SourceCodeBuilder.java

package hasnaer.java.bytecode;

import hasnaer.java.bytecode.attribute.Code;
import hasnaer.java.bytecode.attribute.Exceptions;
import hasnaer.java.bytecode.attribute.LocalVariableTable;
import hasnaer.java.bytecode.nodes.ConditionalBlockNode;
import hasnaer.java.bytecode.nodes.JVMNode;
import java.io.FileInputStream;
import java.util.HashMap;
import java.util.List;
import javax.swing.JFileChooser;

/**
 *
 * @author hasnae rehioui
 */
public class SourceCodeBuilder {

    private static String OBJECT_CLASS = "java.lang.Object";
    public static String INDENT = "\t";

    public static String visitClass(ClassFile class_file) {
        StringBuilder builder = new StringBuilder();

        if (AccessFlags.isPrivate(class_file.getAccess_flags())) {
            builder.append("private ");
        } else if (AccessFlags.isPublic(class_file.getAccess_flags())) {
            builder.append("public ");
        }

        if (class_file.isAbstract()) {
            builder.append("abstract ");
        }

        if (class_file.isInterface()) {
            builder.append("interface ");
        } else {
            builder.append("class ");
        }

        builder.append(class_file.getClassName());
        builder.append(" ");

        String super_class_name = class_file.getSuperClassName();
        if (!super_class_name.equals(OBJECT_CLASS)) {
            builder.append("extends ");
            builder.append(super_class_name);
            builder.append(" ");
        }

        List<String> interfaces = class_file.getInterfaces();
        if (!interfaces.isEmpty()) {
            builder.append("implements ");
            builder.append(interfaces.get(0));
            for (int i = 1; i < interfaces.size(); i++) {
                builder.append(", ");
                builder.append(interfaces.get(i));
            }
            builder.append(" ");
        }
        builder.append("{\n");
        builder.append(visitFields(class_file.getFields()));
        builder.append(visitMethods(class_file.getMethods()));
        builder.append("}");

        return builder.toString();
    }

    public static String visitFields(List<FieldInfo> fields) {

        StringBuilder builder = new StringBuilder("\n");

        for (FieldInfo field : fields) {

            builder.append(INDENT);
            builder.append(AccessFlags.fieldAccess(field.getAccess_flags()));
            builder.append(Descriptor.fieldDataType(field.getDescriptor()));
            builder.append(field.getName());
            builder.append(";\n");
        }
        return builder.toString();
    }

    public static String visitMethods(List<MethodInfo> methods) {

        StringBuilder builder = new StringBuilder("\n");
        for (MethodInfo method : methods) {
            builder.append(visitMethod(method));
        }

        return builder.toString();
    }

    public static String visitMethod(MethodInfo method) {

        StringBuilder builder = new StringBuilder();

        Code code_attribute = method.getCodeAttribute();
        LocalVariableTable lvt_attribute = null;
        if (code_attribute != null) {
            lvt_attribute = code_attribute.getLocalVariableTableAttribute();
        }

        Exceptions exc_attribute = method.getExceptionsAttibute();

//        System.err.println("constant_pool= ");
//        System.err.println(lvt_attribute.getConstantPool().toString());

        builder.append(INDENT);
        if (!method.isStaticInit()) {
            builder.append(AccessFlags.methodAccess(method.getAccess_flags()));
            if (!method.isConstructor()) {
                builder.append(Descriptor.getReturnDescriptor(method.getDescriptor()));
            }
            builder.append(method.getName());
            builder.append(" (");

            if (lvt_attribute != null) {
                int numOfParameters = Descriptor.getParamCount(method.getDescriptor());
                if (numOfParameters > 0) {
                    String[] variable = lvt_attribute.getVariable(lvt_attribute.THIS_INDEX + 1);
                    builder.append(variable[0]);
                    builder.append(" ");
                    builder.append(variable[1]);

                    for (int i = 2; i <= numOfParameters; i++) {
                        builder.append(", ");
                        variable = lvt_attribute.getVariable(lvt_attribute.THIS_INDEX + i);
                        builder.append(variable[0]);
                        builder.append(" ");
                        builder.append(variable[1]);
                    }
                }
            } else if (method.isAbstract()) {
                String[] param_types = Descriptor.getParamTypes(method.getDescriptor());

                if (param_types != null) {
                    int p = 0;
                    builder.append(param_types[0]);
                    builder.append(" param" + p++);

                    for (int i = 1; i < param_types.length; i++) {
                        builder.append(", ");
                        builder.append(param_types[i]);
                        builder.append(" param" + p++);
                    }
                }
            }

            builder.append(")");
        } else {
            builder.append("static ");
        }
        
        if (exc_attribute != null) {
            int[] exc_ = exc_attribute.getTable();
            if (exc_.length > 0) {
                builder.append(" throws ");
                builder.append(exc_attribute.getExceptionClassName(0));

                for (int i = 1; i < exc_.length; i++) {
                    builder.append(", ");
                    builder.append(exc_attribute.getExceptionClassName(i));
                }

            }
        }

        if (method.isAbstract()) {
            builder.append(";\n\n");
        } else {
            builder.append(" {\n");

            try {
                StatementBuilder st_builder = new StatementBuilder(code_attribute, 0,
                        code_attribute.getCode().length, lvt_attribute,
                        new HashMap<Integer, Integer>());
                st_builder.build();
                List<JVMNode> statements = st_builder.getStatements();

                for (JVMNode statement : statements) {
                    builder.append(statement.toJava(INDENT + INDENT));
                    if(!(statement instanceof ConditionalBlockNode)){
                        builder.append(";");
                    }
                    builder.append("\n");
                }
            } catch (Exception ex) {
            }

            builder.append(INDENT);
            builder.append("}\n\n");
        }
        
        return builder.toString();
    }

    public static void main(String[] args) throws Exception {
        JFileChooser browser = new JFileChooser();
        int result = browser.showOpenDialog(null);
        if (result == JFileChooser.APPROVE_OPTION) {
            ClassFile c_file = new ClassFile(new FileInputStream(browser.getSelectedFile()));
            System.err.println("\n\n" + SourceCodeBuilder.visitMethod(c_file.getMethod("test")));
//            System.out.println(SourceCodeBuilder.visitClass(c_file));
        }

    }
}