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require "./parser.cr"
require "./map.cr"
require "./exactly.cr"
require "./at_most.cr"
module Parcom
# `Between` is a `Parser` that tries to parse with another parser a number
# of times within a specified range. The results of each successful parse
# are returned in an array. If the number of successful parses is out of
# the lower bound of the range, the parser fails. If the number of successful
# parses reaches thhe upper bound of the range, the parsing stops, even if it
# is possible to keep parsing.
class Between(T, V) < Parser(T, Array(V))
@p : Map(T, {Array(V), Array(V)}, Array(V))
# Accepts the lower and upper bounds for the number of parsing attempts,
# as well as the parser to use. This method works the same way whether or
# not the larger value is passed first or second. If a negative int value
# is given for either parameter, it is treated as `0`.
# TODO: Overload to allow for Range objects.
def initialize(i : Int, j : Int, p : Parser(T, V))
lower = i < j ? i : j
upper = (i - j).abs
@p = (Exactly.new(lower, p) + AtMost.new(upper, p)).map do |tup|
tup[0] + tup[1]
end
end
# Tries to parse a numebr of times within the given range.
def parse(tokens : Tokens(T)) : Result(T, Array(V))
@p.parse(tokens)
rescue ex : ParserFail
raise ParserFail.new("Between: #{ex.message}")
end
end
end
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