refactor: MethodTypingContext#isOverriding/isSameSignature/isSubSigna…

…ture moved to ClassTypingContext (#1299)

src/main/java/spoon/reflect/visitor/filter/OverriddenMethodFilter.java

@@ -18,14 +18,14 @@
 
 import spoon.reflect.declaration.CtMethod;
 import spoon.reflect.visitor.Filter;
-import spoon.support.visitor.MethodTypingContext;
+import spoon.support.visitor.ClassTypingContext;
 
 /**
  * Gets all overridden method from the method given.
  */
 public class OverriddenMethodFilter implements Filter<CtMethod<?>> {
 	private final CtMethod<?> method;
-	private final MethodTypingContext context;
+	private final ClassTypingContext context;
 	private boolean includingSelf = false;
 
 	/**
@@ -36,7 +36,7 @@ public class OverriddenMethodFilter implements Filter<CtMethod<?>> {
 	 */
 	public OverriddenMethodFilter(CtMethod<?> method) {
 		this.method = method;
-		context = new MethodTypingContext().setMethod(method);
+		context = new ClassTypingContext(method.getDeclaringType());
 	}
 
 	/**
@@ -53,6 +53,6 @@ public boolean matches(CtMethod<?> element) {
 		if (method == element) {
 			return this.includingSelf;
 		}
-		return context.isOverriding(element);
+		return context.isOverriding(method, element);
 	}
 }

src/main/java/spoon/support/reflect/declaration/CtMethodImpl.java

@@ -26,7 +26,7 @@
 import spoon.reflect.declaration.ModifierKind;
 import spoon.reflect.reference.CtTypeReference;
 import spoon.reflect.visitor.CtVisitor;
-import spoon.support.visitor.MethodTypingContext;
+import spoon.support.visitor.ClassTypingContext;
 
 import java.util.ArrayList;
 import java.util.EnumSet;
@@ -189,7 +189,7 @@ public <R extends T> void replace(CtMethod<T> element) {
 
 	@Override
 	public boolean isOverriding(CtMethod<?> superMethod) {
-		return new MethodTypingContext().setMethod(this).isOverriding(superMethod);
+		return new ClassTypingContext(getDeclaringType()).isOverriding(this, superMethod);
 	}
 
 	boolean isShadow;

src/main/java/spoon/support/reflect/reference/CtExecutableReferenceImpl.java

@@ -23,6 +23,7 @@
 import spoon.reflect.declaration.CtExecutable;
 import spoon.reflect.declaration.CtMethod;
 import spoon.reflect.declaration.CtType;
+import spoon.reflect.declaration.CtTypeMember;
 import spoon.reflect.declaration.ModifierKind;
 import spoon.reflect.reference.CtActualTypeContainer;
 import spoon.reflect.reference.CtExecutableReference;
@@ -31,7 +32,7 @@
 import spoon.reflect.visitor.filter.NameFilter;
 import spoon.support.reflect.declaration.CtElementImpl;
 import spoon.support.util.RtHelper;
-import spoon.support.visitor.MethodTypingContext;
+import spoon.support.visitor.ClassTypingContext;
 import spoon.support.visitor.SignaturePrinter;
 
 import java.lang.reflect.AnnotatedElement;
@@ -247,9 +248,8 @@ public boolean isOverriding(CtExecutableReference<?> executable) {
 			}
 			return true;
 		}
-		if (exec instanceof CtMethod<?>) {
-			CtMethod<?> method = (CtMethod<?>) exec;
-			return new MethodTypingContext().setExecutableReference(this).isOverriding(method);
+		if (exec instanceof CtMethod<?> && thisExec instanceof CtMethod<?>) {
+			return new ClassTypingContext(((CtTypeMember) thisExec).getDeclaringType()).isOverriding((CtMethod<?>) thisExec, (CtMethod<?>) exec);
 		}
 		//it is not a method. So we can return true only if it is reference to the this executable
 		return exec == getDeclaration();

src/main/java/spoon/support/visitor/ClassTypingContext.java

@@ -24,6 +24,7 @@
 import java.util.Set;
 
 import spoon.SpoonException;
+import spoon.reflect.declaration.CtConstructor;
 import spoon.reflect.declaration.CtElement;
 import spoon.reflect.declaration.CtExecutable;
 import spoon.reflect.declaration.CtFormalTypeDeclarer;
@@ -264,6 +265,53 @@ public <T> CtMethod<T> adaptMethod(CtMethod<T> method) {
 		return adaptedMethod;
 	}
 
+	/**
+	 * @param thatMethod - to be checked method
+	 * @return true if scope method overrides `thatMethod`
+	 */
+	public boolean isOverriding(CtMethod<?> thisMethod, CtMethod<?> thatMethod) {
+		if (thisMethod == thatMethod) {
+			//method overrides itself in spoon model
+			return true;
+		}
+		CtType<?> thatDeclType = thatMethod.getDeclaringType();
+		CtType<?> thisDeclType = getAdaptationScope();
+		if (thatDeclType != thisDeclType) {
+			if (isSubtypeOf(thatDeclType.getReference()) == false) {
+				//the declaringType of that method must be superType of this scope type
+				return false;
+			}
+		}
+		//TODO check method visibility following https://docs.oracle.com/javase/specs/jls/se8/html/jls-8.html#jls-8.4.8.1
+		return isSubSignature(thisMethod, thatMethod);
+	}
+
+	/**
+	 * scope method is subsignature of thatMethod if either
+	 * A) scope method is same signature like thatMethod
+	 * B) scope method is same signature like type erasure of thatMethod
+	 * See https://docs.oracle.com/javase/specs/jls/se8/html/jls-8.html#jls-8.4.2
+	 *
+	 * @param thatMethod - the checked method
+	 * @return true if scope method is subsignature of thatMethod
+	 */
+	public boolean isSubSignature(CtMethod<?> thisMethod, CtMethod<?> thatMethod) {
+		return isSameSignature(thisMethod, thatMethod, true);
+	}
+
+	/**
+	 * The same signature is the necessary condition for method A overrides method B.
+	 * @param thatExecutable - the checked method
+	 * @return true if this method and `thatMethod` has same signature
+	 */
+	public boolean isSameSignature(CtExecutable<?> thisExecutable, CtMethod<?> thatExecutable) {
+		if ((thatExecutable instanceof CtMethod || thatExecutable instanceof CtConstructor) == false) {
+			//only method or constructor can have same signature
+			return false;
+		}
+		return isSameSignature(thisExecutable, thatExecutable, false);
+	}
+
 	@Override
 	public ClassTypingContext getEnclosingGenericTypeAdapter() {
 		return enclosingClassTypingContext;
@@ -563,4 +611,99 @@ private CtTypeReference<?> adaptTypeForNewMethod(CtTypeReference<?> typeRef) {
 		}
 		return adaptType(typeRef);
 	}
+
+	private boolean isSameSignature(CtExecutable<?> thisMethod, CtExecutable<?> thatMethod, boolean canTypeErasure) {
+		if (thisMethod == thatMethod) {
+			return true;
+		}
+		ExecutableContext mtc = new ExecutableContext();
+		mtc.setClassTypingContext(this);
+
+		if (thisMethod instanceof CtMethod) {
+			if (thatMethod instanceof CtMethod) {
+				mtc.setMethod((CtMethod<?>) thisMethod);
+			} else {
+				return false;
+			}
+		} else if (thisMethod instanceof CtConstructor) {
+			if (thatMethod instanceof CtConstructor) {
+				mtc.setConstructor((CtConstructor<?>) thisMethod);
+			} else {
+				return false;
+			}
+		} else {
+			//only method or constructor can compare signatures
+			return false;
+		}
+		return mtc.isSameSignatureLikeScopeMethod(thatMethod, canTypeErasure);
+	}
+
+	private static class ExecutableContext extends MethodTypingContext {
+		private boolean isSameSignatureLikeScopeMethod(CtExecutable<?> thatExecutable, boolean canTypeErasure) {
+			//https://docs.oracle.com/javase/specs/jls/se8/html/jls-8.html#jls-8.4.2
+			CtFormalTypeDeclarer thatDeclarer = (CtFormalTypeDeclarer) thatExecutable;
+			CtFormalTypeDeclarer thisDeclarer = getAdaptationScope();
+			CtExecutable<?> thisExecutable = (CtExecutable<?>) thisDeclarer;
+			if (thatExecutable.getSimpleName().equals(thisExecutable.getSimpleName()) == false) {
+				return false;
+			}
+			if (thisExecutable.getParameters().size() != thatExecutable.getParameters().size()) {
+				//the executables has different count of parameters they cannot have same signature
+				return false;
+			}
+			List<CtTypeParameter> thisTypeParameters = thisDeclarer.getFormalCtTypeParameters();
+			List<CtTypeParameter> thatTypeParameters = thatDeclarer.getFormalCtTypeParameters();
+			boolean useTypeErasure = false;
+			if (thisTypeParameters.size() == thatTypeParameters.size()) {
+				//the methods has same count of formal parameters
+				//check that formal type parameters are same
+				if (hasSameMethodFormalTypeParameters((CtFormalTypeDeclarer) thatExecutable) == false) {
+					return false;
+				}
+			} else {
+				//the methods has different count of formal type parameters.
+				if (canTypeErasure == false) {
+					//type erasure is not allowed. So non-generic methods cannot match with generic methods
+					return false;
+				}
+				//non-generic method can override a generic one if type erasure is allowed
+				if (thisTypeParameters.isEmpty() == false) {
+					//scope methods has some parameters. It is generic too, it is not a subsignature of that method
+					return false;
+				}
+				//scope method has zero formal type parameters. It is not generic.
+				useTypeErasure = true;
+			}
+			List<CtTypeReference<?>> thisParameterTypes = getParameterTypes(thisExecutable.getParameters());
+			List<CtTypeReference<?>> thatParameterTypes = getParameterTypes(thatExecutable.getParameters());
+			//check that parameters are same after adapting to the same scope
+			for (int i = 0; i < thisParameterTypes.size(); i++) {
+				CtTypeReference<?> thisType = thisParameterTypes.get(i);
+				CtTypeReference<?> thatType = thatParameterTypes.get(i);
+				if (useTypeErasure) {
+					if (thatType instanceof CtTypeParameterReference) {
+						thatType = ((CtTypeParameterReference) thatType).getTypeErasure();
+					}
+				} else {
+					thatType = adaptType(thatType);
+				}
+				if (thatType == null) {
+					//the type cannot be adapted.
+					return false;
+				}
+				if (thisType.equals(thatType) == false) {
+					return false;
+				}
+			}
+			return true;
+		}
+
+		private static List<CtTypeReference<?>> getParameterTypes(List<CtParameter<?>> params) {
+			List<CtTypeReference<?>> types = new ArrayList<>(params.size());
+			for (CtParameter<?> param : params) {
+				types.add(param.getType());
+			}
+			return types;
+		}
+	}
 }