Tokens for the language ICPL

Reserved Words

program
identifier
begin
end
integer
if
then
elseif
else
loop
when
exit
get
put
putln
not
and note: not a token
or note: not a token
mod note: not a token

Operators (according to precidence level, highest first)

exp_op ^
mult_op * | /
add_op + | -
rel_op = | < | > | <= | >= | #
bool_op and | or

Symbol tokens

; , := ( )

Constants

let char-d be the set of all ASCII characters except a double quote.
let char-s be the set of all ASCII characters except a single quote.
let digit be the set of digits from 0 to 9.

str_const = ' char-s* ' | " char-d* " note: a string constant may not extend beyond a line. Thus if a string constant that is started and not terminated prior to the end of a line is considered to be in error.
int_const = digit digit* note: while a digit may be of any length, if it causes an overflow it will be considered to be in error. An int_const will be terminated with an operator, a symbol or a space. It may not be terminated with a letter.

Identifiers

let letter be the 52 letters of the alphabet (upper or lower case letters will be considered distinct)
let digit be the 10 digits

identifier = letter (letter | digit)* note: an identifier can have any length. However, only the first 63 are to be significant. An identifier will be terminated with an operator, a symbol or a space.

Comments and Spaces

Blank characters, tab characters, and end of line characters will all be considered to be spaces. Two or more consecutive spaces are to be considered as a single space. Spaces are not tokens, but may separate tokens. No token may contain an embedded space, thus a space will terminate any token.

A comment may take on either of the following forms:

line comment: '--' will start a line comment. The end of the line will terminate the comment.
block comment: '{' will start a block comment. '}' or the end of the file will end a block comment. Block comments may extend over any number of lines. Block comments may not be nested.

A comment, either line or block, will be treated as a single space.