Classify a unicode char into 3 classes or unknown.

Return None if a given string can be used as a (Coq) identifier. Return Some (b,s) otherwise, where s is an explanation and b is severity.

Tells if a valid initial character for an identifier

Tells if a valid non-initial character for an identifier

Tells if a letter

Tells if a character is unclassified

First char of a string, converted to lowercase

• raises Assert_failure

  if the input string is empty.

Split a string supposed to be an ident at the first letter; as an optimization, return None if the first character is a letter

Return true if all UTF-8 characters in the input string are just plain ASCII characters. Returns false otherwise.

ascii_of_ident s maps UTF-8 string to a string composed solely from ASCII characters. The non-ASCII characters are translated to "_UUxxxx_" where xxxx is the Unicode index of the character in hexadecimal (from four to six hex digits). To avoid potential name clashes, any preexisting substring "_UU" is turned into "_UUU".

Validate an UTF-8 string

Return the length of a valid UTF-8 string.

Variant of String.sub for UTF-8 strings.

Return a "%XX"-escaped string if it contains non UTF-8 characters.