ATL Standard Library
< To: ATL
The ATL standard library consists of the types built into ATL and of their operations. It is based on the OCL 2.0 standard library as described in chapter 11 of the UML 2.0 OCL Final Adopted specification. However, some extensions have been made (see ATL_FAQ#How_close_is_ATL_navigation_language_from_the_OCL_2.0_standard.3F).
This page describes how the ATL standard library is implemented in the two ATL Virtual Machines (VMs) available from Eclipse.org.
EMF VM Implementation
In EMFVM, the ATL standard library is mostly implemented in the ExecEnv Java class. Most types are not wrapped, and Java objects are used directly in many cases.
Some EMF-specific operations (or operations that have an EMF-specific part) are implemented in EMFModelAdapter
Regular VM Implementation
In the Regular VM, Java objects are wrapped by specific objects (instances of subclasses of ASMOclAny). In the description that follows, for each type T a CVS link is given to the Java class implementing T in the Regular ATL virtual machine. In each class, operations available from the ATL language (as opposed to implementation-specific methods) are represented as Java methods located below the following comment:
// Native Operations Below
In some of these classes, there are two additional comments delimiting:
- Operations specified by OCL 2.0:
// OCL Operations
- Operations added in ATL:
// Additional Operations
When the description given here is not complete enough, it is possible to go and read the Java implementation. This way, it is possible to know, for instance: the list of available operations and their semantics (e.g. operation String.regexReplaceAll(a : String, b : String) is implemented in ASMString using java.lang.String.replaceAll(String a, String b)).
The Collection OCL type is implemented by the ASMCollection (deprecated version) Java class. There is no underlying Java type for this abstract type. However, all concrete collection types are implemented by sub-classes of java.util.Collection.
Model elements are handled as a special case in a model-handler-specific way.
These operations are implemented in ASMEMFModelElement:
- EClassifier.getInstanceById(String, String)
Additionally, ATL will look for a called operation in the underlying EObject using Java reflection. This makes many operations (i.e., those for which type translation is implemented for arguments and returned value) from Ecore, as well as from a specific implementation of EObject available.
These operations are implemented in ASMMDRModelElement:
- Classifier.getElementById(String, OclAny)
- Classifier.getElementsById(String, OclAny)
In addition, a few MOF-specific operations are made available, but other operations are generally not available (there is no similar mechanism to what is supported in the EMF-specific version described above):
- GeneralizableElement.findElementsByTypeExtended(ModelElement, Boolean)
The types described in this section are not part of the OCL 2.0 specification.