#
#--
# Copyright (c) 2006-2008, John Mettraux, OpenWFE.org
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
# . Redistributions of source code must retain the above copyright notice, this
#   list of conditions and the following disclaimer.
#
# . Redistributions in binary form must reproduce the above copyright notice,
#   this list of conditions and the following disclaimer in the documentation
#   and/or other materials provided with the distribution.
#
# . Neither the name of the "OpenWFE" nor the names of its contributors may be
#   used to endorse or promote products derived from this software without
#   specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
#++
#

#
# "made in Japan"
#
# John Mettraux at openwfe.org
#

require 'openwfe/expressions/flowexpression'


module OpenWFE

    #
    # This expression sequentially executes each of its children expression.
    # For a more sophisticated version of it, see the 'cursor' expression
    # (fe_cursor.rb).
    #
    #     <sequence>
    #         <participant ref="alice" />
    #         <participant ref="service_b" />
    #     </sequence>
    #
    # In a Ruby process definition, it looks like :
    #
    #     sequence do
    #         participant "alice"
    #         participant "service_b"
    #     end
    #
    class SequenceExpression < FlowExpression

        names :sequence


        def apply (workitem)

            reply workitem
        end

        def reply (workitem)

            cfei = next_child workitem.fei

            return reply_to_parent(workitem) \
                unless cfei

            #ldebug do
            #    "reply() self : \n#{self.to_s}\n" +
            #    "reply() next is #{@current_child_id} : #{cfei.to_debug_s}"
            #end

            get_expression_pool.apply cfei, workitem
        end

        protected

            #
            # Returns the flowExpressionId of the next child to apply, or
            # nil if the sequence is over.
            #
            def next_child (current_fei)

                next_id = if (current_fei == self.fei)
                    0
                else
                    @children.index(current_fei) + 1
                end

                loop do

                    break if next_id >= @children.length

                    child = @children[next_id]

                    return child if child.is_a?(FlowExpressionId)

                    next_id += 1
                end

                nil
            end
    end

end