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require "./parser.cr"
module Parcom
# `Exactly` is a `Parser` that tries to parse with another parser
# a specific number of times. The results of each successful parse
# are returned in an array. If the number of successes is less than
# OR greater than the specified number, the parser fails.
class Exactly(T, V) < Parser(T, Array(V))
@p : Sequence(T, V)
# Accepts the number of parsing attempts, and the parser to use.
# If a negative int is given, it is treated as if it were `0`.
def initialize(i : Int, p : Parser(T, V))
i = i.negative? ? 0 : i
# put `i` copies of `p` into an array
ps = ([p] of Parser(T, V)) * i
@p = Sequence.new(ps)
end
# Tries to parse the given number of times.
def parse(tokens : Tokens(T)) : Result(T, Array(V))
@p.parse(tokens)
rescue ex : ParserFail
raise ParserFail.new("Exactly: #{ex.message}")
end
end
end
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