wip: Try to use kotlinx/ast

kotlinx/ast does not support generating code from AST
kotlinx/ast#43

app/build.gradle.kts

@@ -18,6 +18,7 @@ plugins {
 repositories {
     // Use Maven Central for resolving dependencies.
     mavenCentral()
+    maven("https://jitpack.io")
 }
 
 dependencies {
@@ -27,8 +28,8 @@ dependencies {
     // Use the Kotlin JDK 8 standard library.
     implementation("org.jetbrains.kotlin:kotlin-stdlib-jdk8")
 
-    // This dependency is used by the application.
-    implementation("com.google.guava:guava:30.1.1-jre")
+    implementation("com.github.kotlinx.ast:common:v0.1.0")
+    implementation("com.github.kotlinx.ast:grammar-kotlin-parser-antlr-kotlin:v0.1.0")
 }
 
 testing {

app/src/main/kotlin/ktcodeshift/FlattenListTransform.kt

@@ -0,0 +1,8 @@
+package ktcodeshift
+
+class FlattenListTransform : Transform {
+    override fun transform(fileInfo: FileInfo, api: Api): String {
+        val ast = api.parse(fileInfo.source)
+        return ast.toString()
+    }
+}

app/src/main/kotlin/ktcodeshift/KtCodeShift.kt

@@ -0,0 +1,11 @@
+package ktcodeshift
+
+import kotlinx.ast.common.AstSource
+import kotlinx.ast.common.ast.Ast
+import kotlinx.ast.grammar.kotlin.target.antlr.kotlin.KotlinGrammarAntlrKotlinParser
+
+fun applyTransform(transform: Transform, fileInfo: FileInfo): String {
+    val api = Api()
+    return transform.transform(fileInfo, api)
+}
+

app/src/main/kotlin/ktcodeshift/Transform.kt

@@ -0,0 +1,30 @@
+package ktcodeshift
+
+import kotlinx.ast.common.AstSource
+import kotlinx.ast.common.ast.Ast
+import kotlinx.ast.grammar.kotlin.target.antlr.kotlin.KotlinGrammarAntlrKotlinParser
+
+interface Transform {
+    fun transform(fileInfo: FileInfo, api: Api/*, options: Options*/): String
+}
+
+interface FileInfo {
+    val path: String
+    val source: String
+}
+
+//interface Api {
+//
+//}
+
+class Api {
+    fun parse(source: String): Ast {
+        val astSource = AstSource.String("file", source)
+        val ast = KotlinGrammarAntlrKotlinParser.parseKotlinFile(astSource)
+        return ast
+    }
+}
+
+//interface Options {
+//
+//}

app/src/test/kotlin/ktcodeshift/AppTest.kt

@@ -4,11 +4,25 @@
 package ktcodeshift
 
 import kotlin.test.Test
+import kotlin.test.assertEquals
 import kotlin.test.assertNotNull
 
 class AppTest {
-    @Test fun appHasAGreeting() {
-        val classUnderTest = App()
-        assertNotNull(classUnderTest.greeting, "app should have a greeting")
+    @Test
+    fun transform() {
+        val changedSource = applyTransform(FlattenListTransform(), object : FileInfo {
+            override val path = "Test.kt"
+            override val source = """
+                package testing
+                
+                val a = listOf(listOf(1, 2), listOf(3))
+            """.trimIndent()
+        })
+
+        assertEquals("""
+            package testing
+                
+            val a = listOf(1, 2, 3)
+        """.trimIndent(), changedSource)
     }
 }