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require "./parser.cr"
module Parcom
# `Sequence` is a `Parser` that combines multiple parsers and
# tries to parse all of them in succession. If all of the parsers
# succeed, the values parsed are returned in an array, in the order
# they were parsed in. If any of the parsers fail,
# the `Sequence` also fails.
class Sequence(T, V) < Parser(T, Array(V))
# Accepts the parsers to use.
def initialize(@ps : Iterable(Parser(T, V)))
end
# Tries each parser in order, and returns their results.
# Fail if any of the wrapped parsers fail.
# TODO: this can probably be optimised more for Arrays
# TODO: might be better to use #zip
def parse(tokens : Tokens(T)) : Result(T, Array(V))
parsed = [] of V
@ps.each do |p|
r = p.parse(tokens)
parsed << r.value
tokens = r.tokens
end
Result.new(tokens, parsed)
rescue ex : ParserFail
raise ParserFail.new("Sequence: #{ex.message}")
end
end
end
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