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package javax.lang.model.util;
import java.util.Arrays;
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 javax.lang.model.AnnotatedConstruct;
import javax.lang.model.element.*;
/**
* Utility methods for operating on program elements.
*
* Compatibility Note: Methods may be added to this interface
* in future releases of the platform.
*
* @see javax.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:
*
* - find non-empty packages with the given name returned by
* {@link #getPackageElement(ModuleElement, CharSequence)},
* where the provided ModuleSymbol is any
* root module,
*
* - if the above yields an empty list, search
* {@link #getAllModuleElements() all modules} for observable
* packages with the given name
*
*
*
* If this process leads to a list with a single element, the
* single element is returned, otherwise {@code 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 getAllPackageElements(CharSequence name) {
Set modules = getAllModuleElements();
if (modules.isEmpty()) {
PackageElement packageElt = getPackageElement(name);
return (packageElt != null) ?
Collections.singleton(packageElt):
Collections.emptySet();
} else {
Set 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:
*
* - find type elements with the given name returned by
* {@link #getTypeElement(ModuleElement, CharSequence)},
* where the provided ModuleSymbol is any
* root module,
*
* - if the above yields an empty list, search
* {@link #getAllModuleElements() all modules} for observable
* type elements with the given name
*
*
*
* If this process leads to a list with a single element, the
* single element is returned, otherwise {@code 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 getAllTypeElements(CharSequence name) {
Set modules = getAllModuleElements();
if (modules.isEmpty()) {
TypeElement typeElt = getTypeElement(name);
return (typeElt != null) ?
Collections.singleton(typeElt):
Collections.emptySet();
} else {
Set 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
* javax.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
* javax.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 getAllModuleElements() {
return Collections.emptySet();
}
/**
* {@return the values of an annotation's elements, including defaults}
*
* @see AnnotationMirror#getElementValues()
* @param a annotation to examine
*/
Map
getElementValuesWithDefaults(AnnotationMirror a);
/**
* Returns the text of the documentation ("Javadoc")
* comment of an element.
*
* A documentation comment of an element is a comment that
* begins with "{@code /**}", ends with a separate
* "*/", 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 "*/" 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 origin of the given element}
*
*
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 default constructor.
*
* @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 origin of the given annotation mirror}
*
* An annotation mirror is {@linkplain Origin#MANDATED mandated}
* if it is an implicitly declared container annotation
* used to hold repeated annotations of a repeatable annotation
* interface.
*
*
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 container annotation.
*
* @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 Interfaces
* @jls 9.7.5 Multiple Annotations of the Same Interface
* @since 9
*/
default Origin getOrigin(AnnotatedConstruct c,
AnnotationMirror a) {
return Origin.EXPLICIT;
}
/**
* {@return the origin of the given module directive}
*
*
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.
*
*
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 origin 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.
*
*
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 default
* constructor in a class that contains no explicit
* constructor declarations.
*
* Another example of a mandated construct is an implicitly
* declared container annotation used to hold
* multiple annotations of a repeatable annotation interface.
*
* @jls 8.8.9 Default Constructor
* @jls 8.9.3 Enum Members
* @jls 8.10.3 Record Members
* @jls 9.6.3 Repeatable Annotation Interfaces
* @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 binary name 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
* javax.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 getAllMembers(TypeElement type);
/**
* {@return the outermost type element an element is contained in
* if such a containing element exists; otherwise returns {@code
* null}}
*
* {@linkplain ModuleElement Modules} and {@linkplain
* PackageElement packages} do not have a containing type
* element and therefore {@code null} is returned for those kinds
* of elements.
*
* A {@linkplain NestingKind#TOP_LEVEL top-level} class or
* interface is its own outermost type element.
*
* @implSpec
* The default implementation of this method first checks the kind
* of the argument. For elements of kind {@code PACKAGE}, {@code
* MODULE}, and {@code OTHER}, {@code null} is returned. For
* elements of other kinds, the element is examined to see if it
* is a top-level class or interface. If so, that element is
* returned; otherwise, the {@linkplain
* Element#getEnclosingElement enclosing element} chain is
* followed until a top-level class or interface is found. The
* element for the eventual top-level class or interface is
* returned.
*
* @param e the element being examined
* @see Element#getEnclosingElement
* @since 18
*/
default TypeElement getOutermostTypeElement(Element e) {
return switch (e.getKind()) {
case PACKAGE,
MODULE -> null; // Per the general spec above.
case OTHER -> null; // Outside of base model of the javax.lang.model API
// Elements of all remaining kinds should be enclosed in some
// sort of class or interface. Check to see if the element is
// a top-level type; if so, return it. Otherwise, keep going
// up the enclosing element chain until a top-level type is
// found.
default -> {
Element enclosing = e;
// This implementation is susceptible to infinite loops
// for misbehaving element implementations.
while (true) {
// Conceptual instanceof TypeElement check. If the
// argument is a type element, put it into a
// one-element list, otherwise an empty list.
List possibleTypeElement = ElementFilter.typesIn(Collections.unmodifiableList(Arrays.asList(enclosing)));
if (!possibleTypeElement.isEmpty()) {
TypeElement typeElement = possibleTypeElement.get(0);
if (typeElement.getNestingKind() == NestingKind.TOP_LEVEL) {
yield typeElement;
}
}
enclosing = enclosing.getEnclosingElement();
}
}
};
}
/**
* Returns all annotations present on an element, whether
* directly present or present via inheritance.
*
* 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 javax.lang.model.AnnotatedConstruct
*/
List 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 implement the latter.
*
*
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):
*
*
* {@code assert elements.overrides(m1, m2,
* elements.getTypeElement("java.lang.String")); }
*
*
* 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}:
*
*
* {@code class A { public void m() {} } }
* {@code interface B { void m(); } }
* ...
* {@code m1 = ...; // A.m }
* {@code m2 = ...; // B.m }
* {@code assert ! elements.overrides(m1, m2,
* elements.getTypeElement("A")); }
*
*
* When viewed as a member of a third class {@code C}, however,
* the method in {@code A} does override the one in {@code B}:
*
*
* {@code class C extends A implements B {} }
* ...
* {@code assert elements.overrides(m1, m2,
* elements.getTypeElement("C")); }
*
*
* @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 constant expression 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 not
* 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
* {@code 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 {@code null} if the given
* method is not a 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;
}
/**
* {@return the file object for this element or {@code null} if
* there is no such file object}
*
* The returned file object is for the reference
* representation of the information used to construct the
* element. For example, if during compilation or annotation
* processing, a source file for class {@code Foo} is compiled
* into a class file, the file object returned for the element
* representing {@code Foo} would be for the source file and
* not for the class file.
*
*
An implementation may choose to not support the
* functionality of this method, in which case {@link
* UnsupportedOperationException} is thrown.
*
*
In the context of annotation processing, a non-{@code null}
* value is returned if the element was included as part of the
* initial inputs or the containing file was created during the
* run of the annotation processing tool. Otherwise, a {@code
* null} may be returned. In annotation processing, if a
* {@linkplain javax.annotation.processing.Filer#createClassFile
* class file is created}, that class file can serve as the
* reference representation for elements.
*
*
If it has a file object, the file object for a package will
* be a {@code package-info} file. A package may exist and not
* have any {@code package-info} file even if the package is
* (implicitly) created during an annotation processing run from
* the creation of source or class files in that package. An
* {@linkplain PackageElement#isUnnamed unnamed package} will have
* a {@code null} file since it cannot be declared in a
* compilation unit.
*
*
If it has a file object, the file object for a module will
* be a {@code module-info} file. An {@linkplain
* ModuleElement#isUnnamed unnamed module} will have a {@code
* null} file since it cannot be declared in a compilation unit.
* An {@linkplain #isAutomaticModule automatic module} will have a
* {@code null} file since it is implicitly declared.
*
*
If it has a file object, the file object for a top-level
* {@code public} class or interface will be a source or class
* file corresponding to that class or interface. In this case,
* typically the leading portion of the name of the file will
* match the name of the class or interface. A single compilation
* unit can define multiple top-level classes and interfaces, such
* as a primary {@code public} class or interfaces whose name
* corresponds to the file name and one or more auxiliary
* classes or interfaces whose names do not correspond to the file
* name. If a source file is providing the reference
* representation of an auxiliary class or interface, the file for
* the primary class is returned. (An auxiliary class or interface
* can also be defined in a {@code package-info} source file, in
* which case the file for the {@code package-info} file is
* returned.) If a class file is providing the reference
* representation of an auxiliary class or interface, the separate
* class file for the auxiliary class is returned.
*
*
For a nested class or interface, if it has a file object:
*
*
*
* - if a source file is providing the reference representation,
* the file object will be that of the {@linkplain
* #getOutermostTypeElement(Element) outermost enclosing} class or
* interface
*
*
- if a class file is providing the reference representation,
* the file object will be that of the nested class or interface
* itself
*
*
*
* For other lexically enclosed elements, such as {@linkplain
* VariableElement#getEnclosingElement() variables}, {@linkplain
* ExecutableElement#getEnclosingElement() methods, and
* constructors}, if they have a file object, the file object will
* be the object associated with the {@linkplain
* Element#getEnclosingElement() enclosing element} of the
* lexically enclosed element.
*
* @implSpec The default implementation unconditionally throws
* {@link UnsupportedOperationException}.
*
* @throws UnsupportedOperationException if this functionality is
* not supported
*
* @param e the element to find a file object for
* @since 18
*/
default javax.tools.JavaFileObject getFileObjectOf(Element e) {
throw new UnsupportedOperationException();
}
}