Software Engineering for Smart Data Analytics & Smart Data Analytics for Software Engineering

User Tools

Site Tools

Writing your own transformation

This tutorial explains how to write your own transformation. If you are just interested in how to add your transformation as a quickfix to a JT analysis, have a look at this page.

A strength of JTransformer is that it capable of doing analysis on the source code and transformations. In this section, we are writing a transformation that could be applied to code found by the System.out.println detector from the "Write your own analysis"-Example.

Conditional Tranformations (CTs)

If you want to learn what Conditional Transformations are and how you can use them (run a ct, run a sequence of cts, examine the results of a ct …) please have a look at this page: Conditional Tranformations. If you need more examples for transformations you can have a look at the Tutorial Project 1).

The transformation for our System.out.println detector has to replace the call to System.out.println by a call to a logging method. How the logging method can be detected has to be defined in the condition part of the ct.

:- multifile(user:ct/3).     % Dont forget the declaration!

user:ct( replaceSysoutWithLogging(CallId),              % HEAD
    (                                                   % CONDITION
      sysout_analysis:sysout_call(CallId,CallParent, Enclosing, FieldAccess, StaticTypeRef, Argument),
                                                        % Call the analysis predicate and bind all IDs
      get_term(FieldAccess, FieldAccessTerm),           % get the terms which should be deleted
      get_term(StaticTypeRef, StaticTypeRefTerm),
      classT(MyLoggerClass, _, 'MyLogger', _, _),       % Get the ID belonging to class 'MyLogger'
      methodT(LoggingMethod, MyLoggerClass, println, _, MethodType, _, _, _),
                                                        % ... and the ID for the logging method

      new_id(NewTypeRef)                                % NewTypeRef is a yet unused ID
    (                                                   % TRANSFORMATION:
      delete(FieldAccessTerm),                          % delete the field access
      delete(StaticTypeRefTerm),                        % delete the static type reference
      replace(callT(CallId, CallParent, Enclosing, NewTypeRef, [Argument], LoggingMethod, [], MethodType))
                                                        % replace the existing callT fact with the new one 
                                                        % (call the logging method instead of System.out.println)
      add(staticTypeRefT(NewTypeRef, CallId, Enclosing, MyLoggerClass)),
                                                        % add the static type reference to the class "MyLogger"
New → Example → JTransformer Example Projects → JTransformer Tutorial - Prolog Files → refactorings
research/jtransformer/tutorial/transformation.txt · Last modified: 2018/05/09 01:59 (external edit)

SEWiki, © 2024