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Support getting a value or invoking a supplier if the value is not set #24

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bdb6343
Support getting a value or invoking a supplier if the value is not set
hduelme Mar 16, 2026
91df785
added test for public api
hduelme Mar 16, 2026
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17 changes: 17 additions & 0 deletions api/pom.xml
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,19 @@
<packaging>jar</packaging>
<name>MapStruct Tools Gem API</name>

<dependencies>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.assertj</groupId>
<artifactId>assertj-core</artifactId>
<scope>test</scope>
</dependency>
</dependencies>

<build>
<plugins>
<plugin>
Expand Down Expand Up @@ -71,6 +84,10 @@
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
</plugin>
<plugin>
<groupId>org.apache.felix</groupId>
<artifactId>maven-bundle-plugin</artifactId>
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11 changes: 11 additions & 0 deletions api/src/main/java/org/mapstruct/tools/gem/GemValue.java
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Expand Up @@ -8,6 +8,7 @@
import java.util.ArrayList;
import java.util.List;
import java.util.function.Function;
import java.util.function.Supplier;
import javax.lang.model.element.AnnotationMirror;
import javax.lang.model.element.AnnotationValue;
import javax.lang.model.element.AnnotationValueVisitor;
Expand Down Expand Up @@ -113,6 +114,16 @@ public T getValue() {
return value;
}

/**
* Returns the value set by the user, if present, otherwise invoke other and return the result of that invocation.
*
* @param other a Supplier whose result is returned if no value is present
* @return the value set by the user, if present, otherwise the result of {@code other.get()}
*/
public T getValueOrElseGet(Supplier<T> other) {
return value != null ? value : other.get();
}

/**
* The default value, as declared in the annotation
*
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195 changes: 195 additions & 0 deletions api/src/test/java/org/mapstruct/tools/gem/GemValueTest.java
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@@ -0,0 +1,195 @@
/*
* Copyright MapStruct Authors.
*
* Licensed under the Apache License version 2.0, available at https://www.apache.org/licenses/LICENSE-2.0
*/
package org.mapstruct.tools.gem;

import org.junit.jupiter.api.Nested;
import org.junit.jupiter.api.Test;

import javax.lang.model.element.AnnotationValue;
import javax.lang.model.element.AnnotationValueVisitor;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

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

class GemValueTest {

static class SimpleAnnotationValue implements AnnotationValue {

private final int value;

SimpleAnnotationValue(int value) {
this.value = value;
}

@Override
public Object getValue() {
return value;
}

@Override
public <R, P> R accept(AnnotationValueVisitor<R, P> v, P p) {
return v.visitInt( value, p );
}
}

@Nested
class CreateSimpleValueTest {

@Test
void createSimpleValue() {
SimpleAnnotationValue annotationValue = new SimpleAnnotationValue(1);
GemValue<Integer> gemValue = GemValue.create( annotationValue, new SimpleAnnotationValue(2),
Integer.class );
assertThat( gemValue ).isNotNull();
assertThat( gemValue.isValid() ).isTrue();
assertThat( gemValue.hasValue() ).isTrue();
assertThat( gemValue.getValue() ).isEqualTo( 1 );
assertThat( gemValue.getDefaultValue() ).isEqualTo( 2 );
assertThat( gemValue.get() ).as( "get should return value" ).isEqualTo( 1 );
assertThat( gemValue.getAnnotationValue() ).isEqualTo( annotationValue );
assertThat( gemValue.getValueOrElseGet( () -> 3 ) )
.as( "getValueOrElseGet should return value" ).isEqualTo( 1 );
}

@Test
void createSimpleValueWithoutAnnotationValue() {
GemValue<Integer> gemValue = GemValue.create( null, new SimpleAnnotationValue(2),
Integer.class );
assertThat( gemValue ).isNotNull();
assertThat( gemValue.isValid() ).isTrue();
assertThat( gemValue.hasValue() ).isFalse();
assertThat( gemValue.getValue() ).isNull();
assertThat( gemValue.getDefaultValue() ).isEqualTo( 2 );
assertThat( gemValue.get() ).as( "get should return defaultValue" ).isEqualTo( 2 );
assertThat( gemValue.getAnnotationValue() ).isNull();
assertThat( gemValue.getValueOrElseGet( () -> 3 ) )
.as( "getValueOrElseGet should return other" ).isEqualTo( 3 );
}

@Test
void createSimpleValueWithoutAnnotationDefaultValue() {
SimpleAnnotationValue annotationValue = new SimpleAnnotationValue(1);
GemValue<Integer> gemValue = GemValue.create( annotationValue, null, Integer.class );
assertThat( gemValue ).isNotNull();
assertThat( gemValue.isValid() ).isTrue();
assertThat( gemValue.hasValue() ).isTrue();
assertThat( gemValue.getValue() ).isEqualTo( 1 );
assertThat( gemValue.getDefaultValue() ).isNull();
assertThat( gemValue.get() ).as( "get should return value" ).isEqualTo( 1 );
assertThat( gemValue.getAnnotationValue() ).isEqualTo( annotationValue );
assertThat( gemValue.getValueOrElseGet( () -> 3 ) )
.as( "getValueOrElseGet should return value" ).isEqualTo( 1 );
}

@Test
void createSimpleValueInvalid() {
GemValue<Integer> gemValue = GemValue.create( null, null, Integer.class );
assertThat( gemValue ).isNotNull();
assertThat( gemValue.isValid() ).isFalse();
assertThat( gemValue.hasValue() ).isFalse();
assertThat( gemValue.getValue() ).isNull();
assertThat( gemValue.getDefaultValue() ).isNull();
assertThat( gemValue.get() ).as( "get should return null" ).isNull();
assertThat( gemValue.getAnnotationValue() ).isNull();
assertThat( gemValue.getValueOrElseGet( () -> 3 ) )
.as( "getValueOrElseGet should return other" ).isEqualTo( 3 );
}
}

static class SimpleArrayAnnotationValue implements AnnotationValue {

private final List<SimpleAnnotationValue> value;

SimpleArrayAnnotationValue(int... intValues) {
this.value = new ArrayList<>( intValues.length );
for ( int v : intValues ) {
value.add( new SimpleAnnotationValue( v ) );
}
}

@Override
public Object getValue() {
return value;
}

@Override
public <R, P> R accept(AnnotationValueVisitor<R, P> v, P p) {
return v.visitArray( value, p );
}
}

@Nested
class CreateArrayTest {

@Test
void createArrayValue() {
SimpleArrayAnnotationValue annotationValue = new SimpleArrayAnnotationValue(1);
GemValue<List<Integer>> gemValue = GemValue.createArray( annotationValue,
new SimpleArrayAnnotationValue(2), Integer.class );
assertThat( gemValue ).isNotNull();
assertThat( gemValue.isValid() ).isTrue();
assertThat( gemValue.hasValue() ).isTrue();
assertThat( gemValue.getValue() ).isEqualTo( Collections.singletonList( 1 ) );
assertThat( gemValue.getDefaultValue() ).isEqualTo( Collections.singletonList( 2 ) );
assertThat( gemValue.get() ).as( "get should return value" ).isEqualTo(
Collections.singletonList( 1 ) );
assertThat( gemValue.getAnnotationValue() ).isEqualTo( annotationValue );
assertThat( gemValue.getValueOrElseGet( Collections::emptyList ) )
.as( "getValueOrElseGet should return value" )
.isEqualTo( Collections.singletonList( 1 ) );
}

@Test
void createArrayValueWithoutAnnotationValue() {
GemValue<List<Integer>> gemValue = GemValue.createArray( null,
new SimpleArrayAnnotationValue(2), Integer.class );
assertThat( gemValue ).isNotNull();
assertThat( gemValue.isValid() ).isTrue();
assertThat( gemValue.hasValue() ).isFalse();
assertThat( gemValue.getValue() ).isNull();
assertThat( gemValue.getDefaultValue() ).isEqualTo( Collections.singletonList( 2 ) );
assertThat( gemValue.get() ).as( "get should return defaultValue" )
.isEqualTo( Collections.singletonList( 2 ) );
assertThat( gemValue.getAnnotationValue() ).isNull();
assertThat( gemValue.getValueOrElseGet( Collections::emptyList ) )
.as( "getValueOrElseGet should return other" ).isEqualTo( Collections.emptyList() );
}

@Test
void createArrayValueWithoutAnnotationDefaultValue() {
SimpleArrayAnnotationValue annotationValue = new SimpleArrayAnnotationValue(1);
GemValue<List<Integer>> gemValue = GemValue.createArray( annotationValue, null, Integer.class );
assertThat( gemValue ).isNotNull();
assertThat( gemValue.isValid() ).isTrue();
assertThat( gemValue.hasValue() ).isTrue();
assertThat( gemValue.getValue() ).isEqualTo( Collections.singletonList( 1 ) );
assertThat( gemValue.getDefaultValue() ).isNull();
assertThat( gemValue.get() ).as( "get should return value" )
.isEqualTo( Collections.singletonList( 1 ) );
assertThat( gemValue.getAnnotationValue() ).isEqualTo( annotationValue );
assertThat( gemValue.getValueOrElseGet( Collections::emptyList ) )
.as( "getValueOrElseGet should return value" )
.isEqualTo( Collections.singletonList( 1 ) );
}

@Test
void createArrayValueInvalid() {
GemValue<List<Integer>> gemValue = GemValue.createArray( null, null, Integer.class );
assertThat( gemValue ).isNotNull();
assertThat( gemValue.isValid() ).isFalse();
assertThat( gemValue.hasValue() ).isFalse();
assertThat( gemValue.getValue() ).isNull();
assertThat( gemValue.getDefaultValue() ).isNull();
assertThat( gemValue.get() ).as( "get should return null" ).isNull();
assertThat( gemValue.getAnnotationValue() ).isNull();
assertThat( gemValue.getValueOrElseGet( () -> Collections.singletonList( 3 ) ) )
.as( "getValueOrElseGet should return other" ).isEqualTo( Collections.singletonList( 3 ) );
}
}
}