build.gradle

apply plugin: 'java'

repositories {
    jcenter()
}

dependencies {
    implementation 'org.antlr:antlr4:4.7.2'
}

clean {
    delete "src/main/java/generated-parser"
    delete "static/generated-parser"
}

task generateParser4JS(type:JavaExec) {
   main = 'org.antlr.v4.Tool'
   classpath = sourceSets.main.runtimeClasspath
   args = ['-Dlanguage=JavaScript', 'calc.g4', '-o', 'static/generated-parser']
}

task generateParser4Java(type:JavaExec) {
    main = 'org.antlr.v4.Tool'
    classpath = sourceSets.main.runtimeClasspath
    args = ['-Dlanguage=Java', 'calc.g4', '-o', 'src/main/java/generated-parser']
}

/**
 * java org.antlr.v4.gui.TestRig GrammarName startRuleName
 *   [-tokens] [-tree] [-gui] [-ps file.ps] [-encoding encodingname]
 *   [-trace] [-diagnostics] [-SLL]
 *   [input-filename(s)]
 * Use startRuleName='tokens' if GrammarName is a lexer grammar.
 * Omitting input-filename makes rig read from stdin.
 */
task runExpr(type:JavaExec) {
    main = 'org.antlr.v4.gui.TestRig'
    classpath = sourceSets.main.runtimeClasspath
    args = ['calc', 'expression', '-tokens', '-trace', "test.txt"]
}