io.smallrye.mutiny.vertx.codegen.lang.IteratorMethodsCodeWriter Maven / Gradle / Ivy

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package io.smallrye.mutiny.vertx.codegen.lang;

import io.vertx.codegen.ClassModel;
import io.vertx.codegen.type.ClassKind;
import io.vertx.codegen.type.TypeInfo;

import java.io.PrintWriter;
import java.util.Spliterator;
import java.util.Spliterators;
import java.util.stream.StreamSupport;

/**
 * Add methods if the class implements {@code Iterator} interface.
 * It also injects a {@code toMulti} method if not present.
 */
public class IteratorMethodsCodeWriter implements ConditionalCodeWriter {

    @Override
    public void generate(ClassModel model, PrintWriter writer) {
        if (model.getMethods().stream().noneMatch(it -> it.getParams().isEmpty() && "hasNext".equals(it.getName()))) {
            writer.println("  @Override");
            writer.println("  public boolean hasNext() {");
            writer.println("    return delegate.hasNext();");
            writer.println("  }");
            writer.println();
        }

        TypeInfo iteratorArg = model.getIteratorArg();
        if (model.getMethods().stream().noneMatch(it -> it.getParams().isEmpty() && "next".equals(it.getName()))) {

            writer.println("  @Override");
            writer.printf("  public %s next() {%n", genTypeName(iteratorArg));

            if (iteratorArg.getKind() == ClassKind.API) {
                writer.format("    return %s.newInstance(delegate.next());%n", genTypeName(iteratorArg));
            } else if (iteratorArg.isVariable()) {
                writer.println("    return __typeArg_0.wrap(delegate.next());");
            } else {
                writer.println("    return delegate.next();");
            }

            writer.println("  }");
            writer.println();
        }

        if (model.getMethods().stream().noneMatch(it -> it.getParams().isEmpty() && "toMulti".equals(it.getName()))) {
            writer.print("  @CheckReturnValue\n");
            writer.printf("  public Multi<%s> toMulti() {%n", genTypeName(iteratorArg));
            String support = StreamSupport.class.getName();
            String splitIterators = Spliterators.class.getName() + ".spliteratorUnknownSize";
            String ordered = Spliterator.class.getName() + ".ORDERED";
            writer.printf("    return Multi.createFrom().items(%n"
                            + "      %s.stream(%n"
                            + "        %s(this, %s), false)%n"
                            + "    );%n",
                    support, splitIterators, ordered);
            writer.println("  }");
            writer.println();
        }
    }

    @Override
    public boolean test(ClassModel model) {
        return model.isConcrete() && model.isIterator();
    }
}