fix(model-api-gen): disable ModelQL generation by default

The generated code requires a dependency on the ModelQL runtime which
breaks existing projects.
You now have to specify a 'modelqlKotlinDir' to enable the generator
which is also useful if you have to split the generated API classes into
a separate subproject because of Kotlin compiler memory usage.

Author: slisson

model-api-gen-gradle-test/build.gradle.kts

@@ -91,6 +91,7 @@ metamodel {
     dependsOn(resolveMps)
     mpsHome = mpsDir
     kotlinDir = kotlinGenDir
+    modelqlKotlinDir = kotlinGenDir
     kotlinProject = project
     typescriptDir = projectDir.resolve("typescript_src")
     includeNamespace("jetbrains")

model-api-gen-gradle/src/main/kotlin/org/modelix/metamodel/gradle/GenerateMetaModelSources.kt

@@ -20,6 +20,10 @@ abstract class GenerateMetaModelSources @Inject constructor(of: ObjectFactory) :
     @Optional
     val kotlinOutputDir: DirectoryProperty = of.directoryProperty()
 
+    @get:OutputDirectory
+    @Optional
+    val modelqlKotlinOutputDir: DirectoryProperty = of.directoryProperty()
+
     @get:OutputDirectory
     @Optional
     val typescriptOutputDir: DirectoryProperty = of.directoryProperty()
@@ -79,7 +83,11 @@ abstract class GenerateMetaModelSources @Inject constructor(of: ObjectFactory) :
 
         val kotlinOutputDir = this.kotlinOutputDir.orNull?.asFile
         if (kotlinOutputDir != null) {
-            val generator = MetaModelGenerator(kotlinOutputDir.toPath(), nameConfig.get())
+            val generator = MetaModelGenerator(
+                kotlinOutputDir.toPath(),
+                nameConfig.get(),
+                this.modelqlKotlinOutputDir.orNull?.asFile?.toPath()
+            )
             generator.generate(processedLanguages)
             registrationHelperName.orNull?.let {
                 generator.generateRegistrationHelper(it, processedLanguages)

model-api-gen-gradle/src/main/kotlin/org/modelix/metamodel/gradle/MetaModelGradlePlugin.kt

@@ -86,6 +86,7 @@ class MetaModelGradlePlugin: Plugin<Project> {
         project.afterEvaluate {
             generateMetaModelSources.configure { task ->
                 settings.kotlinDir?.let { task.kotlinOutputDir.set(it) }
+                settings.modelqlKotlinDir?.let { task.modelqlKotlinOutputDir.set(it) }
                 settings.typescriptDir?.let { task.typescriptOutputDir.set(it) }
                 task.includedNamespaces.addAll(settings.includedLanguageNamespaces)
                 task.includedLanguages.addAll(settings.includedLanguages)

model-api-gen-gradle/src/main/kotlin/org/modelix/metamodel/gradle/MetaModelGradleSettings.kt

@@ -20,6 +20,7 @@ open class MetaModelGradleSettings {
     val includedConcepts: MutableSet<String> = HashSet()
     val includedModules: MutableSet<String> = HashSet()
     var kotlinDir: File? = null
+    var modelqlKotlinDir: File? = null
     var kotlinProject: Project? = null
         set(value) {
             if (kotlinDir == null && value != null) {

model-api-gen/src/main/kotlin/org/modelix/metamodel/generator/MetaModelGenerator.kt

@@ -14,7 +14,7 @@ import org.modelix.modelql.typed.TypedModelQL
 import java.nio.file.Path
 import kotlin.reflect.KClass
 
-class MetaModelGenerator(val outputDir: Path, val nameConfig: NameConfig = NameConfig()) {
+class MetaModelGenerator(val outputDir: Path, val nameConfig: NameConfig = NameConfig(), val modelqlOutputDir: Path? = null) {
     var alwaysUseNonNullableProperties: Boolean = true
 
     private val headerComment = "\ngenerated by modelix model-api-gen \n"
@@ -82,16 +82,18 @@ class MetaModelGenerator(val outputDir: Path, val nameConfig: NameConfig = NameC
                 FileSpec.builder(language.generatedClassName().packageName, language.generatedClassName().simpleName)
             val file = builder.addFileComment(headerComment)
                 .addType(generateLanguage(language)).build()
+            file.write()
+
             for (enum in language.getEnums()) {
                 generateEnumFile(enum)
             }
+
             for (concept in language.getConcepts()) {
                 generateConceptFile(concept)
-                if (concept.getOwnRoles().isNotEmpty()) {
+                if (modelqlOutputDir != null && concept.getOwnRoles().isNotEmpty()) {
                     generateModelQLFile(concept)
                 }
             }
-            file.write()
         }
     }
 
@@ -405,7 +407,7 @@ class MetaModelGenerator(val outputDir: Path, val nameConfig: NameConfig = NameC
                     }
                 }
             }
-            .build().write()
+            .build().writeTo(modelqlOutputDir!!)
     }
 
     private fun generateConceptObject(concept: ProcessedConcept): TypeSpec {