/*

 * Copyright (c) 2008, 2012, 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.  Oracle designates this

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

 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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

 * questions.

 */

package sun.invoke.util;

public enum Wrapper {

    //        wrapperType      simple     primitiveType  simple     char  emptyArray     format

    BOOLEAN(  Boolean.class,   "Boolean", boolean.class, "boolean", 'Z', new boolean[0], Format.unsigned( 1)),

    // These must be in the order defined for widening primitive conversions in JLS 5.1.2

    // Avoid boxing integral types here to defer initialization of internal caches

    BYTE   (     Byte.class,      "Byte",    byte.class,    "byte", 'B', new    byte[0], Format.signed(   8)),

    SHORT  (    Short.class,     "Short",   short.class,   "short", 'S', new   short[0], Format.signed(  16)),

    CHAR   (Character.class, "Character",    char.class,    "char", 'C', new    char[0], Format.unsigned(16)),

    INT    (  Integer.class,   "Integer",     int.class,     "int", 'I', new     int[0], Format.signed(  32)),

    LONG   (     Long.class,      "Long",    long.class,    "long", 'J', new    long[0], Format.signed(  64)),

    FLOAT  (    Float.class,     "Float",   float.class,   "float", 'F', new   float[0], Format.floating(32)),

    DOUBLE (   Double.class,    "Double",  double.class,  "double", 'D', new  double[0], Format.floating(64)),

    OBJECT (   Object.class,    "Object",  Object.class,  "Object", 'L', new  Object[0], Format.other(    1)),

    // VOID must be the last type, since it is "assignable" from any other type:

    VOID   (     Void.class,      "Void",    void.class,    "void", 'V',           null, Format.other(    0)),

    ;

    public static final int COUNT = 10;

    private final Class<?> wrapperType;

    private final Class<?> primitiveType;

    private final char     basicTypeChar;

    private final Object   emptyArray;

    private final int      format;

    private final String   wrapperSimpleName;

    private final String   primitiveSimpleName;

    private Wrapper(Class<?> wtype, String wtypeName, Class<?> ptype, String ptypeName, char tchar, Object emptyArray, int format) {

        this.wrapperType = wtype;

        this.primitiveType = ptype;

        this.basicTypeChar = tchar;

        this.emptyArray = emptyArray;

        this.format = format;

        this.wrapperSimpleName = wtypeName;

        this.primitiveSimpleName = ptypeName;

    }

    /** For debugging, give the details of this wrapper. */

    public String detailString() {

        return wrapperSimpleName+

                java.util.Arrays.asList(wrapperType, primitiveType,

                basicTypeChar, zero(),

                "0x"+Integer.toHexString(format));

    }

    private abstract static class Format {

        static final int SLOT_SHIFT = 0, SIZE_SHIFT = 2, KIND_SHIFT = 12;

        static final int

                SIGNED   = (-1) << KIND_SHIFT,

                UNSIGNED = 0    << KIND_SHIFT,

                FLOATING = 1    << KIND_SHIFT;

        static final int

                SLOT_MASK = ((1<<(SIZE_SHIFT-SLOT_SHIFT))-1),

                SIZE_MASK = ((1<<(KIND_SHIFT-SIZE_SHIFT))-1);

        static int format(int kind, int size, int slots) {

            assert(((kind >> KIND_SHIFT) << KIND_SHIFT) == kind);

            assert((size & (size-1)) == 0); // power of two

            assert((kind == SIGNED)   ? (size > 0) :

                   (kind == UNSIGNED) ? (size > 0) :

                   (kind == FLOATING) ? (size == 32 || size == 64)  :

                   false);

            assert((slots == 2) ? (size == 64) :

                   (slots == 1) ? (size <= 32) :

                   false);

            return kind | (size << SIZE_SHIFT) | (slots << SLOT_SHIFT);

        }

        static final int

                INT      = SIGNED   | (32 << SIZE_SHIFT) | (1 << SLOT_SHIFT),

                SHORT    = SIGNED   | (16 << SIZE_SHIFT) | (1 << SLOT_SHIFT),

                BOOLEAN  = UNSIGNED | (1  << SIZE_SHIFT) | (1 << SLOT_SHIFT),

                CHAR     = UNSIGNED | (16 << SIZE_SHIFT) | (1 << SLOT_SHIFT),

                FLOAT    = FLOATING | (32 << SIZE_SHIFT) | (1 << SLOT_SHIFT),

                VOID     = UNSIGNED | (0  << SIZE_SHIFT) | (0 << SLOT_SHIFT),

                NUM_MASK = (-1) << SIZE_SHIFT;

        static int signed(int size)   { return format(SIGNED,   size, (size > 32 ? 2 : 1)); }

        static int unsigned(int size) { return format(UNSIGNED, size, (size > 32 ? 2 : 1)); }

        static int floating(int size) { return format(FLOATING, size, (size > 32 ? 2 : 1)); }

        static int other(int slots)   { return slots << SLOT_SHIFT; }

    }

    /// format queries:

    /** How many bits are in the wrapped value?  Returns 0 for OBJECT or VOID. */

    public int     bitWidth()      { return (format >> Format.SIZE_SHIFT) & Format.SIZE_MASK; }

    /** How many JVM stack slots occupied by the wrapped value?  Returns 0 for VOID. */

    public int     stackSlots()    { return (format >> Format.SLOT_SHIFT) & Format.SLOT_MASK; }

    /** Does the wrapped value occupy a single JVM stack slot? */

    public boolean isSingleWord()  { return (format & (1 << Format.SLOT_SHIFT)) != 0; }

    /** Does the wrapped value occupy two JVM stack slots? */

    public boolean isDoubleWord()  { return (format & (2 << Format.SLOT_SHIFT)) != 0; }

    /** Is the wrapped type numeric (not void or object)? */

    public boolean isNumeric()     { return (format & Format.NUM_MASK) != 0; }

    /** Is the wrapped type a primitive other than float, double, or void? */

    public boolean isIntegral()    { return isNumeric() && format < Format.FLOAT; }

    /** Is the wrapped type one of int, boolean, byte, char, or short? */

    public boolean isSubwordOrInt() { return isIntegral() && isSingleWord(); }

    /* Is the wrapped value a signed integral type (one of byte, short, int, or long)? */

    public boolean isSigned()      { return format < Format.VOID; }

    /* Is the wrapped value an unsigned integral type (one of boolean or char)? */

    public boolean isUnsigned()    { return format >= Format.BOOLEAN && format < Format.FLOAT; }

    /** Is the wrapped type either float or double? */

    public boolean isFloating()    { return format >= Format.FLOAT; }

    /** Is the wrapped type either void or a reference? */

    public boolean isOther()       { return (format & ~Format.SLOT_MASK) == 0; }

    /** Does the JLS 5.1.2 allow a variable of this wrapper's

     *  primitive type to be assigned from a value of the given wrapper's primitive type?

     *  Cases:

     *  <ul>

     *  <li>unboxing followed by widening primitive conversion

     *  <li>any type converted to {@code void} (i.e., dropping a method call's value)

     *  <li>boxing conversion followed by widening reference conversion to {@code Object}

     *  </ul>

     *  These are the cases allowed by MethodHandle.asType.

     */

    public boolean isConvertibleFrom(Wrapper source) {

        if (this == source)  return true;

        if (this.compareTo(source) < 0) {

            // At best, this is a narrowing conversion.

            return false;

        }

        // All conversions are allowed in the enum order between floats and signed ints.

        // First detect non-signed non-float types (boolean, char, Object, void).

        boolean floatOrSigned = (((this.format & source.format) & Format.SIGNED) != 0);

        if (!floatOrSigned) {

            if (this.isOther())  return true;

            // can convert char to int or wider, but nothing else

            if (source.format == Format.CHAR)  return true;

            // no other conversions are classified as widening

            return false;

        }

        // All signed and float conversions in the enum order are widening.

        assert(this.isFloating() || this.isSigned());

        assert(source.isFloating() || source.isSigned());

        return true;

    }

    static {

        assert(checkConvertibleFrom());

        assert(COUNT == Wrapper.values().length);

    }

    private static boolean checkConvertibleFrom() {

        // Check the matrix for correct classification of widening conversions.

        for (Wrapper w : values()) {

            assert(w.isConvertibleFrom(w));

            assert(VOID.isConvertibleFrom(w));

            if (w != VOID) {

                assert(OBJECT.isConvertibleFrom(w));

                assert(!w.isConvertibleFrom(VOID));

            }

            // check relations with unsigned integral types:

            if (w != CHAR) {

                assert(!CHAR.isConvertibleFrom(w));

                if (!w.isConvertibleFrom(INT))

                    assert(!w.isConvertibleFrom(CHAR));

            }

            if (w != BOOLEAN) {

                assert(!BOOLEAN.isConvertibleFrom(w));

                if (w != VOID && w != OBJECT)

                    assert(!w.isConvertibleFrom(BOOLEAN));

            }

            // check relations with signed integral types:

            if (w.isSigned()) {

                for (Wrapper x : values()) {

                    if (w == x)  continue;

                    if (x.isFloating())

                        assert(!w.isConvertibleFrom(x));

                    else if (x.isSigned()) {

                        if (w.compareTo(x) < 0)

                            assert(!w.isConvertibleFrom(x));

                        else

                            assert(w.isConvertibleFrom(x));

                    }

                }

            }

            // check relations with floating types:

            if (w.isFloating()) {

                for (Wrapper x : values()) {

                    if (w == x)  continue;

                    if (x.isSigned())

                        assert(w.isConvertibleFrom(x));

                    else if (x.isFloating()) {

                        if (w.compareTo(x) < 0)

                            assert(!w.isConvertibleFrom(x));

                        else

                            assert(w.isConvertibleFrom(x));

                    }

                }

            }

        }

        return true;  // i.e., assert(true)

    }

    /** Produce a zero value for the given wrapper type.

     *  This will be a numeric zero for a number or character,

     *  false for a boolean, and null for a reference or void.

     *  The common thread is that this is what is contained

     *  in a default-initialized variable of the given primitive

     *  type.  (For void, it is what a reflective method returns

     *  instead of no value at all.)

     */

    public Object zero() {

        switch (this) {

            case BOOLEAN:

                return Boolean.FALSE;

            case INT:

                return (Integer)0;

            case BYTE:

                return (Byte)(byte)0;

            case CHAR:

                return (Character)(char)0;

            case SHORT:

                return (Short)(short)0;

            case LONG:

                return (Long)(long)0;

            case FLOAT:

                return FLOAT_ZERO;

            case DOUBLE:

                return DOUBLE_ZERO;

            case VOID:

            case OBJECT:

            default:

                return null;

        }

    }

    private static final Object DOUBLE_ZERO = (Double)(double)0;

    private static final Object FLOAT_ZERO = (Float)(float)0;

    /** Produce a zero value for the given wrapper type T.

     *  The optional argument must a type compatible with this wrapper.

     *  Equivalent to {@code this.cast(this.zero(), type)}.

     */

    public <T> T zero(Class<T> type) { return convert(zero(), type); }

    /** Return the wrapper that wraps values of the given type.

     *  The type may be {@code Object}, meaning the {@code OBJECT} wrapper.

     *  Otherwise, the type must be a primitive.

     *  @throws IllegalArgumentException for unexpected types

     */

    public static Wrapper forPrimitiveType(Class<?> type) {

        Wrapper w = findPrimitiveType(type);

        if (w != null)  return w;

        if (type.isPrimitive())

            throw new InternalError(); // redo hash function

        throw newIllegalArgumentException("not primitive: "+type);

    }

    static Wrapper findPrimitiveType(Class<?> type) {

        Wrapper w = FROM_PRIM[hashPrim(type)];

        if (w != null && w.primitiveType == type) {

            return w;

        }

        return null;

    }

    /** Return the wrapper that wraps values into the given wrapper type.

     *  If it is {@code Object}, return {@code OBJECT}.

     *  Otherwise, it must be a wrapper type.

     *  The type must not be a primitive type.

     *  @throws IllegalArgumentException for unexpected types

     */

    public static Wrapper forWrapperType(Class<?> type) {

        Wrapper w = findWrapperType(type);

        if (w != null)  return w;

        for (Wrapper x : values())

            if (x.wrapperType == type)

                throw new InternalError(); // redo hash function

        throw newIllegalArgumentException("not wrapper: "+type);

    }

    static Wrapper findWrapperType(Class<?> type) {

        Wrapper w = FROM_WRAP[hashWrap(type)];

        if (w != null && w.wrapperType == type) {

            return w;

        }

        return null;

    }

    /** Return the wrapper that corresponds to the given bytecode

     *  signature character.  Return {@code OBJECT} for the character 'L'.

     *  @throws IllegalArgumentException for any non-signature character or {@code '['}.

     */

    public static Wrapper forBasicType(char type) {

        Wrapper w = FROM_CHAR[hashChar(type)];

        if (w != null && w.basicTypeChar == type) {

            return w;

        }

        for (Wrapper x : values())

            if (w.basicTypeChar == type)

                throw new InternalError(); // redo hash function

        throw newIllegalArgumentException("not basic type char: "+type);

    }

    /** Return the wrapper for the given type, if it is

     *  a primitive type, else return {@code OBJECT}.

     */

    public static Wrapper forBasicType(Class<?> type) {

        if (type.isPrimitive())

            return forPrimitiveType(type);

        return OBJECT;  // any reference, including wrappers or arrays

    }

    // Note on perfect hashes:

    //   for signature chars c, do (c + (c >> 1)) % 16

    //   for primitive type names n, do (n[0] + n[2]) % 16

    // The type name hash works for both primitive and wrapper names.

    // You can add "java/lang/Object" to the primitive names.

    // But you add the wrapper name Object, use (n[2] + (3*n[1])) % 16.

    private static final Wrapper[] FROM_PRIM = new Wrapper[16];

    private static final Wrapper[] FROM_WRAP = new Wrapper[16];

    private static final Wrapper[] FROM_CHAR = new Wrapper[16];

    private static int hashPrim(Class<?> x) {

        String xn = x.getName();

        if (xn.length() < 3)  return 0;

        return (xn.charAt(0) + xn.charAt(2)) % 16;

    }

    private static int hashWrap(Class<?> x) {

        String xn = x.getName();

        final int offset = 10; assert(offset == "java.lang.".length());

        if (xn.length() < offset+3)  return 0;

        return (3*xn.charAt(offset+1) + xn.charAt(offset+2)) % 16;

    }

    private static int hashChar(char x) {

        return (x + (x >> 1)) % 16;

    }

    static {

        for (Wrapper w : values()) {

            int pi = hashPrim(w.primitiveType);

            int wi = hashWrap(w.wrapperType);

            int ci = hashChar(w.basicTypeChar);

            assert(FROM_PRIM[pi] == null);

            assert(FROM_WRAP[wi] == null);

            assert(FROM_CHAR[ci] == null);

            FROM_PRIM[pi] = w;

            FROM_WRAP[wi] = w;

            FROM_CHAR[ci] = w;

        }

        //assert(jdk.sun.invoke.util.WrapperTest.test(false));

    }

    /** What is the primitive type wrapped by this wrapper? */

    public Class<?> primitiveType() { return primitiveType; }

    /** What is the wrapper type for this wrapper? */

    public Class<?> wrapperType() { return wrapperType; }

    /** What is the wrapper type for this wrapper?

     * Otherwise, the example type must be the wrapper type,

     * or the corresponding primitive type.

     * (For {@code OBJECT}, the example type can be any non-primitive,

     * and is normalized to {@code Object.class}.)

     * The resulting class type has the same type parameter.

     */

    public <T> Class<T> wrapperType(Class<T> exampleType) {

        if (exampleType == wrapperType) {

            return exampleType;

        } else if (exampleType == primitiveType ||

                   wrapperType == Object.class ||

                   exampleType.isInterface()) {

            return forceType(wrapperType, exampleType);

        }

        throw newClassCastException(exampleType, primitiveType);

    }

    private static ClassCastException newClassCastException(Class<?> actual, Class<?> expected) {

        return new ClassCastException(actual + " is not compatible with " + expected);

    }

    /** If {@code type} is a primitive type, return the corresponding

     *  wrapper type, else return {@code type} unchanged.

     */

    public static <T> Class<T> asWrapperType(Class<T> type) {

        if (type.isPrimitive()) {

            return forPrimitiveType(type).wrapperType(type);

        }

        return type;

    }

    /** If {@code type} is a wrapper type, return the corresponding

     *  primitive type, else return {@code type} unchanged.

     */

    public static <T> Class<T> asPrimitiveType(Class<T> type) {

        Wrapper w = findWrapperType(type);

        if (w != null) {

            return forceType(w.primitiveType(), type);

        }

        return type;

    }

    /** Query:  Is the given type a wrapper, such as {@code Integer} or {@code Void}? */

    public static boolean isWrapperType(Class<?> type) {

        return findWrapperType(type) != null;

    }

    /** Query:  Is the given type a primitive, such as {@code int} or {@code void}? */

    public static boolean isPrimitiveType(Class<?> type) {

        return type.isPrimitive();

    }

    /** What is the bytecode signature character for this type?

     *  All non-primitives, including array types, report as 'L', the signature character for references.

     */

    public static char basicTypeChar(Class<?> type) {

        if (!type.isPrimitive())

            return 'L';

        else

            return forPrimitiveType(type).basicTypeChar();

    }

    /** What is the bytecode signature character for this wrapper's

     *  primitive type?

     */

    public char basicTypeChar() { return basicTypeChar; }

    /** What is the simple name of the wrapper type?

     */

    public String wrapperSimpleName() { return wrapperSimpleName; }

    /** What is the simple name of the primitive type?

     */

    public String primitiveSimpleName() { return primitiveSimpleName; }

//    /** Wrap a value in the given type, which may be either a primitive or wrapper type.

//     *  Performs standard primitive conversions, including truncation and float conversions.

//     */

//    public static <T> T wrap(Object x, Class<T> type) {

//        return Wrapper.valueOf(type).cast(x, type);

//    }

    /** Cast a wrapped value to the given type, which may be either a primitive or wrapper type.

     *  The given target type must be this wrapper's primitive or wrapper type.

     *  If this wrapper is OBJECT, the target type may also be an interface, perform no runtime check.

     *  Performs standard primitive conversions, including truncation and float conversions.

     *  The given type must be compatible with this wrapper.  That is, it must either

     *  be the wrapper type (or a subtype, in the case of {@code OBJECT}) or else

     *  it must be the wrapper's primitive type.

     *  Primitive conversions are only performed if the given type is itself a primitive.

     *  @throws ClassCastException if the given type is not compatible with this wrapper

     */

    public <T> T cast(Object x, Class<T> type) {

        return convert(x, type, true);

    }

    /** Convert a wrapped value to the given type.

     *  The given target type must be this wrapper's primitive or wrapper type.

     *  This is equivalent to {@link #cast}, except that it refuses to perform

     *  narrowing primitive conversions.

     */

    public <T> T convert(Object x, Class<T> type) {

        return convert(x, type, false);

    }

    private <T> T convert(Object x, Class<T> type, boolean isCast) {

        if (this == OBJECT) {

            // If the target wrapper is OBJECT, just do a reference cast.

            // If the target type is an interface, perform no runtime check.

            // (This loophole is safe, and is allowed by the JVM verifier.)

            // If the target type is a primitive, change it to a wrapper.

            assert(!type.isPrimitive());

            if (!type.isInterface())

                type.cast(x);

            @SuppressWarnings("unchecked")

            T result = (T) x;  // unchecked warning is expected here

            return result;

        }

        Class<T> wtype = wrapperType(type);

        if (wtype.isInstance(x)) {

            return wtype.cast(x);

        }

        if (!isCast) {

            Class<?> sourceType = x.getClass();  // throw NPE if x is null

            Wrapper source = findWrapperType(sourceType);

            if (source == null || !this.isConvertibleFrom(source)) {

                throw newClassCastException(wtype, sourceType);

            }

        } else if (x == null) {

            @SuppressWarnings("unchecked")

            T z = (T) zero();