SoMoX Extractor / JDT-Based Java Extractor

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Overview

The JDT-based Java extractor is an extractor plugin for the SoMoX Extractor able to parse java source code and build up according elements in a GAST model. The according workflow job reads the GAST Model from the SoMoX Extractor blackboard and uses this as an input for the Java extractor itself which is workflow independent by default. This GAST model handed over to the extractor is then filled with the information extracted from the source code.

Features

Auto Sourcepath Detection

The JDT-based extractor requires a GAST model as input which includes a representation of the file system (files and directories) of the software. It makes use of an auto detection, which receives all java files from the gast model and parse them to extract the java source code information and entities.

Reference Solving

While the code is parsed, a class may be processed which extends another class that has not been processed yet and no according element in the GAST model exists which could be linked. As a result, this reference could not be solved while the JDT AST ist traversed.

To handle those references a reference registry and solver are provided to take care for this. While the JDT AST is traversed, type specific references (e.g. "extends") are registered in the ReferenceRegistry. As a post processing, a ReferenceSolver checks this registry and tries to solve those references based on the GAST model that has been build up during the initial JDT AST processing.


JDT Elements to GAST Mapping

JAVA Model GAST Model Status Used by SoMoX
Package Package implemented yes
Class (Regular) GASTClass implemented yes
Class (Inner) GASTClass (inner: true) open unknown
Interface (Regular) GASTClass (isInterface: true) implemented unknown
Class Extends Class Relationship InheritanceTypeAccess implemented yes
Class Implements Interface Relationship InheritanceTypeAccess open yes
Root open yes
BasePath open yes
Directory open yes
File open yes
Method open yes
Function open yes
BlockStatement open yes
Visibilities open yes
FormalParameter open yes
Access open yes
FunctionAccess open yes
CompositeAccess open yes
ModelElement open yes
GASTStruct open yes

SISSy SQL Statements to get SoMoX GAST usage

Java Language Enhancements: http://download.oracle.com/javase/7/docs/technotes/guides/language/enhancements.html

Extraction Method

The JDT provides two different extraction methods (Java Model and AST Parser) but SoMoX uses only the AST Parser based method.

This decision is done because of the pros and cons of those two. However, the main reason was the requirement of the Java Model alternative to have all the source code within a java project what might not be realistic in a general application of the parser. Further Details about the comparision of those two extraction alternatives:


AST – Abstract Syntax Tree

Advantages

  • Complete representation of the code (including expressions)
  • Allows code manipulation
  • Is not limited to Eclipse JAVA projects

Disadvantages

  • slower than java model because of more extracted information
  • requires code without compilation errors (Not clear if this holds because it is also able access problems in the compilation units)
  • not able to let the parser solve all references by himself when he is working with an incomplete context (i.e. parsing a single java file)

Java Model

Is used i.e. for the outline view because faster to be updated.

Advantages

  • Faster because of less information extracted
  • is able to handle code with compilation errors

Disadvantages

  • Not all information (e.g., the body of a method is not available)
  • Disadvantage using IJavaProject
    • The libraries available in the current eclipse environment become available, too
    • it is required to create a new project in the workspace. That needs to be cleaned up. The extractor cannot run within a simple unit test. A plugin unit test is required to ramp up an eclipse environment -> resource demanding
    • All sources must be located within the project or a subdirectory of the project. It is not possible to link external resources. -> it is required to copy all sources into the project


Resources

Good Tutorials about working with the JDT:

GAST Elements used by SoMoX

Paket Klasse Methode Attributbezug Rückgabetyp
de.fzi.gast.accesses Access getAccessedClass GASTClass
de.fzi.gast.accesses Access setAccessedTarget void
de.fzi.gast.accesses InheritanceTypeAccess setImplementationInheritance implementationInheritance void
de.fzi.gast.core BasePath getDirectories EList<Directory>
de.fzi.gast.core BasePath setPath path void
de.fzi.gast.core BasePath setRoot void
de.fzi.gast.core Directory getFiles EList<File>
de.fzi.gast.core Directory getFileSystemPath fileSystemPath String
de.fzi.gast.core Directory getParentDirectory Directory
de.fzi.gast.core Directory getSubDirectory EList<Directory>
de.fzi.gast.core Directory setBasePath void
de.fzi.gast.core Directory setParentDirectory void
de.fzi.gast.core File getDirectory Directory
de.fzi.gast.core File getFileSystemPath fileSystemPath String
de.fzi.gast.core File getFullQualifiedPath fullQualifiedPath String
de.fzi.gast.core File getTypes EList<GASTType>
de.fzi.gast.core File setDirectory void
de.fzi.gast.core File setLinesOfCode linesOfCode void
de.fzi.gast.core File setSize size void
de.fzi.gast.core File setSourceFile sourceFile void
de.fzi.gast.core ModelElement getSissyId sissyId int
de.fzi.gast.core ModelElement setSissyId sissyId void
de.fzi.gast.core ModelElement setStatus void
de.fzi.gast.core Package getClasses EList<GASTClass>
de.fzi.gast.core Package getQualifiedName qualifiedName String
de.fzi.gast.core Package getSubPackages EList<Package>
de.fzi.gast.core Package getSurroundingPackage Package
de.fzi.gast.core Package setSurroundingPackage void
de.fzi.gast.core Root getAllInterfaces interface EList<GASTClass>
de.fzi.gast.core Root getAllNormalClasses EList<GASTClass>
de.fzi.gast.core Root getBasePaths EList<BasePath>
de.fzi.gast.core Root getPackageByQualifiedName qualifiedName (Package) Package
de.fzi.gast.core Root getPackages EList<Package>
de.fzi.gast.functions Function getBody BlockStatement
de.fzi.gast.functions Function getFormalParameters EList<FormalParameter>
de.fzi.gast.functions Function getReturnTypeDeclaration DeclarationTypeAccess
de.fzi.gast.statements BlockStatement getStatements EList<Statement>
de.fzi.gast.types GASTClass getAllAccessedClasses EList<GASTClass>
de.fzi.gast.types GASTClass getAllAccesses EList<Access>
de.fzi.gast.types GASTClass getInheritanceTypeAccesses EList<InheritanceTypeAccess>
de.fzi.gast.types GASTClass getInnerClasses inner EList<GASTClass>
de.fzi.gast.types GASTClass getMethods EList<Method>
de.fzi.gast.types GASTClass getSuperTypes EList<GASTClass>
de.fzi.gast.types GASTClass getSurroundingPackage Package
de.fzi.gast.types GASTClass isInner inner boolean
de.fzi.gast.types GASTClass isInterface interface boolean
de.fzi.gast.types GASTClass isPrimitive primitive boolean
de.fzi.gast.types GASTClass setSurroundingPackage void
de.fzi.gast.accesses DeclarationTypeAccess (parameter from return type)
de.fzi.gast.variables FormalParameter (parameter from return type)
de.fzi.gast.statements Statement (parameter from return type)
de.fzi.gast.types GASTType (parameter from return type)
de.fzi.gast.functions Method (parameter from return type)