/*

 * Copyright (c) 2010, 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.

 */

package jdk.vm.ci.code;

import java.util.Arrays;

import java.util.Collections;

import java.util.IdentityHashMap;

import java.util.Set;

import jdk.vm.ci.meta.JavaKind;

import jdk.vm.ci.meta.JavaValue;

import jdk.vm.ci.meta.ResolvedJavaField;

import jdk.vm.ci.meta.ResolvedJavaType;

/**

 * An instance of this class represents an object whose allocation was removed by escape analysis.

 * The information stored in the {@link VirtualObject} is used during deoptimization to recreate the

 * object.

 */

public final class VirtualObject implements JavaValue {

    private final ResolvedJavaType type;

    private JavaValue[] values;

    private JavaKind[] slotKinds;

    private final int id;

    private boolean isAutoBox;

    /**

     * Creates a new {@link VirtualObject} for the given type, with the given fields. If

     * {@code type} is an instance class then {@code values} provides the values for the fields

     * returned by {@link ResolvedJavaType#getInstanceFields(boolean) getInstanceFields(true)}. If

     * {@code type} is an array then the length of the values array determines the reallocated array

     * length.

     *

     * @param type the type of the object whose allocation was removed during compilation. This can

     *            be either an instance of an array type.

     * @param id a unique id that identifies the object within the debug information for one

     *            position in the compiled code.

     * @return a new {@link VirtualObject} instance.

     */

    public static VirtualObject get(ResolvedJavaType type, int id) {

        return new VirtualObject(type, id, false);

    }

    /**

     * Creates a new {@link VirtualObject} for the given type, with the given fields. If

     * {@code type} is an instance class then {@code values} provides the values for the fields

     * returned by {@link ResolvedJavaType#getInstanceFields(boolean) getInstanceFields(true)}. If

     * {@code type} is an array then the length of the values array determines the reallocated array

     * length.

     *

     * @param type the type of the object whose allocation was removed during compilation. This can

     *            be either an instance of an array type.

     * @param id a unique id that identifies the object within the debug information for one

     *            position in the compiled code.

     * @param isAutoBox a flag that tells the runtime that the object may be a boxed primitive and

     *            that it possibly needs to be obtained for the box cache instead of creating

     *            a new instance.

     * @return a new {@link VirtualObject} instance.

     */

    public static VirtualObject get(ResolvedJavaType type, int id, boolean isAutoBox) {

        return new VirtualObject(type, id, isAutoBox);

    }

    private VirtualObject(ResolvedJavaType type, int id, boolean isAutoBox) {

        this.type = type;

        this.id = id;

        this.isAutoBox = isAutoBox;

    }

    private static StringBuilder appendValue(StringBuilder buf, JavaValue value, Set<VirtualObject> visited) {

        if (value instanceof VirtualObject) {

            VirtualObject vo = (VirtualObject) value;

            buf.append("vobject:").append(vo.type.toJavaName(false)).append(':').append(vo.id);

            if (!visited.contains(vo)) {

                visited.add(vo);

                buf.append('{');

                if (vo.values == null) {

                    buf.append("<uninitialized>");

                } else {

                    if (vo.type.isArray()) {

                        for (int i = 0; i < vo.values.length; i++) {

                            if (i != 0) {

                                buf.append(',');

                            }

                            buf.append(i).append('=');

                            appendValue(buf, vo.values[i], visited);

                        }

                    } else {

                        ResolvedJavaField[] fields = vo.type.getInstanceFields(true);

                        assert fields.length == vo.values.length : vo.type + ", fields=" + Arrays.toString(fields) + ", values=" + Arrays.toString(vo.values);

                        for (int i = 0; i < vo.values.length; i++) {

                            if (i != 0) {

                                buf.append(',');

                            }

                            buf.append(fields[i].getName()).append('=');

                            appendValue(buf, vo.values[i], visited);

                        }

                    }

                }

                buf.append('}');

            }

        } else {

            buf.append(value);

        }

        return buf;

    }

    @Override

    public String toString() {

        Set<VirtualObject> visited = Collections.newSetFromMap(new IdentityHashMap<VirtualObject, Boolean>());

        return appendValue(new StringBuilder(), this, visited).toString();

    }

    /**

     * Returns the type of the object whose allocation was removed during compilation. This can be

     * either an instance of an array type.

     */

    public ResolvedJavaType getType() {

        return type;

    }

    /**

     * Returns the array containing all the values to be stored into the object when it is

     * recreated. This field is intentional exposed as a mutable array that a compiler may modify

     * (e.g. during register allocation).

     */

    @SuppressFBWarnings(value = "EI_EXPOSE_REP", justification = "`values` is intentional mutable")//

    public JavaValue[] getValues() {

        return values;

    }

    /**

     * Returns the kind of the value at {@code index}.

     */

    public JavaKind getSlotKind(int index) {

        return slotKinds[index];

    }

    /**

     * Returns the unique id that identifies the object within the debug information for one

     * position in the compiled code.

     */

    public int getId() {

        return id;

    }

    /**

     * Returns true if the object is a box. For boxes the deoptimization would check if the value of

     * the box is in the cache range and try to return a cached object.

     */

    public boolean isAutoBox() {

      return isAutoBox;

    }

    /**

     * Sets the value of the box flag.

     * @param isAutoBox a flag that tells the runtime that the object may be a boxed primitive and that

     *            it possibly needs to be obtained for the box cache instead of creating a new instance.

     */

    public void setIsAutoBox(boolean isAutoBox) {

      this.isAutoBox = isAutoBox;

    }

    /**

     * Overwrites the current set of values with a new one.

     *

     * @param values an array containing all the values to be stored into the object when it is

     *            recreated.

     * @param slotKinds an array containing the Java kinds of the values. This must have the same

     *            length as {@code values}. This array is now owned by this object and must not be

     *            mutated by the caller.

     */

    @SuppressFBWarnings(value = "EI_EXPOSE_REP2", justification = "caller transfers ownership of `slotKinds`")

    public void setValues(JavaValue[] values, JavaKind[] slotKinds) {

        assert values.length == slotKinds.length;

        this.values = values;

        this.slotKinds = slotKinds;

    }

    @Override

    public int hashCode() {

        return 42 + type.hashCode();

    }

    @Override

    public boolean equals(Object o) {

        if (o == this) {

            return true;

        }

        if (o instanceof VirtualObject) {

            VirtualObject l = (VirtualObject) o;

            if (!l.type.equals(type) || l.values.length != values.length) {

                return false;

            }

            for (int i = 0; i < values.length; i++) {

                /*

                 * Virtual objects can form cycles. Calling equals() could therefore lead to

                 * infinite recursion.

                 */

                if (!same(values[i], l.values[i])) {

                    return false;

                }

            }

            return true;

        }

        return false;

    }

    private static boolean same(Object o1, Object o2) {

        return o1 == o2;

    }

}