Extensible File Processor

Command-line tool for batch-processing files of arbitrary type, that includes its own plugin-framework, provides an API for plugin-developers and supports specification of runtime-dependencies among plugins (usefull if some plugin depends on the output of other plugins).

Motivation

• includes plugin-framework to make FileProcessor extensible

• provides Extension-API for plugin-developers

• extensible by providing a Plug-in interface API for plugin-developers

• runtime-dependencies among plugins may be list-like, tree-like or graph-like (directed and acyclic)

• software architecture and design-patterns

Features

• inspired by the concept of command-pipelines on the linux shell (namely bash)

• resolves runtime-dependencies in a Makefile/ant-like style

• each plugin is a file-converter, that is able to consume and produce files

Example :: FileProcessorTest.testFileProcessor1()

This example demonstrates usage of different FileProcessor built-in plugins. It takes a textfile contaning a list of java-files and injects some static import statements by modifying the AbstractSyntaxTree (AST) of the corresponding Java-Code. Then it compares the original java-file with the rewritten one and outputs the diff to stderr.

• FileProcessorTest.java code includes code like

  // create new instance of FileProcessor with 5 plugins
  // each of which is able to consume and produce 0..* files.
  // Every plugin is annotated, according to it's capabilities.
  FileProcessor fileproc = new FileProcessor(filelist, inject, copy, diff, stderr);
  
  // define dependency structure
  fileproc.addDependency(filelist, copy);
  fileproc.addDependency(filelist, inject);
  fileproc.addDependency(inject, diff);
  fileproc.addDependency(copy, diff);
  fileproc.addDependency(diff, stderr);
  
  // start processing given file
  fileproc.addItem(file);
  List<File> result = inject.getResult();    
  

• this JUnit.TestCase sets-up the following dependency graph …

  

• … and produces the following output

  > import static java.lang.System.out;
  > import static java.lang.System.err;
  

Annotations for FileProcessor-Plugins

• @Unary only

  plugin produces as many files as it consumes

  plugin processes exactly 1 file at every single call

  Example: JavaImportDeclarationInjector.java

• @Demuxer + @Unary

  plugin produces more files, than it consumes

  plugin processes exactly 1 file at every single call

  Example: FileListReader

• @Muxer + @Binary

  plugin produces less files, than it consumes

  plugin processes exactly 2 file at every single call