Grule

Grule is Kotlin multiplatform library as a general-purpose parser.

NOTE: grule is experimental yet.

Sample - Json parser

class JsonRegMatcherTest : Grammar() {
    val string by lexer { X / """(".*?")""" }
    val number by lexer { X / "\\d+(\\.\\d+)?" }
    val bool by lexer { X / "true|false" }
    val nil by lexer { X / "null" }

    init {
        lexer.token { X - "{}[]:," }
        lexer.skip { SPACE or WRAP }
    }

    val jObject: Parser by parser { jString or jNumber or jBool or jNil or jArray or jDict }
    val jString by parser { X + string }
    val jNumber by parser { X + number }
    val jBool by parser { X + bool }
    val jNil by parser { X + nil }
    val jArray by parser { X + "[" + jObject.join(X + ",") + "]" }
    val jPair by parser { X + jString + ":" + jObject }
    val jDict by parser { X + "{" + jPair.join(X + ",") + "}" }

    @Test
    fun json() {
        val source = """{ "a": [1, 2.34], "b": "hello" }"""
        println(source)
        println("-----------------")

        val astNode = jObject.parse(tokenStream(source))
        println(astNode.toStringTree())
    }
}

Output

{ "a": [1, 2.34], "b": "hello" }
-----------------
jObject/jDict
 ├─ {
 ├─ jPair
 │   ├─ jString/string("a")
 │   ├─ :
 │   └─ jObject/jArray
 │       ├─ [
 │       ├─ jObject/jNumber/number(1)
 │       ├─ ,
 │       ├─ jObject/jNumber/number(2.34)
 │       └─ ]
 ├─ ,
 ├─ jPair
 │   ├─ jString/string("b")
 │   ├─ :
 │   └─ jObject/jString/string("hello")
 └─ }

Setting up the dependency

Add it in your root build.gradle at the end of repositories:

allprojects {
    repositories {
        maven("https://jitpack.io")
    }
}

dependencies {
    implementation("com.github.7hens.grule:grule:0.2")
}