Return the number of string taken by a the first byte (as character) of a UTF-8 character.

utf8_index_of_char str n returns the position in byte of the nth character. n is 0-based.

• raises Not_found

  if there is no nth character.

utf8_char_of_index str n returns the utf8 character position corresponding to the given byte index n.

utf8_string_length str returns the number of utf8 characters in str.

utf8_substr str pos l returns the substring of str from utf8 position pos to pos+l-1.

utf8_is_prefix s1 s2 returns whether s2 is prefix of s1.

utf8_is_suffix s1 s2 returns whether s2 is suffix of s1.

utf8_substr_pos s1 s2 returns Some n if s2 is found at position n in s1, starting to search from the beginning of s1. Else return None.

utf8_contains s1 s2 returns whether s1 contains s2.

utf8_strbefore s1 s2 returns the substring before s2 in s1. See details.

utf8_strafter s1 s2 returns the substring after s2 in s1. See details.

utf8_char_of_code n return the UTF8 character from a given codepoint.

utf8_get_bol str returns the list of pairs (line number, char position) giving the position of beginning of each line in the given string.

utf8_count_nl str returns the number of newline \n characters found in the given UTF-8 string.

utf8_escape str \-escapes the following characters : \n, \r, \b, \t, \f, \(quotes), \' and \\ but does not escape \u nor \U.

utf8_unescape str unescapes the following escaped characters: \n, \r, \b, \t, \f, \quotes, \' and \\, and also \u... and \U... sequences.

utf8_unescape_to_percent str unescapes the following escaped characters: \n, \r, \b, \t, \f, \quotes, \' and \\, and also \u... and \U... sequences to percent-encoded characters, to be parsable by an IRI parser.

utf8_lowercase s returns a new string, with some characters mapped to corresponding lowercase characters.

utf8_uppercase s returns a new string, with some characters mapped to corresponding uppercase characters.

utf8_backslash_quotes s returns a new string like s with a backslash before each double quotes.