Performance feature: copy collections only when they were changed. Fixes #114. (#118)

record-builder-core/src/main/java/io/soabase/recordbuilder/core/RecordBuilder.java

@@ -252,6 +252,24 @@ public @interface RecordBuilder {
          * without {@code new}.
          */
         boolean addStaticBuilder() default true;
+
+        /**
+         * If {@link #addSingleItemCollectionBuilders()} and {@link #useImmutableCollections()} are enabled the builder
+         * uses an internal class to track changes to lists. This is the name of that class.
+         */
+        String mutableListClassName() default "_MutableList";
+
+        /**
+         * If {@link #addSingleItemCollectionBuilders()} and {@link #useImmutableCollections()} are enabled the builder
+         * uses an internal class to track changes to sets. This is the name of that class.
+         */
+        String mutableSetClassName() default "_MutableSet";
+
+        /**
+         * If {@link #addSingleItemCollectionBuilders()} and {@link #useImmutableCollections()} are enabled the builder
+         * uses an internal class to track changes to maps. This is the name of that class.
+         */
+        String mutableMapClassName() default "_MutableMap";
     }
 
     @Retention(RetentionPolicy.CLASS)

record-builder-processor/src/main/java/io/soabase/recordbuilder/processor/CollectionBuilderUtils.java

@@ -22,24 +22,38 @@ import javax.lang.model.element.Modifier;
 import java.util.*;
 
 import static io.soabase.recordbuilder.processor.RecordBuilderProcessor.generatedRecordBuilderAnnotation;
+import static io.soabase.recordbuilder.processor.RecordBuilderProcessor.recordBuilderGeneratedAnnotation;
 
 class CollectionBuilderUtils {
     private final boolean useImmutableCollections;
     private final boolean addSingleItemCollectionBuilders;
+    private final boolean addClassRetainedGenerated;
     private final String listShimName;
     private final String mapShimName;
     private final String setShimName;
     private final String collectionShimName;
 
+    private final String listMakerMethodName;
+    private final String mapMakerMethodName;
+    private final String setMakerMethodName;
+
     private boolean needsListShim;
     private boolean needsMapShim;
     private boolean needsSetShim;
     private boolean needsCollectionShim;
 
-    private static final TypeName listType = TypeName.get(List.class);
-    private static final TypeName mapType = TypeName.get(Map.class);
-    private static final TypeName setType = TypeName.get(Set.class);
-    private static final TypeName collectionType = TypeName.get(Collection.class);
+    private boolean needsListMutableMaker;
+    private boolean needsMapMutableMaker;
+    private boolean needsSetMutableMaker;
+
+    private static final Class<?> listType = List.class;
+    private static final Class<?> mapType = Map.class;
+    private static final Class<?> setType = Set.class;
+    private static final Class<?> collectionType = Collection.class;
+    private static final TypeName listTypeName = TypeName.get(listType);
+    private static final TypeName mapTypeName = TypeName.get(mapType);
+    private static final TypeName setTypeName = TypeName.get(setType);
+    private static final TypeName collectionTypeName = TypeName.get(collectionType);
 
     private static final TypeVariableName tType = TypeVariableName.get("T");
     private static final TypeVariableName kType = TypeVariableName.get("K");
@@ -49,14 +63,33 @@ class CollectionBuilderUtils {
     private static final ParameterizedTypeName parameterizedSetType = ParameterizedTypeName.get(ClassName.get(Set.class), tType);
     private static final ParameterizedTypeName parameterizedCollectionType = ParameterizedTypeName.get(ClassName.get(Collection.class), tType);
 
+    private static final Class<?> mutableListType = ArrayList.class;
+    private static final Class<?> mutableMapType = HashMap.class;
+    private static final Class<?> mutableSetType = HashSet.class;
+    private static final ClassName mutableListTypeName = ClassName.get(mutableListType);
+    private static final ClassName mutableMapTypeName = ClassName.get(mutableMapType);
+    private static final ClassName mutableSetTypeName = ClassName.get(mutableSetType);
+    private final TypeSpec mutableListSpec;
+    private final TypeSpec mutableSetSpec;
+    private final TypeSpec mutableMapSpec;
+
     CollectionBuilderUtils(List<RecordClassType> recordComponents, RecordBuilder.Options metaData) {
         useImmutableCollections = metaData.useImmutableCollections();
         addSingleItemCollectionBuilders = metaData.addSingleItemCollectionBuilders();
+        addClassRetainedGenerated = metaData.addClassRetainedGenerated();
 
-        listShimName = adjustShimName(recordComponents, "__list", 0);
-        mapShimName = adjustShimName(recordComponents, "__map", 0);
-        setShimName = adjustShimName(recordComponents, "__set", 0);
-        collectionShimName = adjustShimName(recordComponents, "__collection", 0);
+        listShimName = disambiguateGeneratedMethodName(recordComponents, "__list", 0);
+        mapShimName = disambiguateGeneratedMethodName(recordComponents, "__map", 0);
+        setShimName = disambiguateGeneratedMethodName(recordComponents, "__set", 0);
+        collectionShimName = disambiguateGeneratedMethodName(recordComponents, "__collection", 0);
+
+        listMakerMethodName = disambiguateGeneratedMethodName(recordComponents, "__ensureListMutable", 0);
+        setMakerMethodName = disambiguateGeneratedMethodName(recordComponents, "__ensureSetMutable", 0);
+        mapMakerMethodName = disambiguateGeneratedMethodName(recordComponents, "__ensureMapMutable", 0);
+
+        mutableListSpec = buildMutableCollectionSubType(metaData.mutableListClassName(), mutableListTypeName, parameterizedListType, tType);
+        mutableSetSpec = buildMutableCollectionSubType(metaData.mutableSetClassName(), mutableSetTypeName, parameterizedSetType, tType);
+        mutableMapSpec = buildMutableCollectionSubType(metaData.mutableMapClassName(), mutableMapTypeName, parameterizedMapType, kType, vType);
     }
 
     enum SingleItemsMetaDataMode {
@@ -65,7 +98,8 @@ class CollectionBuilderUtils {
         EXCLUDE_WILDCARD_TYPES
     }
 
-    record SingleItemsMetaData(Class<?> singleItemCollectionClass, List<TypeName> typeArguments, TypeName wildType) {}
+    record SingleItemsMetaData(Class<?> singleItemCollectionClass, List<TypeName> typeArguments, TypeName wildType) {
+    }
 
     Optional<SingleItemsMetaData> singleItemsMetaData(RecordClassType component, SingleItemsMetaDataMode mode) {
         if (addSingleItemCollectionBuilders && (component.typeName() instanceof ParameterizedTypeName parameterizedTypeName)) {
@@ -73,15 +107,15 @@ class CollectionBuilderUtils {
             ClassName wildcardClass = null;
             int typeArgumentQty = 0;
             if (isList(component)) {
-                collectionClass = ArrayList.class;
+                collectionClass = mutableListType;
                 wildcardClass = ClassName.get(Collection.class);
                 typeArgumentQty = 1;
             } else if (isSet(component)) {
-                collectionClass = HashSet.class;
+                collectionClass = mutableSetType;
                 wildcardClass = ClassName.get(Collection.class);
                 typeArgumentQty = 1;
             } else if (isMap(component)) {
-                collectionClass = HashMap.class;
+                collectionClass = mutableMapType;
                 wildcardClass = (ClassName) component.rawTypeName();
                 typeArgumentQty = 2;
             }
@@ -110,33 +144,36 @@ class CollectionBuilderUtils {
     }
 
     boolean isImmutableCollection(RecordClassType component) {
-        return useImmutableCollections && (isList(component) || isMap(component) || isSet(component) || component.rawTypeName().equals(collectionType));
+        return useImmutableCollections && (isList(component) || isMap(component) || isSet(component) || component.rawTypeName().equals(collectionTypeName));
     }
 
     boolean isList(RecordClassType component) {
-        return component.rawTypeName().equals(listType);
+        return component.rawTypeName().equals(listTypeName);
     }
 
     boolean isMap(RecordClassType component) {
-        return component.rawTypeName().equals(mapType);
+        return component.rawTypeName().equals(mapTypeName);
     }
 
     boolean isSet(RecordClassType component) {
-        return component.rawTypeName().equals(setType);
+        return component.rawTypeName().equals(setTypeName);
     }
 
-    void add(CodeBlock.Builder builder, RecordClassType component) {
+    void addShimCall(CodeBlock.Builder builder, RecordClassType component) {
         if (useImmutableCollections) {
             if (isList(component)) {
                 needsListShim = true;
+                needsListMutableMaker = true;
                 builder.add("$L($L)", listShimName, component.name());
             } else if (isMap(component)) {
                 needsMapShim = true;
+                needsMapMutableMaker = true;
                 builder.add("$L($L)", mapShimName, component.name());
             } else if (isSet(component)) {
                 needsSetShim = true;
+                needsSetMutableMaker = true;
                 builder.add("$L($L)", setShimName, component.name());
-            } else if (component.rawTypeName().equals(collectionType)) {
+            } else if (component.rawTypeName().equals(collectionTypeName)) {
                 needsCollectionShim = true;
                 builder.add("$L($L)", collectionShimName, component.name());
             } else {
@@ -147,22 +184,67 @@ class CollectionBuilderUtils {
         }
     }
 
+    String shimName(RecordClassType component) {
+        if (isList(component)) {
+            return listShimName;
+        } else if (isMap(component)) {
+            return mapShimName;
+        } else if (isSet(component)) {
+            return setShimName;
+        } else if (component.rawTypeName().equals(collectionTypeName)) {
+            return collectionShimName;
+        } else {
+            throw new IllegalArgumentException(component + " is not a supported collection type");
+        }
+    }
+
+    String mutableMakerName(RecordClassType component) {
+        if (isList(component)) {
+            return listMakerMethodName;
+        } else if (isMap(component)) {
+            return mapMakerMethodName;
+        } else if (isSet(component)) {
+            return setMakerMethodName;
+        } else {
+            throw new IllegalArgumentException(component + " is not a supported collection type");
+        }
+    }
+
     void addShims(TypeSpec.Builder builder) {
         if (!useImmutableCollections) {
             return;
         }
 
         if (needsListShim) {
-            builder.addMethod(buildMethod(listShimName, listType, parameterizedListType, tType));
+            builder.addMethod(buildShimMethod(listShimName, listTypeName, collectionType, parameterizedListType, tType));
         }
         if (needsSetShim) {
-            builder.addMethod(buildMethod(setShimName, setType, parameterizedSetType, tType));
+            builder.addMethod(buildShimMethod(setShimName, setTypeName, collectionType, parameterizedSetType, tType));
         }
         if (needsMapShim) {
-            builder.addMethod(buildMethod(mapShimName, mapType, parameterizedMapType, kType, vType));
+            builder.addMethod(buildShimMethod(mapShimName, mapTypeName, mapType, parameterizedMapType, kType, vType));
         }
         if (needsCollectionShim) {
-            builder.addMethod(buildCollectionsMethod());
+            builder.addMethod(buildCollectionsShimMethod());
+        }
+    }
+
+    void addMutableMakers(TypeSpec.Builder builder) {
+        if (!useImmutableCollections) {
+            return;
+        }
+
+        if (needsListMutableMaker) {
+            builder.addMethod(buildMutableMakerMethod(listMakerMethodName, mutableListSpec.name, parameterizedListType, tType));
+            builder.addType(mutableListSpec);
+        }
+        if (needsSetMutableMaker) {
+            builder.addMethod(buildMutableMakerMethod(setMakerMethodName, mutableSetSpec.name, parameterizedSetType, tType));
+            builder.addType(mutableSetSpec);
+        }
+        if (needsMapMutableMaker) {
+            builder.addMethod(buildMutableMakerMethod(mapMakerMethodName, mutableMapSpec.name, parameterizedMapType, kType, vType));
+            builder.addType(mutableMapSpec);
         }
     }
 
@@ -187,34 +269,71 @@ class CollectionBuilderUtils {
         return false;
     }
 
-    private String adjustShimName(List<RecordClassType> recordComponents, String baseName, int index) {
+    private String disambiguateGeneratedMethodName(List<RecordClassType> recordComponents, String baseName, int index) {
         var name = (index == 0) ? baseName : (baseName + index);
         if (recordComponents.stream().anyMatch(component -> component.name().equals(name))) {
-            return adjustShimName(recordComponents, baseName, index + 1);
+            return disambiguateGeneratedMethodName(recordComponents, baseName, index + 1);
         }
         return name;
     }
 
-    private MethodSpec buildMethod(String name, TypeName mainType, ParameterizedTypeName parameterizedType, TypeVariableName... typeVariables) {
+    private MethodSpec buildShimMethod(String name, TypeName mainType, Class<?> abstractType, ParameterizedTypeName parameterizedType, TypeVariableName... typeVariables) {
         var code = CodeBlock.of("return (o != null) ? $T.copyOf(o) : $T.of()", mainType, mainType);
+        TypeName[] wildCardTypeArguments = parameterizedType.typeArguments.stream().map(WildcardTypeName::subtypeOf).toList().toArray(new TypeName[0]);
+        var extendedParameterizedType = ParameterizedTypeName.get(ClassName.get(abstractType), wildCardTypeArguments);
+        return MethodSpec.methodBuilder(name)
+                .addAnnotation(generatedRecordBuilderAnnotation)
+                .addModifiers(Modifier.PRIVATE, Modifier.STATIC)
+                .addTypeVariables(Arrays.asList(typeVariables))
+                .returns(parameterizedType)
+                .addParameter(extendedParameterizedType, "o")
+                .addStatement(code)
+                .build();
+    }
+
+    private MethodSpec buildMutableMakerMethod(String name, String mutableCollectionType, ParameterizedTypeName parameterizedType, TypeVariableName... typeVariables) {
+        var nullCase = CodeBlock.of("if (o == null) return new $L<>()", mutableCollectionType);
+        var isMutableCase = CodeBlock.of("if (o instanceof $L) return o", mutableCollectionType);
+        var defaultCase = CodeBlock.of("return new $L<>(o)", mutableCollectionType);
         return MethodSpec.methodBuilder(name)
                 .addAnnotation(generatedRecordBuilderAnnotation)
                 .addModifiers(Modifier.PRIVATE, Modifier.STATIC)
                 .addTypeVariables(Arrays.asList(typeVariables))
                 .returns(parameterizedType)
                 .addParameter(parameterizedType, "o")
-                .addStatement(code)
+                .addStatement(nullCase)
+                .addStatement(isMutableCase)
+                .addStatement(defaultCase)
                 .build();
     }
 
-    private MethodSpec buildCollectionsMethod() {
+    private TypeSpec buildMutableCollectionSubType(String className, ClassName mutableCollectionType, ParameterizedTypeName parameterizedType, TypeVariableName... typeVariables) {
+        TypeName[] typeArguments = new TypeName[]{};
+        typeArguments = Arrays.stream(typeVariables).toList().toArray(typeArguments);
+
+        TypeSpec.Builder builder = TypeSpec.classBuilder(className)
+                .addAnnotation(generatedRecordBuilderAnnotation)
+                .addModifiers(Modifier.PRIVATE, Modifier.STATIC)
+                .superclass(ParameterizedTypeName.get(mutableCollectionType, typeArguments))
+                .addTypeVariables(Arrays.asList(typeVariables))
+                .addMethod(MethodSpec.constructorBuilder().addAnnotation(generatedRecordBuilderAnnotation).addStatement("super()").build())
+                .addMethod(MethodSpec.constructorBuilder().addAnnotation(generatedRecordBuilderAnnotation).addParameter(parameterizedType, "o").addStatement("super(o)").build());
+
+        if (addClassRetainedGenerated) {
+            builder.addAnnotation(recordBuilderGeneratedAnnotation);
+        }
+
+        return builder.build();
+    }
+
+    private MethodSpec buildCollectionsShimMethod() {
         var code = CodeBlock.builder()
                 .add("if (o instanceof Set) {\n")
                 .indent()
-                .addStatement("return $T.copyOf(o)", setType)
+                .addStatement("return $T.copyOf(o)", setTypeName)
                 .unindent()
                 .addStatement("}")
-                .addStatement("return (o != null) ? $T.copyOf(o) : $T.of()", listType, listType)
+                .addStatement("return (o != null) ? $T.copyOf(o) : $T.of()", listTypeName, listTypeName)
                 .build();
         return MethodSpec.methodBuilder(collectionShimName)
                 .addAnnotation(generatedRecordBuilderAnnotation)

record-builder-processor/src/main/java/io/soabase/recordbuilder/processor/InternalRecordBuilderProcessor.java

@@ -16,7 +16,6 @@
 package io.soabase.recordbuilder.processor;
 
 import static io.soabase.recordbuilder.processor.CollectionBuilderUtils.SingleItemsMetaDataMode.EXCLUDE_WILDCARD_TYPES;
-import static io.soabase.recordbuilder.processor.CollectionBuilderUtils.SingleItemsMetaDataMode.STANDARD;
 import static io.soabase.recordbuilder.processor.CollectionBuilderUtils.SingleItemsMetaDataMode.STANDARD_FOR_SETTER;
 import static io.soabase.recordbuilder.processor.ElementUtils.getBuilderName;
 import static io.soabase.recordbuilder.processor.ElementUtils.getWithMethodName;
@@ -112,6 +111,7 @@ class InternalRecordBuilderProcessor {
             collectionMetaData.ifPresent(meta -> add1CollectionBuilders(meta, component));
         });
         collectionBuilderUtils.addShims(builder);
+        collectionBuilderUtils.addMutableMakers(builder);
         builderType = builder.build();
     }
 
@@ -333,7 +333,7 @@ class InternalRecordBuilderProcessor {
             }
             RecordClassType parameterComponent = recordComponents.get(parameterIndex);
             if (parameterIndex == index) {
-                collectionBuilderUtils.add(codeBlockBuilder, parameterComponent);
+                collectionBuilderUtils.addShimCall(codeBlockBuilder, parameterComponent);
             } else {
                 codeBlockBuilder.add("$L()", prefixedName(parameterComponent, true));
             }
@@ -417,9 +417,7 @@ class InternalRecordBuilderProcessor {
                 .addAnnotation(generatedRecordBuilderAnnotation);
         recordComponents.forEach(component -> {
             constructorBuilder.addParameter(component.typeName(), component.name());
-            var collectionMetaData = collectionBuilderUtils.singleItemsMetaData(component, STANDARD);
-            collectionMetaData.ifPresentOrElse(meta -> constructorBuilder.addStatement("this.$L = new $T<>($L)", component.name(), meta.singleItemCollectionClass(), component.name()),
-                    () -> constructorBuilder.addStatement("this.$L = $L", component.name(), component.name()));
+            constructorBuilder.addStatement("this.$L = $L", component.name(), component.name());
         });
         builder.addMethod(constructorBuilder.build());
     }
@@ -551,7 +549,7 @@ class InternalRecordBuilderProcessor {
             var recordComponent = recordComponents.get(index);
             if (collectionBuilderUtils.isImmutableCollection(recordComponent)) {
                 codeBuilder.add("$[$L = ", recordComponent.name());
-                collectionBuilderUtils.add(codeBuilder, recordComponents.get(index));
+                collectionBuilderUtils.addShimCall(codeBuilder, recordComponents.get(index));
                 codeBuilder.add(";\n$]");
             }
         });
@@ -819,34 +817,34 @@ class InternalRecordBuilderProcessor {
             For a single map record component, add a methods similar to:
 
             public T addP(K key, V value) {
-                if (this.p == null) {
-                    this.p = new HashMap<>();
-                }
+                this.p = __ensureMapMutable(p);
                 this.p.put(key, value);
                 return this;
             }
 
             public T addP(Stream<? extends Map.Entry<K, V> i) {
-                if (p == null) {
-                    p = new HashMap<>();
-                }
+                this.p = __ensureMapMutable(p);
                 i.forEach(this.p::put);
                 return this;
             }
 
             public T addP(Iterable<? extends Map.Entry<K, V> i) {
-                if (p == null) {
-                    p = new HashMap<>();
-                }
+                this.p = __ensureMapMutable(p);
                 i.forEach(this.p::put);
                 return this;
             }
          */
         for (var i = 0; i < 3; ++i) {
-            var codeBlockBuilder = CodeBlock.builder()
-                    .beginControlFlow("if (this.$L == null)", component.name())
-                    .addStatement("this.$L = new $T<>()", component.name(), HashMap.class)
-                    .endControlFlow();
+            var codeBlockBuilder = CodeBlock.builder();
+            if (collectionBuilderUtils.isImmutableCollection(component)) {
+                codeBlockBuilder
+                        .addStatement("this.$L = $L($L)", component.name(), collectionBuilderUtils.mutableMakerName(component), component.name());
+            } else {
+                codeBlockBuilder
+                        .beginControlFlow("if (this.$L == null)", component.name())
+                        .addStatement("this.$L = new $T<>()", component.name(), meta.singleItemCollectionClass())
+                        .endControlFlow();
+            }
             var methodSpecBuilder = MethodSpec.methodBuilder(metaData.singleItemBuilderPrefix() + capitalize(component.name()))
                     .addJavadoc("Add to the internally allocated {@code HashMap} for {@code $L}\n", component.name())
                     .addModifiers(Modifier.PUBLIC)
@@ -874,25 +872,19 @@ class InternalRecordBuilderProcessor {
             For a single list or set record component, add methods similar to:
 
             public T addP(I i) {
-                if (this.p == null) {
-                    this.p = new ArrayList<>();
-                }
+                this.list = __ensureListMutable(list);
                 this.p.add(i);
                 return this;
             }
 
             public T addP(Stream<? extends I> i) {
-                if (this.p == null) {
-                    this.p = new ArrayList<>();
-                }
+                this.list = __ensureListMutable(list);
                 this.p.addAll(i);
                 return this;
             }
 
             public T addP(Iterable<? extends I> i) {
-                if (this.p == null) {
-                    this.p = new ArrayList<>();
-                }
+                this.list = __ensureListMutable(list);
                 this.p.addAll(i);
                 return this;
             }
@@ -908,10 +900,17 @@ class InternalRecordBuilderProcessor {
                 var parameterClass = ClassName.get((i == 1) ? Stream.class : Iterable.class);
                 parameter = ParameterizedTypeName.get(parameterClass, WildcardTypeName.subtypeOf(meta.typeArguments().get(0)));
             }
-            var codeBlockBuilder = CodeBlock.builder()
-                    .beginControlFlow("if (this.$L == null)", component.name())
-                    .addStatement("this.$L = new $T<>()", component.name(), meta.singleItemCollectionClass())
-                    .endControlFlow()
+            var codeBlockBuilder = CodeBlock.builder();
+            if (collectionBuilderUtils.isImmutableCollection(component)) {
+                codeBlockBuilder
+                        .addStatement("this.$L = $L($L)", component.name(), collectionBuilderUtils.mutableMakerName(component), component.name());
+            } else {
+                codeBlockBuilder
+                        .beginControlFlow("if (this.$L == null)", component.name())
+                        .addStatement("this.$L = new $T<>()", component.name(), meta.singleItemCollectionClass())
+                        .endControlFlow();
+            }
+            codeBlockBuilder
                     .add(addClockBlock.build())
                     .addStatement("return this");
             var methodSpecBuilder = MethodSpec.methodBuilder(metaData.singleItemBuilderPrefix() + capitalize(component.name()))
@@ -960,8 +959,8 @@ class InternalRecordBuilderProcessor {
         var collectionMetaData = collectionBuilderUtils.singleItemsMetaData(component, STANDARD_FOR_SETTER);
         var parameterSpecBuilder = collectionMetaData.map(meta -> {
             CodeBlock.Builder codeSpec = CodeBlock.builder();
-            codeSpec.addStatement("this.$L = ($L != null) ? new $T<>($L) : null", component.name(), component.name(), meta.singleItemCollectionClass(), component.name());
-            methodSpec.addJavadoc("Re-create the internally allocated {@code $L} for {@code $L} by copying the argument\n", meta.singleItemCollectionClass().getSimpleName(), component.name())
+            codeSpec.addStatement("this.$L = $L($L)", component.name(), collectionBuilderUtils.shimName(component), component.name());
+            methodSpec.addJavadoc("Re-create the internally allocated {@code $T} for {@code $L} by copying the argument\n", component.typeName(), component.name())
                     .addCode(codeSpec.build());
             return ParameterSpec.builder(meta.wildType(), component.name());
         }).orElseGet(() -> {

record-builder-test/src/main/java/io/soabase/recordbuilder/test/CollectionCopying.java

@@ -0,0 +1,34 @@
+/**
+ * Copyright 2019 Jordan Zimmerman
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.soabase.recordbuilder.test;
+
+import io.soabase.recordbuilder.core.RecordBuilder;
+
+import java.time.Instant;
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+@RecordBuilder
+@RecordBuilder.Options(
+        addSingleItemCollectionBuilders = true,
+        useImmutableCollections = true,
+        mutableListClassName = "PersonalizedMutableList"
+)
+public record CollectionCopying<T>(List<String> list, Set<T> set, Map<Instant, T> map, Collection<T> collection,
+                                   int count) implements CollectionCopyingBuilder.With<T> {
+}

record-builder-test/src/test/java/io/soabase/recordbuilder/test/TestCollections.java

@@ -27,7 +27,7 @@ class TestCollections {
     @Test
     void testRecordBuilderOptionsCopied() {
         try {
-            assertNotNull(CollectionInterfaceRecordBuilder.class.getDeclaredMethod("__list", List.class));
+            assertNotNull(CollectionInterfaceRecordBuilder.class.getDeclaredMethod("__list", Collection.class));
         } catch (NoSuchMethodException e) {
             Assertions.fail(e);
         }

record-builder-test/src/test/java/io/soabase/recordbuilder/test/TestImmutableCollections.java

@@ -0,0 +1,148 @@
+/**
+ * Copyright 2019 Jordan Zimmerman
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.soabase.recordbuilder.test;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+import java.time.Instant;
+import java.util.*;
+
+public class TestImmutableCollections {
+    @Test
+    public void testImmutableListNotCopiedWhenNotChanged() {
+        var item = CollectionCopyingBuilder.<String>builder()
+                .addList("a")
+                .addList("b")
+                .addList("c")
+                .build();
+        Assertions.assertEquals(item.list(), List.of("a", "b", "c"));
+
+        var oldList = item.list();
+
+        var copy = item.with()
+                .count(1)
+                .build();
+
+        Assertions.assertSame(oldList, copy.list());
+
+        var otherCopy = item.with()
+                .count(2)
+                .build();
+
+        Assertions.assertSame(oldList, otherCopy.list());
+    }
+
+    @Test
+    public void testImmutableSetNotCopiedWhenNotChanged() {
+        var item = CollectionCopyingBuilder.<String>builder()
+                .addSet(Arrays.asList("1", "2", "3"))
+                .build();
+        Assertions.assertEquals(item.set(), Set.of("1", "2", "3"));
+
+        var oldSet = item.set();
+
+        var copy = item.with()
+                .count(1)
+                .build();
+
+        Assertions.assertSame(oldSet, copy.set());
+
+        var otherCopy = item.with()
+                .count(2)
+                .build();
+
+        Assertions.assertSame(oldSet, otherCopy.set());
+    }
+
+    @Test
+    public void testImmutableCollectionNotCopiedWhenNotChanged() {
+        var item = CollectionCopyingBuilder.<String>builder()
+                .collection(List.of("foo", "bar", "baz"))
+                .build();
+        Assertions.assertEquals(item.collection(), List.of("foo", "bar", "baz"));
+
+        var oldCollection = item.collection();
+
+        var copy = item.with()
+                .count(1)
+                .build();
+
+        Assertions.assertSame(oldCollection, copy.collection());
+
+        var otherCopy = item.with()
+                .count(2)
+                .build();
+
+        Assertions.assertSame(oldCollection, otherCopy.collection());
+    }
+
+    @Test
+    public void testImmutableMapNotCopiedWhenNotChanged() {
+        var item = CollectionCopyingBuilder.<String>builder()
+                .addMap(Instant.MAX, "future")
+                .addMap(Instant.MIN, "before")
+                .build();
+        Assertions.assertEquals(item.map(), Map.of(Instant.MAX, "future", Instant.MIN, "before"));
+
+        var oldMap = item.map();
+
+        var copy = item.with()
+                .count(1)
+                .build();
+
+        Assertions.assertSame(oldMap, copy.map());
+
+        var otherCopy = item.with()
+                .count(2)
+                .build();
+
+        Assertions.assertSame(oldMap, otherCopy.map());
+    }
+
+    @Test
+    void testSourceListNotModified() {
+        var item = new CollectionCopying<>(new ArrayList<>(), null, null, null, 0);
+        var modifiedItem = CollectionCopyingBuilder.builder(item)
+                .addList("a")
+                .build();
+
+        Assertions.assertEquals(modifiedItem.list(), List.of("a"));
+        Assertions.assertTrue(item.list().isEmpty());
+    }
+
+    @Test
+    void testSourceSetNotModified() {
+        var item = new CollectionCopying<>(null, new HashSet<>(), null, null, 0);
+        var modifiedItem = CollectionCopyingBuilder.builder(item)
+                .addSet("a")
+                .build();
+
+        Assertions.assertEquals(modifiedItem.set(), Set.of("a"));
+        Assertions.assertTrue(item.set().isEmpty());
+    }
+
+    @Test
+    void testSourceMapNotModified() {
+        var item = new CollectionCopying<>(null, null, new HashMap<>(), null, 0);
+        var modifiedItem = CollectionCopyingBuilder.builder(item)
+                .addMap(Instant.MIN, "a")
+                .build();
+
+        Assertions.assertEquals(modifiedItem.map(), Map.of(Instant.MIN, "a"));
+        Assertions.assertTrue(item.map().isEmpty());
+    }
+}