org.apache.tomcat.util.bcel.classfile.StackMapTableEntry Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package org.apache.tomcat.util.bcel.classfile;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.Serializable;
import org.apache.tomcat.util.bcel.Constants;
/**
* This class represents a stack map entry recording the types of
* local variables and the the of stack items at a given byte code offset.
* See CLDC specification §5.3.1.2
*
* @version $Id: StackMapTableEntry.java 1059614 2011-01-16 16:50:25Z markt $
* @author M. Dahm
* @see StackMap
* @see StackMapType
*/
public final class StackMapTableEntry implements Cloneable, Serializable {
private static final long serialVersionUID = 1L;
private int frame_type;
private int byte_code_offset_delta;
private int number_of_locals;
private StackMapType[] types_of_locals;
private int number_of_stack_items;
private StackMapType[] types_of_stack_items;
/**
* Construct object from file stream.
* @param file Input stream
* @throws IOException
*/
StackMapTableEntry(DataInputStream file, ConstantPool constant_pool) throws IOException {
this(file.read(), -1, -1, null, -1, null);
if (frame_type >= Constants.SAME_FRAME && frame_type <= Constants.SAME_FRAME_MAX) {
byte_code_offset_delta = frame_type - Constants.SAME_FRAME;
} else if (frame_type >= Constants.SAME_LOCALS_1_STACK_ITEM_FRAME && frame_type <= Constants.SAME_LOCALS_1_STACK_ITEM_FRAME_MAX) {
byte_code_offset_delta = frame_type - Constants.SAME_LOCALS_1_STACK_ITEM_FRAME;
number_of_stack_items = 1;
types_of_stack_items = new StackMapType[1];
types_of_stack_items[0] = new StackMapType(file, constant_pool);
} else if (frame_type == Constants.SAME_LOCALS_1_STACK_ITEM_FRAME_EXTENDED) {
byte_code_offset_delta = file.readShort();
number_of_stack_items = 1;
types_of_stack_items = new StackMapType[1];
types_of_stack_items[0] = new StackMapType(file, constant_pool);
} else if (frame_type >= Constants.CHOP_FRAME && frame_type <= Constants.CHOP_FRAME_MAX) {
byte_code_offset_delta = file.readShort();
} else if (frame_type == Constants.SAME_FRAME_EXTENDED) {
byte_code_offset_delta = file.readShort();
} else if (frame_type >= Constants.APPEND_FRAME && frame_type <= Constants.APPEND_FRAME_MAX) {
byte_code_offset_delta = file.readShort();
number_of_locals = frame_type - 251;
types_of_locals = new StackMapType[number_of_locals];
for (int i = 0; i < number_of_locals; i++) {
types_of_locals[i] = new StackMapType(file, constant_pool);
}
} else if (frame_type == Constants.FULL_FRAME) {
byte_code_offset_delta = file.readShort();
number_of_locals = file.readShort();
types_of_locals = new StackMapType[number_of_locals];
for (int i = 0; i < number_of_locals; i++) {
types_of_locals[i] = new StackMapType(file, constant_pool);
}
number_of_stack_items = file.readShort();
types_of_stack_items = new StackMapType[number_of_stack_items];
for (int i = 0; i < number_of_stack_items; i++) {
types_of_stack_items[i] = new StackMapType(file, constant_pool);
}
} else {
/* Can't happen */
throw new ClassFormatException ("Invalid frame type found while parsing stack map table: " + frame_type);
}
}
public StackMapTableEntry(int tag, int byte_code_offset_delta, int number_of_locals,
StackMapType[] types_of_locals, int number_of_stack_items,
StackMapType[] types_of_stack_items) {
this.frame_type = tag;
this.byte_code_offset_delta = byte_code_offset_delta;
this.number_of_locals = number_of_locals;
this.types_of_locals = types_of_locals;
this.number_of_stack_items = number_of_stack_items;
this.types_of_stack_items = types_of_stack_items;
}
/**
* Dump stack map entry
*
* @param file Output file stream
* @throws IOException
*/
public final void dump( DataOutputStream file ) throws IOException {
file.write(frame_type);
if (frame_type >= Constants.SAME_FRAME && frame_type <= Constants.SAME_FRAME_MAX) {
// nothing to be done
} else if (frame_type >= Constants.SAME_LOCALS_1_STACK_ITEM_FRAME && frame_type <= Constants.SAME_LOCALS_1_STACK_ITEM_FRAME_MAX) {
types_of_stack_items[0].dump(file);
} else if (frame_type == Constants.SAME_LOCALS_1_STACK_ITEM_FRAME_EXTENDED) {
file.writeShort(byte_code_offset_delta);
types_of_stack_items[0].dump(file);
} else if (frame_type >= Constants.CHOP_FRAME && frame_type <= Constants.CHOP_FRAME_MAX) {
file.writeShort(byte_code_offset_delta);
} else if (frame_type == Constants.SAME_FRAME_EXTENDED) {
file.writeShort(byte_code_offset_delta);
} else if (frame_type >= Constants.APPEND_FRAME && frame_type <= Constants.APPEND_FRAME_MAX) {
file.writeShort(byte_code_offset_delta);
for (int i = 0; i < number_of_locals; i++) {
types_of_locals[i].dump(file);
}
} else if (frame_type == Constants.FULL_FRAME) {
file.writeShort(byte_code_offset_delta);
file.writeShort(number_of_locals);
for (int i = 0; i < number_of_locals; i++) {
types_of_locals[i].dump(file);
}
file.writeShort(number_of_stack_items);
for (int i = 0; i < number_of_stack_items; i++) {
types_of_stack_items[i].dump(file);
}
} else {
/* Can't happen */
throw new ClassFormatException ("Invalid Stack map table tag: " + frame_type);
}
}
/**
* @return String representation.
*/
@Override
public final String toString() {
StringBuffer buf = new StringBuffer(64);
buf.append("(");
if (frame_type >= Constants.SAME_FRAME && frame_type <= Constants.SAME_FRAME_MAX) {
buf.append("SAME");
} else if (frame_type >= Constants.SAME_LOCALS_1_STACK_ITEM_FRAME && frame_type <= Constants.SAME_LOCALS_1_STACK_ITEM_FRAME_MAX) {
buf.append("SAME_LOCALS_1_STACK");
} else if (frame_type == Constants.SAME_LOCALS_1_STACK_ITEM_FRAME_EXTENDED) {
buf.append("SAME_LOCALS_1_STACK_EXTENDED");
} else if (frame_type >= Constants.CHOP_FRAME && frame_type <= Constants.CHOP_FRAME_MAX) {
buf.append("CHOP "+(251-frame_type));
} else if (frame_type == Constants.SAME_FRAME_EXTENDED) {
buf.append("SAME_EXTENDED");
} else if (frame_type >= Constants.APPEND_FRAME && frame_type <= Constants.APPEND_FRAME_MAX) {
buf.append("APPEND "+(frame_type-251));
} else if (frame_type == Constants.FULL_FRAME) {
buf.append("FULL");
} else {
buf.append("UNKNOWN");
}
buf.append(", offset delta=").append(byte_code_offset_delta);
if (number_of_locals > 0) {
buf.append(", locals={");
for (int i = 0; i < number_of_locals; i++) {
buf.append(types_of_locals[i]);
if (i < number_of_locals - 1) {
buf.append(", ");
}
}
buf.append("}");
}
if (number_of_stack_items > 0) {
buf.append(", stack items={");
for (int i = 0; i < number_of_stack_items; i++) {
buf.append(types_of_stack_items[i]);
if (i < number_of_stack_items - 1) {
buf.append(", ");
}
}
buf.append("}");
}
buf.append(")");
return buf.toString();
}
/**
* @return deep copy of this object
*/
public StackMapTableEntry copy() {
try {
return (StackMapTableEntry) clone();
} catch (CloneNotSupportedException e) {
}
return null;
}
}