Model transformations. Model transformations. Model transformations. Model transformations

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1 The initialization of the attributes of a generated target model element by assigning references: Model target element generated by current rule Default target model element generated by another rule Non-default target model element generated by another rule The first case (assigning g a model element produced by the same rule is the simplest one: the considered reference can be initialized with the name of the other target pattern element consider the following example in which the rule Case1 has two target pattern model elements (o_1 and o_2, with o_1 having a reference to a Class2 model element defined (linktoclass2: rule Case1 { from i : MM_A!ClassA to o_1 : MM_B!Class1 ( linktoclass2 <- o_2, o_2 : MM_B!Class2 (... In the second case (assigning g the default target element of another rule: the considered reference has to be initialized with the source model element which is matched by the remote rule for generating the target model element to be assigned In the following example, the rule Case2_R1 aims to generate a target model element (o_1 that has a reference to a target model element that corresponds to the default target pattern (o_1 of the rule Case2_R2 Assuming that the source model element matched by Case2_R1 has a reference (linktoclassb to the relevant MM_ A!ClassB source model element, this assignment is expressed as follows: rule Case2_R1 { from i : MM_A!ClassA to o_ 1 : MM_ B!Class1 ( linktoclass2 <- i.linktoclassb rule Case2_R2 { from i : MM_A!ClassB to o_1 : MM_B!Class2 (...,...

$rule Case2_R1 { from i : MM_A!ClassA to o_1 : MM_B!$ $linktoclassb rule Case2_R2 { from i : MM_A!ClassB to o_1 : MM_B!$ .. Alternative (also used in the non-default target element Class1 (

.. Alternative (also used in the non-default target element Class1 (

$linktoclassb, o_1 rule Case2_R2 { from i : MM_ A!$ .. Example of assignments / Faculteit Wiskunde en Informatica

2 rule Case2_R1 { from i : MM_A!ClassA to o_1 : MM_B!Class1 ( linktoclass2 <- i.linktoclassb rule Case2_R2 { from i : MM_A!ClassB to o_1 : MM_B!Class2 (...,... Alternative (also used in the non-default target element rule Case2_R1 { from i : MM_A!ClassA to o_1 : MM_B!Class1 ( linktoclass2 <- thismodule.resolvetemp(i.linktoclassb, o_1 rule Case2_R2 { from i : MM_ A!ClassB to o_1 : MM_B!Class2 (...,... Example of assignments / Faculteit Wiskunde en Informatica PAGE 5 Lazy rules Lazy rules are like matched rules, but are only applied when called by another rule / Faculteit Wiskunde en Informatica PAGE 6 / Faculteit Wiskunde en Informatica PAGE 7

3 Lazy rules lazy rule rule_name{ from in: MM1!MetaClass using{<variable definitions> to out1: MM2!MetaClass1( <bindings1>, out2: MM2!MetaClass2( <bindings2> do{<imperative block> Generates new target elements for every er call to the rule Invoked from other rules as follows: thismodule.rule_name(<model element of type MM1!MetaClass> / Faculteit Wiskunde en Informatica PAGE 9 Unique lazy matched rules unique lazy rule rule_name{ from in: MM1!MetaClass using{<variable definitions> to out1: MM2!MetaClass1( <bindings1>, out2: MM2!MetaClass2( <bindings2> do{<imperative block> Always returns rns the same target elements for a given source element, i.e., target elements are generated only once per source element Called rules The called rules provide ATL developers with convenient imperative programming facilities. Called rules can be seen as a particular type of helpers: they have to be explicitly called to be executed and they can accept parameters called rules can generate target model elements as matched rules do A called rule has to be called from an imperative code section, either from a match rule or another called rule A called rule does not include a source pattern / Faculteit Wiskunde en Informatica PAGE 11

4 Called rules [entrypoint]? rule rule_name(<parameters>{ using{<variable definitions> to out1: MM2!MetaClass1( <bindings1>, out2: MM2!MetaClass2( <bindings2> do{<imperative block> For generating target elements from imperative code No from clause Example of a called rule rule NewPerson (na: String, s_na: String { to p : MMPerson!Person ( name <- na do { p.surname <- s_na / Faculteit Wiskunde en Informatica PAGE 13 Besides matched rules, ATL defines an additional kind of rules enabling to explicitly generate target model elements from imperative code Except for the entrypoint called rule, this kind of rules must be explicitly called from an ATL imperative block. A called rule is identified by its name (rule_name. A called rule name must be unique within an ATL transformation must not collide with a helper name a called rule cannot be called "main" A called rule can optionally be declared as the transformation entrypoint/endpoint. p an ATL transformation can include one entrypoint/endpoint called rule. it is implicitly invoked at the beginning/ending of the transformation execution / Faculteit Wiskunde en Informatica PAGE 14 / Faculteit Wiskunde en Informatica PAGE 15

5 Helper with context helper context MM!MetaClass def: helper_name(<parameters>: return_type = let <variable definition> in <expression>; Invocation: <model element of type MM!MetaClass>.helper_name(<parameters> The context should never be of a collection type Helper without context helper def: helper_name(<parameters>: return_type = let <variable definition> in <expression>; Invocation: thismodule.helper_name(<parameters> More reading material _Overview_of_the_Atlas_Transformation_Language _The_ATL_Language For OCL functions refer to the ATL user guide / Faculteit Wiskunde en Informatica PAGE 17 XTEND Xtend transformation language: g Model transformation language OCL like expression language strong functional flavour Can be used in constraint checks, model transformations and code generators Add methods to meta types (Java calls are possible if necessary Tool support (syntax highlighting, code completion, debugger / Faculteit Wiskunde en Informatica PAGE 18 / Faculteit Wiskunde en Informatica PAGE 19

6 First we create an Xtend project Getting started Select in Eclipse File/New/Other Select then the Xpand/Xpand d project Select then the Next button Enter project name Select then the Finish button A Xtend project is created Create/copy needed metamodels click on src and then select New/Other Select Ecore Tools/Ecore Diagram / Faculteit Wiskunde en Informatica PAGE 20 / Faculteit Wiskunde en Informatica PAGE 21 Enter Directory Enter Domain file name Select Finish Create an Xtend file Click on src Select New/Other Select Xtend/Xtend File Click Next Enter File name Click Finish / Faculteit Wiskunde en Informatica PAGE 22 / Faculteit Wiskunde en Informatica PAGE 23

7 Xtend language g concepts: File extension must be *.ext Example import my::metamodel; extension other::extensionfile; /** * Documentation */ anexpressionextension(string stringparam : doingstuff(with(stringparam ; /** * java extensions are just mappings */ String ajavaextension(string param : JAVA my.javaclass.staticmethod(java.lang.string ; Extend Import Statements Using the import statement one can import name spaces of different types Syntax is: import my::imported::namespace; / Faculteit Wiskunde en Informatica PAGE 24 / Faculteit Wiskunde en Informatica PAGE 25 Extend Extension Import Statement You can import another extend file using the extension statement The syntax is: extension fully::qualified::extensionfilename; Reexporting Extensions To export extensions from another extension file together with your local extensions, you add the keyword 'reexport' extension fully::qualified::extensionfilename reexport; Extensions The syntax of a simple expression extension is as follows: ReturnType extensionname(paramtype1 paramname1, ParamType2...: expression-using-params; params; Example: String gettername(namedelement ele : 'get'+ele.name.firstupper(; / Faculteit Wiskunde en Informatica PAGE 26 / Faculteit Wiskunde en Informatica PAGE 27

8 Extension Invocation There are two different ways of how to invoke an extension: gettername(mynamedelement mynamedelement.gettername( Issues with extensions: Type Inference Recursion Cached Extensions If you call an extension without side effects very often, you would like to cache the result for each set of parameters, in order improve the performance You can just add the keyword 'cached' to the extension in order to achieve this: cached String gettername(namedelement ele : 'get'+ele.name.firstupper( ; / Faculteit Wiskunde en Informatica PAGE 28 / Faculteit Wiskunde en Informatica PAGE 29 Private Extensions By default all extensions are public, i.e. they are visible from outside the extension file. If you want to hide extensions you can add the keyword 'private' in front of them: private internalhelper(namedelement ele : // implementation... ; Create Extensions (Model Transformation The evaluation of extensions is innermost Circular references may lead to non termination create extensions enforces a non-innermost behaviour: Object is created before children are processed / Faculteit Wiskunde en Informatica PAGE 30 / Faculteit Wiskunde en Informatica PAGE 31

9 Syntax of Xtend (Xpand expressions: There are two different forms of conditional expressions. The first one is the so-called if expression. Syntax: condition? thenexpression : elseexpression The other one is called switch expression. Syntax: switch (expression { (case expression : thenexpression* default : catchallexpression The default part is mandatory, because switch is an expression, therefore it needs to evaluate to something in any case Syntax of Xtend (Xpand expressions: There is an abbreviation for Boolean expressions:switch { case booleanexpression : thenexpression default : catchallexpression Chain expression: expressions and functional languages should be free of side effects as far as possible. But sometimes there you need invocations that do have side effects. If you need to call such operations, you can use the chain expression. Syntax: anexpr -> anotherexpr -> lastexpr Each expression is evaluated in sequence, but only the result of the last expression is returned / Faculteit Wiskunde en Informatica PAGE 32 / Faculteit Wiskunde en Informatica PAGE 33 Syntax of Xtend (Xpand expressions: The create expression is used to instantiate new objects of a given type: new TypeName let expression The let expression lets you define local variables. Syntax is as follows: let v = expression : expression-with-v This is especially useful together with a chain- and a create expressions Recall the Xtext specification for Booleans: Model : OrBool ; OrBool : lhs=andbool (' ' rhs=orbool? ; AndBool : lhs=notbool ('&' rhs=andbool? ; NotBool : (not?='~? arg=bracketbool ; BracketBool : '(' orarg=orbool '' conarg=boolcon ; BoolCon : {TrueNode 'true' {FalseNode 'false' ; / Faculteit Wiskunde en Informatica PAGE 34 / Faculteit Wiskunde en Informatica PAGE 35

Grammars, signatures and meta-models Recall meta-model (of syntax tree for Booleans: First alternative for Boolean meta-model / Faculteit Wiskunde en Informatica 15-12-2010 PAGE 36 / Faculteit

org::eclipse::xtend::util::stdlib::io; mbool::bool convert(abool::orbool model : model.convertorbool(; mbool::bool convertorbool(abool::orbool orbool : if (orbool.rhs!= null then ( orbool.

10 Grammars, signatures and meta-models Recall meta-model (of syntax tree for Booleans: First alternative for Boolean meta-model / Faculteit Wiskunde en Informatica PAGE 36 / Faculteit Wiskunde en Informatica PAGE 37 Model transformation Model transformation From concrete to abstract syntax meta-model import mbool; import ABool; extension org::eclipse::xtend::util::stdlib::io; mbool::bool convert(abool::orbool model : model.convertorbool(; mbool::bool convertorbool(abool::orbool orbool : if (orbool.rhs!= null then ( orbool.makeorbool( else ( orbool.lhs.convertandbool( ; create mbool::orbool makeorbool(abool::orbool orbool : this.setlhs( orbool.lhs.convertandbool( -> this.setrhs( orbool.rhs.convertorbool( ; From concrete to abstract syntax meta-model mbool::bool convertandbool(abool::andbool andbool : if (andbool.rhs!= null then ( andbool.makeandbool( else ( andbool.lhs.convertnotbool( ; create mbool::andbool makeandbool(abool::andbool andbool: this.setlhs(andbool.lhs.convertnotbool( -> this.setrhs(andbool.rhs.convertandbool(; mbool::bool convertnotbool(abool::notbool notbool : if (notbool.not == true then ( makenotbool(notbool.arg else ( convertbracketbool(notbool.arg ; / Faculteit Wiskunde en Informatica PAGE 38 / Faculteit Wiskunde en Informatica PAGE 39

11 Model transformation Overview of workshop From concrete to abstract syntax meta-model create mbool::notbool makenotbool(abool::bracketbool bracketbool : this.setarg(convertbracketbool(bracketbool; mbool::bool convertbracketbool(abool::bracketbool bracketbool : if (bracketbool.orarg!= null then ( bracketbool.orarg.convertorbool( else ( bracketbool.conarg.convertboolcon( ; Model driven software engineering g in general Grammars, signatures and meta-models mbool::boolcon convertboolcon(abool::boolcon boolcon : syserr("unknown boolcon encounterd: " + boolcon.tostring(; create mbool::boolcon convertboolcon(abool::truenode truenode : this.setvalue(mbool::boolliteral::true; create mbool::boolcon convertboolcon(abool::falsenode truenode : this.setvalue(mbool::boolliteral::false; / Faculteit Wiskunde en Informatica PAGE 40 / Faculteit Wiskunde en Informatica PAGE 41 Automatic transformation of domain specific models into software models Automatic translation from software models into executable code Ingredients: syntax and semantics of modeling formalisms should be described correctness preserving transformation steps should be defined code generators should be developed Xpand: Designed specifically for code (actually, text generation OO template engine supporting template polymorphism French quotation ti marks as escape characters Embedded Expressions based on Xtend (OCL like Support for Recursion Metamodel aware Editor with Code Completion and Syntax Highlighting hti Debugger / Faculteit Wiskunde en Informatica PAGE 42 / Faculteit Wiskunde en Informatica PAGE 43

Xpand statements: Import: make meta models visible to template file Define: define a new template File: open a file into which h output t is written Expand: Call another template for one or several

12 Xpand statements: Import: make meta models visible to template file Define: define a new template File: open a file into which h output t is written Expand: Call another template for one or several elements Foreach: iterate over coll., generate e code for each elemente e If: conditional template code Extension: import an extension file for use in the templates t Error: report an error Let: define a temporary variable Import statement Xpand Editor knows your metamodel (code completion, validation You can work on different types of meta metamodels metamodels EMF, UML2, Java, When writing a template you have to specify the metamodel you are using This is done using the import syntax / Faculteit Wiskunde en Informatica PAGE 44 / Faculteit Wiskunde en Informatica PAGE 45 Define statement A Template file contains any number of templates A template is specified using the DEFINE keyword At template t has a name and dis defined dfor a certain type (from your meta model It is possible to have several templates with the same name but different types (i.e. Polymorphism if those are subtypes Optionally, a template may have additional parameters. Example of Xpand code Define / Faculteit Wiskunde en Informatica PAGE 46 / Faculteit Wiskunde en Informatica PAGE 47

13 File statement The FILE statement is used to specify the output file where the contents of a template and its called templates goes to The filename might be an expression Example of Xpand code File / Faculteit Wiskunde en Informatica PAGE 48 / Faculteit Wiskunde en Informatica PAGE 49 Expand statement EXPAND is used to invoke another template You have to specify the target object (if called for this, the FOR part can be omitted It is also possible to call a template FOREACH element in a collection (support for SEPARATOR Example of Xpand code Expand / Faculteit Wiskunde en Informatica PAGE 50 / Faculteit Wiskunde en Informatica PAGE 51

14 Foreach statement FOREACH is used to iterate over a collection The current element from the list is assigned to a local variable (AS part Optionally you may specify a SEPARATOR and ITERATOR If statement IF is used to add conditions to your template You may have any number of ELSE IF statements And one ELSE / Faculteit Wiskunde en Informatica PAGE 52 / Faculteit Wiskunde en Informatica PAGE 53 If statement IF is used to add conditions to your template You may have any number of ELSE IF statements And one ELSE Let statement LET is used to define a local variable (assign once Not used very often better use an extension Example of Xpand code Creation of files Iteration / Faculteit Wiskunde en Informatica PAGE 54 / Faculteit Wiskunde en Informatica PAGE 55

15 Example of Xpand code More information on Xpand: n/4.3.1/html/contents/core_reference.html#xpand_refere nce_introduction / Faculteit Wiskunde en Informatica PAGE 56 / Faculteit Wiskunde en Informatica PAGE 57

Model transformations. Overview of DSLE. Model transformations. Model transformations. The 4-layer architecture

Model transformations. Overview of DSLE. Model transformations. Model transformations. The 4-layer architecture Overview of DSLE Model driven software engineering g in general Grammars, signatures and meta-models DSL Design Code generation Models increase the level of abstraction used for both hardware and software