com.google.auto.common

Class MoreElements

java.lang.Object

com.google.auto.common.MoreElements

@Beta
public final class MoreElements
extends java.lang.Object

Static utility methods pertaining to Element instances.

Field Summary

Fields

Modifier and Type	Field and Description
private static javax.lang.model.element.ElementVisitor<javax.lang.model.element.ExecutableElement,java.lang.Void>	EXECUTABLE_ELEMENT_VISITOR
private static javax.lang.model.element.ElementVisitor<javax.lang.model.element.PackageElement,java.lang.Void>	PACKAGE_ELEMENT_VISITOR
private static javax.lang.model.element.ElementVisitor<javax.lang.model.element.TypeElement,java.lang.Void>	TYPE_ELEMENT_VISITOR
private static javax.lang.model.element.ElementVisitor<javax.lang.model.element.VariableElement,java.lang.Void>	VARIABLE_ELEMENT_VISITOR

Constructor Summary

Constructors

Modifier	Constructor and Description
private	MoreElements()

Method Summary

Modifier and Type	Method and Description
static javax.lang.model.element.ExecutableElement	asExecutable(javax.lang.model.element.Element element) Returns the given Element instance as ExecutableElement.
static javax.lang.model.element.PackageElement	asPackage(javax.lang.model.element.Element element) Returns the given Element instance as PackageElement.
static javax.lang.model.element.TypeElement	asType(javax.lang.model.element.Element element) Returns the given Element instance as TypeElement.
static javax.lang.model.element.VariableElement	asVariable(javax.lang.model.element.Element element) Returns the given Element instance as VariableElement.
static com.google.common.base.Optional<javax.lang.model.element.AnnotationMirror>	getAnnotationMirror(javax.lang.model.element.Element element, java.lang.Class<? extends java.lang.annotation.Annotation> annotationClass) Returns an AnnotationMirror for the annotation of type annotationClass on element, or Optional.absent() if no such annotation exists.
static javax.lang.model.element.PackageElement	getPackage(javax.lang.model.element.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<javax.lang.model.element.Element>	hasModifiers(javax.lang.model.element.Modifier... modifiers) Returns a Predicate that can be used to filter elements by Modifier.
static com.google.common.base.Predicate<javax.lang.model.element.Element>	hasModifiers(java.util.Set<javax.lang.model.element.Modifier> modifiers) Returns a Predicate that can be used to filter elements by Modifier.
static boolean	isAnnotationPresent(javax.lang.model.element.Element element, java.lang.Class<? extends java.lang.annotation.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(javax.lang.model.element.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

Field Detail

PACKAGE_ELEMENT_VISITOR

private static final javax.lang.model.element.ElementVisitor<javax.lang.model.element.PackageElement,java.lang.Void> PACKAGE_ELEMENT_VISITOR

TYPE_ELEMENT_VISITOR

private static final javax.lang.model.element.ElementVisitor<javax.lang.model.element.TypeElement,java.lang.Void> TYPE_ELEMENT_VISITOR

VARIABLE_ELEMENT_VISITOR

private static final javax.lang.model.element.ElementVisitor<javax.lang.model.element.VariableElement,java.lang.Void> VARIABLE_ELEMENT_VISITOR

EXECUTABLE_ELEMENT_VISITOR

private static final javax.lang.model.element.ElementVisitor<javax.lang.model.element.ExecutableElement,java.lang.Void> EXECUTABLE_ELEMENT_VISITOR

Constructor Detail

MoreElements

private MoreElements()

Method Detail

getPackage

public static javax.lang.model.element.PackageElement getPackage(javax.lang.model.element.Element element)

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

Throws:

java.lang.NullPointerException - if element is null

asPackage

public static javax.lang.model.element.PackageElement asPackage(javax.lang.model.element.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:

java.lang.NullPointerException - if element is null

java.lang.IllegalArgumentException - if element isn't a PackageElement.

isType

public static boolean isType(javax.lang.model.element.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:

java.lang.NullPointerException - if element is null

asType

public static javax.lang.model.element.TypeElement asType(javax.lang.model.element.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:

java.lang.NullPointerException - if element is null

java.lang.IllegalArgumentException - if element isn't a TypeElement.

asVariable

public static javax.lang.model.element.VariableElement asVariable(javax.lang.model.element.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:

java.lang.NullPointerException - if element is null

java.lang.IllegalArgumentException - if element isn't a VariableElement.

asExecutable

public static javax.lang.model.element.ExecutableElement asExecutable(javax.lang.model.element.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:

java.lang.NullPointerException - if element is null

java.lang.IllegalArgumentException - if element isn't a ExecutableElement.

isAnnotationPresent

public static boolean isAnnotationPresent(javax.lang.model.element.Element element,
                                          java.lang.Class<? extends java.lang.annotation.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<javax.lang.model.element.AnnotationMirror> getAnnotationMirror(javax.lang.model.element.Element element,
                                                                                                             java.lang.Class<? extends java.lang.annotation.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<javax.lang.model.element.Element> hasModifiers(javax.lang.model.element.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<javax.lang.model.element.Element> hasModifiers(java.util.Set<javax.lang.model.element.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();