content: /*
   *  Licensed to the Apache Software Foundation (ASF) under one
   *  or more contributor license agreements.  See the NOTICE file
   *  distributed with this work for additional information
   *  regarding copyright ownership.  The ASF licenses this file
   *  to you 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 org.apache.causeway.core.metamodel.specloader.typeextract;
  
  import java.lang.reflect.Method;
  import java.util.function.Consumer;
  import java.util.stream.Stream;
  
  import org.apache.causeway.commons.internal.collections._Sets;
  import org.apache.causeway.commons.internal.reflection._GenericResolver.ResolvedMethod;
  import org.apache.causeway.commons.internal.reflection._Generics;
  
  import lombok.experimental.UtilityClass;
  
  /**
   *
   * @since 2.0
   *
   */
  @UtilityClass
  public class TypeExtractor {
  
      /**
       * Helper that finds all parameter types (including generic types) for the
       * provided {@link Method}.
       *
       * <p>
       * For example,
       *
       * <pre>
       * public class CustomerRepository {
       *     public void filterCustomers(List&lt;Customer&gt; customerList) { ... }
       * }
       * </pre>
       * <p>
       * will find both <tt>List</tt> and <tt>Customer</tt>.
       */
      public static Stream<Class<?>> streamMethodParameters(final Method ...methods) {
  
          var set = _Sets.<Class<?>>newHashSet();
  
          for(var method : methods) {
              if(method==null) {
                  continue;
              }
              acceptNonVoid(set::add, method.getParameterTypes());
              _Generics.streamGenericTypeArgumentsOfMethodParameterTypes(method)
                  .forEach(set::add);
          }
  
          return set.stream();
      }
  
      /**
       * Helper that finds all return types (including generic types) for the provided
       * {@link Method}.
       *
       * <p>
       * For example,
       *
       * <pre>
       * public class CustomerRepository {
       *     public List&lt;Customer&gt; findCustomers( ... ) { ... }
       * }
       * </pre>
       * <p>
       * will find both <tt>List</tt> and <tt>Customer</tt>.
       */
      public static Stream<Class<?>> streamMethodReturn(final ResolvedMethod ...methods) {
  
          var set = _Sets.<Class<?>>newHashSet();
  
          for(var method : methods) {
              if(method==null) {
                  continue;
              }
              acceptNonVoid(set::add, method.returnType());
              _Generics.streamGenericTypeArgumentsOfMethodReturnType(method.method())
                  .forEach(set::add);
          }
  
          return set.stream();
      }
  
      // -- VARIANTS
  
      public static Stream<Class<?>> streamMethodReturn(final Iterable<ResolvedMethod> methods) {
          var set = _Sets.<Class<?>>newHashSet();
  
          for(var method : methods) {
              if(method==null) {
                  continue;
              }
              acceptNonVoid(set::add, method.returnType());
              _Generics.streamGenericTypeArgumentsOfMethodReturnType(method.method())
                  .forEach(set::add);
          }
  
          return set.stream();
      }
  
      // -- HELPER
  
      private static void acceptNonVoid(
              final Consumer<Class<?>> onClass,
              final Class<?>... classes) {
  
          for (var cls : classes) {
              if(cls != void.class
                      && cls != Void.class) {
                  onClass.accept(cls);
              }
          }
      }
  
  }
  