Module Char.Ascii

ASCII character set support.

These functions give meaning to the integers [0x00;0x7F] of the ASCII character set.

Since the UTF-8 encoding of Unicode has the same encoding and character semantics (U+0000 to U+001F) for these bytes, the functions can be safely used on elements of UTF-8 encoded string and bytes values. However the functions only deal with ASCII related matters. For example the notion of Unicode whitespace is much larger than the ASCII whitespace determined by Char.Ascii.is_white.

Characters

let min: char;

min is '\x00'.

let max: char;

max is '\x7F'.

Predicates

let is_valid: char => bool;

is_valid c is true if and only if c is an ASCII character, that is a byte in the range [min;max].

let is_upper: char => bool;

is_upper c is true if and only if c is an ASCII uppercase letter 'A' to 'Z', that is a byte in the range [0x41;0x5A].

let is_lower: char => bool;

is_lower c is true if and only if c is an ASCII lowercase letter 'a' to 'z', that is a byte in the range [0x61;0x7A].

let is_letter: char => bool;

is_letter c is is_lower c || is_upper c.

let is_alphanum: char => bool;

is_alphanum c is is_letter c || is_digit c.

let is_white: char => bool;

is_white c is true if and only if c is an ASCII white space character, that is one of tab '\t' (0x09), newline '\n' (0x0A), vertical tab (0x0B), form feed (0x0C), carriage return '\r' (0x0D) or space ' ' (0x20),

let is_blank: char => bool;

is_blank c is true if and only if c is an ASCII blank character, that is either space ' ' (0x20) or tab '\t' (0x09).

let is_graphic: char => bool;

is_graphic c is true if and only if c is an ASCII graphic character, that is a byte in the range [0x21;0x7E].

let is_print: char => bool;

is_print c is is_graphic c || c = ' '.

let is_control: char => bool;

is_control c is true if and only if c is an ASCII control character, that is a byte in the range [0x00;0x1F] or 0x7F.

Decimal digits

let is_digit: char => bool;

is_digit c is true if and only if c is an ASCII decimal digit '0' to '9', that is a byte in the range [0x30;0x39].

let digit_to_int: char => int;

digit_to_int c is the numerical value of a digit that satisfies is_digit. Raises Invalid_argument if is_digit c is false.

let digit_of_int: int => char;

digit_of_int n is an ASCII decimal digit for the decimal value abs (n mod 10).

Hexadecimal digits

let is_hex_digit: char => bool;

is_hex_digit c is true if and only if c is an ASCII hexadecimal digit '0' to '9', 'a' to 'f' or 'A' to 'F', that is a byte in one of the ranges [0x30;0x39], [0x41;0x46], [0x61;0x66].

let hex_digit_to_int: char => int;

hex_digit_to_int c is the numerical value of a digit that satisfies is_hex_digit. Raises Invalid_argument if is_hex_digit c is false.

let lower_hex_digit_of_int: int => char;

lower_hex_digit_of_int n is a lowercase ASCII hexadecimal digit for the hexadecimal value abs (n mod 16).

let upper_hex_digit_of_int: int => char;

upper_hex_digit_of_int n is an uppercase ASCII hexadecimal digit for the hexadecimal value abs (n mod 16).

Casing transforms

let uppercase: char => char;

uppercase c is c with ASCII characters 'a' to 'z' respectively mapped to uppercase characters 'A' to 'Z'. Other characters are left untouched.

let lowercase: char => char;

lowercase c is c with ASCII characters 'A' to 'Z' respectively mapped to lowercase characters 'a' to 'z'. Other characters are left untouched.