#pragma once /* is c the start of a utf8 sequence? */#define isutf(c) (((c)&0xC0) != 0x80) /* next character without NUL character terminator */Rune u8_nextmemchar(const char *s, usize *i) sl_nonnull(1, 2); /* returns length of next utf-8 sequence */usize u8_seqlen(const char *s) sl_purefn sl_nonnull(1); /* length of a utf-8 string in runes */usize u8_runelen(const char *s, usize m, bool *err) sl_purefn sl_nonnull(1); char read_escape_control_char(char c) sl_constfn; /* given a wide character, convert it to an ASCII escape sequence stored in   buf, where buf is "sz" bytes. returns the number of characters output.   sz must be at least 3. */int u8_escape_rune(char *buf, usize sz, Rune ch) sl_nonnull(1); /* convert UTF-8 "src" to escape sequences.    sz is buf size in bytes. must be at least 12.    if escape_quotes is nonzero, quote characters will be escaped.    if ascii is nonzero, the output is 7-bit ASCII, no UTF-8 survives.    starts at src[*pi], updates *pi to point to the first unprocessed   byte of the input.    end is one more than the last allowable value of *pi.    returns number of bytes placed in buf, including a NUL terminator.*/usize u8_escape(char *buf, usize sz, const char *src, usize *pi, usize end,                 bool escape_quotes, bool ascii) sl_nonnull(1, 3, 4); /* utility predicates used by the above */bool octal_digit(char c) sl_constfn;bool hex_digit(char c) sl_constfn; /* same as the above, but searches a buffer of a given size instead of   a NUL-terminated string. */u8int *u8_memchr(u8int *s, Rune ch, usize sz, usize *charn) sl_nonnull(1, 4); /* number of columns occupied by a string */ssize u8_strwidth(const char *s, usize n, bool *err) sl_purefn sl_nonnull(1); /* determine whether a sequence of bytes is valid UTF-8. length is in bytes */bool u8_isvalid(const char *str, int length) sl_purefn sl_nonnull(1); /* reverse a UTF-8 string. len is length in bytes. dest and src must both   be allocated to at least len+1 bytes. returns 1 for error, 0 otherwise */void u8_reverse(char *dest, char *src, usize len) sl_nonnull(1, 2);