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 * published by the Free Software Foundation.  Oracle designates this

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 *

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

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 * 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).

 *

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package jdk.nashorn.internal.runtime.arrays;

import static jdk.nashorn.internal.codegen.CompilerConstants.staticCall;

import static jdk.nashorn.internal.lookup.Lookup.MH;

import static jdk.nashorn.internal.runtime.JSType.getAccessorTypeIndex;

import static jdk.nashorn.internal.runtime.UnwarrantedOptimismException.INVALID_PROGRAM_POINT;

import static jdk.nashorn.internal.runtime.UnwarrantedOptimismException.isValid;

import java.lang.invoke.MethodHandle;

import java.lang.invoke.MethodHandles;

import java.lang.invoke.MethodType;

import java.lang.invoke.SwitchPoint;

import jdk.dynalink.CallSiteDescriptor;

import jdk.dynalink.linker.GuardedInvocation;

import jdk.dynalink.linker.LinkRequest;

import jdk.nashorn.internal.codegen.types.Type;

import jdk.nashorn.internal.lookup.Lookup;

import jdk.nashorn.internal.runtime.ScriptObject;

import jdk.nashorn.internal.runtime.linker.NashornCallSiteDescriptor;

import jdk.nashorn.internal.runtime.logging.Logger;

/**

 * Interface implemented by all arrays that are directly accessible as underlying

 * native arrays

 */

@Logger(name="arrays")

public abstract class ContinuousArrayData extends ArrayData {

    /**

     * Constructor

     * @param length length (elementLength)

     */

    protected ContinuousArrayData(final long length) {

        super(length);

    }

    /**

     * Check if we can put one more element at the end of this continuous

     * array without reallocating, or if we are overwriting an already

     * allocated element

     *

     * @param index index to check

     * @return true if we don't need to do any array reallocation to fit an element at index

     */

    public final boolean hasRoomFor(final int index) {

        return has(index) || (index == length() && ensure(index) == this);

    }

    /**

     * Check if an arraydata is empty

     * @return true if empty

     */

    public boolean isEmpty() {

        return length() == 0L;

    }

    /**

     * Return element getter for a certain type at a certain program point

     * @param returnType   return type

     * @param programPoint program point

     * @return element getter or null if not supported (used to implement slow linkage instead

     *   as fast isn't possible)

     */

    public abstract MethodHandle getElementGetter(final Class<?> returnType, final int programPoint);

    /**

     * Return element getter for a certain type at a certain program point

     * @param elementType element type

     * @return element setter or null if not supported (used to implement slow linkage instead

     *   as fast isn't possible)

     */

    public abstract MethodHandle getElementSetter(final Class<?> elementType);

    /**

     * Version of has that throws a class cast exception if element does not exist

     * used for relinking

     *

     * @param index index to check - currently only int indexes

     * @return index

     */

    protected final int throwHas(final int index) {

        if (!has(index)) {

            throw new ClassCastException();

        }

        return index;

    }

    @Override

    public abstract ContinuousArrayData copy();

    /**

     * Returns the type used to store an element in this array

     * @return element type

     */

    public abstract Class<?> getElementType();

    @Override

    public Type getOptimisticType() {

        return Type.typeFor(getElementType());

    }

    /**

     * Returns the boxed type of the type used to store an element in this array

     * @return element type

     */

    public abstract Class<?> getBoxedElementType();

    /**

     * Get the widest element type of two arrays. This can be done faster in subclasses, but

     * this works for all ContinuousArrayDatas and for where more optimal checks haven't been

     * implemented.

     *

     * @param otherData another ContinuousArrayData

     * @return the widest boxed element type

     */

    public ContinuousArrayData widest(final ContinuousArrayData otherData) {

        final Class<?> elementType = getElementType();

        return Type.widest(elementType, otherData.getElementType()) == elementType ? this : otherData;

    }

    /**

     * Look up a continuous array element getter

     * @param get          getter, sometimes combined with a has check that throws CCE on failure for relink

     * @param returnType   return type

     * @param programPoint program point

     * @return array getter

     */

    protected final MethodHandle getContinuousElementGetter(final MethodHandle get, final Class<?> returnType, final int programPoint) {

        return getContinuousElementGetter(getClass(), get, returnType, programPoint);

    }

    /**

     * Look up a continuous array element setter

     * @param set          setter, sometimes combined with a has check that throws CCE on failure for relink

     * @param returnType   return type

     * @return array setter

     */

    protected final MethodHandle getContinuousElementSetter(final MethodHandle set, final Class<?> returnType) {

        return getContinuousElementSetter(getClass(), set, returnType);

    }

    /**

     * Return element getter for a {@link ContinuousArrayData}

     * @param clazz        clazz for exact type guard

     * @param getHas       has getter

     * @param returnType   return type

     * @param programPoint program point

     * @return method handle for element setter

     */

    protected MethodHandle getContinuousElementGetter(final Class<? extends ContinuousArrayData> clazz, final MethodHandle getHas, final Class<?> returnType, final int programPoint) {

        final boolean isOptimistic = isValid(programPoint);

        final int     fti          = getAccessorTypeIndex(getHas.type().returnType());

        final int     ti           = getAccessorTypeIndex(returnType);

        MethodHandle  mh           = getHas;

        if (isOptimistic) {

            if (ti < fti) {

                mh = MH.insertArguments(ArrayData.THROW_UNWARRANTED.methodHandle(), 1, programPoint);

            }

        }

        mh = MH.asType(mh, mh.type().changeReturnType(returnType).changeParameterType(0, clazz));

        if (!isOptimistic) {

            //for example a & array[17];

            return Lookup.filterReturnType(mh, returnType);

        }

        return mh;

    }

    /**

     * Return element setter for a {@link ContinuousArrayData}

     * @param clazz        class for exact type guard

     * @param setHas       set has guard

     * @param elementType  element type

     * @return method handle for element setter

     */

    protected MethodHandle getContinuousElementSetter(final Class<? extends ContinuousArrayData> clazz, final MethodHandle setHas, final Class<?> elementType) {

        return MH.asType(setHas, setHas.type().changeParameterType(2, elementType).changeParameterType(0, clazz));

    }

    /** Fast access guard - it is impractical for JIT performance reasons to use only CCE asType as guard :-(, also we need

      the null case explicitly, which is the one that CCE doesn't handle */

    protected static final MethodHandle FAST_ACCESS_GUARD =

            MH.dropArguments(

                    staticCall(

                            MethodHandles.lookup(),

                            ContinuousArrayData.class,

                            "guard",

                            boolean.class,

                            Class.class,

                            ScriptObject.class).methodHandle(),

                    2,

                    int.class);

    @SuppressWarnings("unused")

    private static boolean guard(final Class<? extends ContinuousArrayData> clazz, final ScriptObject sobj) {

        return sobj != null && sobj.getArray().getClass() == clazz;

    }

    /**

     * Return a fast linked array getter, or null if we have to dispatch to super class

     * @param desc     descriptor

     * @param request  link request

     * @return invocation or null if needs to be sent to slow relink

     */

    @Override

    public GuardedInvocation findFastGetIndexMethod(final Class<? extends ArrayData> clazz, final CallSiteDescriptor desc, final LinkRequest request) {

        final MethodType callType   = desc.getMethodType();

        final Class<?>   indexType  = callType.parameterType(1);

        final Class<?>   returnType = callType.returnType();

        if (ContinuousArrayData.class.isAssignableFrom(clazz) && indexType == int.class) {

            final Object[] args  = request.getArguments();

            final int      index = (int)args[args.length - 1];

            if (has(index)) {

                final MethodHandle getArray     = ScriptObject.GET_ARRAY.methodHandle();

                final int          programPoint = NashornCallSiteDescriptor.isOptimistic(desc) ? NashornCallSiteDescriptor.getProgramPoint(desc) : INVALID_PROGRAM_POINT;

                MethodHandle       getElement   = getElementGetter(returnType, programPoint);

                if (getElement != null) {

                    getElement = MH.filterArguments(getElement, 0, MH.asType(getArray, getArray.type().changeReturnType(clazz)));

                    final MethodHandle guard = MH.insertArguments(FAST_ACCESS_GUARD, 0, clazz);

                    return new GuardedInvocation(getElement, guard, (SwitchPoint)null, ClassCastException.class);

                }

            }

        }

        return null;

    }

    /**

     * Return a fast linked array setter, or null if we have to dispatch to super class

     * @param desc     descriptor

     * @param request  link request

     * @return invocation or null if needs to be sent to slow relink

     */

    @Override

    public GuardedInvocation findFastSetIndexMethod(final Class<? extends ArrayData> clazz, final CallSiteDescriptor desc, final LinkRequest request) { // array, index, value

        final MethodType callType    = desc.getMethodType();

        final Class<?>   indexType   = callType.parameterType(1);

        final Class<?>   elementType = callType.parameterType(2);

        if (ContinuousArrayData.class.isAssignableFrom(clazz) && indexType == int.class) {

            final Object[]        args  = request.getArguments();

            final int             index = (int)args[args.length - 2];

            if (hasRoomFor(index)) {

                MethodHandle setElement = getElementSetter(elementType); //Z(continuousarraydata, int, int), return true if successful

                if (setElement != null) {

                    //else we are dealing with a wider type than supported by this callsite

                    MethodHandle getArray = ScriptObject.GET_ARRAY.methodHandle();

                    getArray   = MH.asType(getArray, getArray.type().changeReturnType(getClass()));

                    setElement = MH.filterArguments(setElement, 0, getArray);

                    final MethodHandle guard = MH.insertArguments(FAST_ACCESS_GUARD, 0, clazz);

                    return new GuardedInvocation(setElement, guard, (SwitchPoint)null, ClassCastException.class); //CCE if not a scriptObject anymore

                }

            }

        }

        return null;

    }

    /**

     * Specialization - fast push implementation

     * @param arg argument

     * @return new array length

     */

    public double fastPush(final int arg) {

        throw new ClassCastException(String.valueOf(getClass())); //type is wrong, relink

    }

    /**

     * Specialization - fast push implementation

     * @param arg argument

     * @return new array length

     */

    public double fastPush(final long arg) {

        throw new ClassCastException(String.valueOf(getClass())); //type is wrong, relink

    }

    /**

     * Specialization - fast push implementation

     * @param arg argument

     * @return new array length

     */

    public double fastPush(final double arg) {

        throw new ClassCastException(String.valueOf(getClass())); //type is wrong, relink

    }

    /**

     * Specialization - fast push implementation

     * @param arg argument

     * @return new array length

     */

    public double fastPush(final Object arg) {

        throw new ClassCastException(String.valueOf(getClass())); //type is wrong, relink

    }

    /**

     * Specialization - fast pop implementation

     * @return element value

     */

    public int fastPopInt() {

        throw new ClassCastException(String.valueOf(getClass())); //type is wrong, relink

    }

    /**

     * Specialization - fast pop implementation

     * @return element value

     */

    public double fastPopDouble() {

       throw new ClassCastException(String.valueOf(getClass())); //type is wrong, relink

    }

    /**

     * Specialization - fast pop implementation

     * @return element value

     */

    public Object fastPopObject() {

        throw new ClassCastException(String.valueOf(getClass())); //type is wrong, relink

    }

    /**

     * Specialization - fast concat implementation

     * @param otherData data to concat

     * @return new arraydata

     */

    public ContinuousArrayData fastConcat(final ContinuousArrayData otherData) {

        throw new ClassCastException(String.valueOf(getClass()) + " != " + String.valueOf(otherData.getClass()));

    }

}