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processor: refactor class generation
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5 files changed

+439
-270
lines changed

5 files changed

+439
-270
lines changed

‎processor/src/main/java/jtamaro/optics/processor/ComponentLensesGenerator.java‎

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package jtamaro.optics.processor;
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import java.util.List;
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import java.util.SequencedMap;
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import java.util.SequencedSet;
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import javax.lang.model.type.TypeMirror;
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import javax.lang.model.util.Types;
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final class ComponentLensesGenerator {
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private ComponentLensesGenerator() {
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}
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/**
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* Generate lenses for each record component.
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*/
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public static List<String> generate(
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Types types,
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TypeMirror targetRecordType,
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SequencedMap<String, TypeMirror> allComponents,
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SequencedSet<String> allComponentNames
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) {
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return allComponents.sequencedEntrySet()
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.stream()
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.map(e -> lensForComponent(
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types,
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targetRecordType,
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e.getKey(),
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e.getValue(),
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allComponentNames
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))
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.toList();
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}
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/**
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* Generate a lens for a given record component.
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*/
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private static String lensForComponent(
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Types types,
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TypeMirror sourceType,
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String targetName,
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TypeMirror targetType,
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SequencedSet<String> allComponentNames
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) {
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final String sourceTypeStr = Utils.formatType(types, sourceType);
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final String componentTypeStr = Utils.formatType(types, targetType);
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final String overImpl = Utils.newRecordInstanceExpr(
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sourceTypeStr,
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targetName,
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allComponentNames,
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accessor -> "lift.apply(" + accessor + ")"
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);
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return String.format("""
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public static final Lens<%1$s, %1$s, %2$s, %2$s> %3$s = new Lens<>() {
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@Override
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public %1$s over(Function1<%2$s, %2$s> lift, %1$s source) {
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return %4$s;
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}
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@Override
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public %2$s view(%1$s source) {
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return source.%3$s();
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}
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};
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""", // Lower indentation on purpose!
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sourceTypeStr, // S, T
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componentTypeStr, // A, B
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targetName, // 3: target component name
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overImpl // 4: new instance in over
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);
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}
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}

‎processor/src/main/java/jtamaro/optics/processor/ComponentTraversalsGenerator.java‎

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package jtamaro.optics.processor;
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import java.util.List;
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import java.util.SequencedMap;
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import java.util.SequencedSet;
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import javax.lang.model.type.DeclaredType;
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import javax.lang.model.type.TypeMirror;
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import javax.lang.model.util.Types;
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final class ComponentTraversalsGenerator {
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private static final String METHOD_LENS_AT_INDEX = """
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private static <T> Lens<Sequence<T>, Sequence<T>, T, T> lensAtIndex(int idx) {
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return new Lens<>() {
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@Override
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public Sequence<T> over(Function1<T, T> lift, Sequence<T> source) {
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return source.zipWithIndex()
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.map(p -> p.second() == idx
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? lift.apply(p.first())
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: p.first());
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}
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@Override
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public T view(Sequence<T> source) {
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return source.drop(idx).first();
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}
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};
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}
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"""; // Lower indentation on purpose!
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private ComponentTraversalsGenerator() {
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}
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/**
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* Generate a traversal that allows to focus on a lens for each element of a
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* record component of type list.
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*/
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public static List<String> generate(
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Types types,
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TypeMirror targetRecordType,
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SequencedMap<String, TypeMirror> allComponents,
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SequencedSet<String> allComponentNames
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) {
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return allComponents.sequencedEntrySet()
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.stream()
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.map(e -> traversalForComponent(
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types,
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targetRecordType,
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e.getKey(),
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getFirstTypeArgument(e.getValue()),
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allComponentNames
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))
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.toList();
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}
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/**
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* Generate a traversal that allows to focus on a lens for a single element of
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* a record component of type Sequence.
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*/
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private static String traversalForComponent(
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Types types,
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TypeMirror sourceType,
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String targetName,
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TypeMirror targetElementType,
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SequencedSet<String> allComponentNames
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) {
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final String sourceTypeStr = Utils.formatType(types, sourceType);
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final String componentElementTypeStr = Utils.formatType(types, targetElementType);
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final String overImpl = Utils.newRecordInstanceExpr(
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sourceTypeStr,
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targetName,
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allComponentNames,
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ignored -> "newValue"
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);
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return String.format("""
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public static final Traversal<%1$s, %1$s, Lens<%1$s, %1$s, %2$s, %2$s>, %2$s> %3$sElements = new Traversal<>() {
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@Override
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public %1$s over(Function1<Lens<%1$s, %1$s, %2$s, %2$s>, %2$s> lift,
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%1$s source) {
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final Sequence<%2$s> newValue = source.%3$s().zipWithIndex()
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.map(p -> lift.apply(%3$s.then(lensAtIndex(p.second()))));
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return %4$s;
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}
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@Override
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public <R> R foldMap(R neutralElement,
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Function2<R, R, R> reducer,
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Function1<Lens<%1$s, %1$s, %2$s, %2$s>, R> map,
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%1$s source) {
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return source.%3$s().zipWithIndex().foldLeft(
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neutralElement,
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(acc, p) -> reducer.apply(
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acc,
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map.apply(%3$s.then(lensAtIndex(p.second())))
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)
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);
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}
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};
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""", // Lower indentation on purpose!
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sourceTypeStr, // S, T
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componentElementTypeStr, // A, B
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targetName, // 3: target component name
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overImpl // 4: new instance in over
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);
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}
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/**
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* Get the code that implements the method "lensAtIndex(int)".
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*/
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public static String getMethodLensAtIndexImpl() {
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return METHOD_LENS_AT_INDEX;
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}
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/**
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* Get the {@link TypeMirror} of the first type parameter of the given
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* {@link TypeMirror}.
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*/
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private static TypeMirror getFirstTypeArgument(TypeMirror typeMirror) {
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if (typeMirror instanceof DeclaredType declaredType) {
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final List<? extends TypeMirror> typeArgs = declaredType.getTypeArguments();
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if (!typeArgs.isEmpty()) {
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return typeArgs.getFirst();
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}
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}
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throw new IllegalArgumentException("Provided type " + typeMirror + " has no type parameter");
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}
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}

‎processor/src/main/java/jtamaro/optics/processor/GlassesProcessor.java‎

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@@ -66,7 +66,6 @@ private boolean processRecord(TypeElement recordElement) {
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types,
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recordElement,
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genFile,
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packageName,
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simpleName
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);
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return true;

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