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Using Antlr with IntelliJ

First we need to install the intellij plugin located at https://plugins.jetbrains.com/plugin/7358?pr=

Scroll down to the downloads and download the newest one.

In intellij go to Settings > Plugins > Install plugin from disk, and select the zip file you downloaded.

Now to edit our pom

Add the antlr runtime dependency:

<dependencies>
    <dependency>
        <groupId>org.antlr</groupId>
        <artifactId>antlr4-runtime</artifactId>
        <version>4.5.1</version>
    </dependency>
</dependencies>

For the build:

<build>
    <plugins>
        <plugin>
            <groupId>org.antlr</groupId>
            <artifactId>antlr4-maven-plugin</artifactId>
            <version>4.5.1</version>
            <executions>
                <execution>
                    <goals>
                        <goal>antlr4</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

You can see the full pom.xml within this project.

Get the project started

Create a new directory at src/main/antlr4/pack and place your grammar in there.

Create a main class in src/main/[your.package]

I created AlexMain.java under src/main/com/alex

In Intellij, do Build > Make Project.

Configuring Antlr

Right click on your grammar file and click "Configure ANTLR..."

rightantlr

And configure it like so:

configure

Then right click your grammar again and select "Generate ANTLR Recognizer"

generate

This will produce a lot of java classes in the directory that you specified for output. In this case, target/generated-sources/com/alex

We can now use these classes in our original main class to get started.

Take a look at the main class (AlexMain.java) to actually see the code.

The interesting line is ParseTree tree = cparser.compilationUnit();

The method compialtionUnit was created by antlr, and calling this on the parser tells the parser to start at the rule compilationUnit within the grammar. If you need to start at a different rule, call that on the parser. For example, if we wanted to start with the "argumentExpressionList" rule from the C grammar, we would call ParseTree tree = cparser.argumentExpressionList();

USING the plugin view

In Intellij, go to View > Tool Windows > ANTLR preview.

We will pick the file as input, choose the file mergesort.c that we were just working with.

choosefile

Now go into the grammar file (C.g4) and right click on the starting rule, compilationUnit, and click "Test Rule compilationUnit."

testrule

You should now see a visualization of the tree in the antlr tool window.

parsetreeview