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   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.  Oracle designates this
   * particular file as subject to the "Classpath" exception as provided
   * by Oracle in the LICENSE file that accompanied this code.
   *
   * This code is distributed in the hope that it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   * version 2 for more details (a copy is included in the LICENSE file that
   * accompanied this code).
   *
   * You should have received a copy of the GNU General Public License version
   * 2 along with this work; if not, write to the Free Software Foundation,
   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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  package jdkx.lang.model.util;
  
  import java.util.Collections;
  import java.util.List;
  import java.util.Map;
  import java.util.Set;
  import java.util.LinkedHashSet;
  import java.util.Objects;
  
  import jdkx.lang.model.AnnotatedConstruct;
  import jdkx.lang.model.element.*;
  
  
  /**
   * Utility methods for operating on program elements.
   *
   * <p><b>Compatibility Note:</b> Methods may be added to this interface
   * in future releases of the platform.
   *
   * @author Joseph D. Darcy
   * @author Scott Seligman
   * @author Peter von der Ah&eacute;
   * @see jdkx.annotation.processing.ProcessingEnvironment#getElementUtils
   * @since 1.6
   */
  public interface Elements {
  
      /**
       * Returns a package given its fully qualified name if the package is uniquely
       * determinable in the environment.
       *
       * If running with modules, packages of the given name are searched in a
       * two-stage process:
       * <ul>
       *     <li>find non-empty packages with the given name returned by
       *         {@link #getPackageElement(ModuleElement, CharSequence)},
       *         where the provided ModuleSymbol is any
       *         <a href="../../../../../java.base/java/lang/module/package-summary.html#root-modules">root module</a>,
       *     </li>
       *     <li>if the above yields an empty list, search
       *         {@link #getAllModuleElements() all modules} for observable
       *         packages with the given name
       *     </li>
       * </ul>
       *
       * If this process leads to a list with a single element,
       * the single element is returned, otherwise null is returned.
       *
       * @param name fully qualified package name,
       *             or an empty string for an unnamed package
       * @return the specified package,
       *         or {@code null} if no package can be uniquely determined.
       */
      PackageElement getPackageElement(CharSequence name);
  
      /**
       * Returns a package given its fully qualified name, as seen from the given module.
       *
       * @implSpec The default implementation of this method returns
       * {@code null}.
       *
       * @param name  fully qualified package name, or an empty string for an unnamed package
       * @param module module relative to which the lookup should happen
       * @return the specified package, or {@code null} if it cannot be found
       * @see #getAllPackageElements
       * @since 9
       */
      default PackageElement getPackageElement(ModuleElement module, CharSequence name) {
          return null;
      }
  
      /**
       * Returns all package elements with the given canonical name.
       *
       * There may be more than one package element with the same canonical
       * name if the package elements are in different modules.
       *
       * @implSpec The default implementation of this method calls
       * {@link #getAllModuleElements() getAllModuleElements} and stores
       * the result. If the set of modules is empty, {@link
       * #getPackageElement(CharSequence) getPackageElement(name)} is
       * called passing through the name argument. If {@code
       * getPackageElement(name)} is {@code null}, an empty set of
       * package elements is returned; otherwise, a single-element set
       * with the found package element is returned. If the set of
       * modules is nonempty, the modules are iterated over and any
       * non-{@code null} results of {@link
       * #getPackageElement(ModuleElement, CharSequence)
       * getPackageElement(module, name)} are accumulated into a
       * set. The set is then returned.
       *
       * @param name  the canonical name
       * @return the package elements, or an empty set if no package with the name can be found
       * @see #getPackageElement(ModuleElement, CharSequence)
       * @since 9
       */
      default Set<? extends PackageElement> getAllPackageElements(CharSequence name) {
          Set<? extends ModuleElement> modules = getAllModuleElements();
          if (modules.isEmpty()) {
              PackageElement packageElt = getPackageElement(name);
              return (packageElt != null) ?
                  Collections.singleton(packageElt):
                  Collections.emptySet();
          } else {
              Set<PackageElement> result = new LinkedHashSet<>(1); // Usually expect at most 1 result
              for (ModuleElement module: modules) {
                  PackageElement packageElt = getPackageElement(module, name);
                  if (packageElt != null)
                      result.add(packageElt);
              }
              return Collections.unmodifiableSet(result);
          }
      }
  
      /**
       * Returns a type element given its canonical name if the type element is uniquely
       * determinable in the environment.
       *
       * If running with modules, type elements of the given name are
       * searched in a two-stage process:
       * <ul>
       *     <li>find type elements with the given name returned by
       *         {@link #getTypeElement(ModuleElement, CharSequence)},
       *         where the provided ModuleSymbol is any
       *         <a href="../../../../../java.base/java/lang/module/package-summary.html#root-modules">root module</a>,
       *     </li>
       *     <li>if the above yields an empty list, search
       *         {@link #getAllModuleElements() all modules} for observable
       *         type elements with the given name
       *     </li>
       * </ul>
       *
       * If this process leads to a list with a single element,
       * the single element is returned, otherwise null is returned.
       *
       * @param name the canonical name
       * @return the named type element,
       *         or {@code null} if no type element can be uniquely determined.
       */
      TypeElement getTypeElement(CharSequence name);
  
      /**
       * Returns a type element given its canonical name, as seen from the given module.
       *
       * @implSpec The default implementation of this method returns
       * {@code null}.
       *
       * @param name  the canonical name
       * @param module module relative to which the lookup should happen
       * @return the named type element, or {@code null} if it cannot be found
       * @see #getAllTypeElements
       * @since 9
       */
      default TypeElement getTypeElement(ModuleElement module, CharSequence name) {
          return null;
      }
  
      /**
       * Returns all type elements with the given canonical name.
       *
       * There may be more than one type element with the same canonical
       * name if the type elements are in different modules.
       *
       * @implSpec The default implementation of this method calls
       * {@link #getAllModuleElements() getAllModuleElements} and stores
       * the result. If the set of modules is empty, {@link
       * #getTypeElement(CharSequence) getTypeElement(name)} is called
       * passing through the name argument. If {@code
       * getTypeElement(name)} is {@code null}, an empty set of type
       * elements is returned; otherwise, a single-element set with the
       * found type element is returned. If the set of modules is
       * nonempty, the modules are iterated over and any non-{@code null}
       * results of {@link #getTypeElement(ModuleElement,
       * CharSequence) getTypeElement(module, name)} are accumulated
       * into a set. The set is then returned.
       *
       * @param name  the canonical name
       * @return the type elements, or an empty set if no type with the name can be found
       * @see #getTypeElement(ModuleElement, CharSequence)
       * @since 9
       */
      default Set<? extends TypeElement> getAllTypeElements(CharSequence name) {
          Set<? extends ModuleElement> modules = getAllModuleElements();
          if (modules.isEmpty()) {
              TypeElement typeElt = getTypeElement(name);
              return (typeElt != null) ?
                  Collections.singleton(typeElt):
                  Collections.emptySet();
          } else {
              Set<TypeElement> result = new LinkedHashSet<>(1); // Usually expect at most 1 result
              for (ModuleElement module: modules) {
                  TypeElement typeElt = getTypeElement(module, name);
                  if (typeElt != null)
                      result.add(typeElt);
              }
              return Collections.unmodifiableSet(result);
          }
      }
  
      /**
       * Returns a module element given its fully qualified name.
       *
       * If the requested module cannot be found, {@code null} is
       * returned. One situation where a module cannot be found is if
       * the environment does not include modules, such as an annotation
       * processing environment configured for a {@linkplain
       * jdkx.annotation.processing.ProcessingEnvironment#getSourceVersion
       * source version} without modules.
       *
       * @implSpec The default implementation of this method returns
       * {@code null}.
       *
       * @param name  the name, or an empty string for an unnamed module
       * @return the named module element, or {@code null} if it cannot be found
       * @see #getAllModuleElements
       * @since 9
       */
      default ModuleElement getModuleElement(CharSequence name) {
          return null;
      }
  
      /**
       * Returns all module elements in the current environment.
       *
       * If no modules are present, an empty set is returned. One
       * situation where no modules are present occurs when the
       * environment does not include modules, such as an annotation
       * processing environment configured for a {@linkplain
       * jdkx.annotation.processing.ProcessingEnvironment#getSourceVersion
       * source version} without modules.
       *
       * @implSpec The default implementation of this method returns
       * an empty set.
       *
       * @return the known module elements, or an empty set if there are no modules
       * @see #getModuleElement(CharSequence)
       * @since 9
       */
      default Set<? extends ModuleElement> getAllModuleElements() {
          return Collections.emptySet();
      }
  
      /**
       * {@return the values of an annotation's elements, including defaults}
       *
       * @see AnnotationMirror#getElementValues()
       * @param a  annotation to examine
       */
      Map<? extends ExecutableElement, ? extends AnnotationValue>
              getElementValuesWithDefaults(AnnotationMirror a);
  
      /**
       * Returns the text of the documentation (&quot;Javadoc&quot;)
       * comment of an element.
       *
       * <p> A documentation comment of an element is a comment that
       * begins with "{@code /**}", ends with a separate
       * "<code>*&#47;</code>", and immediately precedes the element,
       * ignoring white space.  Therefore, a documentation comment
       * contains at least three "{@code *}" characters.  The text
       * returned for the documentation comment is a processed form of
       * the comment as it appears in source code.  The leading "{@code /**}"
       * and trailing "<code>*&#47;</code>" are removed.  For lines
       * of the comment starting after the initial "{@code /**}",
       * leading white space characters are discarded as are any
       * consecutive "{@code *}" characters appearing after the white
       * space or starting the line.  The processed lines are then
       * concatenated together (including line terminators) and
       * returned.
       *
       * @param e  the element being examined
       * @return the documentation comment of the element, or {@code null}
       *          if there is none
       * @jls 3.6 White Space
       */
      String getDocComment(Element e);
  
      /**
       * {@return {@code true} if the element is deprecated, {@code false} otherwise}
       *
       * @param e  the element being examined
       */
      boolean isDeprecated(Element e);
  
      /**
       * {@return the <em>origin</em> of the given element}
       *
       * <p>Note that if this method returns {@link Origin#EXPLICIT
       * EXPLICIT} and the element was created from a class file, then
       * the element may not, in fact, correspond to an explicitly
       * declared construct in source code. This is due to limitations
       * of the fidelity of the class file format in preserving
       * information from source code. For example, at least some
       * versions of the class file format do not preserve whether a
       * constructor was explicitly declared by the programmer or was
       * implicitly declared as the <em>default constructor</em>.
       *
       * @implSpec The default implementation of this method returns
       * {@link Origin#EXPLICIT EXPLICIT}.
       *
       * @param e  the element being examined
       * @since 9
       */
      default Origin getOrigin(Element e) {
          return Origin.EXPLICIT;
      }
  
      /**
       * {@return the <em>origin</em> of the given annotation mirror}
       *
       * An annotation mirror is {@linkplain Origin#MANDATED mandated}
       * if it is an implicitly declared <em>container annotation</em>
       * used to hold repeated annotations of a repeatable annotation
       * interface.
       *
       * <p>Note that if this method returns {@link Origin#EXPLICIT
       * EXPLICIT} and the annotation mirror was created from a class
       * file, then the element may not, in fact, correspond to an
       * explicitly declared construct in source code. This is due to
       * limitations of the fidelity of the class file format in
       * preserving information from source code. For example, at least
       * some versions of the class file format do not preserve whether
       * an annotation was explicitly declared by the programmer or was
       * implicitly declared as a <em>container annotation</em>.
       *
       * @implSpec The default implementation of this method returns
       * {@link Origin#EXPLICIT EXPLICIT}.
       *
       * @param c the construct the annotation mirror modifies
       * @param a the annotation mirror being examined
       * @jls 9.6.3 Repeatable Annotation Types
       * @jls 9.7.5 Multiple Annotations of the Same Interface
       * @since 9
       */
      default Origin getOrigin(AnnotatedConstruct c,
                               AnnotationMirror a) {
          return Origin.EXPLICIT;
      }
  
      /**
       * {@return the <em>origin</em> of the given module directive}
       *
       * <p>Note that if this method returns {@link Origin#EXPLICIT
       * EXPLICIT} and the module directive was created from a class
       * file, then the module directive may not, in fact, correspond to
       * an explicitly declared construct in source code. This is due to
       * limitations of the fidelity of the class file format in
       * preserving information from source code. For example, at least
       * some versions of the class file format do not preserve whether
       * a {@code uses} directive was explicitly declared by the
       * programmer or was added as a synthetic construct.
       *
       * <p>Note that an implementation may not be able to reliably
       * determine the origin status of the directive if the directive
       * is created from a class file due to limitations of the fidelity
       * of the class file format in preserving information from source
       * code.
       *
       * @implSpec The default implementation of this method returns
       * {@link Origin#EXPLICIT EXPLICIT}.
       *
       * @param m the module of the directive
       * @param directive  the module directive being examined
       * @since 9
       */
      default Origin getOrigin(ModuleElement m,
                               ModuleElement.Directive directive) {
          return Origin.EXPLICIT;
      }
  
      /**
       * The <em>origin</em> of an element or other language model
       * item. The origin of an element or item models how a construct
       * in a program is declared in the source code, explicitly,
       * implicitly, etc.
       *
       * <p>Note that it is possible additional kinds of origin values
       * will be added in future versions of the platform.
       *
       * @jls 13.1 The Form of a Binary
       * @since 9
       */
      public enum Origin {
          /**
           * Describes a construct explicitly declared in source code.
           */
          EXPLICIT,
  
          /**
           * A mandated construct is one that is not explicitly declared
           * in the source code, but whose presence is mandated by the
           * specification. Such a construct is said to be implicitly
           * declared.
           *
           * One example of a mandated element is a <em>default
           * constructor</em> in a class that contains no explicit
           * constructor declarations.
           *
           * Another example of a mandated construct is an implicitly
           * declared <em>container annotation</em> used to hold
           * multiple annotations of a repeatable annotation interface.
           *
           * @jls 8.8.9 Default Constructor
           * @jls 8.9.3 Enum Members
           * @jls 9.6.3 Repeatable Annotation Types
           * @jls 9.7.5 Multiple Annotations of the Same Interface
           */
          MANDATED,
  
          /**
           * A synthetic construct is one that is neither implicitly nor
           * explicitly declared in the source code. Such a construct is
           * typically a translation artifact created by a compiler.
           */
          SYNTHETIC;
  
          /**
           * Returns {@code true} for values corresponding to constructs
           * that are implicitly or explicitly declared, {@code false}
           * otherwise.
           * @return {@code true} for {@link #EXPLICIT} and {@link #MANDATED},
           *         {@code false} otherwise.
           */
          public boolean isDeclared() {
              return this != SYNTHETIC;
          }
      }
  
      /**
       * {@return {@code true} if the executable element is a bridge
       * method, {@code false} otherwise}
       *
       * @implSpec The default implementation of this method returns {@code false}.
       *
       * @param e  the executable being examined
       * @since 9
       */
      default boolean isBridge(ExecutableElement e) {
          return false;
      }
  
      /**
       * {@return the <i>binary name</i> of a type element}
       *
       * @param type  the type element being examined
       *
       * @see TypeElement#getQualifiedName
       * @jls 13.1 The Form of a Binary
       */
      Name getBinaryName(TypeElement type);
  
  
      /**
       * {@return the package of an element}  The package of a package is
       * itself.
       * The package of a module is {@code null}.
       *
       * The package of a top-level class or interface is its {@linkplain
       * TypeElement#getEnclosingElement enclosing package}. Otherwise,
       * the package of an element is equal to the package of the
       * {@linkplain Element#getEnclosingElement enclosing element}.
       *
       * @param e the element being examined
       */
      PackageElement getPackageOf(Element e);
  
      /**
       * {@return the module of an element}  The module of a module is
       * itself.
       *
       * If a package has a module as its {@linkplain
       * PackageElement#getEnclosingElement enclosing element}, that
       * module is the module of the package. If the enclosing element
       * of a package is {@code null}, {@code null} is returned for the
       * package's module.
       *
       * (One situation where a package may have a {@code null} module
       * is if the environment does not include modules, such as an
       * annotation processing environment configured for a {@linkplain
       * jdkx.annotation.processing.ProcessingEnvironment#getSourceVersion
       * source version} without modules.)
       *
       * Otherwise, the module of an element is equal to the module
       * {@linkplain #getPackageOf(Element) of the package} of the
       * element.
       *
       * @implSpec The default implementation of this method returns
       * {@code null}.
       *
       * @param e the element being examined
       * @since 9
       */
      default ModuleElement getModuleOf(Element e) {
          return null;
      }
  
      /**
       * Returns all members of a type element, whether inherited or
       * declared directly.  For a class the result also includes its
       * constructors, but not local or anonymous classes.
       *
       * @apiNote Elements of certain kinds can be isolated using
       * methods in {@link ElementFilter}.
       *
       * @param type  the type being examined
       * @return all members of the type
       * @see Element#getEnclosedElements
       */
      List<? extends Element> getAllMembers(TypeElement type);
  
      /**
       * Returns all annotations <i>present</i> on an element, whether
       * directly present or present via inheritance.
       *
       * <p>Note that any annotations returned by this method are
       * declaration annotations.
       *
       * @param e  the element being examined
       * @return all annotations of the element
       * @see Element#getAnnotationMirrors
       * @see jdkx.lang.model.AnnotatedConstruct
       */
      List<? extends AnnotationMirror> getAllAnnotationMirrors(Element e);
  
      /**
       * Tests whether one type, method, or field hides another.
       *
       * @param hider   the first element
       * @param hidden  the second element
       * @return {@code true} if and only if the first element hides
       *          the second
       * @jls 8.4.8 Inheritance, Overriding, and Hiding
       */
      boolean hides(Element hider, Element hidden);
  
      /**
       * Tests whether one method, as a member of a given class or interface,
       * overrides another method.
       * When a non-abstract method overrides an abstract one, the
       * former is also said to <i>implement</i> the latter.
       *
       * <p> In the simplest and most typical usage, the value of the
       * {@code type} parameter will simply be the class or interface
       * directly enclosing {@code overrider} (the possibly-overriding
       * method).  For example, suppose {@code m1} represents the method
       * {@code String.hashCode} and {@code m2} represents {@code
       * Object.hashCode}.  We can then ask whether {@code m1} overrides
       * {@code m2} within the class {@code String} (it does):
       *
       * <blockquote>
       * {@code assert elements.overrides(m1, m2,
       *          elements.getTypeElement("java.lang.String")); }
       * </blockquote>
       *
       * A more interesting case can be illustrated by the following example
       * in which a method in class {@code A} does not override a
       * like-named method in interface {@code B}:
       *
       * <blockquote>
       * {@code class A { public void m() {} } }<br>
       * {@code interface B { void m(); } }<br>
       * ...<br>
       * {@code m1 = ...;  // A.m }<br>
       * {@code m2 = ...;  // B.m }<br>
       * {@code assert ! elements.overrides(m1, m2,
       *          elements.getTypeElement("A")); }
       * </blockquote>
       *
       * When viewed as a member of a third class {@code C}, however,
       * the method in {@code A} does override the one in {@code B}:
       *
       * <blockquote>
       * {@code class C extends A implements B {} }<br>
       * ...<br>
       * {@code assert elements.overrides(m1, m2,
       *          elements.getTypeElement("C")); }
       * </blockquote>
       *
       * @param overrider  the first method, possible overrider
       * @param overridden  the second method, possibly being overridden
       * @param type   the class or interface of which the first method is a member
       * @return {@code true} if and only if the first method overrides
       *          the second
       * @jls 8.4.8 Inheritance, Overriding, and Hiding
       * @jls 9.4.1 Inheritance and Overriding
       */
      boolean overrides(ExecutableElement overrider, ExecutableElement overridden,
                        TypeElement type);
  
      /**
       * Returns the text of a <i>constant expression</i> representing a
       * primitive value or a string.
       * The text returned is in a form suitable for representing the value
       * in source code.
       *
       * @param value  a primitive value or string
       * @return the text of a constant expression
       * @throws IllegalArgumentException if the argument is not a primitive
       *          value or string
       *
       * @see VariableElement#getConstantValue()
       */
      String getConstantExpression(Object value);
  
      /**
       * Prints a representation of the elements to the given writer in
       * the specified order.  The main purpose of this method is for
       * diagnostics.  The exact format of the output is <em>not</em>
       * specified and is subject to change.
       *
       * @param w the writer to print the output to
       * @param elements the elements to print
       */
      void printElements(java.io.Writer w, Element... elements);
  
      /**
       * {@return a name with the same sequence of characters as the
       * argument}
       *
       * @param cs the character sequence to return as a name
       */
      Name getName(CharSequence cs);
  
      /**
       * {@return {@code true} if the type element is a functional
       * interface, {@code false} otherwise}
       *
       * @param type the type element being examined
       * @jls 9.8 Functional Interfaces
       * @since 1.8
       */
      boolean isFunctionalInterface(TypeElement type);
  
      /**
       * {@return {@code true} if the module element is an automatic
       * module, {@code false} otherwise}
       *
       * @implSpec
       * The default implementation of this method returns {@code
       * false}.
       *
       * @param module the module element being examined
       * @jls 7.7.1 Dependences
       * @since 17
       */
      default boolean isAutomaticModule(ModuleElement module) {
          return false;
      }
  
      /**
       * Returns the record component for the given accessor. Returns null if the
       * given method is not a record component accessor.
       *
       * @implSpec The default implementation of this method checks if the element
       * enclosing the accessor has kind {@link ElementKind#RECORD RECORD} if that is
       * the case, then all the record components on the accessor's enclosing element
       * are retrieved by invoking {@link ElementFilter#recordComponentsIn(Iterable)}.
       * If the accessor of at least one of the record components retrieved happen to
       * be equal to the accessor passed as a parameter to this method, then that
       * record component is returned, in any other case {@code null} is returned.
       *
       * @param accessor the method for which the record component should be found.
       * @return the record component, or null if the given method is not an record
       * component accessor
       * @since 16
       */
      default RecordComponentElement recordComponentFor(ExecutableElement accessor) {
          if (accessor.getEnclosingElement().getKind() == ElementKind.RECORD) {
              for (RecordComponentElement rec : ElementFilter.recordComponentsIn(accessor.getEnclosingElement().getEnclosedElements())) {
                  if (Objects.equals(rec.getAccessor(), accessor)) {
                      return rec;
                  }
              }
          }
          return null;
      }
  }
  