Implement more general "apply defaults" functionality for host configurations

libraries/scripting/common/build.gradle.kts

@@ -11,11 +11,12 @@ dependencies {
     compileOnly(project(":kotlin-reflect-api"))
     compile(commonDep("org.jetbrains.kotlinx", "kotlinx-coroutines-core")) { isTransitive = false }
     runtime(project(":kotlin-reflect"))
+    testCompile(commonDep("junit"))
 }
 
 sourceSets {
     "main" { projectDefault() }
-    "test" {}
+    "test" { projectDefault() }
 }
 
 publish()

libraries/scripting/common/src/kotlin/script/experimental/host/configurationFromTemplate.kt

@@ -23,23 +23,23 @@ private abstract class DummyScriptTemplate
 /**
  * Creates compilation configuration from annotated script base class
  * @param baseClassType the annotated script base class to construct the configuration from
- * @param hostConfiguration scripting host configuration properties
+ * @param baseHostConfiguration scripting host configuration properties
  * @param contextClass optional context class to extract classloading strategy from
  * @param body optional configuration function to add more properties to the compilation configuration
  */
 fun createCompilationConfigurationFromTemplate(
     baseClassType: KotlinType,
-    hostConfiguration: ScriptingHostConfiguration,
+    baseHostConfiguration: ScriptingHostConfiguration,
     contextClass: KClass<*> = ScriptCompilationConfiguration::class,
     body: ScriptCompilationConfiguration.Builder.() -> Unit = {}
 ): ScriptCompilationConfiguration {
 
-    val templateClass: KClass<*> = baseClassType.getTemplateClass(hostConfiguration, contextClass)
+    val templateClass: KClass<*> = baseClassType.getTemplateClass(baseHostConfiguration, contextClass)
 
     val mainAnnotation: KotlinScript = templateClass.kotlinScriptAnnotation
 
     return ScriptCompilationConfiguration(scriptConfigInstance(mainAnnotation.compilationConfiguration)) {
-        hostConfiguration(hostConfiguration)
+        hostConfiguration.update { it.withDefaultsFrom(baseHostConfiguration) }
         propertiesFromTemplate(templateClass, baseClassType, mainAnnotation)
         body()
     }
@@ -48,23 +48,23 @@ fun createCompilationConfigurationFromTemplate(
 /**
  * Creates evaluation configuration from annotated script base class
  * @param baseClassType the annotated script base class to construct the configuration from
- * @param hostConfiguration scripting host configuration properties
+ * @param baseHostConfiguration scripting host configuration properties
  * @param contextClass optional context class to extract classloading strategy from
  * @param body optional configuration function to add more properties to the evaluation configuration
  */
 fun createEvaluationConfigurationFromTemplate(
     baseClassType: KotlinType,
-    hostConfiguration: ScriptingHostConfiguration,
+    baseHostConfiguration: ScriptingHostConfiguration,
     contextClass: KClass<*> = ScriptEvaluationConfiguration::class,
     body: ScriptEvaluationConfiguration.Builder.() -> Unit = {}
 ): ScriptEvaluationConfiguration {
 
-    val templateClass: KClass<*> = baseClassType.getTemplateClass(hostConfiguration, contextClass)
+    val templateClass: KClass<*> = baseClassType.getTemplateClass(baseHostConfiguration, contextClass)
 
     val mainAnnotation = templateClass.kotlinScriptAnnotation
 
     return ScriptEvaluationConfiguration(scriptConfigInstance(mainAnnotation.evaluationConfiguration)) {
-        hostConfiguration(hostConfiguration)
+        hostConfiguration.update { it.withDefaultsFrom(baseHostConfiguration) }
         body()
     }
 }

libraries/scripting/common/src/kotlin/script/experimental/host/hostConfiguration.kt

@@ -43,6 +43,16 @@ fun ScriptingHostConfiguration?.with(body: ScriptingHostConfiguration.Builder.()
     return if (newConfiguration != this) newConfiguration else this
 }
 
+/**
+ * Add the values not explicitly set in the receiver from the [defaults] configuration
+ */
+fun ScriptingHostConfiguration?.withDefaultsFrom(defaults: ScriptingHostConfiguration): ScriptingHostConfiguration =
+    when {
+        this == defaults || defaults.isEmpty() -> this ?: defaults
+        this == null || this.isEmpty() -> defaults
+        else -> ScriptingHostConfiguration(defaults, this)
+    }
+
 /**
  * The list of all dependencies required for the script base class and refinement callbacks
  */

libraries/scripting/common/src/kotlin/script/experimental/util/propertiesCollection.kt

@@ -123,6 +123,10 @@ open class PropertiesCollection(protected var properties: Map<Key<*>, Any?> = em
             }
         }
 
+        fun <T> PropertiesCollection.Key<T>.update(body: (T?) -> T?) {
+            putIfNotNull(body(data[this]?.let { it as T }))
+        }
+
         // generic for lists
 
         fun <T> PropertiesCollection.Key<in List<T>>.putIfAny(vals: Iterable<T>?) {

libraries/scripting/common/test/kotlin/script/experimental/test/ConfigurationsTest.kt

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package kotlin.script.experimental.test
+
+import junit.framework.TestCase
+import org.junit.Test
+import kotlin.script.experimental.host.ScriptingHostConfiguration
+import kotlin.script.experimental.host.ScriptingHostConfigurationKeys
+import kotlin.script.experimental.host.withDefaultsFrom
+import kotlin.script.experimental.util.PropertiesCollection
+
+class ConfigurationsTest : TestCase() {
+
+    @Test
+    fun testHostConfigWithDefaultsFrom() {
+        val c0 = ScriptingHostConfiguration()
+        val c1 = ScriptingHostConfiguration {
+            p1(1)
+        }
+        val c2 = ScriptingHostConfiguration {
+            p1(2)
+            p2("yes")
+        }
+
+        assertEquals(c1, c1.withDefaultsFrom(c0))
+        assertEquals(c1, c0.withDefaultsFrom(c1))
+        assertEquals(c1, c1.withDefaultsFrom(c1))
+
+        val c1c2 = c1.withDefaultsFrom(c2)
+        val c2c1 = c2.withDefaultsFrom(c1)
+
+        assertEquals(1, c1c2[ScriptingHostConfiguration.p1])
+        assertEquals("yes", c1c2[ScriptingHostConfiguration.p2])
+        assertEquals(2, c2c1[ScriptingHostConfiguration.p1])
+    }
+}
+
+private val ScriptingHostConfigurationKeys.p1 by PropertiesCollection.key<Int>(-1)
+private val ScriptingHostConfigurationKeys.p2 by PropertiesCollection.key<String>("-")