Add naive JSON grammar test

src/commonTest/kotlin/me/alllex/parsus/GrammarTests.kt

@@ -4,6 +4,7 @@ import assertk.assertThat
 import assertk.assertions.isEqualTo
 import me.alllex.parsus.parser.*
 import me.alllex.parsus.token.literalToken
+import me.alllex.parsus.token.regexToken
 import me.alllex.parsus.tree.SyntaxTree
 import me.alllex.parsus.tree.lexeme
 import kotlin.test.Test
@@ -80,4 +81,56 @@ class GrammarTests {
         }
     }
 
+    @Test
+    fun naiveJsonGrammarTest() {
+        NaiveJsonGrammar.run {
+            assertParsed("""{${'\n'}"a": 1,${'\n'}"b": {"c":false}${'\n'}}""").isEqualTo(
+                Json.Obj(
+                    mapOf(
+                        "a" to Json.Num(1.0),
+                        "b" to Json.Obj(mapOf("c" to Json.Bool(false)))
+                    )
+                )
+            )
+        }
+    }
+
+    sealed class Json {
+        object Null : Json() {
+            override fun toString(): String = "Null"
+        }
+
+        data class Bool(val value: Boolean) : Json()
+        data class Num(val value: Double) : Json()
+        data class Str(val value: String) : Json()
+        data class Arr(val values: List<Json>) : Json()
+        data class Obj(val values: Map<String, Json>) : Json()
+    }
+
+    object NaiveJsonGrammar : Grammar<Json>() {
+        init {
+            regexToken("\\s+", ignored = true)
+        }
+
+        private val comma by literalToken(",")
+        private val colon by literalToken(":")
+        private val lbrace by literalToken("{")
+        private val rbrace by literalToken("}")
+        private val lbracket by literalToken("[")
+        private val rbracket by literalToken("]")
+        private val str by regexToken("\"[^\\\\\"]*(\\\\[\"nrtbf\\\\][^\\\\\"]*)*\"") map { it.text.run { substring(1, lastIndex) } }
+        private val jsonTrue by literalToken("true") map { Json.Bool(true) }
+        private val jsonFalse by literalToken("false") map { Json.Bool(false) }
+        private val jsonNull by literalToken("null") map Json.Null
+        private val jsonNum by regexToken("-?(?:0|[1-9]\\d*)(?:\\.\\d+)?(?:[eE][+-]?\\d+)?") map { Json.Num(it.text.toDouble()) }
+        private val jsonStr by str map { Json.Str(it) }
+
+        private val keyValue by str * -colon and ref(::jsonValue) map { it.toPair() }
+        private val jsonObj by -lbrace * separated(keyValue, comma) * -rbrace map { Json.Obj(it.toMap()) }
+
+        private val jsonArr by -lbracket * separated(ref(::jsonValue), comma) * -rbracket map { Json.Arr(it) }
+        private val jsonValue: Parser<Json> by jsonNull or jsonTrue or jsonFalse or jsonNum or jsonStr or jsonArr or jsonObj
+        override val root by jsonValue
+    }
+
 }