https://github.com/kevinhinterlong/jsonit

A guide to setting up antlr4 grammar projects
https://github.com/kevinhinterlong/jsonit

antlr4 example gradle java

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A guide to setting up antlr4 grammar projects

• Host: GitHub
• URL: https://github.com/kevinhinterlong/jsonit
• Owner: kevinhinterlong
• License: mit
• Created: 2018-08-03T15:29:00.000Z (over 7 years ago)
• Default Branch: master
• Last Pushed: 2018-08-03T21:55:52.000Z (over 7 years ago)
• Last Synced: 2025-02-08T18:32:25.204Z (12 months ago)
• Topics: antlr4, example, gradle, java
• Language: Java
• Homepage:
• Size: 59.6 KB
• Stars: 1
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

          
# jsonit

`jsonit` is a simple example of how to use [`Antlr`](https://www.antlr.org/) to define a grammar and use it in a Java (and gradle) based project

The project uses the [`JSON.g4`](https://github.com/antlr/grammars-v4/blob/master/json/JSON.g4) grammar from the  [antlr/grammars-v4](https://github.com/antlr/grammars-v4) repo

> NOTE: This project is _not_ meant to be a useful json parser.

## Antlr setup with gradle

The following lines from [`build.gradle`](build.gradle) define how to set up the `antlr` plugin which will generate the Java sources for you Parser/Lexer

```groovy

// First we must pull in the antlr plugin

apply plugin: 'antlr'

// then decide where to store the generated java code

def generatedSources = [

    rootDir: 'generated-src/',

    javaDir: 'generated-src/java'

]

// then add the generated sources to our project

sourceSets {

    main {

        java {

            srcDir generatedSources.javaDir

        }

    }

}

dependencies {

    // pull in 'org.antlr:antlr4:4.7' for the `antlr` configuration

    // (this is just for building the sources files)

    antlr 'org.antlr:antlr4:4.7'

    // add the antlr runtime so we can use the generated sources

    implementation 'org.antlr:antlr4-runtime:4.7'

}

// configure the grammar generation

// more info: https://docs.gradle.org/current/userguide/antlr_plugin.html

generateGrammarSource {

    arguments += ['-visitor', '-long-messages']

    outputDirectory = file(generatedSources.javaDir)

}

// ensures the grammar source files are generated before building the project

compileJava.dependsOn generateGrammarSource

// delete the generated sources as part of the 'clean' step

clean {

    delete generatedSources.rootDir

}

```

## Working with IntelliJ

IntelliJ by default will use it's own configuration for running Gradle project which is great for most cases; however it does not work with complex configurations.

If you try to run the project with IntelliJ it will fail because it does not run this step

```groovy

compileJava.dependsOn generateGrammarSource

```

To solve this you can set

**Build, Execution, Deployment** → **Build Tools** → **Gradle** → **Runner** → `Delegate IDE build/run actions to gradle` to true

> NOTE: You could also manually generate the grammar once (or whenever you change it)

> ```bash

> $ ./gradlew generateGrammarSource 

> ```

## Build

To build the project, clone it then run

```bash

$ ./gradlew build

```