Implement support for "resX" result fields in REPL

compiler/frontend/src/org/jetbrains/kotlin/resolve/lazy/descriptors/LazyScriptClassMemberScope.kt

@@ -53,9 +53,8 @@ class LazyScriptClassMemberScope(
             )
             var paramsIndexBase = baseConstructorDescriptor.valueParameters.lastIndex + 1
             val syntheticParameters =
-                (implicitReceiversParamTypes + environmentVarsParamTypes).mapNotNull { param: Pair<String, KotlinType> ->
-                    if (param == null) null
-                    else ValueParameterDescriptorImpl(
+                (implicitReceiversParamTypes + environmentVarsParamTypes).map { param: Pair<String, KotlinType> ->
+                    ValueParameterDescriptorImpl(
                         constructorDescriptor,
                         null,
                         paramsIndexBase++,
@@ -90,6 +89,15 @@ class LazyScriptClassMemberScope(
         return constructor
     }
 
+    override fun getNonDeclaredProperties(name: Name, result: MutableSet<PropertyDescriptor>) {
+        super.getNonDeclaredProperties(name, result)
+        if (scriptDescriptor.resultFieldName() == name.asString()) {
+            scriptDescriptor.resultValue?.let {
+                result.add(it)
+            }
+        }
+    }
+
     override fun createPropertiesFromPrimaryConstructorParameters(name: Name, result: MutableSet<PropertyDescriptor>) {
     }
 

compiler/frontend/src/org/jetbrains/kotlin/resolve/lazy/descriptors/LazyScriptDescriptor.kt

@@ -24,6 +24,11 @@ import org.jetbrains.kotlin.diagnostics.DiagnosticFactory1
 import org.jetbrains.kotlin.diagnostics.Errors
 import org.jetbrains.kotlin.name.ClassId
 import org.jetbrains.kotlin.name.Name
+import org.jetbrains.kotlin.psi.KtBlockExpression
+import org.jetbrains.kotlin.psi.KtExpression
+import org.jetbrains.kotlin.psi.KtScriptInitializer
+import org.jetbrains.kotlin.psi.psiUtil.getChildOfType
+import org.jetbrains.kotlin.psi.psiUtil.getChildrenOfType
 import org.jetbrains.kotlin.resolve.BindingContext
 import org.jetbrains.kotlin.resolve.descriptorUtil.builtIns
 import org.jetbrains.kotlin.resolve.descriptorUtil.module
@@ -31,6 +36,7 @@ import org.jetbrains.kotlin.resolve.lazy.LazyClassContext
 import org.jetbrains.kotlin.resolve.lazy.ResolveSession
 import org.jetbrains.kotlin.resolve.lazy.data.KtScriptInfo
 import org.jetbrains.kotlin.resolve.lazy.declarations.ClassMemberDeclarationProvider
+import org.jetbrains.kotlin.resolve.lazy.descriptors.script.ReplResultPropertyDescriptor
 import org.jetbrains.kotlin.resolve.lazy.descriptors.script.ScriptEnvironmentDescriptor
 import org.jetbrains.kotlin.resolve.lazy.descriptors.script.classId
 import org.jetbrains.kotlin.resolve.scopes.LexicalScope
@@ -40,6 +46,8 @@ import org.jetbrains.kotlin.resolve.source.toSourceElement
 import org.jetbrains.kotlin.script.KotlinScriptDefinition
 import org.jetbrains.kotlin.script.ScriptPriorities
 import org.jetbrains.kotlin.types.TypeSubstitutor
+import org.jetbrains.kotlin.types.typeUtil.isNothing
+import org.jetbrains.kotlin.types.typeUtil.isUnit
 import kotlin.reflect.KClass
 import kotlin.reflect.KType
 
@@ -59,6 +67,42 @@ class LazyScriptDescriptor(
         resolveSession.trace.record(BindingContext.SCRIPT, scriptInfo.script, this)
     }
 
+    val resultValue: ReplResultPropertyDescriptor? by lazy { provideResultValue() }
+
+    private fun provideResultValue(): ReplResultPropertyDescriptor? {
+        val expression = scriptInfo.script
+            .getChildOfType<KtBlockExpression>()
+            ?.getChildrenOfType<KtScriptInitializer>()?.lastOrNull()
+            ?.getChildOfType<KtExpression>()
+
+        val type = expression?.let {
+            resolveSession.trace.bindingContext.getType(it)
+        }
+
+        return if (type != null && !type.isUnit() && !type.isNothing()) {
+            resultFieldName()?.let {
+                ReplResultPropertyDescriptor(
+                    Name.identifier(it),
+                    type,
+                    this.thisAsReceiverParameter,
+                    this,
+                    expression.toSourceElement()
+                )
+            }
+        } else null
+    }
+
+    fun resultFieldName(): String? {
+        val scriptPriority = scriptInfo.script.getUserData(ScriptPriorities.PRIORITY_KEY)
+        if (scriptPriority != null) {
+            return "res$scriptPriority"
+        }
+        val scriptName = name.asString()
+        return if (scriptName.startsWith("Line_")) {
+            "res${scriptName.split("_")[1]}"
+        } else "\$\$result"
+    }
+
     private val sourceElement = scriptInfo.script.toSourceElement()
 
     override fun getSource() = sourceElement

compiler/frontend/src/org/jetbrains/kotlin/resolve/lazy/descriptors/script/ReplResultPropertyDescriptor.kt

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2010-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.resolve.lazy.descriptors.script
+
+import org.jetbrains.kotlin.descriptors.*
+import org.jetbrains.kotlin.descriptors.annotations.Annotations
+import org.jetbrains.kotlin.descriptors.impl.PropertyDescriptorImpl
+import org.jetbrains.kotlin.name.Name
+import org.jetbrains.kotlin.resolve.lazy.descriptors.LazyScriptDescriptor
+import org.jetbrains.kotlin.types.KotlinType
+
+class ReplResultPropertyDescriptor(
+    name: Name,
+    kotlinType: KotlinType,
+    receiver: ReceiverParameterDescriptor?,
+    script: LazyScriptDescriptor,
+    source: SourceElement
+) : PropertyDescriptorImpl(
+    script,
+    null,
+    Annotations.EMPTY,
+    Modality.FINAL,
+    Visibilities.PUBLIC,
+    false,
+    name,
+    CallableMemberDescriptor.Kind.SYNTHESIZED,
+    source,
+    /* lateInit = */ false, /* isConst = */ false, /* isExpect = */ false, /* isActual = */ false, /* isExternal = */ false,
+    /* isDelegated = */ false
+) {
+    init {
+        setType(kotlinType, emptyList(), receiver, null)
+        initialize(
+            null, null
+        )
+    }
+}