com.google.auto.common

Class MoreElements

java.lang.Object

com.google.auto.common.MoreElements

@Beta
public final class MoreElements
extends Object

Static utility methods pertaining to Element instances.

Author:

Gregory Kick

Method Summary

Methods

Modifier and Type	Method and Description
static ExecutableElement	asExecutable(Element element) Returns the given Element instance as ExecutableElement.
static PackageElement	asPackage(Element element) Returns the given Element instance as PackageElement.
static TypeElement	asType(Element element) Returns the given Element instance as TypeElement.
static VariableElement	asVariable(Element element) Returns the given Element instance as VariableElement.
static com.google.common.base.Optional<AnnotationMirror>	getAnnotationMirror(Element element, Class<? extends Annotation> annotationClass) Returns an AnnotationMirror for the annotation of type annotationClass on element, or Optional.absent() if no such annotation exists.
static com.google.common.collect.ImmutableSet<ExecutableElement>	getLocalAndInheritedMethods(TypeElement type, Elements elementUtils) Returns the set of all non-private methods from type, including methods that it inherits from its ancestors.
static PackageElement	getPackage(Element element) An alternate implementation of Elements.getPackageOf(javax.lang.model.element.Element) that does not require an Elements instance.
static com.google.common.base.Predicate<Element>	hasModifiers(Modifier... modifiers) Returns a Predicate that can be used to filter elements by Modifier.
static com.google.common.base.Predicate<Element>	hasModifiers(Set<Modifier> modifiers) Returns a Predicate that can be used to filter elements by Modifier.
static boolean	isAnnotationPresent(Element element, Class<? extends Annotation> annotationClass) Returns true iff the given element has an AnnotationMirror whose annotation type has the same canonical name as that of annotationClass.
static boolean	isType(Element element) Returns true if the given Element instance is a TypeElement.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

getPackage

public static PackageElement getPackage(Element element)

An alternate implementation of Elements.getPackageOf(javax.lang.model.element.Element) that does not require an Elements instance.

Throws:

NullPointerException - if element is null

asPackage

public static PackageElement asPackage(Element element)

Returns the given Element instance as PackageElement.

This method is functionally equivalent to an instanceof check and a cast, but should always be used over that idiom as instructed in the documentation for Element.

Throws:

NullPointerException - if element is null

IllegalArgumentException - if element isn't a PackageElement.

isType

public static boolean isType(Element element)

Returns true if the given Element instance is a TypeElement.

This method is functionally equivalent to an instanceof check, but should always be used over that idiom as instructed in the documentation for Element.

Throws:

NullPointerException - if element is null

asType

public static TypeElement asType(Element element)

Returns the given Element instance as TypeElement.

This method is functionally equivalent to an instanceof check and a cast, but should always be used over that idiom as instructed in the documentation for Element.

Throws:

NullPointerException - if element is null

IllegalArgumentException - if element isn't a TypeElement.

asVariable

public static VariableElement asVariable(Element element)

Returns the given Element instance as VariableElement.

This method is functionally equivalent to an instanceof check and a cast, but should always be used over that idiom as instructed in the documentation for Element.

Throws:

NullPointerException - if element is null

IllegalArgumentException - if element isn't a VariableElement.

asExecutable

public static ExecutableElement asExecutable(Element element)

Returns the given Element instance as ExecutableElement.

This method is functionally equivalent to an instanceof check and a cast, but should always be used over that idiom as instructed in the documentation for Element.

Throws:

NullPointerException - if element is null

IllegalArgumentException - if element isn't a ExecutableElement.

isAnnotationPresent

public static boolean isAnnotationPresent(Element element,
                          Class<? extends Annotation> annotationClass)

Returns true iff the given element has an AnnotationMirror whose annotation type has the same canonical name as that of annotationClass. This method is a safer alternative to calling Element.getAnnotation(java.lang.Class<A>) and checking for null as it avoids any interaction with annotation proxies.

getAnnotationMirror

public static com.google.common.base.Optional<AnnotationMirror> getAnnotationMirror(Element element,
                                                                    Class<? extends Annotation> annotationClass)

Returns an AnnotationMirror for the annotation of type annotationClass on element, or Optional.absent() if no such annotation exists. This method is a safer alternative to calling Element.getAnnotation(java.lang.Class<A>) as it avoids any interaction with annotation proxies.

hasModifiers

public static com.google.common.base.Predicate<Element> hasModifiers(Modifier... modifiers)

Returns a Predicate that can be used to filter elements by Modifier. The predicate returns true if the input Element has all of the given modifiers, perhaps in addition to others.

Here is an example how one could get a List of static methods of a class:

FluentIterable.from(ElementFilter.methodsIn(clazzElement.getEnclosedElements()))
     .filter(MoreElements.hasModifiers(Modifier.STATIC).toList();
 

hasModifiers

public static com.google.common.base.Predicate<Element> hasModifiers(Set<Modifier> modifiers)

Returns a Predicate that can be used to filter elements by Modifier. The predicate returns true if the input Element has all of the given modifiers, perhaps in addition to others.

Here is an example how one could get a List of methods with certain modifiers of a class:

Set<Modifier> modifiers = ...;
 FluentIterable.from(ElementFilter.methodsIn(clazzElement.getEnclosedElements()))
     .filter(MoreElements.hasModifiers(modifiers).toList();
 

getLocalAndInheritedMethods

public static com.google.common.collect.ImmutableSet<ExecutableElement> getLocalAndInheritedMethods(TypeElement type,
                                                                                    Elements elementUtils)

Returns the set of all non-private methods from type, including methods that it inherits from its ancestors. Inherited methods that are overridden are not included in the result. So if type defines public String toString(), the returned set will contain that method, but not the toString() method defined by Object.

Parameters:

type - the type whose own and inherited methods are to be returned

elementUtils - an Elements object, typically returned by processingEnv.getElementUtils()