Spoon-maven-plugin

Spoon-maven-plugin is a maven plugin for performing code analysis or transformation during build.

It can be used for instance:

to implement architectural checks, design pattern check and make the build fail if required
execute pre-compilation source code transformations, for instance to automatically add logging, error-handling code, dependency injection, etc.

To report an issue, please use the main Spoon issue tracker: https://github.com/INRIA/spoon/issues.

Goals

The plugin provided two goals:

generate to execute source-code transformation
check to execute source-code analysis

Please note that the two goals take exactly the same arguments and configuration. The only change is that generate will create java source files in the target directory, where check will only fail the build in case of analysis error.

Basic usage

To use spoon-maven-plugin, you need to declare it on the build tag in the pom.xml file of your project and specify an execution during the generate-source phase of the maven lifecycle.

The usage below is the minimum to execute the plugin and run spoon on your project.

<plugin>
  <groupId>fr.inria.gforge.spoon</groupId>
  <artifactId>spoon-maven-plugin</artifactId>
  <version>LATEST</version>
  <executions>
    <execution>
      <phase>generate-sources</phase>
      <goals>
        <goal>generate</goal>
      </goals>
    </execution>
  </executions>
</plugin>

Consequently, when mvn clean install is run on your project, the source code is first rewritten by spoon before compilation. Note that Spoon takes as input the original sources of the project, but also the sources generated by another tools (like antlr, for example).

How to skip generated sources?

If you want Spoon to not pass generated sources as input, just provide the following configuration:

<plugin>
  <groupId>fr.inria.gforge.spoon</groupId>
  <artifactId>spoon-maven-plugin</artifactId>
  <version>LATEST</version>
  <configuration>
    <skipGeneratedSources>true</skipGeneratedSources>
  </configuration>
  <executions>
    <execution>
      <phase>generate-sources</phase>
      <goals>
        <goal>generate</goal>
      </goals>
    </execution>
  </executions>
</plugin>

or in command line: mvn compile -DskipGeneratedSources=true

How to add processors?

Spoon can use processors to analyse and transform source code.

To add processors, one must:

add a dependency in the plugin block.
add a processor with its full qualified name in the configuration block.

In the example below, we add processor fr.inria.gforge.spoon.processors.CountStatementProcessor and the dependency necessary to locate the processor.

<configuration>
  <processors>
    <processor>
      fr.inria.gforge.spoon.processors.CountStatementProcessor
    </processor>
  </processors>
</configuration>
<dependencies>
  <dependency>
    <groupId>fr.inria.gforge.spoon</groupId>
    <artifactId>spoon-processors</artifactId>
    <version>1.0-SNAPSHOT</version>
  </dependency>
</dependencies>

How to pass properties to a processor?

Spoon allow to pass custom properties to the processor you want to use, directly in the pom.xml.

For passing properties, one must:

Add annotated fields to the processor being configured from the POM
Add XML configuration for passing the values to those fields
Use JSON format to specify the value of the fields

For example, let us consider the following Processor that changes the name of a specific class. The usage of Property annotation for the fields (eg @Property String oldClassName) means that this field will be set through the POM.

package my.app.pkg;

import spoon.processing.AbstractProcessor;
import spoon.processing.Property;
import spoon.reflect.declaration.CtClass;

public class ProcessorWithProperty extends AbstractProcessor<CtClass> {

    @Property
    String oldClassName;

    @Property
    String newClassName;

    @Override
    public void process(CtClass element) {
        if (element.getSimpleName().equals(this.oldClassName)) {
            element.setSimpleName(this.newClassName);
        }
    }
}

Then the following configuration sets the processor's fields:

<plugin>
    <groupId>fr.inria.gforge.spoon</groupId>
    <artifactId>spoon-maven-plugin</artifactId>
    <configuration>
      <processors>
        <processor>my.app.pkg.ProcessorWithProperty</processor>
      </processors>
      <processorProperties>
        <processorProperty>
          <name>my.app.pkg.ProcessorWithProperty</name>
          <properties>
            <property>
              <name>oldClassName</name>
              <value>App</value>
            </property>
            <property>
              <name>newClassName</name>
              <value>NewName</value>
            </property>
          </properties>
        </processorProperty>
      </processorProperties>
    </configuration>
</plugin>

Please note that you have to specify for which processor the properties should be used with the name attribute (here my.app.pkg.ProcessorWithProperty). Values must use JSON formatting. Primitive types are supported as well as list, maps and custom types. Value types are automatically inferred from their field type and JSON values are deserialized using Jackson library. As en examples, list are created as JSON lists:

<value>["one","two","three","value containing a, comma"]</value>

Maps and objects are created like this:

<value>{"one":1,"two":2,"three":"a value with a,comma"}</value>

How to change source and output folder?

You can specify at spoon its input and output directories with, respectively, srcFolder and outFolder tags.

How to compile original sources?

By default, spoon generate your source code and compile these sources but you can specify at the plugin that you want to compile your original sources with the tag compileOriginalSources sets to true.

How to specify a custom version for Spoon?

Spoon maven plugin defines a default value for spoon's version but you can override it to another one.

For example, if you would like the version 2.4 of spoon and not the version 3.0, you must add the dependency below.

<plugin>
  <groupId>fr.inria.gforge.spoon</groupId>
  <artifactId>spoon-maven-plugin</artifactId>
  <executions>
    <execution>
      <phase>generate-sources</phase>
      <goals>
        <goal>generate</goal>
      </goals>
    </execution>
  </executions>
  <dependencies>
    <dependency>
      <groupId>fr.inria.gforge.spoon</groupId>
      <artifactId>spoon-core</artifactId>
      <version>2.4</version>
    </dependency>
  </dependencies>
</plugin>

How to make the build fail?

If you want to use a custom Processor for assessing properties (checkstyle-like, architectural rule checking, pattern checking, etc) and make the build fail if those properties are not verified, throw a SpoonException in the method process() of the processor.

Reports

The plugin creates some reports about its context and the execution of spoon on your project. These reports are available according to your definition of the plugin.

If you have a simple project, you can retrieve the report at this location: target/spoon-maven-plugin/result-spoon.xml.
If you have a multi-module project, you can retrieve on each sub module at the some location: target/spoon-maven-plugin/result-spoon.xml.
If you have a multi-module project but you didn't declared your plugin at the root pom.xml file, you can retrieve the report on each sub module from your declaration.

Skipping

It's possible to skip the plugin execution using skip property as in :

<plugin>
  <groupId>fr.inria.gforge.spoon</groupId>
  <artifactId>spoon-maven-plugin</artifactId>
  <configuration>
    <skip>true</skip>
  </configuration>
</plugin>

or from command line using -Dspoon.skip=true.

Command-line usage

If you add the following to your ~/.m2/settings.xml

<pluginGroups>
    <pluginGroup>fr.inria.gforge.spoon</pluginGroup>
</pluginGroups>

Then, the plugin is automatically discovered (through prefix resolution), and you can simply run mvn spoon:generate.

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