range-pattern ( pattern -- parser )

Vocabulary

peg.parsers

Inputs

pattern

a string

Outputs

parser

a parser

Word description

Returns a parser that matches a single character based on the set of characters in the pattern string. Any single character in the pattern matches that character. If the pattern begins with a ^ then the set is negated (the element matches any character not in the set). Any pair of characters separated with a dash (-) represents the range of characters from the first to the second, inclusive.

Examples

USING: peg peg.parsers prettyprint strings ; "a" "_a-zA-Z" range-pattern parse 1string .
"a"

USING: peg peg.parsers prettyprint ; "0" "^0-9" range-pattern parse => exception

Definition

USING: kernel peg sequences splitting ;

IN: peg.parsers

: range-pattern ( pattern -- parser )
    "^" ?head [
        (range-pattern) dup length 1 =
        [ first [ = ] curry ] [ [ member? ] curry ] if
    ] [ [ [ not ] compose ] when satisfy ] bi* ;