[enh] Support overloaded ServiceMethod references

Add overload-safe ServiceMethod factories that accept explicit Java
signature types so ambiguous service method references can be resolved.

Also store the resolved Method declaration instead of only the method
name, add focused tests for overloaded services, and update the
developer documentation with the new API usage.

Signed-off-by: Axel RICHARD <axel.richard@obeo.fr>

Author: AxelRICHARD

backend/services/syson-services/src/main/java/org/eclipse/syson/util/ServiceMethod.java

@@ -13,6 +13,7 @@
 package org.eclipse.syson.util;
 
 import java.io.Serializable;
+import java.lang.invoke.MethodType;
 import java.lang.invoke.SerializedLambda;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
@@ -72,6 +73,10 @@
  * }
  * </pre>
  * <p>
+ * Overloaded services: if several service methods share the same name, use the factory overloads that also take the
+ * service class and Java parameter types, for example
+ * {@code ServiceMethod.of1(EObjectServices.class, EObjectServices::eGet, EObject.class, EStructuralFeature.class)}.
+ * <p>
  * Performance: this uses reflection once per reference at startup to read a method name. The cost is negligible
  * compared to normal init work.
  *
@@ -80,12 +85,15 @@
  */
 public final class ServiceMethod {
 
+    private final Method declaration;
+
     private final String name;
 
     private final int arity;
 
-    private ServiceMethod(String name, int arity) {
-        this.name = name;
+    private ServiceMethod(Method declaration, int arity) {
+        this.declaration = declaration;
+        this.name = declaration.getName();
         this.arity = arity;
     }
 
@@ -98,6 +106,15 @@ public String name() {
         return this.name;
     }
 
+    /**
+     * the Java declaration that will be called from AQL.
+     *
+     * @return the declaration.
+     */
+    public Method declaration() {
+        return this.declaration;
+    }
+
     /**
      * Build {@code aql:self.method(...)} for the captured service name.
      * <p>
@@ -149,79 +166,230 @@ public String aql(String var, String... params) {
      * Instance method with signature {@code R method(T self)}.
      */
     public static <S, T> ServiceMethod of0(Inst0<S, T> ref) {
-        return new ServiceMethod(methodName(ref), 0);
+        return new ServiceMethod(method(ref), 0);
+    }
+
+    /**
+     * Instance method with signature {@code R method(T self)}.
+     * <p>
+     * Use this overload when the referenced Java service is overloaded and you need to disambiguate on the
+     * {@code self} type.
+     */
+    public static <S, T> ServiceMethod of0(Class<T> selfType, Inst0<S, T> ref) {
+        return new ServiceMethod(method(ref, selfType), 0);
+    }
+
+    /**
+     * Instance method with signature {@code R method(T self)}.
+     * <p>
+     * Use this overload when the referenced Java service is overloaded and you need to disambiguate on the declaring
+     * service and {@code self} types.
+     */
+    public static <S, T> ServiceMethod of0(Class<S> serviceType, Inst0<S, T> ref, Class<T> selfType) {
+        return new ServiceMethod(method(serviceType, ref, selfType), 0);
     }
 
     /**
      * Instance method with signature {@code R method(T self, P1 p1)}.
      */
     public static <S, T, P1> ServiceMethod of1(Inst1<S, T, P1> ref) {
-        return new ServiceMethod(methodName(ref), 1);
+        return new ServiceMethod(method(ref), 1);
+    }
+
+    /**
+     * Instance method with signature {@code R method(T self, P1 p1)}.
+     * <p>
+     * Use this overload when the referenced Java service is overloaded and you need to disambiguate on parameter
+     * types.
+     */
+    public static <S, T, P1> ServiceMethod of1(Class<T> selfType, Class<P1> p1Type, Inst1<S, T, P1> ref) {
+        return new ServiceMethod(method(ref, selfType, p1Type), 1);
+    }
+
+    /**
+     * Instance method with signature {@code R method(T self, P1 p1)}.
+     * <p>
+     * Use this overload when the referenced Java service is overloaded and you need to disambiguate on the declaring
+     * service and parameter types.
+     */
+    public static <S, T, P1> ServiceMethod of1(Class<S> serviceType, Inst1<S, T, P1> ref, Class<T> selfType, Class<P1> p1Type) {
+        return new ServiceMethod(method(serviceType, ref, selfType, p1Type), 1);
     }
 
     /**
      * Instance method with signature {@code R method(T self, P1 p1, P2 p2)}.
      */
     public static <S, T, P1, P2> ServiceMethod of2(Inst2<S, T, P1, P2> ref) {
-        return new ServiceMethod(methodName(ref), 2);
+        return new ServiceMethod(method(ref), 2);
+    }
+
+    /**
+     * Instance method with signature {@code R method(T self, P1 p1, P2 p2)}.
+     */
+    public static <S, T, P1, P2> ServiceMethod of2(Class<T> selfType, Class<P1> p1Type, Class<P2> p2Type, Inst2<S, T, P1, P2> ref) {
+        return new ServiceMethod(method(ref, selfType, p1Type, p2Type), 2);
+    }
+
+    /**
+     * Instance method with signature {@code R method(T self, P1 p1, P2 p2)}.
+     */
+    public static <S, T, P1, P2> ServiceMethod of2(Class<S> serviceType, Inst2<S, T, P1, P2> ref, Class<T> selfType, Class<P1> p1Type, Class<P2> p2Type) {
+        return new ServiceMethod(method(serviceType, ref, selfType, p1Type, p2Type), 2);
     }
 
     /**
      * Instance method with signature {@code R method(T self, P1 p1, P2 p2, P3 p3)}.
      */
     public static <S, T, P1, P2, P3> ServiceMethod of3(Inst3<S, T, P1, P2, P3> ref) {
-        return new ServiceMethod(methodName(ref), 3);
+        return new ServiceMethod(method(ref), 3);
+    }
+
+    /**
+     * Instance method with signature {@code R method(T self, P1 p1, P2 p2, P3 p3)}.
+     */
+    public static <S, T, P1, P2, P3> ServiceMethod of3(Class<T> selfType, Class<P1> p1Type, Class<P2> p2Type, Class<P3> p3Type, Inst3<S, T, P1, P2, P3> ref) {
+        return new ServiceMethod(method(ref, selfType, p1Type, p2Type, p3Type), 3);
+    }
+
+    /**
+     * Instance method with signature {@code R method(T self, P1 p1, P2 p2, P3 p3)}.
+     */
+    public static <S, T, P1, P2, P3> ServiceMethod of3(Class<S> serviceType, Inst3<S, T, P1, P2, P3> ref, Class<T> selfType, Class<P1> p1Type, Class<P2> p2Type,
+            Class<P3> p3Type) {
+        return new ServiceMethod(method(serviceType, ref, selfType, p1Type, p2Type, p3Type), 3);
     }
 
     /**
      * Instance method with signature {@code R method(T self, P1 p1, P2 p2, P3 p3, P4 p4)}.
      */
     public static <S, T, P1, P2, P3, P4> ServiceMethod of4(Inst4<S, T, P1, P2, P3, P4> ref) {
-        return new ServiceMethod(methodName(ref), 4);
+        return new ServiceMethod(method(ref), 4);
+    }
+
+    /**
+     * Instance method with signature {@code R method(T self, P1 p1, P2 p2, P3 p3, P4 p4)}.
+     */
+    public static <S, T, P1, P2, P3, P4> ServiceMethod of4(Class<T> selfType, Class<P1> p1Type, Class<P2> p2Type, Class<P3> p3Type, Class<P4> p4Type,
+            Inst4<S, T, P1, P2, P3, P4> ref) {
+        return new ServiceMethod(method(ref, selfType, p1Type, p2Type, p3Type, p4Type), 4);
+    }
+
+    /**
+     * Instance method with signature {@code R method(T self, P1 p1, P2 p2, P3 p3, P4 p4)}.
+     */
+    public static <S, T, P1, P2, P3, P4> ServiceMethod of4(Class<S> serviceType, Inst4<S, T, P1, P2, P3, P4> ref, Class<T> selfType, Class<P1> p1Type,
+            Class<P2> p2Type, Class<P3> p3Type, Class<P4> p4Type) {
+        return new ServiceMethod(method(serviceType, ref, selfType, p1Type, p2Type, p3Type, p4Type), 4);
     }
 
     /**
      * Instance method with signature {@code R method(T self, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5)}.
      */
     public static <S, T, P1, P2, P3, P4, P5> ServiceMethod of5(Inst5<S, T, P1, P2, P3, P4, P5> ref) {
-        return new ServiceMethod(methodName(ref), 5);
+        return new ServiceMethod(method(ref), 5);
+    }
+
+    /**
+     * Instance method with signature {@code R method(T self, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5)}.
+     */
+    public static <S, T, P1, P2, P3, P4, P5> ServiceMethod of5(Class<T> selfType, Class<P1> p1Type, Class<P2> p2Type, Class<P3> p3Type, Class<P4> p4Type,
+            Class<P5> p5Type, Inst5<S, T, P1, P2, P3, P4, P5> ref) {
+        return new ServiceMethod(method(ref, selfType, p1Type, p2Type, p3Type, p4Type, p5Type), 5);
     }
 
+    /**
+     * Instance method with signature {@code R method(T self, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5)}.
+     */
+    // CHECKSTYLE:OFF
+    public static <S, T, P1, P2, P3, P4, P5> ServiceMethod of5(Class<S> serviceType, Inst5<S, T, P1, P2, P3, P4, P5> ref, Class<T> selfType, Class<P1> p1Type,
+            Class<P2> p2Type, Class<P3> p3Type, Class<P4> p4Type, Class<P5> p5Type) {
+        return new ServiceMethod(method(serviceType, ref, selfType, p1Type, p2Type, p3Type, p4Type, p5Type), 5);
+    }
+    // CHECKSTYLE:ON
+
     /**
      * Instance method with signature {@code R method(T self, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6)}.
      */
     public static <S, T, P1, P2, P3, P4, P5, P6> ServiceMethod of6(Inst6<S, T, P1, P2, P3, P4, P5, P6> ref) {
-        return new ServiceMethod(methodName(ref), 6);
+        return new ServiceMethod(method(ref), 6);
+    }
+
+    /**
+     * Instance method with signature {@code R method(T self, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6)}.
+     */
+    // CHECKSTYLE:OFF
+    public static <S, T, P1, P2, P3, P4, P5, P6> ServiceMethod of6(Class<T> selfType, Class<P1> p1Type, Class<P2> p2Type, Class<P3> p3Type, Class<P4> p4Type,
+            Class<P5> p5Type, Class<P6> p6Type, Inst6<S, T, P1, P2, P3, P4, P5, P6> ref) {
+        return new ServiceMethod(method(ref, selfType, p1Type, p2Type, p3Type, p4Type, p5Type, p6Type), 6);
     }
+    // CHECKSTYLE:ON
+
+    /**
+     * Instance method with signature {@code R method(T self, P1 p1, P2 p2, P3 p3, P4 p4, P5 p5, P6 p6)}.
+     */
+    // CHECKSTYLE:OFF
+    public static <S, T, P1, P2, P3, P4, P5, P6> ServiceMethod of6(Class<S> serviceType, Inst6<S, T, P1, P2, P3, P4, P5, P6> ref, Class<T> selfType,
+            Class<P1> p1Type, Class<P2> p2Type, Class<P3> p3Type, Class<P4> p4Type, Class<P5> p5Type, Class<P6> p6Type) {
+        return new ServiceMethod(method(serviceType, ref, selfType, p1Type, p2Type, p3Type, p4Type, p5Type, p6Type), 6);
+    }
+    // CHECKSTYLE:ON
 
     // ---------------------- Factories for static methods ----------------------
 
     /**
      * Static method with signature {@code R method(T self)}.
      */
     public static <T> ServiceMethod ofStatic0(IStat0<T> ref) {
-        return new ServiceMethod(methodName(ref), 0);
+        return new ServiceMethod(method(ref), 0);
+    }
+
+    /**
+     * Static method with signature {@code R method(T self)}.
+     */
+    public static <T> ServiceMethod ofStatic0(Class<T> selfType, IStat0<T> ref) {
+        return new ServiceMethod(method(ref, selfType), 0);
     }
 
     /**
      * Static method with signature {@code R method(T self, P1 p1)}.
      */
     public static <T, P1> ServiceMethod ofStatic1(IStat1<T, P1> ref) {
-        return new ServiceMethod(methodName(ref), 1);
+        return new ServiceMethod(method(ref), 1);
+    }
+
+    /**
+     * Static method with signature {@code R method(T self, P1 p1)}.
+     */
+    public static <T, P1> ServiceMethod ofStatic1(Class<T> selfType, Class<P1> p1Type, IStat1<T, P1> ref) {
+        return new ServiceMethod(method(ref, selfType, p1Type), 1);
     }
 
     /**
      * Static method with signature {@code R method(T self, P1 p1, P2 p2)}.
      */
     public static <T, P1, P2> ServiceMethod ofStatic2(IStat2<T, P1, P2> ref) {
-        return new ServiceMethod(methodName(ref), 2);
+        return new ServiceMethod(method(ref), 2);
+    }
+
+    /**
+     * Static method with signature {@code R method(T self, P1 p1, P2 p2)}.
+     */
+    public static <T, P1, P2> ServiceMethod ofStatic2(Class<T> selfType, Class<P1> p1Type, Class<P2> p2Type, IStat2<T, P1, P2> ref) {
+        return new ServiceMethod(method(ref, selfType, p1Type, p2Type), 2);
     }
 
     /**
      * Static method with signature {@code R method(T self, P1 p1, P2 p2, P3 p3)}.
      */
     public static <T, P1, P2, P3> ServiceMethod ofStatic3(IStat3<T, P1, P2, P3> ref) {
-        return new ServiceMethod(methodName(ref), 3);
+        return new ServiceMethod(method(ref), 3);
+    }
+
+    /**
+     * Static method with signature {@code R method(T self, P1 p1, P2 p2, P3 p3)}.
+     */
+    public static <T, P1, P2, P3> ServiceMethod ofStatic3(Class<T> selfType, Class<P1> p1Type, Class<P2> p2Type, Class<P3> p3Type, IStat3<T, P1, P2, P3> ref) {
+        return new ServiceMethod(method(ref, selfType, p1Type, p2Type, p3Type), 3);
     }
 
     // ---------------------- SAMs for method references ----------------------
@@ -427,14 +595,42 @@ public interface IStat3<T, P1, P2, P3> extends Serializable {
 
     // ---------------------- Lambda -> method name ----------------------
 
-    private static String methodName(Serializable lambdaRef) {
+    private static Method method(Serializable lambdaRef, Class<?>... expectedParameterTypes) {
+        try {
+            SerializedLambda lambda = serializedLambda(lambdaRef);
+            Class<?> implementationClass = Class.forName(lambda.getImplClass().replace('/', '.'), false, lambdaRef.getClass().getClassLoader());
+            MethodType methodType = MethodType.fromMethodDescriptorString(lambda.getImplMethodSignature(), implementationClass.getClassLoader());
+            Method method = thisClassMethod(implementationClass, lambda.getImplMethodName(), methodType.parameterArray());
+            if (expectedParameterTypes.length > 0 && !Arrays.equals(method.getParameterTypes(), expectedParameterTypes)) {
+                throw new IllegalArgumentException(
+                        MessageFormat.format("Resolved method {0} has parameters {1} but expected {2}", method, Arrays.toString(method.getParameterTypes()), Arrays.toString(expectedParameterTypes)));
+            }
+            return method;
+        } catch (ClassNotFoundException | InvocationTargetException | NoSuchMethodException | SecurityException | IllegalAccessException e) {
+            throw new IllegalStateException("Cannot resolve method declaration from lambda", e);
+        }
+    }
+
+    private static Method method(Class<?> expectedServiceType, Serializable lambdaRef, Class<?>... expectedParameterTypes) {
+        Method method = method(lambdaRef, expectedParameterTypes);
+        if (!expectedServiceType.isAssignableFrom(method.getDeclaringClass())) {
+            throw new IllegalArgumentException(MessageFormat.format("Resolved method {0} is declared on {1} but expected a service assignable to {2}", method,
+                    method.getDeclaringClass().getName(), expectedServiceType.getName()));
+        }
+        return method;
+    }
+
+    private static SerializedLambda serializedLambda(Serializable lambdaRef) throws NoSuchMethodException, IllegalAccessException, InvocationTargetException {
+        Method writeReplace = lambdaRef.getClass().getDeclaredMethod("writeReplace");
+        writeReplace.setAccessible(true);
+        return (SerializedLambda) writeReplace.invoke(lambdaRef);
+    }
+
+    private static Method thisClassMethod(Class<?> implementationClass, String methodName, Class<?>[] parameterTypes) throws NoSuchMethodException {
         try {
-            Method m = lambdaRef.getClass().getDeclaredMethod("writeReplace");
-            m.setAccessible(true);
-            SerializedLambda sl = (SerializedLambda) m.invoke(lambdaRef);
-            return sl.getImplMethodName();
-        } catch (InvocationTargetException | NoSuchMethodException | SecurityException | IllegalAccessException e) {
-            throw new IllegalStateException("Cannot resolve method name from lambda", e);
+            return implementationClass.getDeclaredMethod(methodName, parameterTypes);
+        } catch (NoSuchMethodException exception) {
+            return implementationClass.getMethod(methodName, parameterTypes);
         }
     }
 
@@ -457,4 +653,3 @@ private void checkArity(String... params) {
         }
     }
 }
-