Implement copied key with ability to take default from source config

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

@@ -37,6 +37,18 @@ open class PropertiesCollection(protected var properties: Map<Key<*>, Any?> = em
         getDefaultValue: PropertiesCollection.() -> T?
     ) : Key<T>(name, getDefaultValue)
 
+    class CopiedKey<T>(
+        source: Key<T>,
+        getSourceProperties: PropertiesCollection.() -> PropertiesCollection?
+    ) : Key<T>(
+        source.name,
+        {
+            val sourceProperties = getSourceProperties()
+            if (sourceProperties == null) source.getDefaultValue(this)
+            else sourceProperties.get(source)
+        }
+    )
+
     class PropertyKeyDelegate<T>(private val getDefaultValue: PropertiesCollection.() -> T?, val isTransient: Boolean = false) {
         constructor(defaultValue: T?, isTransient: Boolean = false) : this({ defaultValue }, isTransient)
 
@@ -45,8 +57,10 @@ open class PropertiesCollection(protected var properties: Map<Key<*>, Any?> = em
             else Key(property.name, getDefaultValue)
     }
 
-    class PropertyKeyCopyDelegate<T>(val source: Key<T>) {
+    class PropertyKeyCopyDelegate<T>(
-        operator fun getValue(thisRef: Any?, property: KProperty<*>): Key<T> = source
+        val source: Key<T>, val getSourceProperties: PropertiesCollection.() -> PropertiesCollection? = { null }
+    ) {
+        operator fun getValue(thisRef: Any?, property: KProperty<*>): Key<T> = CopiedKey(source, getSourceProperties)
     }
 
     @Suppress("UNCHECKED_CAST")
@@ -87,7 +101,12 @@ open class PropertiesCollection(protected var properties: Map<Key<*>, Any?> = em
         fun <T> key(getDefaultValue: PropertiesCollection.() -> T?, isTransient: Boolean = false): PropertyKeyDelegate<T> =
             PropertyKeyDelegate(getDefaultValue, isTransient)
 
-        fun <T> keyCopy(source: Key<T>): PropertyKeyCopyDelegate<T> = PropertyKeyCopyDelegate(source)
+//        fun <T> keyCopy(source: Key<T>): PropertyKeyCopyDelegate<T> = PropertyKeyCopyDelegate(source)
+
+        fun <T> keyCopy(
+            source: Key<T>, getSourceProperties: PropertiesCollection.() -> PropertiesCollection? = { null }
+        ): PropertyKeyCopyDelegate<T> =
+            PropertyKeyCopyDelegate(source, getSourceProperties)
 
         @JvmStatic
         private val serialVersionUID = 1L

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

@@ -7,6 +7,8 @@ package kotlin.script.experimental.test
 
 import junit.framework.TestCase
 import org.junit.Test
+import kotlin.script.experimental.api.ScriptCompilationConfiguration
+import kotlin.script.experimental.api.ScriptCompilationConfigurationKeys
 import kotlin.script.experimental.host.ScriptingHostConfiguration
 import kotlin.script.experimental.host.ScriptingHostConfigurationKeys
 import kotlin.script.experimental.host.withDefaultsFrom
@@ -23,6 +25,7 @@ class ConfigurationsTest : TestCase() {
         val c2 = ScriptingHostConfiguration {
             p1(2)
             p2("yes")
+            p4("local")
         }
 
         assertEquals(c1, c1.withDefaultsFrom(c0))
@@ -35,8 +38,20 @@ class ConfigurationsTest : TestCase() {
         assertEquals(1, c1c2[ScriptingHostConfiguration.p1])
         assertEquals("yes", c1c2[ScriptingHostConfiguration.p2])
         assertEquals(2, c2c1[ScriptingHostConfiguration.p1])
+
+        assertEquals("from delegated", c1[ScriptingHostConfiguration.p4])
+        assertEquals("local", c2[ScriptingHostConfiguration.p4])
     }
 }
 
-private val ScriptingHostConfigurationKeys.p1 by PropertiesCollection.key<Int>(-1)
+private val ScriptingHostConfigurationKeys.p1 by PropertiesCollection.key(-1)
-private val ScriptingHostConfigurationKeys.p2 by PropertiesCollection.key<String>("-")
+private val ScriptingHostConfigurationKeys.p2 by PropertiesCollection.key("-")
+
+private val ScriptCompilationConfigurationKeys.p3 by PropertiesCollection.key<String>()
+
+private val delegatedConfig = ScriptCompilationConfiguration {
+    p3("from delegated")
+}
+
+private val ScriptingHostConfigurationKeys.p4 by PropertiesCollection.keyCopy(ScriptCompilationConfiguration.p3, { delegatedConfig })
+