package org.checkerframework.javacutil;
/*>>>
import org.checkerframework.checker.nullness.qual.Nullable;
*/
import static com.sun.tools.javac.code.Flags.ABSTRACT;
import static com.sun.tools.javac.code.Flags.EFFECTIVELY_FINAL;
import static com.sun.tools.javac.code.Flags.FINAL;
import com.sun.tools.javac.code.Symbol;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Deque;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import javax.annotation.processing.ProcessingEnvironment;
import javax.lang.model.element.Element;
import javax.lang.model.element.ElementKind;
import javax.lang.model.element.ExecutableElement;
import javax.lang.model.element.Modifier;
import javax.lang.model.element.Name;
import javax.lang.model.element.PackageElement;
import javax.lang.model.element.TypeElement;
import javax.lang.model.element.VariableElement;
import javax.lang.model.type.DeclaredType;
import javax.lang.model.type.TypeKind;
import javax.lang.model.type.TypeMirror;
import javax.lang.model.util.ElementFilter;
import javax.lang.model.util.Elements;
/** A Utility class for analyzing {@code Element}s. */
public class ElementUtils {
// Class cannot be instantiated.
private ElementUtils() {
throw new AssertionError("Class ElementUtils cannot be instantiated.");
}
/**
* Returns the innermost type element enclosing the given element
*
* @param elem the enclosed element of a class
* @return the innermost type element
*/
public static TypeElement enclosingClass(final Element elem) {
Element result = elem;
while (result != null && !result.getKind().isClass() && !result.getKind().isInterface()) {
/*@Nullable*/ Element encl = result.getEnclosingElement();
result = encl;
}
return (TypeElement) result;
}
/**
* Returns the innermost package element enclosing the given element. The same effect as {@link
* javax.lang.model.util.Elements#getPackageOf(Element)}. Returns the element itself if it is a
* package.
*
* @param elem the enclosed element of a package
* @return the innermost package element
*/
public static PackageElement enclosingPackage(final Element elem) {
Element result = elem;
while (result != null && result.getKind() != ElementKind.PACKAGE) {
/*@Nullable*/ Element encl = result.getEnclosingElement();
result = encl;
}
return (PackageElement) result;
}
/**
* Returns the "parent" package element for the given package element. For package "A.B" it
* gives "A". For package "A" it gives the default package. For the default package it returns
* null;
*
* <p>Note that packages are not enclosed within each other, we have to manually climb the
* namespaces. Calling "enclosingPackage" on a package element returns the package element
* itself again.
*
* @param elem the package to start from
* @return the parent package element
*/
public static PackageElement parentPackage(final Elements e, final PackageElement elem) {
// The following might do the same thing:
// ((Symbol) elt).owner;
// TODO: verify and see whether the change is worth it.
String fqnstart = elem.getQualifiedName().toString();
String fqn = fqnstart;
if (fqn != null && !fqn.isEmpty() && fqn.contains(".")) {
fqn = fqn.substring(0, fqn.lastIndexOf('.'));
return e.getPackageElement(fqn);
}
return null;
}
/**
* Returns true if the element is a static element: whether it is a static field, static method,
* or static class
*
* @return true if element is static
*/
public static boolean isStatic(Element element) {
return element.getModifiers().contains(Modifier.STATIC);
}
/**
* Returns true if the element is a final element: a final field, final method, or final class
*
* @return true if the element is final
*/
public static boolean isFinal(Element element) {
return element.getModifiers().contains(Modifier.FINAL);
}
/**
* Returns true if the element is a effectively final element.
*
* @return true if the element is effectively final
*/
public static boolean isEffectivelyFinal(Element element) {
Symbol sym = (Symbol) element;
if (sym.getEnclosingElement().getKind() == ElementKind.METHOD
&& (sym.getEnclosingElement().flags() & ABSTRACT) != 0) {
return true;
}
return (sym.flags() & (FINAL | EFFECTIVELY_FINAL)) != 0;
}
/**
* Returns the {@code TypeMirror} for usage of Element as a value. It returns the return type of
* a method element, the class type of a constructor, or simply the type mirror of the element
* itself.
*
* @return the type for the element used as a value
*/
public static TypeMirror getType(Element element) {
if (element.getKind() == ElementKind.METHOD) {
return ((ExecutableElement) element).getReturnType();
} else if (element.getKind() == ElementKind.CONSTRUCTOR) {
return enclosingClass(element).asType();
} else {
return element.asType();
}
}
/**
* Returns the qualified name of the inner most class enclosing the provided {@code Element}
*
* @param element an element enclosed by a class, or a {@code TypeElement}
* @return the qualified {@code Name} of the innermost class enclosing the element
*/
public static /*@Nullable*/ Name getQualifiedClassName(Element element) {
if (element.getKind() == ElementKind.PACKAGE) {
PackageElement elem = (PackageElement) element;
return elem.getQualifiedName();
}
TypeElement elem = enclosingClass(element);
if (elem == null) {
return null;
}
return elem.getQualifiedName();
}
/** Returns a verbose name that identifies the element. */
public static String getVerboseName(Element elt) {
if (elt.getKind() == ElementKind.PACKAGE
|| elt.getKind().isClass()
|| elt.getKind().isInterface()) {
return getQualifiedClassName(elt).toString();
} else {
return getQualifiedClassName(elt) + "." + elt.toString();
}
}
/**
* Check if the element is an element for 'java.lang.Object'
*
* @param element the type element
* @return true iff the element is java.lang.Object element
*/
public static boolean isObject(TypeElement element) {
return element.getQualifiedName().contentEquals("java.lang.Object");
}
/** Returns true if the element is a constant time reference */
public static boolean isCompileTimeConstant(Element elt) {
return elt != null
&& (elt.getKind() == ElementKind.FIELD
|| elt.getKind() == ElementKind.LOCAL_VARIABLE)
&& ((VariableElement) elt).getConstantValue() != null;
}
/**
* Returns true if the element is declared in ByteCode. Always return false if elt is a package.
*/
public static boolean isElementFromByteCode(Element elt) {
if (elt == null) {
return false;
}
if (elt instanceof Symbol.ClassSymbol) {
Symbol.ClassSymbol clss = (Symbol.ClassSymbol) elt;
if (null != clss.classfile) {
// The class file could be a .java file
return clss.classfile.getName().endsWith(".class");
} else {
return false;
}
}
return isElementFromByteCode(elt.getEnclosingElement(), elt);
}
/**
* Returns true if the element is declared in ByteCode. Always return false if elt is a package.
*/
private static boolean isElementFromByteCode(Element elt, Element orig) {
if (elt == null) {
return false;
}
if (elt instanceof Symbol.ClassSymbol) {
Symbol.ClassSymbol clss = (Symbol.ClassSymbol) elt;
if (null != clss.classfile) {
// The class file could be a .java file
return (clss.classfile.getName().endsWith(".class")
|| clss.classfile.getName().endsWith(".class)")
|| clss.classfile.getName().endsWith(".class)]"));
} else {
return false;
}
}
return isElementFromByteCode(elt.getEnclosingElement(), elt);
}
/** Returns the field of the class */
public static VariableElement findFieldInType(TypeElement type, String name) {
for (VariableElement field : ElementFilter.fieldsIn(type.getEnclosedElements())) {
if (field.getSimpleName().toString().equals(name)) {
return field;
}
}
return null;
}
/**
* Returns the elements of the fields whose simple names are {@code names} and are declared in
* {@code type}.
*
* <p>If a field isn't declared in {@code type}, its element isn't included in the returned set.
* If none of the fields is declared in {@code type}, the empty set is returned.
*
* @param type where to look for fields
* @param names simple names of fields that might be declared in {@code type}
* @return the elements of the fields whose simple names are {@code names} and are declared in
* {@code type}
*/
public static Set<VariableElement> findFieldsInType(
TypeElement type, Collection<String> names) {
Set<VariableElement> results = new HashSet<VariableElement>();
for (VariableElement field : ElementFilter.fieldsIn(type.getEnclosedElements())) {
if (names.contains(field.getSimpleName().toString())) {
results.add(field);
}
}
return results;
}
/**
* Returns non-private field elements, and side-effects {@code names} to remove them. For every
* field name in {@code names} that is declared in {@code type} or a supertype, add its element
* to the returned set and remove it from {@code names}.
*
* <p>When this routine returns, the combination of the return value and {@code names} has the
* same cardinality, and represents the same fields, as {@code names} did when the method was
* called.
*
* @param type where to look for fields
* @param names simple names of fields that might be declared in {@code type} or a supertype.
* (Names that are found are removed from this list.)
* @return the {@code VariableElement}s for non-private fields that are declared in {@code type}
* whose simple names were in {@code names} when the method was called.
*/
public static Set<VariableElement> findFieldsInTypeOrSuperType(
TypeMirror type, Collection<String> names) {
Set<VariableElement> elements = new HashSet<>();
findFieldsInTypeOrSuperType(type, names, elements);
return elements;
}
/**
* Side-effects both {@code foundFields} (which starts empty) and {@code notFound}, conceptually
* moving elements from {@code notFound} to {@code foundFields}.
*/
private static void findFieldsInTypeOrSuperType(
TypeMirror type, Collection<String> notFound, Set<VariableElement> foundFields) {
if (TypesUtils.isObject(type)) {
return;
}
TypeElement elt = InternalUtils.getTypeElement(type);
Set<VariableElement> fieldElts = findFieldsInType(elt, notFound);
for (VariableElement field : new HashSet<>(fieldElts)) {
if (!field.getModifiers().contains(Modifier.PRIVATE)) {
notFound.remove(field.getSimpleName().toString());
} else {
fieldElts.remove(field);
}
}
foundFields.addAll(fieldElts);
if (!notFound.isEmpty()) {
findFieldsInTypeOrSuperType(elt.getSuperclass(), notFound, foundFields);
}
}
public static boolean isError(Element element) {
return element.getClass()
.getName()
.equals("com.sun.tools.javac.comp.Resolve$SymbolNotFoundError");
}
/**
* Does the given element need a receiver for accesses? For example, an access to a local
* variable does not require a receiver.
*
* @param element the element to test
* @return whether the element requires a receiver for accesses
*/
public static boolean hasReceiver(Element element) {
return (element.getKind().isField()
|| element.getKind() == ElementKind.METHOD
|| element.getKind() == ElementKind.CONSTRUCTOR)
&& !ElementUtils.isStatic(element);
}
/**
* Determine all type elements for the classes and interfaces referenced in the
* extends/implements clauses of the given type element. TODO: can we learn from the
* implementation of com.sun.tools.javac.model.JavacElements.getAllMembers(TypeElement)?
*/
public static List<TypeElement> getSuperTypes(Elements elements, TypeElement type) {
List<TypeElement> superelems = new ArrayList<TypeElement>();
if (type == null) {
return superelems;
}
// Set up a stack containing type, which is our starting point.
Deque<TypeElement> stack = new ArrayDeque<TypeElement>();
stack.push(type);
while (!stack.isEmpty()) {
TypeElement current = stack.pop();
// For each direct supertype of the current type element, if it
// hasn't already been visited, push it onto the stack and
// add it to our superelems set.
TypeMirror supertypecls = current.getSuperclass();
if (supertypecls.getKind() != TypeKind.NONE) {
TypeElement supercls = (TypeElement) ((DeclaredType) supertypecls).asElement();
if (!superelems.contains(supercls)) {
stack.push(supercls);
superelems.add(supercls);
}
}
for (TypeMirror supertypeitf : current.getInterfaces()) {
TypeElement superitf = (TypeElement) ((DeclaredType) supertypeitf).asElement();
if (!superelems.contains(superitf)) {
stack.push(superitf);
superelems.add(superitf);
}
}
}
// Include java.lang.Object as implicit superclass for all classes and interfaces.
TypeElement jlobject = elements.getTypeElement("java.lang.Object");
if (!superelems.contains(jlobject)) {
superelems.add(jlobject);
}
return Collections.<TypeElement>unmodifiableList(superelems);
}
/**
* Return all fields declared in the given type or any superclass/interface. TODO: should this
* use javax.lang.model.util.Elements.getAllMembers(TypeElement) instead of our own
* getSuperTypes?
*/
public static List<VariableElement> getAllFieldsIn(Elements elements, TypeElement type) {
List<VariableElement> fields = new ArrayList<VariableElement>();
fields.addAll(ElementFilter.fieldsIn(type.getEnclosedElements()));
List<TypeElement> alltypes = getSuperTypes(elements, type);
for (TypeElement atype : alltypes) {
fields.addAll(ElementFilter.fieldsIn(atype.getEnclosedElements()));
}
return Collections.<VariableElement>unmodifiableList(fields);
}
/**
* Return all methods declared in the given type or any superclass/interface. Note that no
* constructors will be returned. TODO: should this use
* javax.lang.model.util.Elements.getAllMembers(TypeElement) instead of our own getSuperTypes?
*/
public static List<ExecutableElement> getAllMethodsIn(Elements elements, TypeElement type) {
List<ExecutableElement> meths = new ArrayList<ExecutableElement>();
meths.addAll(ElementFilter.methodsIn(type.getEnclosedElements()));
List<TypeElement> alltypes = getSuperTypes(elements, type);
for (TypeElement atype : alltypes) {
meths.addAll(ElementFilter.methodsIn(atype.getEnclosedElements()));
}
return Collections.<ExecutableElement>unmodifiableList(meths);
}
public static boolean isTypeDeclaration(Element elt) {
switch (elt.getKind()) {
// These tree kinds are always declarations. Uses of the declared
// types have tree kind IDENTIFIER.
case ANNOTATION_TYPE:
case CLASS:
case ENUM:
case INTERFACE:
case TYPE_PARAMETER:
return true;
default:
return false;
}
}
/**
* Check that a method Element matches a signature.
*
* <p>Note: Matching the receiver type must be done elsewhere as the Element receiver type is
* only populated when annotated.
*
* @param method the method Element
* @param methodName the name of the method
* @param parameters the formal parameters' Classes
* @return true if the method matches
*/
public static boolean matchesElement(
ExecutableElement method, String methodName, Class<?>... parameters) {
if (!method.getSimpleName().toString().equals(methodName)) {
return false;
}
if (method.getParameters().size() != parameters.length) {
return false;
} else {
for (int i = 0; i < method.getParameters().size(); i++) {
if (!method.getParameters()
.get(i)
.asType()
.toString()
.equals(parameters[i].getName())) {
return false;
}
}
}
return true;
}
/** Returns true if the given element is, or overrides, method. */
public static boolean isMethod(
ExecutableElement questioned, ExecutableElement method, ProcessingEnvironment env) {
TypeElement enclosing = (TypeElement) questioned.getEnclosingElement();
return questioned.equals(method)
|| env.getElementUtils().overrides(questioned, method, enclosing);
}
}