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Merged
filiphr merged 3 commits into from
May 14, 2026
+671 −46
Merged

add support for generics in Arrays and fix initialization of multidimensional arrays #4050

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9574501
add support for generics in Arrays and fix initialization of multidim…
hduelme May 9, 2026
779b2b9
polish
filiphr May 14, 2026
a9969a4
fix whitespace
filiphr May 14, 2026
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54 changes: 41 additions & 13 deletions processor/src/main/java/org/mapstruct/ap/internal/model/common/Type.java
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Original file line number Diff line number Diff line change
Expand Up @@ -697,20 +697,34 @@ public Type replaceSuperBoundWith( Type compare, Type replacement ) {
return this;
}

DeclaredType declaredType = typeUtils.getDeclaredType(
TypeElement typeElementWithoutBounds;
Type componentTypeWithoutBounds;
TypeMirror typeMirrorWithoutBounds;
if ( this.componentType != null ) {
typeElementWithoutBounds = null;
componentTypeWithoutBounds = this.componentType.replaceSuperBoundWith( compare, replacement );
typeMirrorWithoutBounds = typeUtils.getArrayType( componentTypeWithoutBounds.getTypeMirror() );
}
else {
DeclaredType declaredType = typeUtils.getDeclaredType(
typeElement,
mirrors
);
);
typeMirrorWithoutBounds = declaredType;
typeElementWithoutBounds = (TypeElement) declaredType.asElement();
componentTypeWithoutBounds = null;
}

return new Type(
typeUtils,
elementUtils,
typeFactory,
accessorNaming,
declaredType,
(TypeElement) declaredType.asElement(),
typeMirrorWithoutBounds,
typeElementWithoutBounds,
bounds,
implementationType,
componentType,
componentTypeWithoutBounds,
packageName,
name,
qualifiedName,
Expand Down Expand Up @@ -740,20 +754,34 @@ public Type withoutBounds() {
mirrors.add( typeParameter.getTypeBound().getTypeMirror() );
}

DeclaredType declaredType = typeUtils.getDeclaredType(
typeElement,
mirrors.toArray( new TypeMirror[] {} )
);
TypeElement typeElementWithoutBounds;
Type componentTypeWithoutBounds;
TypeMirror typeMirrorWithoutBounds;
if ( this.componentType != null ) {
typeElementWithoutBounds = null;
componentTypeWithoutBounds = this.componentType.withoutBounds();
typeMirrorWithoutBounds = typeUtils.getArrayType( componentTypeWithoutBounds.getTypeMirror() );
}
else {
DeclaredType declaredType = typeUtils.getDeclaredType(
typeElement,
mirrors.toArray( new TypeMirror[] {} )
);
typeMirrorWithoutBounds = declaredType;
typeElementWithoutBounds = (TypeElement) declaredType.asElement();
componentTypeWithoutBounds = null;
}

return new Type(
typeUtils,
elementUtils,
typeFactory,
accessorNaming,
declaredType,
(TypeElement) declaredType.asElement(),
typeMirrorWithoutBounds,
typeElementWithoutBounds,
bounds,
implementationType,
componentType,
componentTypeWithoutBounds,
packageName,
name,
qualifiedName,
Expand All @@ -772,7 +800,7 @@ public Type withoutBounds() {
}

private Type replaceGeneric(Type oldGenericType, Type newType) {
if ( !typeParameters.contains( oldGenericType ) || newType == null ) {
if ( !typeParameters.contains( oldGenericType ) || newType == null || oldGenericType.equals( newType ) ) {
return this;
}
newType = newType.getBoxedEquivalent();
Expand Down
3 changes: 3 additions & 0 deletions processor/src/main/java/org/mapstruct/ap/internal/model/common/TypeFactory.java
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Original file line number Diff line number Diff line change
Expand Up @@ -518,6 +518,9 @@ private List<Type> extractTypes(List<? extends TypeMirror> typeMirrors) {
}

private List<Type> getTypeParameters(TypeMirror mirror, boolean isImplementationType) {
while ( mirror.getKind() == TypeKind.ARRAY ) {
mirror = getComponentType( mirror );
}
if ( mirror.getKind() != TypeKind.DECLARED ) {
return java.util.Collections.emptyList();
}
Expand Down
24 changes: 11 additions & 13 deletions processor/src/main/resources/org/mapstruct/ap/internal/model/IterableMappingMethod.ftl
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@

-->
<#-- @ftlvariable name="" type="org.mapstruct.ap.internal.model.IterableMappingMethod" -->
<#import "macro/CommonMacros.ftl" as lib>
<#list annotations as annotation>
<#nt><@includeModel object=annotation/>
</#list>
Expand All @@ -28,7 +29,7 @@
}
return<#if returnType.name != "void"> ${resultName}</#if>;
<#else>
return new <@includeModel object=resultElementType/>[0];
return <@lib.constructArrayType targetType=resultType targetSize=0/>;
</#if>
<#else>
<#if existingInstanceMapping>
Expand All @@ -43,8 +44,7 @@

<#if resultType.arrayType>
<#if !existingInstanceMapping>
<#assign elementTypeString><@includeModel object=resultElementType/></#assign>
${elementTypeString}[] ${resultName} = new ${elementTypeString?keep_before('[]')}[<@iterableSize/>]${elementTypeString?replace('[^\\[\\]]+', '', 'r')};
<@includeModel object=resultElementType/>[] ${resultName} = <@lib.constructArrayType targetType=resultType targetSize=iterableSize()/>;
</#if>
<#else>
<#if existingInstanceMapping>
Expand All @@ -64,7 +64,7 @@
int ${index1Name} = 0;
for ( <@includeModel object=sourceElementType/> ${loopVariableName} : ${sourceParameter.name} ) {
<#if existingInstanceMapping>
if ( ( ${index1Name} >= ${resultName}.length ) || ( ${index1Name} >= <@iterableSize/> ) ) {
if ( ( ${index1Name} >= ${resultName}.length ) || ( ${index1Name} >= ${iterableSize()} ) ) {
break;
}
</#if>
Expand Down Expand Up @@ -95,15 +95,13 @@
</#list>
</@compress>
</#macro>
<#macro iterableSize>
<@compress single_line=true>
<#if sourceParameter.type.arrayType>
${sourceParameter.name}.length
<#else>
${sourceParameter.name}.size()
</#if>
</@compress>
</#macro>
<#function iterableSize>
<#if sourceParameter.type.arrayType>
<#return sourceParameter.name + ".length">
<#else>
<#return sourceParameter.name + ".size()">
</#if>
</#function>
<#macro iterableLocalVarDef>
<@compress single_line=true>
<#if resultType.fullyQualifiedName == "java.lang.Iterable">
Expand Down
7 changes: 4 additions & 3 deletions processor/src/main/resources/org/mapstruct/ap/internal/model/StreamMappingMethod.ftl
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@

-->
<#-- @ftlvariable name="" type="org.mapstruct.ap.internal.model.StreamMappingMethod" -->
<#import "macro/CommonMacros.ftl" as lib>
<#list annotations as annotation>
<#nt><@includeModel object=annotation/>
</#list>
Expand All @@ -29,7 +30,7 @@
}
return<#if returnType.name != "void"> ${resultName}</#if>;
<#else>
return new <@includeModel object=resultElementType/>[0];
return <@lib.constructArrayType targetType=resultType targetSize=0/>;
</#if>
<#elseif resultType.iterableType>
<#if existingInstanceMapping>
Expand Down Expand Up @@ -88,15 +89,15 @@
<#if resultType.arrayType>
<#if existingInstanceMapping>
int ${index1Name} = 0;
for ( <@includeModel object=resultElementType/> ${loopVariableName} : ${sourceParameter.name}.limit( ${resultName}.length )<@streamMapSupplier />.toArray( ${resultElementType}[]::new ) ) {
for ( <@includeModel object=resultElementType/> ${loopVariableName} : ${sourceParameter.name}.limit( ${resultName}.length )<@streamMapSupplier />.toArray( <@includeModel object=resultElementType raw=true/>[]::new ) ) {
if ( ( ${index1Name} >= ${resultName}.length ) ) {
break;
}
${resultName}[${index1Name}++] = ${loopVariableName};
}
<#else>
<#if canReturnImmediatelly><#if returnType.name != "void">return </#if><#else> <#if needVarDefine>${resultElementType}[] <#else>${resultName} = </#if></#if>${sourceParameter.name}<@streamMapSupplier />
.toArray( <@includeModel object=resultElementType/>[]::new );
.toArray( <@includeModel object=resultElementType raw=true/>[]::new );
</#if>
<#elseif resultType.iterableType>
<#if existingInstanceMapping || !canReturnImmediatelly>
Expand Down
3 changes: 2 additions & 1 deletion processor/src/main/resources/org/mapstruct/ap/internal/model/common/Type.ftl
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,7 @@
<#elseif hasSuperBound()>
? super <@includeModel object=typeBound />
<#else>
<#if ext.asVarArgs!false>${createReferenceName()?remove_ending("[]")}...<#else>${createReferenceName()}</#if></#if><#if (!ext.raw?? && typeParameters?size > 0) ><<#list typeParameters as typeParameter><@includeModel object=typeParameter /><#if typeParameter_has_next>, </#if></#list>>
<#assign createReferenceName = createReferenceName() />
${createReferenceName?keep_before("[]")}<#if (!ext.raw?? && typeParameters?size > 0) ><<#list typeParameters as typeParameter><@includeModel object=typeParameter /><#if typeParameter_has_next>, </#if></#list>></#if>${createReferenceName?keep_after("[]")}<#if ext.asVarArgs!false>...<#elseif isArrayType()>[]</#if>
</#if>
</@compress>
8 changes: 7 additions & 1 deletion processor/src/main/resources/org/mapstruct/ap/internal/model/macro/CommonMacros.ftl
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Original file line number Diff line number Diff line change
Expand Up @@ -166,6 +166,12 @@ Performs a default assignment with a default value.
<@constructTargetObject targetType=ext.targetType/>
</#if>
</@compress></#macro>
<#--
-->
<#macro constructArrayType targetType targetSize><@compress single_line=true>
<#assign targetTypeString><@includeModel object=targetType raw=true/></#assign>
new ${targetTypeString?keep_before("[")}[${targetSize}]${targetTypeString?keep_after("]")}
</@compress></#macro>
<#--
macro: constructTargetObject

Expand All @@ -178,7 +184,7 @@ Performs a default assignment with a default value.
<#if targetType.implementationType??>
new <@includeModel object=targetType.implementationType raw=true/><#if targetType.implementationType.typeParameters?size != 0><></#if>()
<#elseif targetType.arrayType>
new <@includeModel object=targetType.componentType/>[0]
<@constructArrayType targetType=targetType targetSize=0/>
<#elseif targetType.sensibleDefault??>
${targetType.sensibleDefault}
<#elseif targetType.optionalType>
Expand Down
121 changes: 114 additions & 7 deletions processor/src/test/java/org/mapstruct/ap/test/array/ArrayMappingTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,9 @@
import java.util.List;

import org.junit.jupiter.api.extension.RegisterExtension;
import org.mapstruct.ap.test.array._target.GenericScientistDto;
import org.mapstruct.ap.test.array._target.ScientistDto;
import org.mapstruct.ap.test.array.source.GenericScientist;
import org.mapstruct.ap.test.array.source.Scientist;
import org.mapstruct.ap.testutil.IssueKey;
import org.mapstruct.ap.testutil.ProcessorTest;
Expand All @@ -18,7 +20,8 @@

import static org.assertj.core.api.Assertions.assertThat;

@WithClasses( { Scientist.class, ScientistDto.class, ScienceMapper.class } )
@WithClasses( { Scientist.class, ScientistDto.class, GenericScientist.class, GenericScientistDto.class,
ScienceMapper.class } )
@IssueKey("108")
public class ArrayMappingTest {

Expand Down Expand Up @@ -56,30 +59,134 @@ public void shouldForgeMappingForIntToString() {
}

@ProcessorTest
public void shouldMapArrayToArray() {
public void shouldMapArrayToArrayAndNullToNull() {
ScientistDto[] dtos = ScienceMapper.INSTANCE
.scientistsToDtos( new Scientist[]{ new Scientist( "Bob" ), new Scientist( "Larry" ) } );
.scientistsToDtosReturnNull( new Scientist[]{ new Scientist( "Bob" ), new Scientist( "Larry" ) } );

assertThat( dtos ).isNotNull();
assertThat( dtos ).extracting( "name" ).containsOnly( "Bob", "Larry" );

assertThat( ScienceMapper.INSTANCE.scientistsToDtosReturnNull( (Scientist[]) null ) ).isNull();
}

@ProcessorTest
public void shouldMapArrayToArrayAndNullToDefault() {
ScientistDto[] dtos = ScienceMapper.INSTANCE
.scientistsToDtosReturnDefault( new Scientist[]{ new Scientist( "Bob" ), new Scientist( "Larry" ) } );

assertThat( dtos ).isNotNull();
assertThat( dtos ).extracting( "name" ).containsOnly( "Bob", "Larry" );

assertThat( ScienceMapper.INSTANCE.scientistsToDtosReturnDefault( (Scientist[]) null ) ).isEmpty();
}

@ProcessorTest
public void shouldMapListToArray() {
public void shouldMapListToArrayAndNullToNull() {
ScientistDto[] dtos = ScienceMapper.INSTANCE
.scientistsToDtos( Arrays.asList( new Scientist( "Bob" ), new Scientist( "Larry" ) ) );
.scientistsToDtosReturnNull( Arrays.asList( new Scientist( "Bob" ), new Scientist( "Larry" ) ) );

assertThat( dtos ).isNotNull();
assertThat( dtos ).extracting( "name" ).containsOnly( "Bob", "Larry" );

assertThat( ScienceMapper.INSTANCE.scientistsToDtosReturnNull( (List<Scientist>) null ) ).isNull();
}

@ProcessorTest
public void shouldMapArrayToList() {
public void shouldMapListToArrayAndNullToDefault() {
ScientistDto[] dtos = ScienceMapper.INSTANCE
.scientistsToDtosReturnDefault( Arrays.asList( new Scientist( "Bob" ), new Scientist( "Larry" ) ) );

assertThat( dtos ).isNotNull();
assertThat( dtos ).extracting( "name" ).containsOnly( "Bob", "Larry" );

assertThat( ScienceMapper.INSTANCE.scientistsToDtosReturnDefault( (List<Scientist>) null ) ).isEmpty();
}

@ProcessorTest
public void shouldMapArrayToListAndNullToNull() {
List<ScientistDto> dtos = ScienceMapper.INSTANCE
.scientistsToDtosAsList( new Scientist[]{ new Scientist( "Bob" ), new Scientist( "Larry" ) } );
.scientistsToDtosAsListReturnNull( new Scientist[]{ new Scientist( "Bob" ), new Scientist( "Larry" ) } );

assertThat( dtos ).isNotNull();
assertThat( dtos ).extracting( "name" ).containsOnly( "Bob", "Larry" );

assertThat( ScienceMapper.INSTANCE.scientistsToDtosAsListReturnNull( null ) ).isNull();
}

@ProcessorTest
public void shouldMapArrayToListAndNullToDefault() {
List<ScientistDto> dtos = ScienceMapper.INSTANCE
.scientistsToDtosAsListReturnDefault(
new Scientist[]{ new Scientist( "Bob" ), new Scientist( "Larry" ) } );

assertThat( dtos ).isNotNull();
assertThat( dtos ).extracting( "name" ).containsOnly( "Bob", "Larry" );

assertThat( ScienceMapper.INSTANCE.scientistsToDtosAsListReturnDefault( null ) ).isEmpty();
}

@ProcessorTest
@SuppressWarnings("unchecked")
public void shouldMapGenericArrayToGenericArrayAndNullToNull() {
GenericScientistDto<String>[] dtos = ScienceMapper.INSTANCE
.genericScientistToDtosReturnNull(
new GenericScientist[]{ new GenericScientist<>( "Bob" ), new GenericScientist<>( "Larry" ) } );

assertThat( dtos ).isNotNull();
assertThat( dtos ).extracting( "name" ).containsOnly( "Bob", "Larry" );

assertThat( ScienceMapper.INSTANCE.genericScientistToDtosReturnNull( (GenericScientist<String>[]) null ) )
.isNull();
}

@ProcessorTest
@SuppressWarnings("unchecked")
public void shouldMapGenericArrayToGenericArrayAndNullToDefault() {
GenericScientistDto<String>[] dtos = ScienceMapper.INSTANCE.genericScientistToDtosReturnDefault(
new GenericScientist[]{ new GenericScientist<>( "Bob" ), new GenericScientist<>( "Larry" ) } );

assertThat( dtos ).isNotNull();
assertThat( dtos ).extracting( "name" ).containsOnly( "Bob", "Larry" );

assertThat( ScienceMapper.INSTANCE.genericScientistToDtosReturnDefault( (GenericScientist<String>[]) null ) )
.isEmpty();
}

@ProcessorTest
public void shouldMapListToGenericArrayAndNullToNull() {
GenericScientistDto<String>[] dtos = ScienceMapper.INSTANCE.genericScientistToDtosReturnNull(
Arrays.asList( new GenericScientist<>( "Bob" ), new GenericScientist<>( "Larry" ) ) );

assertThat( dtos ).isNotNull();
assertThat( dtos ).extracting( "name" ).containsOnly( "Bob", "Larry" );

assertThat( ScienceMapper.INSTANCE.genericScientistToDtosReturnNull( (List<GenericScientist<String>>) null ) )
.isNull();
}

@ProcessorTest
public void shouldMapListToGenericArrayAndNullToDefault() {
GenericScientistDto<String>[] dtos = ScienceMapper.INSTANCE
.genericScientistToDtosReturnDefault(
Arrays.asList( new GenericScientist<>("Bob"), new GenericScientist<>( "Larry" ) ) );

assertThat( dtos ).isNotNull();
assertThat( dtos ).extracting( "name" ).containsOnly( "Bob", "Larry" );

assertThat( ScienceMapper.INSTANCE
.genericScientistToDtosReturnDefault( (List<GenericScientist<String>>) null ) ).isEmpty();
}

@ProcessorTest
@SuppressWarnings("unchecked")
public void shouldMapGenericArrayToListAndNullToNull() {
List<GenericScientist<String>> dtos = ScienceMapper.INSTANCE.genericScientistToDtosAsList(
new GenericScientist[]{ new GenericScientist<>( "Bob" ), new GenericScientist<>( "Larry" ) } );

assertThat( dtos ).isNotNull();
assertThat( dtos ).extracting( "name" ).containsOnly( "Bob", "Larry" );

assertThat( ScienceMapper.INSTANCE.genericScientistToDtosAsList( null ) ).isNull();
}

@ProcessorTest
Expand Down
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