rubyx/lib/parslet/atoms/sequence.rb

46 lines
1.0 KiB
Ruby
Raw Normal View History

# A sequence of parslets, matched from left to right. Denoted by '>>'
#
# Example:
#
# str('a') >> str('b') # matches 'a', then 'b'
#
class Parslet::Atoms::Sequence < Parslet::Atoms::Base
attr_reader :parslets
def initialize(*parslets)
super()
@parslets = parslets
@error_msgs = {
:failed => "Failed to match sequence (#{self.inspect})"
}
end
def >>(parslet)
self.class.new(* @parslets+[parslet])
end
def try(source, context, consume_all)
# Presize an array
result = Array.new(parslets.size + 1)
result[0] = :sequence
parslets.each_with_index do |p, idx|
child_consume_all = consume_all && (idx == parslets.size-1)
success, value = p.apply(source, context, child_consume_all)
unless success
return context.err(self, source, @error_msgs[:failed], [value])
end
result[idx+1] = value
end
return succ(result)
end
precedence SEQUENCE
def to_s_inner(prec)
parslets.map { |p| p.to_s(prec) }.join(' ')
end
end