Visitor - Revision history

Hzwakenberg: Object Menter URL no longer exits, adapted text accordingly

2021-12-25T11:48:15Z

Object Menter URL no longer exits, adapted text accordingly

← Older revision		Revision as of 13:48, 25 December 2021
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	This is how [[eiffeldoc]], for example, was built without the need to touch the system kernel.		This is how [[eiffeldoc]], for example, was built without the need to touch the system kernel.

−	The origin of visitors is a ''[[Glossary#DesignPattern\|design pattern]]'', in fact the ~~[http://www.objectmentor.com/resources/articles/acv.pdf~~ ~~acyclic visitor]~~ developed by Robert C. Martin.	+	The origin of visitors is a ''[[Glossary#DesignPattern\|design pattern]]'', in fact the Acyclic Visitor developed by Robert C. Martin.

	Liberty Eiffel adopted and adapted this design pattern. All the framework classes are in the <tt>SmartEiffel/tools/visitor</tt> directory.		Liberty Eiffel adopted and adapted this design pattern. All the framework classes are in the <tt>SmartEiffel/tools/visitor</tt> directory.

Hzwakenberg: Spelling & style corrections

2021-12-25T11:44:47Z

Spelling & style corrections

← Older revision		Revision as of 13:44, 25 December 2021
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	[[Category: Design Pattern]]		[[Category: Design Pattern]]
−	Liberty Eiffel ~~vistors~~ are a mechanism that let you reuse the Liberty Eiffel kernel in order to build new applications.	+	Liberty Eiffel visitors are a mechanism that let you reuse the Liberty Eiffel kernel in order to build new applications.

	This is how [[eiffeldoc]], for example, was built without the need to touch the system kernel.		This is how [[eiffeldoc]], for example, was built without the need to touch the system kernel.
Line 6:		Line 6:
	The origin of visitors is a ''[[Glossary#DesignPattern\|design pattern]]'', in fact the [http://www.objectmentor.com/resources/articles/acv.pdf acyclic visitor] developed by Robert C. Martin.		The origin of visitors is a ''[[Glossary#DesignPattern\|design pattern]]'', in fact the [http://www.objectmentor.com/resources/articles/acv.pdf acyclic visitor] developed by Robert C. Martin.

−	~~This~~ ~~design pattern has been~~ adopted and adapted by ~~Liberty~~ ~~Eiffel~~. All the framework classes are in the <tt>SmartEiffel/tools/visitor</tt> directory.	+	Liberty Eiffel adopted and adapted this design pattern. All the framework classes are in the <tt>SmartEiffel/tools/visitor</tt> directory.

	== Framework ==		== Framework ==
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	[[tool_class:IN_OUT_VISITOR\|<tt>IN_OUT_VISITOR</tt>]] is a class that lets you do a complete search of a class's syntactic tree, depth-first.		[[tool_class:IN_OUT_VISITOR\|<tt>IN_OUT_VISITOR</tt>]] is a class that lets you do a complete search of a class's syntactic tree, depth-first.

−	~~Each~~ ~~node~~ is ~~visited~~ by ~~the following algorithm~~ (the NODE class is imaginary):	+	The following algorithm visits each node (the NODE class is imaginary):
	feature {NODE}		feature {NODE}
	visit_node (a_node: NODE) is		visit_node (a_node: NODE) is

Dkearns: s/LibertyEiffel/Liberty Eiffel/

2016-06-14T17:15:40Z

s/LibertyEiffel/Liberty Eiffel/

← Older revision		Revision as of 19:15, 14 June 2016
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	[[Category: Design Pattern]]		[[Category: Design Pattern]]
−	~~LibertyEiffel~~ vistors are a mechanism that let you reuse the ~~LibertyEiffel~~ kernel in order to build new applications.	+	Liberty Eiffel vistors are a mechanism that let you reuse the Liberty Eiffel kernel in order to build new applications.

	This is how [[eiffeldoc]], for example, was built without the need to touch the system kernel.		This is how [[eiffeldoc]], for example, was built without the need to touch the system kernel.
Line 6:		Line 6:
	The origin of visitors is a ''[[Glossary#DesignPattern\|design pattern]]'', in fact the [http://www.objectmentor.com/resources/articles/acv.pdf acyclic visitor] developed by Robert C. Martin.		The origin of visitors is a ''[[Glossary#DesignPattern\|design pattern]]'', in fact the [http://www.objectmentor.com/resources/articles/acv.pdf acyclic visitor] developed by Robert C. Martin.

−	This design pattern has been adopted and adapted by ~~LibertyEiffel~~. All the framework classes are in the <tt>SmartEiffel/tools/visitor</tt> directory.	+	This design pattern has been adopted and adapted by Liberty Eiffel. All the framework classes are in the <tt>SmartEiffel/tools/visitor</tt> directory.

	== Framework ==		== Framework ==

Hzwakenberg at 17:18, 14 September 2014

2014-09-14T17:18:12Z

← Older revision		Revision as of 19:18, 14 September 2014
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	LibertyEiffel vistors are a mechanism that let you reuse the LibertyEiffel kernel in order to build new applications.		LibertyEiffel vistors are a mechanism that let you reuse the LibertyEiffel kernel in order to build new applications.

−	This is how [[eiffeldoc]], for example, was built without ~~touching~~ the system kernel.	+	This is how [[eiffeldoc]], for example, was built without the need to touch the system kernel.

	The origin of visitors is a ''[[Glossary#DesignPattern\|design pattern]]'', in fact the [http://www.objectmentor.com/resources/articles/acv.pdf acyclic visitor] developed by Robert C. Martin.		The origin of visitors is a ''[[Glossary#DesignPattern\|design pattern]]'', in fact the [http://www.objectmentor.com/resources/articles/acv.pdf acyclic visitor] developed by Robert C. Martin.

Hzwakenberg: English grammar

2014-09-14T17:17:42Z

English grammar

← Older revision		Revision as of 19:17, 14 September 2014
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	LibertyEiffel vistors are a mechanism that let you reuse the LibertyEiffel kernel in order to build new applications.		LibertyEiffel vistors are a mechanism that let you reuse the LibertyEiffel kernel in order to build new applications.

−	This is how [[eiffeldoc]], for example, ~~can have been~~ built without touching the system kernel.	+	This is how [[eiffeldoc]], for example, was built without touching the system kernel.

	The origin of visitors is a ''[[Glossary#DesignPattern\|design pattern]]'', in fact the [http://www.objectmentor.com/resources/articles/acv.pdf acyclic visitor] developed by Robert C. Martin.		The origin of visitors is a ''[[Glossary#DesignPattern\|design pattern]]'', in fact the [http://www.objectmentor.com/resources/articles/acv.pdf acyclic visitor] developed by Robert C. Martin.

Hzwakenberg at 20:52, 7 September 2014

2014-09-07T20:52:25Z

← Older revision		Revision as of 22:52, 7 September 2014
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		+	[[Category: Design Pattern]]
	LibertyEiffel vistors are a mechanism that let you reuse the LibertyEiffel kernel in order to build new applications.		LibertyEiffel vistors are a mechanism that let you reuse the LibertyEiffel kernel in order to build new applications.

Hzwakenberg at 17:31, 5 September 2014

2014-09-05T17:31:12Z

← Older revision		Revision as of 19:31, 5 September 2014
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−	[[Category:Smarteiffel]]
	LibertyEiffel vistors are a mechanism that let you reuse the LibertyEiffel kernel in order to build new applications.		LibertyEiffel vistors are a mechanism that let you reuse the LibertyEiffel kernel in order to build new applications.

Hzwakenberg at 17:30, 5 September 2014

2014-09-05T17:30:14Z

← Older revision		Revision as of 19:30, 5 September 2014
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	[[Category:Smarteiffel]]		[[Category:Smarteiffel]]
−	~~SmartEiffel~~ vistors are a mechanism that let you reuse the ~~SmartEiffel~~ kernel in order to build new ~~applicationss~~.	+	LibertyEiffel vistors are a mechanism that let you reuse the LibertyEiffel kernel in order to build new applications.

	This is how [[eiffeldoc]], for example, can have been built without touching the system kernel.		This is how [[eiffeldoc]], for example, can have been built without touching the system kernel.
Line 6:		Line 6:
	The origin of visitors is a ''[[Glossary#DesignPattern\|design pattern]]'', in fact the [http://www.objectmentor.com/resources/articles/acv.pdf acyclic visitor] developed by Robert C. Martin.		The origin of visitors is a ''[[Glossary#DesignPattern\|design pattern]]'', in fact the [http://www.objectmentor.com/resources/articles/acv.pdf acyclic visitor] developed by Robert C. Martin.

−	This design pattern has been adopted and adapted by ~~SmartEiffel~~. All the framework classes are in the <tt>SmartEiffel/tools/visitor</tt> directory.	+	This design pattern has been adopted and adapted by LibertyEiffel. All the framework classes are in the <tt>SmartEiffel/tools/visitor</tt> directory.

	== Framework ==		== Framework ==

Ramack at 21:12, 4 March 2013

2013-03-04T21:12:38Z

← Older revision		Revision as of 23:12, 4 March 2013
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−	[[Category:~~Book~~]]	+	[[Category:Smarteiffel]]
−
	SmartEiffel vistors are a mechanism that let you reuse the SmartEiffel kernel in order to build new applicationss.		SmartEiffel vistors are a mechanism that let you reuse the SmartEiffel kernel in order to build new applicationss.

Ramack: 11 revisions: initial import from SamrtEiffel Wiki - The Grand SmartEiffel Book

2013-03-03T21:50:50Z

11 revisions: initial import from SamrtEiffel Wiki - The Grand SmartEiffel Book

New page

[[Category:Book]]

SmartEiffel vistors are a mechanism that let you reuse the SmartEiffel kernel in order to build new applicationss.

This is how [[eiffeldoc]], for example, can have been built without touching the system kernel.

The origin of visitors is a ''[[Glossary#DesignPattern|design pattern]]'', in fact the [http://www.objectmentor.com/resources/articles/acv.pdf acyclic visitor] developed by Robert C. Martin.

This design pattern has been adopted and adapted by SmartEiffel. All the framework classes are in the <tt>SmartEiffel/tools/visitor</tt> directory.

== Framework ==

Every visitable class inherits from [[library_class:VISITABLE|<tt>VISITABLE</tt>]]. With it are associated:
* a class derived from [[library_class:VISITOR|<tt>VISITOR</tt>]],
* a [[Glossary#Feature|feature]] <tt>accept</tt> which has for its parameter an object of that class.

== Visitable classes ==

The visitable classes are all the classes of the syntactic and semantic tree. There we find in particular
* [[tool_class:EXPRESSION|<tt>EXPRESSION</tt>]], [[tool_class:INSTRUCTION|<tt>INSTRUCTION</tt>]] (syntactic classes)
* [[tool_class:TYPE|<tt>TYPE</tt>]], [[tool_class:FEATURE_STAMP|<tt>FEATURE_STAMP</tt>]], [[tool_class:LIVE_TYPE|<tt>LIVE_TYPE</tt>]]... (semantic classes)

== Using visitors ==

=== Simple cases ===

Each visitor can be used separately, but you can also use several in the same class; this is the most common case.

To use visitors, you have to create a '''visitor class'''. This class will have the following properties:
* inherits all the visitor classes of the framework (conforming inheritance)
* also inherits from the [[library_class:VISITOR|<tt>VISITOR</tt>]] class itself (conforming inheritance)
* defines all the <tt>visit_*</tt> features of the visitor classes.

Usually, such a class also provides a [[Glossary#Feature|feature]] which lets you start a search. If that does not exist, it is enough to run the <tt>accept</tt> [[Glossary#Feature|feature]] on a visitable object. Of course, that object must be visitable ''by that visitor'', in other words, that visitor must inherit from the framework visitor class which is able to visit the object.

For some examples, see [[tool_class:AGENT_CREATION_HELPER|<tt>AGENT_CREATION_HELPER</tt>]] or again [[tool_class:HIDDEN_EXPRESSION_DETECTOR|<tt>HIDDEN_EXPRESSION_DETECTOR</tt>]].

=== Using [[tool_class:IN_OUT_VISITOR|<tt>IN_OUT_VISITOR</tt>]] ===

[[tool_class:IN_OUT_VISITOR|<tt>IN_OUT_VISITOR</tt>]] is a class that lets you do a complete search of a class's syntactic tree, depth-first.

Each node is visited by the following algorithm (the NODE class is imaginary):
feature {NODE}
visit_node (a_node: NODE) is
do
if enter_node(a_node) then
node.child.accept(Current);
exit_node(a_node);
end
end

feature {}
enter_node (a_node: NODE): BOOLEAN is
do
Result := True
end

exit_node (a_node: NODE) is
do
end

The interesting point is that a class inheriting from [[tool_class:IN_OUT_VISITOR|<tt>IN_OUT_VISITOR</tt>]] has to redefine only what is strictly necessary.

See, for example, [[tool_class:EIFFELDOC_SHORTER_CLASSDOC|<tt>EIFFELDOC_SHORTER_CLASSDOC</tt>]] and [[tool_class:EIFFELDOC_SHORTER_FIND_CLIENTS|<tt>EIFFELDOC_SHORTER_FIND_CLIENTS</tt>]].