Maven pom.xml to support automatic code generation for ANTLR 4 grammar(s) during an Eclipse build. This configuration does not support (and is not intended for) building using Maven alone.

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>org.uiuc</groupId>
  <artifactId>cchistory</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <name>CodeCompletionWithHistory</name>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <antlr4.visitor>true</antlr4.visitor>
    <antlr4.listener>true</antlr4.listener>
  </properties>

  <dependencies>
    <dependency>
      <groupId>org.antlr</groupId>
      <artifactId>antlr4-runtime</artifactId>
      <version>4.0</version>
      <scope>compile</scope>
    </dependency>
    <dependency>
      <groupId>org.eclipse.jgit</groupId>
      <artifactId>org.eclipse.jgit</artifactId>
      <version>2.1.0.201209190230-r</version>
      <scope>compile</scope>
    </dependency>
  </dependencies>

  <build>
    <sourceDirectory>src</sourceDirectory>
    <outputDirectory>bin</outputDirectory>

    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.0</version>
        <configuration>
          <source>6</source>
          <target>6</target>
          <showWarnings>true</showWarnings>
          <showDeprecation>true</showDeprecation>
          <compilerArguments>
            <Xlint />
          </compilerArguments>
        </configuration>
      </plugin>

      <plugin>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>build-helper-maven-plugin</artifactId>
        <version>1.7</version>
        <executions>
          <execution>
            <phase>generate-sources</phase>
            <goals>
              <goal>add-source</goal>
            </goals>
            <configuration>
              <sources>
                <source>target/generated-sources/antlr4</source>
              </sources>
            </configuration>
          </execution>
        </executions>
      </plugin>

      <plugin>
        <groupId>org.antlr</groupId>
        <artifactId>antlr4-maven-plugin</artifactId>
        <version>4.0</version>
        <configuration>
          <sourceDirectory>src</sourceDirectory>
        </configuration>
        <executions>
          <execution>
            <goals>
              <goal>antlr4</goal>
            </goals>
          </execution>
        </executions>
      </plugin>

    </plugins>
    <pluginManagement>
      <plugins>
        <!--This plugin's configuration is used to store Eclipse m2e settings 
          only. It has no influence on the Maven build itself. -->
        <plugin>
          <groupId>org.eclipse.m2e</groupId>
          <artifactId>lifecycle-mapping</artifactId>
          <version>1.0.0</version>
          <configuration>
            <lifecycleMappingMetadata>
              <pluginExecutions>
                <pluginExecution>
                  <pluginExecutionFilter>
                    <groupId>org.antlr</groupId>
                    <artifactId>antlr4-maven-plugin</artifactId>
                    <versionRange>[4.0,)</versionRange>
                    <goals>
                      <goal>antlr4</goal>
                    </goals>
                  </pluginExecutionFilter>
                  <action>
                    <execute>
                      <runOnIncremental>true</runOnIncremental>
                    </execute>
                  </action>
                </pluginExecution>
              </pluginExecutions>
            </lifecycleMappingMetadata>
          </configuration>
        </plugin>
      </plugins>
    </pluginManagement>
  </build>
</project>

Hi. We should use build-helper-maven-plugin version 1.8 instead of 1.7 with Eclipse Juno on Mac OSX, I think.
We can't import a maven project into Eclipse Juno on Mac OSX when using 1.7. Thanks.

Not sure why. This generated sources has duplicate declarations of "package" in the top. It ignores package declaration from grammar files.

@Vadi: Don't use package declaration in grammar file and configure the antlr4-maven-plugin like this:

<configuration>
   <arguments>
      <argument>-package</argument>
      <argument>my.package.path</argument>
   </arguments>
</configuration>

You shouldn't use build-helper-maven-plugin here, cause antlr4-maven-plugin already adds the sources to the compile roots.. Furthermore the life cycle mapping for m2e are not needed cause antlr4-maven-plugin (using newer version 4.5.X ?) already contains appropriate mapping in the plugin itself. So it shouldn't be necessary...