned int UTF16FromUTF32Character(unsigned int val, wchar_t *tbuf) noexcept;
bool UTF8IsValid(const char *s, size_t len) noexcept;
std::string FixInvalidUTF8(const std::string &text);
 
extern const unsigned char UTF8BytesOfLead[256];
 
inline int UnicodeFromUTF8(const unsigned char *us) noexcept {
    switch (UTF8BytesOfLead[us[0]]) {
    case 1:
        return us[0];
    case 2:
        return ((us[0] & 0x1F) << 6) + (us[1] & 0x3F);
    case 3:
        return ((us[0] & 0xF) << 12) + ((us[1] & 0x3F) << 6) + (us[2] & 0x3F);
    default:
        return ((us[0] & 0x7) << 18) + ((us[1] & 0x3F) << 12) + ((us[2] & 0x3F) << 6) + (us[3] & 0x3F);
    }
}
 
inline constexpr bool UTF8IsTrailByte(unsigned char ch) noexcept {
    return (ch >= 0x80) && (ch < 0xc0);
}
 
inline constexpr bool UTF8IsAscii(int ch) noexcept {
    return ch < 0x80;
}
 
enum { UTF8MaskWidth=0x7, UTF8MaskInvalid=0x8 };
int UTF8Classify(const unsigned char *us, size_t len) noexcept;
 
// Similar to UTF8Classify but returns a length of 1 for invalid bytes
// instead of setting the invalid flag
int UTF8DrawBytes(const unsigned char *us, int len) noexcept;
 
// Line separator is U+2028 \xe2\x80\xa8
// Paragraph separator is U+2029 \xe2\x80\xa9
constexpr int UTF8SeparatorLength = 3;
inline bool UTF8IsSeparator(const unsigned char *us) noexcept {
    return (us[0] == 0xe2) && (us[1] == 0x80) && ((us[2] == 0xa8) || (us[2] == 0xa9));
}
 
// NEL is U+0085 \xc2\x85
constexpr int UTF8NELLength = 2;
inline bool UTF8IsNEL(const unsigned char *us) noexcept {
    return (us[0] == 0xc2) && (us[1] == 0x85);
}
 
// Is the sequence of 3 char a UTF-8 line end? Only the last two char are tested for a NEL. 
constexpr bool UTF8IsMultibyteLineEnd(unsigned char ch0, unsigned char ch1, unsigned char ch2) noexcept {
    return
        ((ch0 == 0xe2) && (ch1 == 0x80) && ((ch2 == 0xa8) || (ch2 == 0xa9))) ||
        ((ch1 == 0xc2) && (ch2 == 0x85));
}
 
enum { SURROGATE_LEAD_FIRST = 0xD800 };
enum { SURROGATE_LEAD_LAST = 0xDBFF };
enum { SURROGATE_TRAIL_FIRST = 0xDC00 };
enum { SURROGATE_TRAIL_LAST = 0xDFFF };
enum { SUPPLEMENTAL_PLANE_FIRST = 0x10000 };
 
inline constexpr unsigned int UTF16CharLength(wchar_t uch) noexcept {
    return ((uch >= SURROGATE_LEAD_FIRST) && (uch <= SURROGATE_LEAD_LAST)) ? 2 : 1;
}
 
inline constexpr unsigned int UTF16LengthFromUTF8ByteCount(unsigned int byteCount) noexcept {
    return (byteCount < 4) ? 1 : 2;
}
 
}
 
#endif