Re: [gobo-eiffel-develop] Precondition violated in XPath test

[Eric B. <er...@go...>]

Colin Adams wrote:
> It's up to you.
> 6155 has fewer bugs.

Hmm, this is not making things easy.

Here is what I found:

In XM_XPATH_COMPUTED_EXPRESSION:

~~~~~~~~~~~~~~
	compute_special_properties is
			-- Compute special properties.
		require
			not_yet_computed: not are_special_properties_computed
			all_sub_expressions_computed: sub_expressions_have_special_properties
		do
			initialize_special_properties
		ensure
			computed: are_special_properties_computed and then special_properties 
/= Void
		end

~~~~~~~~~~~~~~

And in XM_XPATH_MAPPED_PATH_EXPRESSION (6155):

~~~~~~~~~~~~~~
	compute_special_properties is
			-- Compute special properties.
		local
			l_expression: XM_XPATH_COMPUTED_EXPRESSION
		do
			Precursor
			initialize_special_properties

			if not are_cardinalities_computed then compute_cardinality end
			if not start.are_special_properties_computed then
				l_expression := start.as_computed_expression
				l_expression.compute_special_properties
			end
			if not step.are_special_properties_computed then
				l_expression := step.as_computed_expression
				l_expression.compute_special_properties
			end

			if start.non_creating and then step.non_creating then
				set_non_creating
			end
		end
~~~~~~~~~~~~~~

So `initialize_special_properties' is called twice (in the Precursor
and on the next line), which explains the precondition violation:
-------------------------------------------------------------------------------
Class / Object      Routine                Nature of exception
   Effect
-------------------------------------------------------------------------------
XM_XPATH_MAPPED_PATH_EXPRESSION
                      initialize_special_properties @5
 
special_properties_not_computed:
<00000000046E47B8>  (From XM_XPATH_STATIC_PROPERTY)
                                             Precondition violated.
    Fail
-------------------------------------------------------------------------------
XM_XPATH_MAPPED_PATH_EXPRESSION
                      compute_special_properties @4
<00000000046E47B8>                         Routine failure.
   Fail
-------------------------------------------------------------------------------
XM_XPATH_MAPPED_PATH_EXPRESSION
                      compute_static_properties @29
<00000000046E47B8>  (From XM_XPATH_COMPUTED_EXPRESSION)
                                             Routine failure.
    Fail
-------------------------------------------------------------------------------
XM_XPATH_MAPPED_PATH_EXPRESSION
                      make @7
<00000000046E47B8>                         Routine failure.
   Fail
-------------------------------------------------------------------------------

Therefore, I suggest removing the call to
`initialize_special_properties' after the call
to Precursor.

-- 
Eric Bezault
mailto:er...@go...
http://www.gobosoft.com