Class: OpenWFE::IfExpression

Inherits:
FlowExpression show all
Includes:
ConditionMixin
Defined in:
lib/openwfe/expressions/fe_if.rb

Overview

The ‘if’ expression.

<if>
    <equals field-value="f0" other-value="true" />
    <participant ref="alpha" />
</if>

It accepts an ‘else’ clause :

<if>
    <equals field-value="f0" other-value="true" />
    <participant ref="alpha" />
    <participant ref="bravo" />
</if>

The ‘test’ attribute can be used instead of a condition child :

<if test="${f:f0}">
    <participant ref="alpha" />
</if>

The ‘rtest’ attribute can be used to embed a condition expressed directly in Ruby :

<if rtest="5 * 12 == 61">
    <participant ref="alpha" />
</if>

(Note that ‘rtest’ may only be used if the :ruby_eval_allowed parameter has been set in the engine’s application_context :

engine.application_context[:ruby_eval_allowed] = true

but this is dangerous if the origin of the process defintions to run are not trusted)

Used alone with ‘test’ or ‘rtest’, the ‘if’ expression simply sets the the __result__ field of its workitem to the result of its attribute evaluation :

<if test="5 == 6"/>

will set the __result__ field of the workitem to ‘false’.

Instance Attribute Summary collapse

Attributes inherited from FlowExpression

#apply_time, #attributes, #children, #environment_id, #fei, #parent_id, #raw_representation

Attributes included from Contextual

#application_context

Instance Method Summary collapse

Methods included from ConditionMixin

#determine_condition_attribute, #eval_condition

Methods inherited from FlowExpression

#cancel, #clean_children, #delete_variable, #dup_environment, #fetch_environment, #fetch_text_content, #get_binding, #get_environment, #get_parent, #get_root_environment, #has_attribute, #initialize, is_definition, is_definition?, #lookup_attribute, #lookup_attributes, #lookup_boolean_attribute, #lookup_comma_list_attribute, #lookup_downcase_attribute, #lookup_ref, #lookup_string_attribute, #lookup_sym_attribute, #lookup_value, #lookup_variable, #lookup_vf_attribute, names, #new_environment, new_exp, #owns_its_environment?, #paused?, #remove_child, #set_variable, #store_itself, #synchronize, #to_s, #to_yaml_properties

Methods included from Contextual

#get_work_directory, #init_service, #lookup

Methods included from Logging

#ldebug, #ldebug_callstack, #lerror, #lfatal, #linfo, #llog, #lunknown, #lwarn

Methods included from OwfeServiceLocator

#get_engine, #get_error_journal, #get_expool, #get_expression_map, #get_expression_pool, #get_expression_storage, #get_expression_storages, #get_journal, #get_participant_map, #get_scheduler, #get_wfid_generator

Methods inherited from ObjectWithMeta

#class_def, meta_def, meta_eval, metaclass

Constructor Details

This class inherits a constructor from OpenWFE::FlowExpression

Instance Attribute Details

#condition_replied ⇒ Object

This boolean is set to true when the conditional claused has been evaluated and the ‘if’ is waiting for the consequence’s reply.



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# File 'lib/openwfe/expressions/fe_if.rb', line 107

def condition_replied
  @condition_replied
end

Instance Method Details

#apply(workitem) ⇒ Object 



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# File 'lib/openwfe/expressions/fe_if.rb', line 110

def apply (workitem)

    #workitem.unset_result
        #
        # since OpenWFEru 0.9.16 previous __result__ values
        # are not erased before an 'if'.

    test = eval_condition(:test, workitem, :not)

    if @children.length < 1
        #workitem.set_result test if test
        workitem.set_result((test != nil and test != false))
        reply_to_parent(workitem) 
        return
    end

    @condition_replied = (test != nil)
        #
        # if the "test" attribute is not used, test will be null

    store_itself()

    if test != nil
        apply_consequence(test, workitem, 0)
    else
        get_expression_pool.apply(@children[0], workitem)
    end
end

#reply(workitem) ⇒ Object 



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# File 'lib/openwfe/expressions/fe_if.rb', line 139

def reply (workitem)

    return reply_to_parent(workitem) \
        if @condition_replied

    result = workitem.attributes[FIELD_RESULT]

    @condition_replied = true

    store_itself()

    apply_consequence result, workitem
end

#reply_to_parent(workitem) ⇒ Object

This reply_to_parent takes care of cleaning all the children before replying to the parent expression, this is important because only the ‘then’ or the ‘else’ child got evaluated, the remaining one has to be cleaned out here.



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# File 'lib/openwfe/expressions/fe_if.rb', line 159

def reply_to_parent(workitem)

    clean_children()
    super workitem
end