de.is24.deadcode4j.analyzer.ReferenceToConstantsAnalyzer Maven / Gradle / Ivy
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Finds unused classes of a project
package de.is24.deadcode4j.analyzer;
import com.google.common.base.Function;
import com.google.common.base.Optional;
import com.google.common.base.Predicate;
import com.google.common.collect.Sets;
import de.is24.deadcode4j.AnalysisContext;
import de.is24.deadcode4j.analyzer.javassist.ClassPoolAccessor;
import de.is24.javaparser.FixedVoidVisitorAdapter;
import japa.parser.ast.CompilationUnit;
import japa.parser.ast.ImportDeclaration;
import japa.parser.ast.body.*;
import japa.parser.ast.expr.*;
import japa.parser.ast.stmt.*;
import japa.parser.ast.type.ClassOrInterfaceType;
import javassist.CtClass;
import javassist.CtField;
import javassist.Modifier;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import java.util.Deque;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import static com.google.common.base.Optional.absent;
import static com.google.common.base.Optional.of;
import static com.google.common.base.Predicates.and;
import static com.google.common.base.Predicates.not;
import static com.google.common.collect.Iterables.*;
import static com.google.common.collect.Lists.newLinkedList;
import static com.google.common.collect.Maps.newHashMap;
import static com.google.common.collect.Sets.newHashSet;
import static de.is24.deadcode4j.Utils.checkNotNull;
import static de.is24.deadcode4j.Utils.emptyIfNull;
import static de.is24.deadcode4j.Utils.getOrAddMappedSet;
import static de.is24.deadcode4j.analyzer.javassist.ClassPoolAccessor.classPoolAccessorFor;
import static de.is24.javassist.CtClasses.*;
import static de.is24.javaparser.ImportDeclarations.*;
import static de.is24.javaparser.Nodes.getTypeName;
/**
* Analyzes Java files and reports dependencies to classes that are not part of the byte code due to constant inlining.
* Note that this analyzer does not distinguish between inlined and referenced constants.
*
* @since 2.0.0
*/
@SuppressWarnings("PMD.TooManyStaticImports")
public class ReferenceToConstantsAnalyzer extends JavaFileAnalyzer {
@Nonnull
private static String getFirstElement(@Nonnull FieldAccessExpr fieldAccessExpr) {
return getFirstNode(fieldAccessExpr).getName();
}
@Nonnull
private static NameExpr getFirstNode(@Nonnull FieldAccessExpr fieldAccessExpr) {
Expression scope = fieldAccessExpr.getScope();
if (NameExpr.class.isInstance(scope)) {
return NameExpr.class.cast(scope);
} else if (FieldAccessExpr.class.isInstance(scope)) {
return getFirstNode(FieldAccessExpr.class.cast(scope));
}
throw new RuntimeException("Should not have reached this point!");
}
private static boolean isRegularFieldAccessExpr(@Nonnull FieldAccessExpr fieldAccessExpr) {
Expression scope = fieldAccessExpr.getScope();
if (NameExpr.class.isInstance(scope)) {
return true;
} else if (FieldAccessExpr.class.isInstance(scope)) {
return isRegularFieldAccessExpr(FieldAccessExpr.class.cast(scope));
}
return false;
}
private static String getFullQualifier(FieldAccessExpr reference) {
StringBuilder buffy = new StringBuilder(reference.getField());
for (FieldAccessExpr loop = reference; loop != null; ) {
Expression scope = loop.getScope();
final String qualifier;
if (NameExpr.class.isInstance(scope)) {
loop = null;
qualifier = NameExpr.class.cast(scope).getName();
} else {
loop = FieldAccessExpr.class.cast(scope);
qualifier = loop.getField();
}
buffy.insert(0, '.');
buffy.insert(0, qualifier);
}
return buffy.toString();
}
private static boolean isScopeOfAMethodCall(@Nonnull Expression expression) {
return MethodCallExpr.class.isInstance(expression.getParentNode())
&& expression == MethodCallExpr.class.cast(expression.getParentNode()).getScope();
}
private static boolean isScopeOfThisExpression(@Nonnull Expression expression) {
return ThisExpr.class.isInstance(expression.getParentNode());
}
private static boolean isTargetOfAnAssignment(@Nonnull Expression expression) {
return AssignExpr.class.isInstance(expression.getParentNode())
&& expression == AssignExpr.class.cast(expression.getParentNode()).getTarget();
}
private static Function toImportedType() {
return new Function() {
@Nullable
@Override
public String apply(@Nullable ImportDeclaration input) {
if (input == null)
return null;
NameExpr name = input.getName();
if (input.isStatic() && !input.isAsterisk()) {
name = QualifiedNameExpr.class.cast(name).getQualifier();
}
return name.toString();
}
};
}
private static boolean isConstant(CtField ctField) {
return Modifier.isStatic(ctField.getModifiers()) && Modifier.isFinal(ctField.getModifiers());
}
@Override
protected void analyzeCompilationUnit(@Nonnull final AnalysisContext analysisContext,
@Nonnull final CompilationUnit compilationUnit) {
compilationUnit.accept(new LocalVariableRecordingVisitor() {
private final ClassPoolAccessor classPoolAccessor = classPoolAccessorFor(analysisContext);
private final Map> processedReferences = newHashMap();
@Override
public void visit(FieldAccessExpr n, Void arg) {
if (isTargetOfAnAssignment(n)
|| isScopeOfThisExpression(n)) {
return;
}
if (!isRegularFieldAccessExpr(n)) {
super.visit(n, arg);
return;
}
if (aLocalVariableExists(getFirstElement(n))) {
return;
}
resolveFieldReference(n);
}
@Override
public void visit(NameExpr n, Void arg) {
if (isTargetOfAnAssignment(n)
|| isScopeOfThisExpression(n)
|| aLocalVariableExists(n.getName())) {
return;
}
resolveNameReference(n);
}
private Optional resolveClass(String qualifier) {
return this.classPoolAccessor.resolveClass(qualifier);
}
private void resolveFieldReference(FieldAccessExpr reference) {
if (!needsProcessing(reference)) {
return;
}
Optional resolvedType;
if (isScopeOfAMethodCall(reference)) {
FieldAccessExprQualifier qualifier = new FieldAccessExprQualifier(reference);
resolvedType = resolveType(analysisContext, qualifier);
if (resolvedType.isPresent() && isFullyResolved(resolvedType.get(), qualifier)) {
return; // this is just a static method
}
} else {
resolvedType = resolveType(analysisContext, qualifierFor(reference));
}
String referencingType = getTypeName(reference);
if (resolvedType.isPresent()) {
analysisContext.addDependencies(referencingType, resolvedType.get());
} else {
logger.debug("Could not resolve reference [{}] found within [{}].",
reference, referencingType);
}
}
private boolean needsProcessing(FieldAccessExpr fieldAccessExpr) {
Set references = getOrAddMappedSet(this.processedReferences, getTypeName(fieldAccessExpr));
return references.add(getFullQualifier(fieldAccessExpr));
}
private Qualifier qualifierFor(FieldAccessExpr fieldAccessExpr) {
Expression scope = fieldAccessExpr.getScope();
return NameExpr.class.isInstance(scope)
? new NameExprQualifier(NameExpr.class.cast(scope))
: new FieldAccessExprQualifier(FieldAccessExpr.class.cast(scope));
}
private void resolveNameReference(NameExpr reference) {
if (!needsProcessing(reference)) {
return;
}
if (isScopeOfAMethodCall(reference)
&& resolveType(analysisContext, new NameExprQualifier(reference)).isPresent()) {
return; // this is just a static method call
}
String referringType = getTypeName(reference);
if (refersToInheritedField(reference)
|| refersToStaticImport(reference)
|| refersToAsteriskStaticImport(reference)) {
return;
}
if (SwitchEntryStmt.class.isInstance(reference.getParentNode())) {
return; // see A_ReferenceToConstantsAnalyzer#recognizesReferenceToEnumerationInSwitch()
}
logger.debug("Could not resolve name reference [{}] found within [{}].",
reference, referringType);
}
private boolean needsProcessing(NameExpr nameExpr) {
Set references = getOrAddMappedSet(this.processedReferences, getTypeName(nameExpr));
return references.add(nameExpr.getName());
}
private boolean refersToInheritedField(NameExpr reference) {
CtClass referencingClazz = getCtClass(classPoolAccessor.getClassPool(), getTypeName(reference));
if (referencingClazz == null) {
return false;
}
for (CtClass declaringClazz : getDeclaringClassesOf(referencingClazz)) {
if (refersToInheritedField(referencingClazz, declaringClazz, reference)) {
return true;
}
}
return false;
}
private boolean refersToInheritedField(@Nonnull final CtClass referencingClazz,
@Nullable CtClass clazz,
@Nonnull final NameExpr reference) {
if (clazz == null || isJavaLangObject(clazz)) {
return false;
}
for (CtField ctField : clazz.getDeclaredFields()) {
if (ctField.getName().equals(reference.getName()) && fieldIsVisibleFrom(ctField, referencingClazz)) {
if (isConstant(ctField)) { // we only care for static references
analysisContext.addDependencies(referencingClazz.getName(), clazz.getName());
}
return true;
}
}
if (refersToInheritedField(referencingClazz, getSuperclassOf(clazz), reference)) {
return true;
}
for (CtClass interfaceClazz : getInterfacesOf(clazz)) {
if (refersToInheritedField(referencingClazz, interfaceClazz, reference)) {
return true;
}
}
return false;
}
/**
* Unfortunately, {@link CtField#visibleFrom(CtClass)} is not entirely correct, as anonymous and inner
* classes have access to private fields of the declaring class.
*/
private boolean fieldIsVisibleFrom(CtField ctField, CtClass referencingClazz) {
return ctField.visibleFrom(referencingClazz) ||
(isNestedClass(referencingClazz, ctField.getDeclaringClass())
&& (isStaticField(ctField) || !isStaticClass(referencingClazz)));
}
private boolean isNestedClass(CtClass nestedClass, CtClass parentClass) {
return nestedClass.getName().startsWith(parentClass.getName() + "$");
}
private boolean isStaticClass(CtClass referencingClazz) {
return Modifier.isStatic(referencingClazz.getModifiers());
}
private boolean isStaticField(CtField ctField) {
return Modifier.isStatic(ctField.getModifiers());
}
private boolean refersToStaticImport(NameExpr reference) {
String referenceName = reference.getName();
String staticImport = getStaticImport(referenceName);
if (staticImport == null) {
return false;
}
String typeName = getTypeName(reference);
Optional resolvedClass = resolveClass(staticImport);
if (resolvedClass.isPresent()) {
analysisContext.addDependencies(typeName, resolvedClass.get());
} else {
logger.warn("Could not resolve static import [{}.{}] found within [{}]!",
staticImport, referenceName, typeName);
}
return true;
}
private boolean refersToAsteriskStaticImport(NameExpr reference) {
CtClass referencingClazz = getCtClass(classPoolAccessor.getClassPool(), getTypeName(reference));
if (referencingClazz == null) {
return false;
}
for (String asteriskImport : getStaticAsteriskImports()) {
Optional resolvedClass = resolveClass(asteriskImport);
if (!resolvedClass.isPresent()) {
String typeName = getTypeName(reference);
logger.warn("Could not resolve static import [{}.*] found within [{}]!",
asteriskImport, typeName);
continue;
}
CtClass potentialTarget = getCtClass(classPoolAccessor.getClassPool(), resolvedClass.get());
if (refersToInheritedField(referencingClazz, potentialTarget, reference)) {
return true;
}
}
return false;
}
@Nullable
@SuppressWarnings("unchecked")
private String getStaticImport(String referenceName) {
return getOnlyElement(transform(filter(emptyIfNull(compilationUnit.getImports()),
and(refersTo(referenceName), not(isAsterisk()), isStatic())), toImportedType()), null);
}
@Nonnull
private Iterable getStaticAsteriskImports() {
return transform(filter(emptyIfNull(compilationUnit.getImports()),
and(isAsterisk(), isStatic())), toImportedType());
}
@Override
public void visit(ClassOrInterfaceType n, Void arg) {
// performance
}
@Override
public void visit(CompilationUnit n, Void arg) {
// performance
for (final TypeDeclaration typeDeclaration : emptyIfNull(n.getTypes())) {
typeDeclaration.accept(this, arg);
}
}
@Override
public void visit(MarkerAnnotationExpr n, Void arg) {
// performance
}
@Override
public void visit(NormalAnnotationExpr n, Void arg) {
// performance
for (final MemberValuePair m : emptyIfNull(n.getPairs())) {
m.accept(this, arg);
}
}
@Override
public void visit(SingleMemberAnnotationExpr n, Void arg) {
// performance
n.getMemberValue().accept(this, arg);
}
}, null);
}
private static class LocalVariableRecordingVisitor extends FixedVoidVisitorAdapter {
@Nonnull
private final Deque> localVariables = newLinkedList();
private static Predicate constants() {
return new Predicate() {
@Override
@SuppressWarnings("ConstantConditions")
public boolean apply(@Nullable FieldDeclaration fieldDeclaration) {
int modifiers = checkNotNull(fieldDeclaration).getModifiers();
return ModifierSet.isStatic(modifiers) && ModifierSet.isFinal(modifiers);
}
};
}
@Override
public void visit(ClassOrInterfaceDeclaration n, A arg) {
HashSet fields = newHashSet();
this.localVariables.addLast(fields);
try {
addFieldVariables(n, fields);
super.visit(n, arg);
} finally {
this.localVariables.removeLast();
}
}
@Override
public void visit(EnumDeclaration n, A arg) {
HashSet fieldsAndEnums = newHashSet();
this.localVariables.addLast(fieldsAndEnums);
try {
for (EnumConstantDeclaration enumConstantDeclaration : emptyIfNull(n.getEntries())) {
fieldsAndEnums.add(enumConstantDeclaration.getName());
}
addFieldVariables(n, fieldsAndEnums);
super.visit(n, arg);
} finally {
this.localVariables.removeLast();
}
}
@Override
public void visit(ObjectCreationExpr n, A arg) {
HashSet fields = newHashSet();
this.localVariables.addLast(fields);
try {
addFieldVariables(n.getAnonymousClassBody(), fields);
super.visit(n, arg);
} finally {
this.localVariables.removeLast();
}
}
@Override
public void visit(ConstructorDeclaration n, A arg) {
HashSet blockVariables = newHashSet();
this.localVariables.addLast(blockVariables);
try {
for (Parameter parameter : emptyIfNull(n.getParameters())) {
blockVariables.add(parameter.getId().getName());
}
for (AnnotationExpr annotationExpr : emptyIfNull(n.getAnnotations())) {
annotationExpr.accept(this, arg);
}
BlockStmt body = n.getBlock();
if (body != null) {
visit(body, arg);
}
} finally {
this.localVariables.removeLast();
}
}
@Override
public void visit(MethodDeclaration n, A arg) {
HashSet blockVariables = newHashSet();
this.localVariables.addLast(blockVariables);
try {
for (Parameter parameter : emptyIfNull(n.getParameters())) {
blockVariables.add(parameter.getId().getName());
}
for (AnnotationExpr annotationExpr : emptyIfNull(n.getAnnotations())) {
annotationExpr.accept(this, arg);
}
BlockStmt body = n.getBody();
if (body != null) {
visit(body, arg);
}
} finally {
this.localVariables.removeLast();
}
}
@Override
public void visit(CatchClause n, A arg) {
MultiTypeParameter multiTypeParameter = n.getExcept();
HashSet blockVariables = newHashSet();
this.localVariables.addLast(blockVariables);
try {
blockVariables.add(multiTypeParameter.getId().getName());
for (AnnotationExpr annotationExpr : emptyIfNull(multiTypeParameter.getAnnotations())) {
annotationExpr.accept(this, arg);
}
BlockStmt body = n.getCatchBlock();
if (body != null) {
visit(body, arg);
}
} finally {
this.localVariables.removeLast();
}
}
@Override
public void visit(BlockStmt n, A arg) {
this.localVariables.addLast(Sets.newHashSet());
try {
super.visit(n, arg);
} finally {
this.localVariables.removeLast();
}
}
@Override
public void visit(ForeachStmt n, A arg) {
HashSet blockVariables = newHashSet();
this.localVariables.addLast(blockVariables);
try {
for (VariableDeclarator variableDeclarator : emptyIfNull(n.getVariable().getVars())) {
blockVariables.add(variableDeclarator.getId().getName());
}
n.getIterable().accept(this, arg);
n.getBody().accept(this, arg);
} finally {
this.localVariables.removeLast();
}
}
@Override
public void visit(ForStmt n, A arg) {
this.localVariables.addLast(Sets.newHashSet());
try {
super.visit(n, arg);
} finally {
this.localVariables.removeLast();
}
}
@Override
public void visit(TryStmt n, A arg) {
HashSet blockVariables = newHashSet();
this.localVariables.addLast(blockVariables);
try {
for (VariableDeclarationExpr variableDeclarationExpr : emptyIfNull(n.getResources())) {
for (VariableDeclarator variableDeclarator : variableDeclarationExpr.getVars()) {
blockVariables.add(variableDeclarator.getId().getName());
}
}
super.visit(n, arg);
} finally {
this.localVariables.removeLast();
}
}
@Override
public void visit(VariableDeclarationExpr n, A arg) {
for (AnnotationExpr annotationExpr : emptyIfNull(n.getAnnotations())) {
annotationExpr.accept(this, arg);
}
n.getType().accept(this, arg);
Set blockVariables = this.localVariables.getLast();
for (VariableDeclarator variableDeclarator : n.getVars()) {
Expression expr = variableDeclarator.getInit();
if (expr != null) {
expr.accept(this, arg);
}
blockVariables.add(variableDeclarator.getId().getName());
}
}
protected final boolean aLocalVariableExists(@Nonnull String name) {
return contains(concat(this.localVariables), name);
}
private void addFieldVariables(@Nonnull TypeDeclaration typeDeclaration, @Nonnull Set variables) {
addFieldVariables(typeDeclaration.getMembers(), variables);
}
private void addFieldVariables(@Nullable Iterable declarations, @Nonnull Set variables) {
for (FieldDeclaration fieldDeclaration : emptyIfNull(declarations).
filter(FieldDeclaration.class).filter(not(constants()))) {
for (VariableDeclarator variableDeclarator : fieldDeclaration.getVariables()) {
variables.add(variableDeclarator.getId().getName());
}
}
}
}
private static class NameExprQualifier extends Qualifier {
public NameExprQualifier(NameExpr nameExpr) {
super(nameExpr);
}
public NameExprQualifier(NameExpr nameExpr, FieldAccessExprQualifier parent) {
super(nameExpr, parent);
}
@Nullable
@Override
protected Qualifier getScopeQualifier(@Nonnull NameExpr reference) {
return null;
}
@Nonnull
@Override
protected String getName(@Nonnull NameExpr reference) {
return reference.getName();
}
@Nonnull
@Override
protected String getFullQualifier(@Nonnull NameExpr reference) {
return reference.getName();
}
@Override
public boolean allowsPartialResolving() {
return true;
}
@Nonnull
@Override
public Optional examineInheritedType(@Nonnull CtClass referencingClazz,
@Nonnull CtClass inheritedClazz) {
for (CtField ctField : inheritedClazz.getDeclaredFields()) {
if (ctField.getName().equals(getName()) && ctField.visibleFrom(referencingClazz)) {
if (isConstant(ctField)) {
return of(inheritedClazz.getName());
}
// we want no reference to be established, so we refer to ourselves
return of(referencingClazz.getName());
}
}
return absent();
}
}
private static class FieldAccessExprQualifier extends Qualifier {
public FieldAccessExprQualifier(FieldAccessExpr fieldAccessExpr) {
super(fieldAccessExpr);
}
private FieldAccessExprQualifier(FieldAccessExpr fieldAccessExpr, FieldAccessExprQualifier parent) {
super(fieldAccessExpr, parent);
}
@Nullable
@Override
protected Qualifier getScopeQualifier(@Nonnull FieldAccessExpr reference) {
Expression scope = reference.getScope();
return NameExpr.class.isInstance(scope)
? new NameExprQualifier(NameExpr.class.cast(scope), this)
: new FieldAccessExprQualifier(FieldAccessExpr.class.cast(scope), this);
}
@Nonnull
@Override
protected String getName(@Nonnull FieldAccessExpr reference) {
return reference.getField();
}
@Nonnull
@Override
protected String getFullQualifier(@Nonnull FieldAccessExpr reference) {
return ReferenceToConstantsAnalyzer.getFullQualifier(reference);
}
@Override
public boolean allowsPartialResolving() {
return true;
}
}
}
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