How to automatically generate lexer+parser with ANTLR4 and Maven?

Question

I'am new to ANTLR4, and it seems that there is no Eclipse-Plug-In for v4. So it would nice to build automatically the Java sources from the .g4 grammars. I have a simple, empty Maven-project with src/main/java, src/test/java. Where to place the .g4 files? How can I automatically build the grammars with Maven?

My own POM-test failed:

<repository>
    <id>mvn-public</id>
    <name>MVNRepository</name>
    <url>http://mvnrepository.com</url>
</repository>

...

<build>
    <plugins>
        <plugin>
            <groupId>org.antlr</groupId>
            <artifactId>antlr4-maven-plugin</artifactId>
            <version>4.0.0</version>
            <executions>
                <execution>
                    <goals>
                        <goal>antlr</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

Eclipse says:

Failure to find org.antlr:antlr4-maven-plugin:pom:4.0.0 in http://repo.maven.apache.org/maven2 was cached in the local repository, resolution will not be reattempted until the update interval of
central has elapsed or updates are forced

Answer 1

I created the following Gist with a pom.xml designed solely for supporting automatic code generation from ANTLR 4 grammars during an Eclipse build. It includes the necessary lifecycle information for m2e to know that the code generation is necessary, and explicitly adds the code generation folder using the build-helper-maven-plugin since Eclipse seemed to have some trouble locating it otherwise.

In this configuration, grammar files (*.g4) are placed alongside the other Java source files. The Maven plugin will automatically add the proper package ... statement to the generated files, so you shouldn't include a @header{package ...} line in the grammar itself.

https://gist.github.com/sharwell/4979017