/*

 * Copyright (c) 2005, 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 org.apidesign.javap;

import java.io.*;

import static org.apidesign.javap.RuntimeConstants.*;

/* represents one entry of StackMapTable attribute

 */

abstract class StackMapTableData {

    final int frameType;

    int offsetDelta;

    StackMapTableData(int frameType) {

        this.frameType = frameType;

    }

    abstract int getStackItemsCount();

    static class SameFrame extends StackMapTableData {

        SameFrame(int frameType, int offsetDelta) {

            super(frameType);

            this.offsetDelta = offsetDelta;

        }

        @Override

        int getStackItemsCount() {

            return 0;

        }

        @Override

        public String toString() {

            return "SAME"

                       + ((frameType == SAME_FRAME_EXTENDED)

                              ? "_FRAME_EXTENDED" : "")

                       + "(" + offsetDelta + ")";

        }

    }

    static class SameLocals1StackItem extends StackMapTableData {

        final int[] stack;

        SameLocals1StackItem(int frameType, int offsetDelta, int[] stack) {

            super(frameType);

            this.offsetDelta = offsetDelta;

            this.stack = stack;

        }

        @Override

        int getStackItemsCount() {

            return 1;

        }

        @Override

        public String toString() {

            return "SAME_LOCALS_1_STACK_ITEM"

                       + ((frameType == SAME_LOCALS_1_STACK_ITEM_EXTENDED)

                              ? "_EXTENDED" : "")

                       + "(" + offsetDelta + ")";

        }

    }

    static class ChopFrame extends StackMapTableData {

        ChopFrame(int frameType, int offsetDelta) {

            super(frameType);

            this.offsetDelta = offsetDelta;

        }

        @Override

        int getStackItemsCount() {

            return 0;

        }

        @Override

        public String toString() {

            return "CHOP(" + offsetDelta + ")";

        }

    }

    static class AppendFrame extends StackMapTableData {

        final int[] locals;

        AppendFrame(int frameType, int offsetDelta, int[] locals) {

            super(frameType);

            this.offsetDelta = offsetDelta;

            this.locals = locals;

        }

        @Override

        int getStackItemsCount() {

            return 0;

        }

        @Override

        public String toString() {

            return "APPEND(" + offsetDelta + ")";

        }

    }

    static class FullFrame extends StackMapTableData {

        final int[] locals;

        final int[] stack;

        FullFrame(int offsetDelta, int[] locals, int[] stack) {

            super(FULL_FRAME);

            this.offsetDelta = offsetDelta;

            this.locals = locals;

            this.stack = stack;

        }

        @Override

        int getStackItemsCount() {

            return stack.length;

        }

        @Override

        public String toString() {

            return "FULL(" + offsetDelta + ")";

        }

    }

    static StackMapTableData getInstance(DataInputStream in, MethodData method)

                  throws IOException {

        int frameType = in.readUnsignedByte();

        if (frameType < SAME_FRAME_BOUND) {

            // same_frame

            return new SameFrame(frameType, frameType);

        } else if (SAME_FRAME_BOUND <= frameType && frameType < SAME_LOCALS_1_STACK_ITEM_BOUND) {

            // same_locals_1_stack_item_frame

            // read additional single stack element

            return new SameLocals1StackItem(frameType,

                                            (frameType - SAME_FRAME_BOUND),

                                            StackMapData.readTypeArray(in, 1, method));

        } else if (frameType == SAME_LOCALS_1_STACK_ITEM_EXTENDED) {

            // same_locals_1_stack_item_extended

            return new SameLocals1StackItem(frameType,

                                            in.readUnsignedShort(),

                                            StackMapData.readTypeArray(in, 1, method));

        } else if (SAME_LOCALS_1_STACK_ITEM_EXTENDED < frameType  && frameType < SAME_FRAME_EXTENDED) {

            // chop_frame or same_frame_extended

            return new ChopFrame(frameType, in.readUnsignedShort());

        } else if (frameType == SAME_FRAME_EXTENDED) {

            // chop_frame or same_frame_extended

            return new SameFrame(frameType, in.readUnsignedShort());

        } else if (SAME_FRAME_EXTENDED < frameType  && frameType < FULL_FRAME) {

            // append_frame

            return new AppendFrame(frameType, in.readUnsignedShort(),

                                   StackMapData.readTypeArray(in, frameType - SAME_FRAME_EXTENDED, method));

        } else if (frameType == FULL_FRAME) {

            // full_frame

            int offsetDelta = in.readUnsignedShort();

            int locals_size = in.readUnsignedShort();

            int[] locals = StackMapData.readTypeArray(in, locals_size, method);

            int stack_size = in.readUnsignedShort();

            int[] stack = StackMapData.readTypeArray(in, stack_size, method);

            return new FullFrame(offsetDelta, locals, stack);

        } else {

            throw new ClassFormatError("unrecognized frame_type in StackMapTable");

        }

    }

}