/*

 * Copyright 2008-2009 Sun Microsystems, Inc.  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.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package java.dyn;

import java.util.Arrays;

import java.util.Collections;

import java.util.HashMap;

import java.util.List;

import sun.dyn.Access;

import sun.dyn.Invokers;

import sun.dyn.MethodTypeImpl;

import sun.dyn.util.BytecodeDescriptor;

import static sun.dyn.MemberName.newIllegalArgumentException;

/**

 * The structure is a return type accompanied by any number of parameter types.

 * The types (primitive, void, and reference) are represented by Class objects.

 * All instances of <code>MethodType</code> are immutable.

 * Two instances are completely interchangeable if they compare equal.

 * <p>

 * @author John Rose, JSR 292 EG

 */

public final

class MethodType {

    private final Class<?>   rtype;

    private final Class<?>[] ptypes;

    private MethodTypeForm form; // erased form, plus cached data about primitives

    private MethodType wrapAlt;  // alternative wrapped/unwrapped version

    private Invokers invokers;   // cache of handy higher-order adapters

    private static final Access IMPL_TOKEN = Access.getToken();

    // share a cache with a friend in this package

    Invokers getInvokers() { return invokers; }

    void setInvokers(Invokers inv) { invokers = inv; }

    static {

        // This hack allows the implementation package special access to

        // the internals of MethodType.  In particular, the MTImpl has all sorts

        // of cached information useful to the implementation code.

        MethodTypeImpl.setMethodTypeFriend(IMPL_TOKEN, new MethodTypeImpl.MethodTypeFriend() {

            public Class<?>[] ptypes(MethodType mt)        { return mt.ptypes; }

            public MethodTypeImpl form(MethodType mt)      { return mt.form; }

            public void setForm(MethodType mt, MethodTypeImpl form) {

                assert(mt.form == null);

                mt.form = (MethodTypeForm) form;

            }

            public MethodType makeImpl(Class<?> rtype, Class<?>[] ptypes, boolean trusted) {

                return MethodType.makeImpl(rtype, ptypes, trusted);

            }

            public MethodTypeImpl newMethodTypeForm(MethodType mt) {

                return new MethodTypeForm(mt);

            }

            public Invokers getInvokers(MethodType mt)    { return mt.invokers; }

            public void setInvokers(MethodType mt, Invokers inv) { mt.invokers = inv; }

        });

    }

    private MethodType(Class<?> rtype, Class<?>[] ptypes) {

        checkRtype(rtype);

        checkPtypes(ptypes);

        this.rtype = rtype;

        this.ptypes = ptypes;

    }

    private void checkRtype(Class<?> rtype) {

        rtype.equals(rtype);  // null check

    }

    private void checkPtypes(Class<?>[] ptypes) {

        for (Class<?> ptype : ptypes) {

            ptype.equals(ptype);  // null check

            if (ptype == void.class)

                throw newIllegalArgumentException("void parameter: "+this);

        }

    }

    static final HashMap<MethodType,MethodType> internTable

            = new HashMap<MethodType, MethodType>();

    static final Class<?>[] NO_PTYPES = {};

    /** Find or create an instance of the given method type.

     * @param rtype  the return type

     * @param ptypes the parameter types

     * @throws NullPointerException if rtype or any ptype is null

     * @throws IllegalArgumentException if any of the ptypes is void

     */

    public static

    MethodType methodType(Class<?> rtype, Class<?>[] ptypes) {

        return makeImpl(rtype, ptypes, false);

    }

    @Deprecated public static

    MethodType make(Class<?> rtype, Class<?>[] ptypes) {

        return methodType(rtype, ptypes);

    }

    /** Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[])}. */

    public static

    MethodType methodType(Class<?> rtype, List<? extends Class<?>> ptypes) {

        boolean notrust = false;  // random List impl. could return evil ptypes array

        return makeImpl(rtype, ptypes.toArray(NO_PTYPES), notrust);

    }

    @Deprecated public static

    MethodType make(Class<?> rtype, List<? extends Class<?>> ptypes) {

        return methodType(rtype, ptypes);

    }

    /** Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[])}.

     *  The leading parameter type is prepended to the remaining array.

     */

    public static

    MethodType methodType(Class<?> rtype, Class<?> ptype0, Class<?>... ptypes) {

        Class<?>[] ptypes1 = new Class<?>[1+ptypes.length];

        ptypes1[0] = ptype0;

        System.arraycopy(ptypes, 0, ptypes1, 1, ptypes.length);

        return makeImpl(rtype, ptypes1, true);

    }

    @Deprecated public static

    MethodType make(Class<?> rtype, Class<?> ptype0, Class<?>... ptypes) {

        return methodType(rtype, ptype0, ptypes);

    }

    /** Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[])}.

     *  The resulting method has no parameter types.

     */

    public static

    MethodType methodType(Class<?> rtype) {

        return makeImpl(rtype, NO_PTYPES, true);

    }

    @Deprecated public static

    MethodType make(Class<?> rtype) {

        return methodType(rtype);

    }

    /** Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[])}.

     *  The resulting method has the single given parameter type.

     */

    public static

    MethodType methodType(Class<?> rtype, Class<?> ptype0) {

        return makeImpl(rtype, new Class<?>[]{ ptype0 }, true);

    }

    @Deprecated public static

    MethodType make(Class<?> rtype, Class<?> ptype0) {

        return methodType(rtype, ptype0);

    }

    /** Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[])}.

     *  The resulting method has the same parameter types as {@code ptypes},

     *  and the specified return type.

     */

    public static

    MethodType methodType(Class<?> rtype, MethodType ptypes) {

        return makeImpl(rtype, ptypes.ptypes, true);

    }

    @Deprecated public static

    MethodType make(Class<?> rtype, MethodType ptypes) {

        return methodType(rtype, ptypes);

    }

    /**

     * Sole factory method to find or create an interned method type.

     * @param rtype desired return type

     * @param ptypes desired parameter types

     * @param trusted whether the ptypes can be used without cloning

     * @return the unique method type of the desired structure

     */

    private static

    MethodType makeImpl(Class<?> rtype, Class<?>[] ptypes, boolean trusted) {

        if (ptypes == null || ptypes.length == 0) {

            ptypes = NO_PTYPES; trusted = true;

        }

        MethodType mt1 = new MethodType(rtype, ptypes);

        MethodType mt0;

        synchronized (internTable) {

            mt0 = internTable.get(mt1);

            if (mt0 != null)

                return mt0;

        }

        if (!trusted)

            // defensively copy the array passed in by the user

            mt1 = new MethodType(rtype, ptypes.clone());

        // promote the object to the Real Thing, and reprobe

        MethodTypeImpl.initForm(IMPL_TOKEN, mt1);

        synchronized (internTable) {

            mt0 = internTable.get(mt1);

            if (mt0 != null)

                return mt0;

            internTable.put(mt1, mt1);

        }

        return mt1;

    }

    // Entry point from JVM.  TODO: Change the name & signature.

    private static MethodType makeImpl(Class<?> rtype, Class<?>[] ptypes,

            boolean ignore1, boolean ignore2) {

        return makeImpl(rtype, ptypes, true);

    }

    private static final MethodType[] objectOnlyTypes = new MethodType[20];

    /**

     * Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[])}.

     * All parameters and the return type will be {@code Object},

     * except the final varargs parameter if any, which will be {@code Object[]}.

     * @param objectArgCount number of parameters (excluding the varargs parameter if any)

     * @param varargs whether there will be a varargs parameter, of type {@code Object[]}

     * @return a totally generic method type, given only its count of parameters and varargs

     * @see #genericMethodType(int)

     */

    public static

    MethodType genericMethodType(int objectArgCount, boolean varargs) {

        MethodType mt;

        int ivarargs = (!varargs ? 0 : 1);

        int ootIndex = objectArgCount*2 + ivarargs;

        if (ootIndex < objectOnlyTypes.length) {

            mt = objectOnlyTypes[ootIndex];

            if (mt != null)  return mt;

        }

        Class<?>[] ptypes = new Class<?>[objectArgCount + ivarargs];

        Arrays.fill(ptypes, Object.class);

        if (ivarargs != 0)  ptypes[objectArgCount] = Object[].class;

        mt = makeImpl(Object.class, ptypes, true);

        if (ootIndex < objectOnlyTypes.length) {

            objectOnlyTypes[ootIndex] = mt;     // cache it here also!

        }

        return mt;

    }

    @Deprecated public static

    MethodType makeGeneric(int objectArgCount, boolean varargs) {

        return genericMethodType(objectArgCount, varargs);

    }

    /**

     * All parameters and the return type will be Object.

     * @param objectArgCount number of parameters

     * @return a totally generic method type, given only its count of parameters

     * @see #genericMethodType(int, boolean)

     */

    public static

    MethodType genericMethodType(int objectArgCount) {

        return genericMethodType(objectArgCount, false);

    }

    @Deprecated public static

    MethodType makeGeneric(int objectArgCount) {

        return genericMethodType(objectArgCount);

    }

    /** Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[])}.

     * @param num    the index (zero-based) of the parameter type to change

     * @param nptype a new parameter type to replace the old one with

     * @return the same type, except with the selected parameter changed

     */

    public MethodType changeParameterType(int num, Class<?> nptype) {

        if (parameterType(num) == nptype)  return this;

        Class<?>[] nptypes = ptypes.clone();

        nptypes[num] = nptype;

        return makeImpl(rtype, nptypes, true);

    }

    /** Convenience method for {@link #insertParameterTypes}.

     * @deprecated Use {@link #insertParameterTypes} instead.

     */

    @Deprecated

    public MethodType insertParameterType(int num, Class<?> nptype) {

        int len = ptypes.length;

        Class<?>[] nptypes = Arrays.copyOfRange(ptypes, 0, len+1);

        System.arraycopy(nptypes, num, nptypes, num+1, len-num);

        nptypes[num] = nptype;

        return makeImpl(rtype, nptypes, true);

    }

    /** Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[])}.

     * @param num    the position (zero-based) of the inserted parameter type(s)

     * @param ptypesToInsert zero or more a new parameter types to insert into the parameter list

     * @return the same type, except with the selected parameter(s) inserted

     */

    public MethodType insertParameterTypes(int num, Class<?>... ptypesToInsert) {

        int len = ptypes.length;

        if (num < 0 || num > len)

            throw newIllegalArgumentException("num="+num); //SPECME

        int ilen = ptypesToInsert.length;

        if (ilen == 0)  return this;

        Class<?>[] nptypes = Arrays.copyOfRange(ptypes, 0, len+ilen);

        System.arraycopy(nptypes, num, nptypes, num+ilen, len-num);

        System.arraycopy(ptypesToInsert, 0, nptypes, num, ilen);

        return makeImpl(rtype, nptypes, true);

    }

    /** Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[])}.

     * @param num    the position (zero-based) of the inserted parameter type(s)

     * @param ptypesToInsert zero or more a new parameter types to insert into the parameter list

     * @return the same type, except with the selected parameter(s) inserted

     */

    public MethodType insertParameterTypes(int num, List<Class<?>> ptypesToInsert) {

        return insertParameterTypes(num, ptypesToInsert.toArray(NO_PTYPES));

    }

    /** Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[])}.

     * @param start  the index (zero-based) of the first parameter type to remove

     * @param end    the index (greater than {@code start}) of the first parameter type after not to remove

     * @return the same type, except with the selected parameter(s) removed

     */

    public MethodType dropParameterTypes(int start, int end) {

        int len = ptypes.length;

        if (!(0 <= start && start <= end && end <= len))

            throw newIllegalArgumentException("start="+start+" end="+end); //SPECME

        if (start == end)  return this;

        Class<?>[] nptypes;

        if (start == 0) {

            if (end == len) {

                // drop all parameters

                nptypes = NO_PTYPES;

            } else {

                // drop initial parameter(s)

                nptypes = Arrays.copyOfRange(ptypes, end, len);

            }

        } else {

            if (end == len) {

                // drop trailing parameter(s)

                nptypes = Arrays.copyOfRange(ptypes, 0, start);

            } else {

                int tail = len - end;

                nptypes = Arrays.copyOfRange(ptypes, 0, start + tail);

                System.arraycopy(ptypes, end, nptypes, start, tail);

            }

        }

        return makeImpl(rtype, nptypes, true);

    }

    /** Convenience method for {@link #dropParameterTypes}.

     * @deprecated Use {@link #dropParameterTypes} instead.

     */

    @Deprecated

    public MethodType dropParameterType(int num) {

        return dropParameterTypes(num, num+1);

    }

    /** Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[])}.

     * @param nrtype a return parameter type to replace the old one with

     * @return the same type, except with the return type change

     */

    public MethodType changeReturnType(Class<?> nrtype) {

        if (returnType() == nrtype)  return this;

        return makeImpl(nrtype, ptypes, true);

    }

    /** Convenience method.

     * Report if this type contains a primitive argument or return value.

     * The return type {@code void} counts as a primitive.

     * @return true if any of the types are primitives

     */

    public boolean hasPrimitives() {

        return form.hasPrimitives();

    }

    /** Convenience method.

     * Report if this type contains a wrapper argument or return value.

     * Wrappers are types which box primitive values, such as {@link Integer}.

     * The reference type {@code java.lang.Void} counts as a wrapper.

     * @return true if any of the types are wrappers

     */

    public boolean hasWrappers() {

        return unwrap() != this;

    }

    /** Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[])}.

     * Erase all reference types to {@code Object}.

     * All primitive types (including {@code void}) will remain unchanged.

     * @return a version of the original type with all reference types replaced

     */

    public MethodType erase() {

        return form.erasedType();

    }

    /** Convenience method for {@link #genericMethodType(int)}.

     * Convert all types, both reference and primitive, to {@code Object}.

     * The expression {@code type.wrap().erase()} produces the same value

     * as {@code type.generic()}.

     * @return a version of the original type with all types replaced

     */

    public MethodType generic() {

        return genericMethodType(parameterCount());

    }

    /** Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[])}.

     * Convert all primitive types to their corresponding wrapper types.

     * All reference types (including wrapper types) will remain unchanged.

     * A {@code void} return type is changed to the type {@code java.lang.Void}.

     * The expression {@code type.wrap().erase()} produces the same value

     * as {@code type.generic()}.

     * @return a version of the original type with all primitive types replaced

     */

    public MethodType wrap() {

        return hasPrimitives() ? wrapWithPrims(this) : this;

    }

    /** Convenience method for {@link #methodType(java.lang.Class, java.lang.Class[])}.

     * Convert all wrapper types to their corresponding primitive types.

     * All primitive types (including {@code void}) will remain unchanged.

     * A return type of {@code java.lang.Void} is changed to {@code void}.

     * @return a version of the original type with all wrapper types replaced

     */

    public MethodType unwrap() {

        MethodType noprims = !hasPrimitives() ? this : wrapWithPrims(this);

        return unwrapWithNoPrims(noprims);

    }

    private static MethodType wrapWithPrims(MethodType pt) {

        assert(pt.hasPrimitives());

        MethodType wt = pt.wrapAlt;

        if (wt == null) {

            // fill in lazily

            wt = MethodTypeImpl.canonicalize(pt, MethodTypeImpl.WRAP, MethodTypeImpl.WRAP);

            assert(wt != null);

            pt.wrapAlt = wt;

        }

        return wt;

    }

    private static MethodType unwrapWithNoPrims(MethodType wt) {

        assert(!wt.hasPrimitives());

        MethodType uwt = wt.wrapAlt;

        if (uwt == null) {

            // fill in lazily

            uwt = MethodTypeImpl.canonicalize(wt, MethodTypeImpl.UNWRAP, MethodTypeImpl.UNWRAP);

            if (uwt == null)

                uwt = wt;    // type has no wrappers or prims at all

            wt.wrapAlt = uwt;

        }

        return uwt;

    }

    /** @param num the index (zero-based) of the desired parameter type

     *  @return the selected parameter type

     */

    public Class<?> parameterType(int num) {

        return ptypes[num];

    }

    /** @return the number of parameter types */

    public int parameterCount() {

        return ptypes.length;

    }

    /** @return the return type */

    public Class<?> returnType() {

        return rtype;

    }

    /**

     * Convenience method to present the arguments as a list.

     * @return the parameter types (as an immutable list)

     */

    public List<Class<?>> parameterList() {

        return Collections.unmodifiableList(Arrays.asList(ptypes));

    }

    /**

     * Convenience method to present the arguments as an array.

     * Changes to the array will not result in changes to the type.

     * @return the parameter types (as a fresh copy if necessary)

     */

    public Class<?>[] parameterArray() {

        return ptypes.clone();

    }

    /**

     * Compares the specified object with this type for equality.

     * That is, it returns <tt>true</tt> if and only if the specified object

     * is also a method type with exactly the same parameters and return type.

     * @param x object to compare

     * @see Object#equals(Object)

     */

    @Override

    public boolean equals(Object x) {

        return this == x || x instanceof MethodType && equals((MethodType)x);

    }