Extraction Engine: Suggest function names based on the name of the result variable (if applicable)

#KT-6291 Fixed

idea/src/org/jetbrains/kotlin/idea/debugger/evaluate/extractFunctionForDebuggerUtil.kt

@@ -103,7 +103,7 @@ fun getFunctionForExtractedFragment(
 
         val config = ExtractionGeneratorConfiguration(
                 validationResult.descriptor,
-                ExtractionGeneratorOptions(inTempFile = true, flexibleTypesAllowed = true)
+                ExtractionGeneratorOptions(inTempFile = true, flexibleTypesAllowed = true, allowDummyName = true)
         )
         return config.generateDeclaration()
     }

idea/src/org/jetbrains/kotlin/idea/refactoring/introduce/extractFunction/ui/KotlinExtractFunctionDialog.form

@@ -99,14 +99,16 @@
               <visible value="true"/>
             </properties>
           </component>
-          <component id="bee3c" class="com.intellij.ui.EditorTextField" binding="functionNameField">
+          <grid id="d0f58" binding="functionNamePanel" layout-manager="BorderLayout" hgap="0" vgap="0">
             <constraints>
               <grid row="1" column="1" row-span="1" col-span="1" vsize-policy="0" hsize-policy="6" anchor="8" fill="1" indent="0" use-parent-layout="false">
                 <preferred-size width="150" height="-1"/>
               </grid>
             </constraints>
             <properties/>
-          </component>
+            <border type="none"/>
+            <children/>
+          </grid>
           <component id="71ee7" class="javax.swing.JComboBox" binding="visibilityBox">
             <constraints>
               <grid row="1" column="0" row-span="1" col-span="1" vsize-policy="0" hsize-policy="2" anchor="8" fill="0" indent="0" use-parent-layout="false">

idea/src/org/jetbrains/kotlin/idea/refactoring/introduce/extractFunction/ui/KotlinExtractFunctionDialog.java

@@ -16,19 +16,19 @@
 
 package org.jetbrains.kotlin.idea.refactoring.introduce.extractFunction.ui;
 
-import com.intellij.openapi.editor.event.DocumentAdapter;
-import com.intellij.openapi.editor.event.DocumentEvent;
 import com.intellij.openapi.project.Project;
 import com.intellij.openapi.ui.DialogWrapper;
 import com.intellij.psi.PsiElement;
-import com.intellij.ui.EditorTextField;
+import com.intellij.refactoring.ui.NameSuggestionsField;
 import com.intellij.ui.TitledSeparator;
+import com.intellij.util.ArrayUtil;
 import com.intellij.util.containers.ContainerUtil;
 import com.intellij.util.containers.MultiMap;
 import kotlin.Function0;
 import kotlin.Function1;
 import kotlin.Unit;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.kotlin.idea.JetFileType;
 import org.jetbrains.kotlin.idea.refactoring.JetNameSuggester;
 import org.jetbrains.kotlin.idea.refactoring.JetRefactoringBundle;
 import org.jetbrains.kotlin.idea.refactoring.RefactoringPackage;
@@ -36,6 +36,7 @@ import org.jetbrains.kotlin.idea.refactoring.introduce.extractionEngine.*;
 import org.jetbrains.kotlin.idea.util.IdeDescriptorRenderers;
 
 import javax.swing.*;
+import java.awt.*;
 import java.awt.event.ItemEvent;
 import java.awt.event.ItemListener;
 import java.util.ArrayList;
@@ -48,7 +49,8 @@ public class KotlinExtractFunctionDialog extends DialogWrapper {
     private TitledSeparator inputParametersPanel;
     private JComboBox visibilityBox;
     private KotlinFunctionSignatureComponent signaturePreviewField;
-    private EditorTextField functionNameField;
+    private JPanel functionNamePanel;
+    private NameSuggestionsField functionNameField;
     private JLabel functionNameLabel;
     private KotlinParameterTablePanel parameterTablePanel;
 
@@ -85,7 +87,7 @@ public class KotlinExtractFunctionDialog extends DialogWrapper {
     }
 
     private String getFunctionName() {
-        return functionNameField.getText();
+        return functionNameField.getEnteredName();
     }
 
     private String getVisibility() {
@@ -118,17 +120,21 @@ public class KotlinExtractFunctionDialog extends DialogWrapper {
     protected void init() {
         super.init();
 
-        functionNameLabel.setLabelFor(functionNameField);
+        functionNameField = new NameSuggestionsField(
-
+                ArrayUtil.toStringArray(originalDescriptor.getDescriptor().getSuggestedNames()),
-        functionNameField.setText(originalDescriptor.getDescriptor().getName());
+                project,
-        functionNameField.addDocumentListener(
+                JetFileType.INSTANCE
-                new DocumentAdapter() {
+        );
+        functionNameField.addDataChangedListener(
+                new NameSuggestionsField.DataChanged() {
                     @Override
-                    public void documentChanged(DocumentEvent event) {
+                    public void dataChanged() {
                         update();
                     }
                 }
         );
+        functionNamePanel.add(functionNameField, BorderLayout.CENTER);
+        functionNameLabel.setLabelFor(functionNameField);
 
         boolean enableVisibility = isVisibilitySectionAvailable();
         visibilityBox.setEnabled(enableVisibility);

idea/src/org/jetbrains/kotlin/idea/refactoring/introduce/extractionEngine/ExtractableCodeDescriptor.kt

@@ -363,7 +363,8 @@ val propertyTargets: List<ExtractionTarget> = listOf(ExtractionTarget.PROPERTY_W
 data class ExtractionGeneratorOptions(
         val inTempFile: Boolean = false,
         val target: ExtractionTarget = ExtractionTarget.FUNCTION,
-        val flexibleTypesAllowed: Boolean = false
+        val flexibleTypesAllowed: Boolean = false,
+        val allowDummyName: Boolean = false
 ) {
     default object {
         val DEFAULT = ExtractionGeneratorOptions()

idea/src/org/jetbrains/kotlin/idea/refactoring/introduce/extractionEngine/extractableAnalysisUtil.kt

@@ -72,8 +72,8 @@ import org.jetbrains.kotlin.resolve.calls.callUtil.*
 import org.jetbrains.kotlin.diagnostics.*
 import java.util.logging.*
 import com.intellij.openapi.diagnostic.Logger
+import org.jetbrains.kotlin.psi.psiUtil.getParentOfTypeAndBranch
 
-private val DEFAULT_FUNCTION_NAME = "myFun"
 private val DEFAULT_RETURN_TYPE = KotlinBuiltIns.getInstance().getUnitType()
 private val DEFAULT_PARAMETER_TYPE = KotlinBuiltIns.getInstance().getNullableAnyType()
 
@@ -804,19 +804,6 @@ fun ExtractionData.performAnalysis(): AnalysisResult {
     val enclosingDeclaration = commonParent.getStrictParentOfType<JetDeclaration>()!!
     checkDeclarationsMovingOutOfScope(enclosingDeclaration, controlFlow, bindingContext)?.let { messages.add(it) }
 
-    val functionNameValidator =
-            JetNameValidatorImpl(
-                    targetSibling.getParent(),
-                    if (targetSibling is JetClassInitializer) targetSibling.getParent() else targetSibling,
-                    if (options.extractAsProperty) JetNameValidatorImpl.Target.PROPERTIES else JetNameValidatorImpl.Target.FUNCTIONS_AND_CLASSES
-            )
-    val functionNames = if (returnType.isDefault()) {
-        Collections.emptyList<String>()
-    }
-    else {
-        JetNameSuggester.suggestNames(returnType, functionNameValidator, DEFAULT_FUNCTION_NAME).toList()
-    }
-
     controlFlow.jumpOutputValue?.elementToInsertAfterCall?.accept(
             object : JetTreeVisitorVoid() {
                 override fun visitSimpleNameExpression(expression: JetSimpleNameExpression) {
@@ -834,7 +821,7 @@ fun ExtractionData.performAnalysis(): AnalysisResult {
             ExtractableCodeDescriptor(
                     this,
                     bindingContext,
-                    functionNames,
+                    suggestFunctionNames(returnType),
                     getDefaultVisibility(),
                     adjustedParameters.sortBy { it.name },
                     receiverParameter,
@@ -847,6 +834,29 @@ fun ExtractionData.performAnalysis(): AnalysisResult {
     )
 }
 
+private fun ExtractionData.suggestFunctionNames(returnType: JetType): List<String> {
+    val functionNames = LinkedHashSet<String>()
+
+    val validator =
+            JetNameValidatorImpl(
+                    targetSibling.getParent(),
+                    if (targetSibling is JetClassInitializer) targetSibling.getParent() else targetSibling,
+                    if (options.extractAsProperty) JetNameValidatorImpl.Target.PROPERTIES else JetNameValidatorImpl.Target.FUNCTIONS_AND_CLASSES
+            )
+    if (!returnType.isDefault()) {
+        functionNames.addAll(JetNameSuggester.suggestNamesForType(returnType, validator))
+    }
+
+    getExpressions().singleOrNull()?.let { expr ->
+        val property = expr.getStrictParentOfType<JetProperty>()
+        if (property?.getInitializer() == expr) {
+            property?.getName()?.let { functionNames.add(validator.validateName("get" + it.capitalize())) }
+        }
+    }
+
+    return functionNames.toList()
+}
+
 private fun JetNamedDeclaration.getGeneratedBody() =
         when (this) {
             is JetNamedFunction -> getBodyExpression()

idea/src/org/jetbrains/kotlin/idea/refactoring/introduce/extractionEngine/extractorUtil.kt

@@ -90,7 +90,7 @@ fun ExtractionGeneratorConfiguration.getDeclarationText(
             builder.receiver(it.getParameterType(descriptor.extractionData.options.allowSpecialClassNames).typeAsString())
         }
 
-        builder.name(if (descriptor.name != "") descriptor.name else DEFAULT_FUNCTION_NAME)
+        builder.name(if (descriptor.name == "" && generatorOptions.allowDummyName) "myFun" else descriptor.name)
 
         descriptor.parameters.forEach { parameter ->
             builder.param(parameter.name,

idea/testData/refactoring/extractFunction/controlFlow/outputValues/outputValueWithExpression.kt

@@ -1,4 +1,5 @@
 // WITH_RUNTIME
+// SUGGESTED_NAMES: pair, getT
 // PARAM_TYPES: kotlin.Int
 // PARAM_TYPES: kotlin.Int
 // PARAM_DESCRIPTOR: value-parameter val a: kotlin.Int defined in foo

idea/testData/refactoring/extractFunction/controlFlow/outputValues/outputValueWithExpression.kt.after

@@ -1,4 +1,5 @@
 // WITH_RUNTIME
+// SUGGESTED_NAMES: pair, getT
 // PARAM_TYPES: kotlin.Int
 // PARAM_TYPES: kotlin.Int
 // PARAM_DESCRIPTOR: value-parameter val a: kotlin.Int defined in foo

idea/testData/refactoring/extractFunction/controlFlow/outputValues/outputValueWithSingleLineExpression.kt

@@ -1,3 +1,4 @@
+// SUGGESTED_NAMES: pair, getT
 // WITH_RUNTIME
 // PARAM_TYPES: kotlin.Int
 // PARAM_TYPES: kotlin.Int

idea/testData/refactoring/extractFunction/controlFlow/outputValues/outputValueWithSingleLineExpression.kt.after

@@ -1,3 +1,4 @@
+// SUGGESTED_NAMES: pair, getT
 // WITH_RUNTIME
 // PARAM_TYPES: kotlin.Int
 // PARAM_TYPES: kotlin.Int

idea/testData/refactoring/extractFunction/controlFlow/outputValues/outputValuesWithExpression.kt

@@ -1,4 +1,5 @@
 // WITH_RUNTIME
+// SUGGESTED_NAMES: triple, getT
 // PARAM_TYPES: kotlin.Int
 // PARAM_TYPES: kotlin.Int
 // PARAM_TYPES: kotlin.Int

idea/testData/refactoring/extractFunction/controlFlow/outputValues/outputValuesWithExpression.kt.after

@@ -1,4 +1,5 @@
 // WITH_RUNTIME
+// SUGGESTED_NAMES: triple, getT
 // PARAM_TYPES: kotlin.Int
 // PARAM_TYPES: kotlin.Int
 // PARAM_TYPES: kotlin.Int

idea/testData/refactoring/extractFunction/controlFlow/throws/evalExpressionWithThrow.kt

@@ -1,3 +1,4 @@
+// SUGGESTED_NAMES: i, getT
 // PARAM_TYPES: kotlin.Int
 // PARAM_TYPES: kotlin.Int
 // PARAM_DESCRIPTOR: value-parameter val a: kotlin.Int defined in foo

idea/testData/refactoring/extractFunction/controlFlow/throws/evalExpressionWithThrow.kt.after

@@ -1,3 +1,4 @@
+// SUGGESTED_NAMES: i, getT
 // PARAM_TYPES: kotlin.Int
 // PARAM_TYPES: kotlin.Int
 // PARAM_DESCRIPTOR: value-parameter val a: kotlin.Int defined in foo

idea/testData/refactoring/extractFunction/duplicates/branchingMatch1.kt

@@ -1,4 +1,5 @@
 // WITH_RUNTIME
+// SUGGESTED_NAMES: i, getT
 // PARAM_TYPES: kotlin.Int
 // PARAM_TYPES: kotlin.Int
 // PARAM_DESCRIPTOR: value-parameter val a: kotlin.Int defined in test

idea/testData/refactoring/extractFunction/duplicates/branchingMatch1.kt.after

@@ -1,4 +1,5 @@
 // WITH_RUNTIME
+// SUGGESTED_NAMES: i, getT
 // PARAM_TYPES: kotlin.Int
 // PARAM_TYPES: kotlin.Int
 // PARAM_DESCRIPTOR: value-parameter val a: kotlin.Int defined in test

idea/testData/refactoring/extractFunction/duplicates/insertAfterDuplicates.kt

@@ -1,3 +1,4 @@
+// SUGGESTED_NAMES: i, getX
 class A {
     val x = <selection>1 + 1</selection>
     val y = 1 + 1

idea/testData/refactoring/extractFunction/duplicates/insertAfterDuplicates.kt.after

@@ -1,3 +1,4 @@
+// SUGGESTED_NAMES: i, getX
 class A {
     val x = i()
     val y = i()

idea/testData/refactoring/extractFunction/duplicates/insertBeforeDuplicates.kt

@@ -1,3 +1,4 @@
+// SUGGESTED_NAMES: i, getY
 fun foo() {
     val x = 1 + 1
     val y = <selection>1 + 1</selection>

idea/testData/refactoring/extractFunction/duplicates/insertBeforeDuplicates.kt.after

@@ -1,3 +1,4 @@
+// SUGGESTED_NAMES: i, getY
 fun foo() {
     val x = i()
     val y = i()

idea/testData/refactoring/extractFunction/duplicates/nestedStrongMatch.kt

@@ -1,3 +1,4 @@
+// SUGGESTED_NAMES: i, getY
 // SIBLING:
 fun main(args: Array<String>) {
     val x = 1 + 1

idea/testData/refactoring/extractFunction/duplicates/nestedStrongMatch.kt.after

@@ -1,3 +1,4 @@
+// SUGGESTED_NAMES: i, getY
 // SIBLING:
 fun main(args: Array<String>) {
     val x = i()

idea/testData/refactoring/extractFunction/parameters/candidateTypes/flexibleTypesWithNull.kt

@@ -1,4 +1,5 @@
 // WITH_RUNTIME
+// SUGGESTED_NAMES: i, getN
 // PARAM_TYPES: String?, String, kotlin.CharSequence?, CharSequence
 // PARAM_DESCRIPTOR: val property: (String..String?) defined in test
 fun test() {

idea/testData/refactoring/extractFunction/parameters/candidateTypes/flexibleTypesWithNull.kt.after

@@ -1,4 +1,5 @@
 // WITH_RUNTIME
+// SUGGESTED_NAMES: i, getN
 // PARAM_TYPES: String?, String, kotlin.CharSequence?, CharSequence
 // PARAM_DESCRIPTOR: val property: (String..String?) defined in test
 fun test() {

idea/testData/refactoring/extractFunction/parameters/candidateTypes/flexibleTypesWithoutNull.kt

@@ -1,4 +1,5 @@
 // WITH_RUNTIME
+// SUGGESTED_NAMES: i, getN
 // PARAM_TYPES: String, CharSequence
 // PARAM_DESCRIPTOR: val property: (String..String?) defined in test
 fun test() {

idea/testData/refactoring/extractFunction/parameters/candidateTypes/flexibleTypesWithoutNull.kt.after

@@ -1,4 +1,5 @@
 // WITH_RUNTIME
+// SUGGESTED_NAMES: i, getN
 // PARAM_TYPES: String, CharSequence
 // PARAM_DESCRIPTOR: val property: (String..String?) defined in test
 fun test() {

idea/tests/org/jetbrains/kotlin/idea/refactoring/introduce/AbstractJetExtractionTest.kt

@@ -110,6 +110,7 @@ public abstract class AbstractJetExtractionTest() : JetLightCodeInsightFixtureTe
             )
 
             val fileText = file.getText() ?: ""
+            val expectedNames = InTextDirectivesUtils.findListWithPrefixes(fileText, "// SUGGESTED_NAMES: ")
             val expectedDescriptors =
                     InTextDirectivesUtils.findLinesWithPrefixesRemoved(fileText, "// PARAM_DESCRIPTOR: ").joinToString()
             val expectedTypes =
@@ -136,12 +137,16 @@ public abstract class AbstractJetExtractionTest() : JetLightCodeInsightFixtureTe
                                 descriptor: ExtractableCodeDescriptor,
                                 generatorOptions: ExtractionGeneratorOptions
                         ): ExtractionGeneratorConfiguration {
+                            val actualNames = descriptor.suggestedNames
                             val allParameters = emptyOrSingletonList(descriptor.receiverParameter) + descriptor.parameters
                             val actualDescriptors = allParameters.map { renderer.render(it.originalDescriptor) }.joinToString()
                             val actualTypes = allParameters.map {
                                 it.getParameterTypeCandidates(false).map { renderer.renderType(it) }.joinToString(", ", "[", "]")
                             }.joinToString()
 
+                            if (actualNames.size() != 1 || expectedNames.isNotEmpty()) {
+                                assertEquals(expectedNames, actualNames, "Expected names mismatch.")
+                            }
                             assertEquals(expectedDescriptors, actualDescriptors, "Expected descriptors mismatch.")
                             assertEquals(expectedTypes, actualTypes, "Expected types mismatch.")