/*

 * Copyright (c) 2009, 2019, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

/*

 * INVOKESPECIAL EXPECTED RESULTS

 *

 * From JVMS 3rd edition: invokespecial instruction:

 *

 * Invoke instance method; special handling for superclass, private, and instance

 * initialization method invocations

 *

 * The named method is resolved (5.4.3.3). Finally, if the resolved method is

 * protected (4.7), and it is a member of a superclass of the current class, and

 * the method is not declared in the same run-time package (5.3) as the current

 * class, then the class of objectref must be either the current class or a

 * subclass of the current class.

 *

 * Next, the resolved method is selected for invocation unless all of the

 * following conditions are true:

 *     * The ACC_SUPER flag (see Table 4.1, "Class access and property modifiers") is set for the current class.

 *     * The class of the resolved method is a superclass of the current class.

 *     * The resolved method is not an instance initialization method (3.9).

 *

 * If the above conditions are true, the actual method to be invoked is selected

 * by the following lookup procedure. Let C be the direct superclass of the

 * current class:

 *     * If C contains a declaration for an instance method with the same name and

 *       descriptor as the resolved method, then this method will be invoked.

 *       The lookup procedure terminates.

 *

 *     * Otherwise, if C has a superclass, this same lookup procedure is performed

 *       recursively using the direct superclass of C. The method to be invoked is

 *       the result of the recursive invocation of this lookup procedure.

 *

 *     * Otherwise, an AbstractMethodError? is raised.

 *

 * During resolution of the symbolic reference to the method, any of the

 * exceptions pertaining to method resolution documented in Section 5.4.3.3 can be

 * thrown.

 *

 * Otherwise, if the resolved method is an instance initialization method, and the

 * class in which it is declared is not the class symbolically referenced by the

 * instruction, a NoSuchMethodError? is thrown.

 *

 * Otherwise, if the resolved method is a class (static) method, the invokespecial

 * instruction throws an IncompatibleClassChangeError?.

 *

 * Otherwise, if no method matching the resolved name and descriptor is selected,

 * invokespecial throws an AbstractMethodError?.

 *

 * Otherwise, if the selected method is abstract, invokespecial throws an

 * AbstractMethodError?.

 *

 * RUNTIME EXCEPTIONS

 *

 * Otherwise, if objectref is null, the invokespecial instruction throws a NullPointerException?.

 *

 * Otherwise, if the selected method is native and the code that implements the

 * method cannot be bound, invokespecial throws an UnsatisfiedLinkError?.

 *

 * NOTES

 *

 * The difference between the invokespecial and the invokevirtual instructions is

 * that invokevirtual invokes a method based on the class of the object. The

 * invokespecial instruction is used to invoke instance initialization methods

 * (3.9) as well as private methods and methods of a superclass of the current

 * class.

 *

 * ACC_SUPER:

 *

 * The setting of the ACC_SUPER flag indicates which of two alternative semantics

 * for its invokespecial instruction the Java virtual machine is to express; the

 * ACC_SUPER flag exists for backward compatibility for code compiled by Sun's

 * older compilers for the Java programming language. All new implementations of

 * the Java virtual machine should implement the semantics for invokespecial

 * documented in this specification. All new compilers to the instruction set of

 * the Java virtual machine should set the ACC_SUPER flag. Sun's older compilers

 * generated ClassFile? flags with ACC_SUPER unset. Sun's older Java virtual

 * machine implementations ignore the flag if it is set.

 *

 * ACC_SUPER 0x0020 Treat superclass methods specially when invoked by the

 * invokespecial instruction.

 *

 * My Translation:

 *     1. compile-time resolved class B

 *     2. A,B,C direct superclass relationships

 *     3. If B.m is protected

 *          - if the caller is in B

 *                then runtime resolved class must be in B or C

 *          - if the caller is in C

 *                then runtime resolved class must be in C

 *     TODO: otherwise what is thrown? <noWikiWord>AbstractMethodError?

 *     4. If B.m is an instance initialization method,

 *          invoke B.m

 *     5. If backward compatible caller does not set ACC_SUPER,

 *          invoke B.m

 *     6. If B is not a superclass of the caller, e.g. A is caller, or unrelated X

 *        is the caller, invoke B.m

 *     7. Otherwise:

 *        If superclass of caller contains name/sig match, use it

 *        Else, recursively through that superclass

 *     8. If none found, throw AbstractMethodError

 *

 * Note: there is NO mention of overriding or accessibility in determining

 * resolved method, except for if the compile-time type is protected.

 *

 * Case 1: B.m is protected

 *         Caller in A: if runtime resolved class in A.m, AbstractMethodError

 *         Caller in B: if runtime resolved class in A.m, AbstractMethodError

 * Case 2: B.m is an instance initialization method

 *         Always invoke B.m

 * Case 3: older javac, caller does not set ACC_SUPER

 *         Always invoke B.m

 * Case 4: A or X (not in hierarchy) calls invokespecial on B.m, invoke B.m

 * Case 5: Caller in B:

 *           if A.m exists, call it, else <noWikiWord>AbstractMethodError

 *         Caller in C:

 *           if B.m exists, call it

 *           if B.m does not exist, and A.m exists, call it

 */

//   TODO: classes without ACC_SUPER attribute

//   TODO: B.m is an instance initialization method

/*

 *   invokespecial <method-spec>

 *

 * invokespecial is used in certain special cases to invoke a method

 * Specifically, invokespecial is used to invoke:

 *      - the instance initialization method, <init>

 *      - a private method of this

 *      - a method in a superclass of this

 *

 * The main use of invokespecial is to invoke an object's instance

 * initialization method, <init>, during the construction phase for a new object.

 * For example, when you write in Java:

 *

 *      new StringBuffer()

 *

 * code like the following is generated:

 *      new java/lang/StringBuffer         ; create a new StringBuffer

 *      dup                                ; make an extra reference to the new instance

 *                                         ; now call an instance initialization method

 *      invokespecial java/lang/StringBuffer/<init>()V

 *                                         ; stack now contains an initialized StringBuffer.

 *

 * invokespecial is also used by the Java language by the 'super' keyword to

 * access a superclass's version of a method. For example, in the class:

 *

 *     class Example {

 *         // override equals

 *         public boolean equals(Object x) {

 *              // call Object's version of equals

 *              return super.equals(x);

 *         }

 *     }

 *

 * the 'super.equals(x)' expression is compiled to:

 *

 *     aload_0  ; push 'this' onto the stack

 *     aload_1  ; push the first argument (i.e. x) onto the stack

 *              ; now invoke Object's equals() method.

 *     invokespecial java/lang/Object/equals(Ljava/lang/Object;)Z

 *

 * Finally, invokespecial is used to invoke a private method. Remember that

 * private methods are only visible to other methods belonging the same class as

 * the private method.

 *

 * Before performing the method invocation, the class and the method identified

 * by <method-spec> are resolved. See Chapter 9 for a description of how methods

 * are resolved.

 *

 * invokespecial first looks at the descriptor given in <method-spec>, and

 * determines how many argument words the method takes (this may be zero). It

 * pops these arguments off the operand stack. Next it pops objectref (a

 * reference to an object) off the operand stack. objectref must be an instance

 * of the class named in <method-spec>, or one of its subclasses. The interpreter

 * searches the list of methods defined by the class named in <method-spec>,

 * looking for a method called methodname whose descriptor is descriptor. This

 * search is not based on the runtime type of objectref, but on the compile time

 * type given in <method-spec>.

 *

 * Once a method has been located, invokespecial calls the method. First, if

 * the method is marked as synchronized, the monitor associated with objectref is

 * entered. Next, a new stack frame structure is established on the call stack.

 * Then the arguments for the method (which were popped off the current method's

 * operand stack) are placed in local variables of the new stack frame structure.

 * arg1 is stored in local variable 1, arg2 is stored in local variable 2 and so

 * on. objectref is stored in local variable 0 (the local variable used for the

 * special Java variable this). Finally, execution continues at the first

 *instruction in the bytecode of the new method.

 *

 * Methods marked as native are handled slightly differently. For native

 * methods, the runtime system locates the platform-specific code for the method,

 * loading it and linking it into the JVM if necessary. Then the native method

 * code is executed with the arguments popped from the operand stack. The exact

 * mechanism used to invoke native methods is implementation-specific.

 *

 * When the method called by invokespecial returns, any single (or double) word

 * return result is placed on the operand stack of the current method. If the

 * invoked method was marked as synchronized, the monitor associated with

 * objectref is exited. Execution continues at the instruction that follows

 * invokespecial in the bytecode.

 *

 * Notes

 *

 * 1. In Java Virtual Machine implementations prior to version JDK 1.02, this

 * instruction was called invokenonvirtual, and was less restrictive than

 * invokespecial - it wasn't limited to invoking only superclass, private or

 * <init> methods. The class access flag ACC_SUPER (see Chapter 4) is used to

 * indicate which semantics are used by a class. In older class files, the

 * ACC_SUPER flag is unset. In all new classes, the ACC_SUPER flag should be set,

 * indicating that the restrictions enforced by invokespecial are obeyed. (In

 * practice, all the common uses of invokenonvirtual continue to be supported

 * by invokespecial, so this change should have little impact on JVM users).

 *

 */

package invokespecial;

import static jdk.internal.org.objectweb.asm.Opcodes.*;

import shared.AbstractGenerator;

import shared.AccessType;

import java.util.HashMap;

import java.util.Map;

public class Generator extends AbstractGenerator {

    public static void main (String[] args) throws Exception {

        new Generator(args).run();

    }

    public Generator(String[] args) {

        super(args);

    }

    protected Checker getChecker(Class paramClass, Class targetClass) {

        return new Checker(paramClass, targetClass);

    }

    public void run() throws Exception {

        // Specify package names

        String pkg1 = "a.";

        String pkg2 = "b.";

        String[] packages = new String[] { "", pkg1, pkg2 };

        boolean isPassed = true;

        // HIERARCHIES

        // The following triples will be used during further

        // hierarchy construction and will specify packages for A, B and C

        String[][] packageSets = new String[][] {

              {   "",   "",   "" }

            , {   "", pkg1, pkg1 }

            , {   "", pkg1, pkg2 }

            , { pkg1,   "", pkg1 }

            , { pkg1,   "", pkg2 }

            , { pkg1, pkg1,   "" }

            , { pkg1, pkg2,   "" }

            , { pkg1, pkg1, pkg1 }

            , { pkg1, pkg1, pkg2 }

            , { pkg1, pkg2, pkg1 }

            , { pkg1, pkg2, pkg2 }

        };

        String [] header = new String[] {

            String.format("%30s %35s", "Method access modifiers", "Call site location")

                , String.format("%4s  %-10s %-10s %-10s   %7s %7s %7s %7s %7s %7s %7s"

                        , "  # "

                        , "A.m()"

                        , "B.m()"

                        , "C.m()"

                        , "  A  "

                        , "pkgA"

                        , "  B  "

                        , " pkgB"

                        , "  C  "

                        , "pkgC "

                        , "  X  "

                        )

                , "-----------------------------------------------------------------------------------------------------------"

        };

        // Print header

        for (String str : header) {

            System.out.println(str);

        }

        // Iterate over all interesting package combinations

        for (String[] pkgSet : packageSets) {

            String packageA = pkgSet[0];

            String packageB = pkgSet[1];

            String packageC = pkgSet[2];

            String classNameA = packageA + "A";

            String classNameB = packageB + "B";

            String classNameC = packageC + "C";

            // For all possible access modifier combinations

            for (AccessType accessFlagA : AccessType.values()) {

                for (AccessType accessFlagB : AccessType.values()) {

                    for (AccessType accessFlagC : AccessType.values()) {

                        Map<String, byte[]> classes = new HashMap<String, byte[]>();

                        String calleeClassName = classNameB;

                        int classFlags = ACC_PUBLIC;

                        // The following hierarhcy is created:

                        //     c.C extends b.B extends a.A extends Object - base hierarchy

                        //     X extends Object - external caller

                        //     c.Caller, b.Caller, a.Caller extends Object - package callers

                        // Generate result storage

                        classes.put(

                                "Result"

                                , new ClassGenerator(

                                    "Result"

                                    , "java.lang.Object"

                                    , ACC_PUBLIC

                                    )

                                .addField(

                                    ACC_PUBLIC | ACC_STATIC

                                    , "value"

                                    , "java.lang.String"

                                    )

                                .getClassFile()

                                );

                        // Generate class A

                        classes.put(

                                classNameA

                                , new ClassGenerator(

                                    classNameA

                                    , "java.lang.Object"

                                    , classFlags

                                    )

                                .addTargetConstructor(accessFlagA)

                                .addTargetMethod(accessFlagA)

                                .addCaller(calleeClassName)

                                .getClassFile()

                                );

                        // Generate class B

                        classes.put(

                                classNameB

                                , new ClassGenerator(

                                    classNameB

                                    , classNameA

                                    , classFlags

                                    )

                                .addTargetConstructor(accessFlagB)

                                .addTargetMethod(accessFlagB)

                                .addCaller(calleeClassName)

                                .getClassFile()

                                );

                        // Generate class C

                        classes.put(

                                classNameC

                                , new ClassGenerator(

                                    classNameC

                                    , classNameB

                                    , classFlags

                                    )

                                .addTargetConstructor(accessFlagC)

                                .addTargetMethod(accessFlagC)

                                .addCaller(calleeClassName)

                                .getClassFile()

                                );

                        // Generate class X

                        String classNameX = "x.X";

                        classes.put(

                                classNameX

                                , new ClassGenerator(

                                    classNameX

                                    , "java.lang.Object"

                                    , classFlags

                                    )

                                .addTargetMethod(accessFlagC)

                                .addCaller(calleeClassName)

                                .getClassFile()

                                );

                        // Generate package callers

                        for (String pkg : packages) {

                            classes.put(

                                    pkg+"Caller"

                                    , new ClassGenerator(

                                        pkg+"Caller"

                                        , "java.lang.Object"

                                        , classFlags

                                        )

                                    .addCaller(calleeClassName)

                                    .getClassFile()

                                    );

                        }

                        String[] callSites = new String[] {

                                classNameA

                                , packageA+"Caller"

                                , classNameB

                                , packageB+"Caller"

                                , classNameC

                                , packageC+"Caller"

                                , classNameX

                        };

                        String caseDescription = String.format(

                                    "%-10s %-10s %-10s| "

                                    , classNameA + " " + accessFlagA

                                    , classNameB + " " + accessFlagB

                                    , classNameC + " " + accessFlagC

                                    );

                        boolean result = exec(classes, caseDescription, calleeClassName, classNameC, callSites);

                        isPassed = isPassed && result;

                    }

                }

            }

        }

        // Print footer

        for (int i = header.length-1; i >= 0; i--) {

            System.out.println(header[i]);

        }

        if (executeTests) {

            System.out.printf("\nEXECUTION STATUS: %s\n", (isPassed? "PASSED" : "FAILED"));

        }

    }

}