sourcecodebuilder.java

JASML is a java byte code compiler, providing yet another approach to view, write and edit java clas

/*
 * Author jyang Created on 2006-4-5 10:30:53
 */
package com.jasml.decompiler;

import java.util.HashSet;

import com.jasml.classes.Attribute;
import com.jasml.classes.Attribute_Code;
import com.jasml.classes.Attribute_ConstantValue;
import com.jasml.classes.Attribute_Deprecated;
import com.jasml.classes.Attribute_Exceptions;
import com.jasml.classes.Attribute_InnerClasses;
import com.jasml.classes.Attribute_LineNumberTable;
import com.jasml.classes.Attribute_LocalVariableTable;
import com.jasml.classes.Attribute_SourceFile;
import com.jasml.classes.Attribute_Synthetic;
import com.jasml.classes.ConstantPool;
import com.jasml.classes.ConstantPoolItem;
import com.jasml.classes.Constant_Class;
import com.jasml.classes.Constant_Double;
import com.jasml.classes.Constant_Fieldref;
import com.jasml.classes.Constant_Float;
import com.jasml.classes.Constant_Integer;
import com.jasml.classes.Constant_InterfaceMethodref;
import com.jasml.classes.Constant_Long;
import com.jasml.classes.Constant_Methodref;
import com.jasml.classes.Constant_NameAndType;
import com.jasml.classes.Constant_String;
import com.jasml.classes.Constant_Utf8;
import com.jasml.classes.Constants;
import com.jasml.classes.Field;
import com.jasml.classes.JavaClass;
import com.jasml.classes.Method;
import com.jasml.classes.Attribute_LocalVariableTable.LocalVariable;
import com.jasml.helper.OpcodeHelper;
import com.jasml.helper.Util;

public class SourceCodeBuilder {
	ConstantPool cpl;

	SourceCodeBuilderConfiguration config;

	public SourceCodeBuilder() {
		config = new SourceCodeBuilderConfiguration();
	}

	public SourceCodeBuilder(SourceCodeBuilderConfiguration config) {
		this.config = config;
	}

	private String toString(Attribute_ConstantValue var) {
		return toString(cpl.getConstant(var.constant_value_index));
	}

	private String toString(Attribute_Deprecated var) {
		return "[" + Constants.ATTRIBUTE_NAME_DEPRECATED + "]";
	}

	private String toString(Attribute_Synthetic var) {
		return "[" + Constants.ATTRIBUTE_NAME_SYNTHETIC + "]";
	}

	private String toString(Attribute_SourceFile var) {
		return "[" + Constants.ATTRIBUTE_NAME_SOURCE_FILE + " : " + toString(cpl.getConstant(var.sourcefile_index)) + "]";
	}

	private String toString(Attribute_LocalVariableTable attr, Attribute_Code.Opcode[] ops) {
		if (attr.local_variable_table_length == 0)
			return "";
		StringBuffer buf = new StringBuffer();
		buf.append("[" + Constants.ATTRIBUTE_NAME_LOCAL_VARIABLE + " :");
		LocalVariable var;
		for (int i = 0; i < attr.local_variable_table_length; i++) {
			var = attr.local_variable_table[i];
			buf.append(Constants.LINE_SEPARATER);
			buf.append(Util.descriptorToString(toString(cpl.getConstant(var.descriptor_index)))); // descriptor
			buf.append(" ");
			buf.append(toString(cpl.getConstant(var.name_index))); // name
			buf.append("  ");
			buf.append("start=" + config.labelPrefix + var.start_pc); // start position
			buf.append(", ");
			buf.append("end=" + config.labelPrefix + (findPreviousInstruction(var.start_pc + var.length, ops)).offset); // valid scope
			buf.append(", ");
			buf.append("index=" + var.index); // index into runtime frame
		}
		buf.append("]");
		return buf.toString();
	}

	private String toString(Attribute_LineNumberTable attr) {
		if (attr.line_number_table_length == 0)
			return "";
		StringBuffer buf = new StringBuffer();
		buf.append("[" + Constants.ATTRIBUTE_NAME_LINE_NUMBER_TABLE + " :");
		for (int i = 0; i < attr.line_number_table_length; i++) {
			buf.append(Constants.LINE_SEPARATER);
			buf.append(config.labelPrefix + attr.lineNumberTable[i].start_pc + " ->  " + attr.lineNumberTable[i].line_number);
		}
		buf.append("]");
		return buf.toString();
	}

	private String toString(Attribute_InnerClasses attr) {
		StringBuffer buf = new StringBuffer();
		Attribute_InnerClasses.InnerClass innerClass;
		buf.append("[" + Constants.ATTRIBUTE_NAME_INNER_CLASSES + " :");
		for (int i = 0; i < attr.number_of_classes; i++) {
			buf.append(Constants.LINE_SEPARATER);
			innerClass = attr.innerClasses[i];
			// access flag
			buf.append("access = " + Util.accessFlagToString_Class((short) innerClass.inner_class_access_flags) + " , ");
			// inner class name
			buf.append("name = ");
			if (innerClass.inner_name_index == 0) {
				buf.append("0 , ");
			} else {
				buf.append(toString(cpl.getConstant(innerClass.inner_name_index)) + " , ");
			}

			// inner class info
			buf.append("fullname = ");
			buf.append(toString(cpl.getConstant(innerClass.inner_class_info_index)) + " , ");

			// outer class info
			buf.append("outername = ");
			if (innerClass.outer_class_info_index == 0) {
				buf.append("0");
			} else {
				buf.append(toString(cpl.getConstant(innerClass.outer_class_info_index)));
			}
		}
		buf.append(']');
		return buf.toString();
	}

	private String toString(Attribute_Exceptions attr) {
		if (attr.number_of_exceptions == 0)
			return "";

		StringBuffer buf = new StringBuffer();
		for (int i = 0; i < attr.number_of_exceptions; i++) {
			buf.append(toString(cpl.getConstant(attr.exception_index_table[i])) + ",");
		}
		buf.deleteCharAt(buf.length() - 1);
		return buf.toString();
	}

	private String getLocalVariableName(int index, int codeOffset, Attribute_LocalVariableTable.LocalVariable[] lvts) {
		if (lvts == null) {
			return "UnknowVariable";
		}
		int i;
		Attribute_LocalVariableTable.LocalVariable lv;
		for (i = 0; i < lvts.length; i++) {
			lv = lvts[i];
			if (lv.index == index && lv.start_pc <= codeOffset && (lv.start_pc + lv.length) >= codeOffset) {
				return toString(cpl.getConstant(lv.name_index));
			}
		}
		// no match found, TODO: why could this happen
		// search for the one with the same index value
		for (i = 0; i < lvts.length; i++) {
			lv = lvts[i];
			if (lv.index == index) {
				return toString(cpl.getConstant(lv.name_index));
			}
		}

		// still not found
		return "unknown_local_variable";

		// TODO: this is little tricky
	}

	private String toString(Attribute_Code code, HashSet referedLines) {
		StringBuffer buf = new StringBuffer();
		Attribute_Code.Opcode op;
		Attribute_Code.Opcode[] ops = code.codes;
		byte[][] operands;
		int ti, def, low, high, jump_count, npairs;
		String soffset;

		Attribute_LocalVariableTable.LocalVariable[] lvts = null;
		for (int i = 0; i < code.attributes_count; i++) {
			if (code.attributes[i] instanceof Attribute_LocalVariableTable) {
				lvts = ((Attribute_LocalVariableTable) code.attributes[i]).local_variable_table;
				break;
			}
		}

		// instructions
		if (code.code_length != 0) {
			for (int t = 0; t < ops.length; t++) {
				op = ops[t];
				operands = op.operands;
				// offset
				soffset = Integer.toString(op.offset);
				if (referedLines.contains(soffset) == true) {
					if (config.labelInSingleLine == true) {
						buf.append(config.labelPrefix + soffset + " : ");
						buf.append(Constants.LINE_SEPARATER);
						buf.append(config.instructionPadding);
					} else {
						buf.append(Util.padChar(config.labelPrefix + soffset, config.labelLength, ' ') + " : ");
					}
				} else {
					buf.append(config.instructionPadding);
				}
				// opcode name
				buf.append(Constants.OPCODE_NAMES[0xFF & op.opcode] + "  ");
				switch (op.opcode) {
				case Constants.TABLESWITCH:
					def = Util.getNum(operands[1]) + op.offset;
					low = Util.getNum(operands[2]);
					high = Util.getNum(operands[3]);
					jump_count = high - low + 1;

					buf.append("default=" + config.labelPrefix + def + ", low=" + low + ", high=" + high + ", jump_table:");

					for (int i = 0; i < jump_count; i++) {
						// jump address is calculated by adding with tableswitch offset.
						buf.append(config.labelPrefix + (Util.getNum(operands[i + 4]) + op.offset) + ",");
					}
					buf.deleteCharAt(buf.length() - 1);
					break;
				case Constants.LOOKUPSWITCH: {
					def = Util.getNum(operands[1]) + op.offset;
					npairs = Util.getNum(operands[2]);

					buf.append("default=" + config.labelPrefix + def + ", npairs=" + npairs + ", jump_table:");
					if (npairs != 0) {
						for (int i = 0; i < npairs; i++) {
							buf.append(Util.getNum(operands[i * 2 + 3]));
							buf.append("->");
							buf.append(config.labelPrefix + (Util.getNum(operands[i * 2 + 4]) + op.offset) + ",");

						}
						buf.deleteCharAt(buf.length() - 1);
					}
				}
					break;
				/*
				 * Two address bytes + offset from start of byte stream form the
				 * jump target
				 */
				case Constants.GOTO:
				case Constants.IFEQ:
				case Constants.IFGE:
				case Constants.IFGT:
				case Constants.IFLE:
				case Constants.IFLT:
				case Constants.JSR:
				case Constants.IFNE:
				case Constants.IFNONNULL:
				case Constants.IFNULL:
				case Constants.IF_ACMPEQ:
				case Constants.IF_ACMPNE:
				case Constants.IF_ICMPEQ:
				case Constants.IF_ICMPGE:
				case Constants.IF_ICMPGT:
				case Constants.IF_ICMPLE:
				case Constants.IF_ICMPLT:
				case Constants.IF_ICMPNE:
				/*
				 * 32-bit wide jumps
				 */
				case Constants.GOTO_W:
				case Constants.JSR_W:
					buf.append(config.labelPrefix + (Util.getSignedNum(operands[0]) + op.offset));
					break;
				/*
				 * Index byte references local variable
				 */
				case Constants.ALOAD:
				case Constants.ASTORE:
				case Constants.DLOAD:
				case Constants.DSTORE:
				case Constants.FLOAD:
				case Constants.FSTORE:
				case Constants.ILOAD:
				case Constants.ISTORE:
				case Constants.LLOAD:
				case Constants.LSTORE:
				case Constants.RET:
					ti = Util.getNum(operands[0]); // the index into local variable
					// table
					buf.append(getLocalVariableName(ti, op.offset, lvts) + "(" + ti + ")");
					break;
				/*
				 * Remember wide byte which is used to form a 16-bit address in the
				 * following instruction. Relies on that the method is called again
				 * with the following opcode.
				 */
				case Constants.WIDE:
					// TODO: testing
					break;
				/*
				 * Array of basic type.
				 */
				case Constants.NEWARRAY:
					buf.append(Constants.TYPE_NAMES[Util.getNum(operands[0])]);
					break;
				/*
				 * Access object/class fields.
				 */
				case Constants.GETFIELD:
				case Constants.GETSTATIC:
				case Constants.PUTFIELD:
				case Constants.PUTSTATIC:
				/*
				 * Operands are references to classes in constant pool
				 */
				case Constants.NEW:
				case Constants.CHECKCAST:
				case Constants.INSTANCEOF:
				/*
				 * Operands are references to methods in constant pool
				 */
				case Constants.INVOKESPECIAL:
				case Constants.INVOKESTATIC:
				case Constants.INVOKEVIRTUAL:
					buf.append(toString(cpl.getConstant(Util.getNum(operands[0]))));
					break;

				case Constants.INVOKEINTERFACE:
					buf.append(toString(cpl.getConstant(Util.getNum(operands[0]))));
					buf.append(" ");
					buf.append(Util.getNum(operands[1]));
					break;

				/*
				 * Operands are references to items in constant pool
				 */
				case Constants.LDC_W:
				case Constants.LDC2_W:
				case Constants.LDC:
					buf.append(toString(cpl.getConstant(Util.getNum(operands[0]))));
					break;

				/*
				 * Array of references.
				 */
				case Constants.ANEWARRAY:
					buf.append(toString(cpl.getConstant(Util.getNum(operands[0]))));
					break;
				/*
				 * Multidimensional array of references.
				 */
				case Constants.MULTIANEWARRAY:
					buf.append(toString(cpl.getConstant(Util.getNum(operands[0]))));
					buf.append(' ');					
					buf.append(Util.getNum(operands[1]));
					break;
				/*
				 * Increment local variable.
				 */
				case Constants.IINC:
					ti = Util.getNum(operands[0]);
					buf.append(getLocalVariableName(ti, op.offset, lvts) + "(" + ti + ") " + Util.getSignedNum(operands[1]));
					break;
				default:
					if (operands != null) {
						for (int i = 0; i < operands.length; i++) {
							buf.append(Util.getNum(operands[i]) + " ");
						}
					}
				}

				if (config.showInfo == true) {
					buf.append("   //");
					buf.append(OpcodeHelper.getOpcodeInfo(op.opcode).operation);
				}
				buf.append(Constants.LINE_SEPARATER);
			}
		}

		// Local variable table
		for (int i = 0; i < code.attributes_count; i++) {
			if (code.attributes[i] instanceof Attribute_LocalVariableTable
					&& ((Attribute_LocalVariableTable) code.attributes[i]).local_variable_table_length != 0) {
				buf.append(Constants.LINE_SEPARATER);
				buf.append(toString((Attribute_LocalVariableTable) code.attributes[i], ops));
				break;
			}
		}

		// Exception table
		if (code.exception_table_length != 0) {
			buf.append(Constants.LINE_SEPARATER);
			buf.append(Constants.LINE_SEPARATER);

			buf.append("[" + Constants.ATTRIBUTE_NAME_EXCEPTION_TABLE + ":");
			for (int i = 0; i < code.exception_table_length; i++) {
				buf.append(Constants.LINE_SEPARATER);
				buf.append("start=" + config.labelPrefix + code.exception_table[i].start_pc);
				buf.append(" , ");
				buf.append("end=" + config.labelPrefix + code.exception_table[i].end_pc);
				buf.append(" , ");
				buf.append("handler=" + config.labelPrefix + code.exception_table[i].handler_pc);
				buf.append(" , ");
				if (code.exception_table[i].catch_type != 0) {
					buf.append("catch_type=" + toString(cpl.getConstant(code.exception_table[i].catch_type)));
				} else {
					buf.append("catch_type=0");
				}
			}
			buf.append("]");
		}

		// Line number table
		if (config.showLineNumber == true) {
			for (int i = 0; i < code.attributes_count; i++) {
				if (code.attributes[i] instanceof Attribute_LineNumberTable
						&& ((Attribute_LineNumberTable) code.attributes[i]).line_number_table_length != 0) {
					buf.append(Constants.LINE_SEPARATER);
					buf.append(Constants.LINE_SEPARATER);
					buf.append(toString((Attribute_LineNumberTable) code.attributes[i]));
					break;
				}
			}
		}

		// max_stack
		buf.append(Constants.LINE_SEPARATER);
		buf.append(Constants.LINE_SEPARATER);
		buf.append("[" + Constants.ATTRIBUTE_NAME_MAX_STACK + " : " + code.max_stack + "]");
		// max_local
		buf.append(Constants.LINE_SEPARATER);
		buf.append("[" + Constants.ATTRIBUTE_NAME_MAX_LOCAL + " : " + code.max_locals + "]");
		return buf.toString();
	}