JDK14/Java14源码在线阅读
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package javax.lang.model.util;
import java.util.ArrayList;
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.
*
* <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 Ahé
* @see javax.annotation.processing.ProcessingEnvironment#getElementUtils
* @since 1.6
*/
public interface Elements {
/**
* Returns a package given its fully qualified name if the package is unique in the environment.
* If running with modules, all modules in the modules graph are searched for matching packages.
*
* @param name fully qualified package name, or an empty string for an unnamed package
* @return the specified package, or {@code null} if it cannot be uniquely found
*/
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 unique in the environment.
* If running with modules, all modules in the modules graph are searched for matching
* type elements.
*
* @param name the canonical name
* @return the named type element, or {@code null} if it cannot be uniquely found
*/
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
* 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
* @spec JPMS
*/
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<? extends ModuleElement> getAllModuleElements() {
return Collections.emptySet();
}
/**
* Returns the values of an annotation's elements, including defaults.
*
* @see AnnotationMirror#getElementValues()
* @param a annotation to examine
* @return the values of the annotation's elements, including defaults
*/
Map<? extends ExecutableElement, ? extends AnnotationValue>
getElementValuesWithDefaults(AnnotationMirror a);
/**
* Returns the text of the documentation ("Javadoc")
* comment of an element.
*
* <p> A documentation comment of an element is a comment that
* begins with "{@code /**}" , ends with a separate
* "<code>*/</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>*/</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);
/**
* Returns {@code true} if the element is deprecated, {@code false} otherwise.
*
* @param e the element being examined
* @return {@code true} if the element is deprecated, {@code false} otherwise
*/
boolean isDeprecated(Element e);
/**
* Returns 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
* @return the origin of the given element
* @since 9
*/
default Origin getOrigin(Element e) {
return Origin.EXPLICIT;
}
/**
* Returns 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
* type.
*
* <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
* @return the origin of the given annotation mirror
* @jls 9.6.3 Repeatable Annotation Types
* @jls 9.7.5 Multiple Annotations of the Same Type
* @since 9
*/
default Origin getOrigin(AnnotatedConstruct c,
AnnotationMirror a) {
return Origin.EXPLICIT;
}
/**
* Returns 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
* @return the origin of the given directive
* @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 type.
*
* @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 Type
*/
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;
}
}
/**
* Returns {@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
* @return {@code true} if the executable element is a bridge
* method, {@code false} otherwise
* @since 9
*/
default boolean isBridge(ExecutableElement e) {
return false;
}
/**
* Returns the <i>binary name</i> of a type element.
*
* @param type the type element being examined
* @return the binary name
*
* @see TypeElement#getQualifiedName
* @jls 13.1 The Form of a Binary
*/
Name getBinaryName(TypeElement type);
/**
* Returns 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 type 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
* @return the package of an element
*/
PackageElement getPackageOf(Element e);
/**
* Returns 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
* @return the module of an element
* @since 9
* @spec JPMS
*/
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.
*
* @param e the element being examined
* @return all annotations of the element
* @see Element#getAnnotationMirrors
* @see javax.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 type,
* 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 type {@code A} does not override a
* like-named method in type {@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 type {@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 type 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
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