at-most-n ( parser n -- parser' )

Vocabulary

peg.parsers

Inputs

parser	a parser
n	an integer

Outputs

parser'

a parser

Word description

Returns a parser that matches n or fewer repetitions of the input parser.

Examples

USING: peg peg.parsers prettyprint ; "aaaa" "a" token 4 at-most-n parse .
V{ "a" "a" "a" "a" }

USING: peg peg.parsers prettyprint ; "aaaaa" "a" token 4 at-most-n parse .
V{ "a" "a" "a" "a" }

See also

exactly-n, at-least-n, from-m-to-n

Definition

USING: kernel math peg ;

IN: peg.parsers

: at-most-n ( parser n -- parser' )
    [ drop epsilon ]
    [ [ exactly-n ] [ 1 - at-most-n ] 2bi 2choice ] if-zero ;