#2668: Added support for collections and maps with a no-args constructor (#2671)

#2668: Added support for collections and maps with a no-args constructor. Added a compiler error in case of a collection or map without either a no-arg constructor or a copy constructor.

processor/src/main/java/org/mapstruct/ap/internal/model/CollectionAssignmentBuilder.java

@@ -5,19 +5,27 @@
  */
 package org.mapstruct.ap.internal.model;
 
+import java.util.function.Predicate;
+import javax.lang.model.element.Element;
+import javax.lang.model.element.ElementKind;
+import javax.lang.model.element.ExecutableElement;
+import javax.lang.model.element.Modifier;
+
+import org.mapstruct.ap.internal.gem.CollectionMappingStrategyGem;
+import org.mapstruct.ap.internal.gem.NullValueCheckStrategyGem;
+import org.mapstruct.ap.internal.gem.NullValuePropertyMappingStrategyGem;
 import org.mapstruct.ap.internal.model.assignment.ExistingInstanceSetterWrapperForCollectionsAndMaps;
 import org.mapstruct.ap.internal.model.assignment.GetterWrapperForCollectionsAndMaps;
+import org.mapstruct.ap.internal.model.assignment.NewInstanceSetterWrapperForCollectionsAndMaps;
 import org.mapstruct.ap.internal.model.assignment.SetterWrapperForCollectionsAndMaps;
 import org.mapstruct.ap.internal.model.assignment.SetterWrapperForCollectionsAndMapsWithNullCheck;
 import org.mapstruct.ap.internal.model.assignment.UpdateWrapper;
 import org.mapstruct.ap.internal.model.common.Assignment;
+import org.mapstruct.ap.internal.model.common.Assignment.AssignmentType;
 import org.mapstruct.ap.internal.model.common.SourceRHS;
 import org.mapstruct.ap.internal.model.common.Type;
 import org.mapstruct.ap.internal.model.source.Method;
 import org.mapstruct.ap.internal.model.source.SelectionParameters;
-import org.mapstruct.ap.internal.gem.CollectionMappingStrategyGem;
-import org.mapstruct.ap.internal.gem.NullValueCheckStrategyGem;
-import org.mapstruct.ap.internal.gem.NullValuePropertyMappingStrategyGem;
 import org.mapstruct.ap.internal.util.Message;
 import org.mapstruct.ap.internal.util.accessor.Accessor;
 import org.mapstruct.ap.internal.util.accessor.AccessorType;
@@ -169,7 +177,8 @@ public class CollectionAssignmentBuilder {
                     targetAccessorType.isFieldAssignment()
                 );
             }
-            else if ( setterWrapperNeedsSourceNullCheck( result ) ) {
+            else if ( setterWrapperNeedsSourceNullCheck( result )
+                && canBeMappedOrDirectlyAssigned( result ) ) {
 
                 result = new SetterWrapperForCollectionsAndMapsWithNullCheck(
                     result,
@@ -179,7 +188,7 @@ public class CollectionAssignmentBuilder {
                     targetAccessorType.isFieldAssignment()
                 );
             }
-            else {
+            else if ( canBeMappedOrDirectlyAssigned( result ) ) {
                 //TODO init default value
 
                 // target accessor is setter, so wrap the setter in setter map/ collection handling
@@ -190,6 +199,21 @@ public class CollectionAssignmentBuilder {
                     targetAccessorType.isFieldAssignment()
                 );
             }
+            else if ( hasNoArgsConstructor() ) {
+                result = new NewInstanceSetterWrapperForCollectionsAndMaps(
+                    result,
+                    method.getThrownTypes(),
+                    targetType,
+                    ctx.getTypeFactory(),
+                    targetAccessorType.isFieldAssignment() );
+            }
+            else {
+                ctx.getMessager().printMessage(
+                    method.getExecutable(),
+                    Message.PROPERTYMAPPING_NO_SUITABLE_COLLECTION_OR_MAP_CONSTRUCTOR,
+                    targetType
+                );
+            }
         }
         else {
             if ( targetImmutable ) {
@@ -212,6 +236,12 @@ public class CollectionAssignmentBuilder {
         return result;
     }
 
+    private boolean canBeMappedOrDirectlyAssigned(Assignment result) {
+        return result.getType() != AssignmentType.DIRECT
+                  || hasCopyConstructor()
+                  || targetType.isEnumSet();
+    }
+
     /**
      * Checks whether the setter wrapper should include a null / presence check or not
      *
@@ -236,4 +266,48 @@ public class CollectionAssignmentBuilder {
         return false;
     }
 
+    private boolean hasCopyConstructor() {
+        return checkConstructorForPredicate( this::hasCopyConstructor );
+    }
+
+    private boolean hasNoArgsConstructor() {
+        return checkConstructorForPredicate( this::hasNoArgsConstructor );
+    }
+
+    private boolean checkConstructorForPredicate(Predicate<Element> predicate) {
+        if ( targetType.isCollectionOrMapType() ) {
+            if ( "java.util".equals( targetType.getPackageName() ) ) {
+                return true;
+            }
+            else {
+                Element sourceElement = targetType.getImplementationType() != null
+                                      ? targetType.getImplementationType().getTypeElement()
+                                      : targetType.getTypeElement();
+                if ( sourceElement != null ) {
+                    for ( Element element : sourceElement.getEnclosedElements() ) {
+                        if ( element.getKind() == ElementKind.CONSTRUCTOR
+                            && element.getModifiers().contains( Modifier.PUBLIC ) ) {
+                            if ( predicate.test( element ) ) {
+                                return true;
+                            }
+                        }
+                    }
+                }
+            }
+        }
+        return false;
+    }
+
+    private boolean hasNoArgsConstructor(Element element) {
+        return ( (ExecutableElement) element ).getParameters().isEmpty();
+    }
+
+    private boolean hasCopyConstructor(Element element) {
+        if ( element instanceof ExecutableElement ) {
+            ExecutableElement ee = (ExecutableElement) element;
+            return ee.getParameters().size() == 1
+                && ctx.getTypeUtils().isAssignable( targetType.getTypeMirror(), ee.getParameters().get( 0 ).asType() );
+        }
+        return false;
+    }
 }

processor/src/main/java/org/mapstruct/ap/internal/model/assignment/NewInstanceSetterWrapperForCollectionsAndMaps.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright MapStruct Authors.
+ *
+ * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+ */
+package org.mapstruct.ap.internal.model.assignment;
+
+import java.util.List;
+
+import org.mapstruct.ap.internal.model.common.Assignment;
+import org.mapstruct.ap.internal.model.common.Type;
+import org.mapstruct.ap.internal.model.common.TypeFactory;
+
+/**
+ * This wrapper handles the situation where an assignment is done via the setter, while creating the collection or map
+ * using a no-args constructor.
+ *
+ * @author Ben Zegveld
+ */
+public class NewInstanceSetterWrapperForCollectionsAndMaps extends SetterWrapperForCollectionsAndMapsWithNullCheck {
+
+    private String instanceVar;
+
+    public NewInstanceSetterWrapperForCollectionsAndMaps(Assignment decoratedAssignment,
+        List<Type> thrownTypesToExclude,
+        Type targetType,
+        TypeFactory typeFactory,
+        boolean fieldAssignment) {
+
+        super(
+            decoratedAssignment,
+            thrownTypesToExclude,
+            targetType,
+            typeFactory,
+            fieldAssignment
+        );
+        this.instanceVar = decoratedAssignment.createUniqueVarName( targetType.getName() );
+    }
+
+    public String getInstanceVar() {
+        return instanceVar;
+    }
+}

processor/src/main/java/org/mapstruct/ap/internal/model/assignment/SetterWrapperForCollectionsAndMapsWithNullCheck.java

@@ -68,7 +68,7 @@ public class SetterWrapperForCollectionsAndMapsWithNullCheck extends WrapperForC
     }
 
     public boolean isEnumSet() {
-        return "java.util.EnumSet".equals( targetType.getFullyQualifiedName() );
+        return targetType.isEnumSet();
     }
 
 }

processor/src/main/java/org/mapstruct/ap/internal/model/common/Type.java

@@ -19,7 +19,6 @@ import java.util.Set;
 import java.util.function.Function;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
-
 import javax.lang.model.element.Element;
 import javax.lang.model.element.ElementKind;
 import javax.lang.model.element.ExecutableElement;
@@ -113,7 +112,6 @@ public class Type extends ModelElement implements Comparable<Type> {
     private List<Accessor> setters = null;
     private List<Accessor> adders = null;
     private List<Accessor> alternativeTargetAccessors = null;
-    private Map<String, Accessor> constructorAccessors = null;
 
     private Type boundingBase = null;
 
@@ -1603,4 +1601,8 @@ public class Type extends ModelElement implements Comparable<Type> {
         return parent == null ? null : typeFactory.getType( parent.asType() );
     }
 
+    public boolean isEnumSet() {
+        return "java.util.EnumSet".equals( getFullyQualifiedName() );
+    }
+
 }

processor/src/main/java/org/mapstruct/ap/internal/util/Message.java

@@ -80,6 +80,7 @@ public enum Message {
     PROPERTYMAPPING_WHITESPACE_TRIMMED( "The property named \"%s\" has whitespaces, using trimmed property \"%s\" instead.", Diagnostic.Kind.WARNING ),
     PROPERTYMAPPING_CANNOT_DETERMINE_SOURCE_PROPERTY_FROM_TARGET("The type of parameter \"%s\" has no property named \"%s\". Please define the source property explicitly."),
     PROPERTYMAPPING_CANNOT_DETERMINE_SOURCE_PARAMETER_FROM_TARGET("No property named \"%s\" exists in source parameter(s). Please define the source explicitly."),
+    PROPERTYMAPPING_NO_SUITABLE_COLLECTION_OR_MAP_CONSTRUCTOR( "%s does not have an accessible copy or no-args constructor." ),
 
     CONVERSION_LOSSY_WARNING( "%s has a possibly lossy conversion from %s to %s.", Diagnostic.Kind.WARNING ),
     CONVERSION_LOSSY_ERROR( "Can't map %s. It has a possibly lossy conversion from %s to %s." ),

processor/src/main/resources/org/mapstruct/ap/internal/model/assignment/NewInstanceSetterWrapperForCollectionsAndMaps.ftl

@@ -0,0 +1,23 @@
+<#--
+
+    Copyright MapStruct Authors.
+
+    Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+
+-->
+<#-- @ftlvariable name="" type="org.mapstruct.ap.internal.model.assignment.SetterWrapperForCollectionsAndMapsWithNullCheck" -->
+<#import "../macro/CommonMacros.ftl" as lib>
+<@lib.sourceLocalVarAssignment/>
+<@lib.handleExceptions>
+  <@callTargetWriteAccessor/>
+</@lib.handleExceptions>
+<#--
+  assigns the target via the regular target write accessor (usually the setter)
+-->
+<#macro callTargetWriteAccessor>
+  <@lib.handleLocalVarNullCheck needs_explicit_local_var=directAssignment>
+      <#if ext.targetType.implementationType??><@includeModel object=ext.targetType.implementationType/><#else><@includeModel object=ext.targetType/></#if> ${instanceVar} = new <#if ext.targetType.implementationType??><@includeModel object=ext.targetType.implementationType/><#else><@includeModel object=ext.targetType/></#if>();
+      ${instanceVar}.<#if ext.targetType.collectionType>addAll<#else>putAll</#if>( ${nullCheckLocalVarName} );
+      <#if ext.targetBeanName?has_content>${ext.targetBeanName}.</#if>${ext.targetWriteAccessorName}<@lib.handleWrite>${instanceVar}</@lib.handleWrite>;
+  </@lib.handleLocalVarNullCheck>
+</#macro>

processor/src/test/java/org/mapstruct/ap/test/bugs/_2668/Erroneous2668ListMapper.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright MapStruct Authors.
+ *
+ * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+ */
+package org.mapstruct.ap.test.bugs._2668;
+
+import java.util.ArrayList;
+
+import org.mapstruct.Mapper;
+import org.mapstruct.factory.Mappers;
+
+/**
+ * @author Ben Zegveld
+ */
+@Mapper
+public interface Erroneous2668ListMapper {
+
+    Erroneous2668ListMapper INSTANCE = Mappers.getMapper( Erroneous2668ListMapper.class );
+
+    CollectionTarget map(CollectionSource source);
+
+    class CollectionTarget {
+        MyArrayList list;
+
+        public MyArrayList getList() {
+            return list;
+        }
+
+        public void setList(MyArrayList list) {
+            this.list = list;
+        }
+    }
+
+    class CollectionSource {
+        MyArrayList list;
+
+        public MyArrayList getList() {
+            return list;
+        }
+
+        public void setList(MyArrayList list) {
+            this.list = list;
+        }
+    }
+
+    class MyArrayList extends ArrayList<String> {
+        private String unusable;
+
+        public MyArrayList(String unusable) {
+            this.unusable = unusable;
+        }
+    }
+}

processor/src/test/java/org/mapstruct/ap/test/bugs/_2668/Erroneous2668MapMapper.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright MapStruct Authors.
+ *
+ * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+ */
+package org.mapstruct.ap.test.bugs._2668;
+
+import java.util.HashMap;
+
+import org.mapstruct.Mapper;
+import org.mapstruct.factory.Mappers;
+
+/**
+ * @author Ben Zegveld
+ */
+@Mapper
+public interface Erroneous2668MapMapper {
+
+    Erroneous2668MapMapper INSTANCE = Mappers.getMapper( Erroneous2668MapMapper.class );
+
+    CollectionTarget map(CollectionSource source);
+
+    class CollectionTarget {
+        MyHashMap map;
+
+        public MyHashMap getMap() {
+            return map;
+        }
+
+        public void setMap(MyHashMap map) {
+            this.map = map;
+        }
+    }
+
+    class CollectionSource {
+        MyHashMap map;
+
+        public MyHashMap getMap() {
+            return map;
+        }
+
+        public void setMap(MyHashMap map) {
+            this.map = map;
+        }
+    }
+
+    class MyHashMap extends HashMap<String, String> {
+        private String unusable;
+
+        public MyHashMap(String unusable) {
+            this.unusable = unusable;
+        }
+    }
+}

processor/src/test/java/org/mapstruct/ap/test/bugs/_2668/Issue2668Mapper.java

@@ -0,0 +1,120 @@
+/*
+ * Copyright MapStruct Authors.
+ *
+ * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+ */
+package org.mapstruct.ap.test.bugs._2668;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.HashMap;
+
+import org.mapstruct.Mapper;
+import org.mapstruct.factory.Mappers;
+
+/**
+ * @author Ben Zegveld
+ */
+@Mapper
+public interface Issue2668Mapper {
+
+    Issue2668Mapper INSTANCE = Mappers.getMapper( Issue2668Mapper.class );
+
+    CollectionTarget map(CollectionSource source);
+
+    class CollectionTarget {
+        MyArrayList list;
+        MyHashMap map;
+        MyCopyArrayList copyList;
+        MyCopyHashMap copyMap;
+
+        public MyArrayList getList() {
+            return list;
+        }
+
+        public MyHashMap getMap() {
+            return map;
+        }
+
+        public void setList(MyArrayList list) {
+            this.list = list;
+        }
+
+        public void setMap(MyHashMap map) {
+            this.map = map;
+        }
+
+        public MyCopyArrayList getCopyList() {
+            return copyList;
+        }
+
+        public MyCopyHashMap getCopyMap() {
+            return copyMap;
+        }
+
+        public void setCopyList(MyCopyArrayList copyList) {
+            this.copyList = copyList;
+        }
+
+        public void setCopyMap(MyCopyHashMap copyMap) {
+            this.copyMap = copyMap;
+        }
+    }
+
+    class CollectionSource {
+        MyArrayList list;
+        MyHashMap map;
+        MyCopyArrayList copyList;
+        MyCopyHashMap copyMap;
+
+        public MyArrayList getList() {
+            return list;
+        }
+
+        public MyHashMap getMap() {
+            return map;
+        }
+
+        public void setList(MyArrayList list) {
+            this.list = list;
+        }
+
+        public void setMap(MyHashMap map) {
+            this.map = map;
+        }
+
+        public MyCopyArrayList getCopyList() {
+            return copyList;
+        }
+
+        public MyCopyHashMap getCopyMap() {
+            return copyMap;
+        }
+
+        public void setCopyList(MyCopyArrayList copyList) {
+            this.copyList = copyList;
+        }
+
+        public void setCopyMap(MyCopyHashMap copyMap) {
+            this.copyMap = copyMap;
+        }
+    }
+
+    class MyArrayList extends ArrayList<String> {
+    }
+
+    class MyHashMap extends HashMap<String, String> {
+    }
+
+    class MyCopyArrayList extends ArrayList<String> {
+        public MyCopyArrayList(Collection<String> copy) {
+            super( copy );
+        }
+    }
+
+    class MyCopyHashMap extends HashMap<String, String> {
+        public MyCopyHashMap(HashMap<String, String> copy) {
+            super( copy );
+        }
+    }
+}

processor/src/test/java/org/mapstruct/ap/test/bugs/_2668/Issue2668Test.java

@@ -0,0 +1,59 @@
+/*
+ * Copyright MapStruct Authors.
+ *
+ * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+ */
+package org.mapstruct.ap.test.bugs._2668;
+
+import javax.tools.Diagnostic.Kind;
+
+import org.mapstruct.ap.testutil.IssueKey;
+import org.mapstruct.ap.testutil.ProcessorTest;
+import org.mapstruct.ap.testutil.WithClasses;
+import org.mapstruct.ap.testutil.compilation.annotation.CompilationResult;
+import org.mapstruct.ap.testutil.compilation.annotation.Diagnostic;
+import org.mapstruct.ap.testutil.compilation.annotation.ExpectedCompilationOutcome;
+
+/**
+ * @author Ben Zegveld
+ */
+@IssueKey( "2668" )
+class Issue2668Test {
+
+    @ProcessorTest
+    @WithClasses( Issue2668Mapper.class )
+    void shouldCompileCorrectlyWithAvailableConstructors() {
+    }
+
+    @ProcessorTest
+    @WithClasses( Erroneous2668ListMapper.class )
+    @ExpectedCompilationOutcome(
+        value = CompilationResult.FAILED,
+        diagnostics = {
+            @Diagnostic(
+                kind = Kind.ERROR,
+                line = 21,
+                message = "org.mapstruct.ap.test.bugs._2668.Erroneous2668ListMapper.MyArrayList"
+                        + " does not have an accessible copy or no-args constructor."
+                )
+            }
+        )
+    void errorExpectedBecauseCollectionIsNotUsable() {
+    }
+
+    @ProcessorTest
+    @WithClasses( Erroneous2668MapMapper.class )
+    @ExpectedCompilationOutcome(
+        value = CompilationResult.FAILED,
+        diagnostics = {
+            @Diagnostic(
+                kind = Kind.ERROR,
+                line = 21,
+                message = "org.mapstruct.ap.test.bugs._2668.Erroneous2668MapMapper.MyHashMap"
+                        + " does not have an accessible copy or no-args constructor."
+                )
+            }
+        )
+    void errorExpectedBecauseMapIsNotUsable() {
+    }
+}