/*

  * Copyright (c) 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 org.apidesign.javap;

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

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

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

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

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

 public final class StackMapIterator {

     private final StackMapTableData[] stackMapTable;

     private final TypeArray argTypes;

     private final TypeArray localTypes;

     private final TypeArray stackTypes;

     private int nextFrameIndex;

     private int lastFrameByteCodeOffset;

     private int byteCodeOffset;

     StackMapIterator(final MethodData methodData) {

         this(methodData.getStackMapTable(),

              methodData.getInternalSig(),

              methodData.isStatic());

     }

     StackMapIterator(final StackMapTableData[] stackMapTable,

                      final String methodSignature,

                      final boolean isStaticMethod) {

         this.stackMapTable = (stackMapTable != null)

                                  ? stackMapTable

                                  : new StackMapTableData[0];

         argTypes = getArgTypes(methodSignature, isStaticMethod);

         localTypes = new TypeArray();

         stackTypes = new TypeArray();

         localTypes.addAll(argTypes);

         lastFrameByteCodeOffset = -1;

         advanceBy(0);

     }

     public String getFrameAsString() {

         return (nextFrameIndex == 0)

                    ? StackMapTableData.toString("INITIAL", 0, null, null)

                    : stackMapTable[nextFrameIndex - 1].toString();

     }

     public int getFrameIndex() {

         return nextFrameIndex;

     }

     public TypeArray getFrameStack() {

         return stackTypes;

     }

     public TypeArray getFrameLocals() {

         return localTypes;

     }

     public TypeArray getArguments() {

         return argTypes;

     }

     public void advanceBy(final int numByteCodes) {

         if (numByteCodes < 0) {

             throw new IllegalStateException("Forward only iterator");

         }

         byteCodeOffset += numByteCodes;

         while ((nextFrameIndex < stackMapTable.length)

                     && ((byteCodeOffset - lastFrameByteCodeOffset)

                             >= (stackMapTable[nextFrameIndex].offsetDelta

                                     + 1))) {

             final StackMapTableData nextFrame = stackMapTable[nextFrameIndex];

             lastFrameByteCodeOffset += nextFrame.offsetDelta + 1;

             nextFrame.applyTo(localTypes, stackTypes);

             ++nextFrameIndex;

         }

     }

     public void advanceTo(final int nextByteCodeOffset) {

         advanceBy(nextByteCodeOffset - byteCodeOffset);

     }

     private static TypeArray getArgTypes(final String methodSignature,

                                          final boolean isStaticMethod) {

         final TypeArray argTypes = new TypeArray();

         if (!isStaticMethod) {

             argTypes.add(ITEM_Object);

         }

         if (methodSignature.charAt(0) != '(') {

             throw new IllegalArgumentException("Invalid method signature");

         }

         final int length = methodSignature.length();

         boolean skipType = false;

         int argType;

         for (int i = 1; i < length; ++i) {

             switch (methodSignature.charAt(i)) {

                 case 'B':

                 case 'C':

                 case 'S':

                 case 'Z':

                 case 'I':

                     argType = ITEM_Integer;

                     break;

                 case 'J':

                     argType = ITEM_Long;

                     break;

                 case 'F':

                     argType = ITEM_Float;

                     break;

                 case 'D':

                     argType = ITEM_Double;

                     break;

                 case 'L': {

                     i = methodSignature.indexOf(';', i + 1);

                     if (i == -1) {

                         throw new IllegalArgumentException(

                                       "Invalid method signature");

                     }

                     argType = ITEM_Object;

                     break;

                 }

                 case ')':

                     // not interested in the return value type

                     return argTypes;

                 case '[':

                     if (!skipType) {

                         argTypes.add(ITEM_Object);

                         skipType = true;

                     }

                     continue;

                 default:

                     throw new IllegalArgumentException(

                                   "Invalid method signature");

             }

             if (!skipType) {

                 argTypes.add(argType);

             } else {

                 skipType = false;

             }

         }

         return argTypes;

     }

 }