module Sexpr
  class Sequence
    include Element

    attr_reader :terms

    def initialize(terms)
      @terms = terms
    end

    def match?(sexp)
      return nil unless sexp.is_a?(Array)
      eat = eat(sexp)
      eat && eat.empty?
    end

    def eat(sexp)
      @terms.inject sexp do |rest,rule|
        rest && rule.eat(rest)
      end
    end

    def inspect
      "(seq #{terms.inspect})"
    end

  end # class Sequence
end # module Sexpr