Core Utilities

/**
 * Represents method signatures for bytecode generation
 */
public class Signature {
    /**
     * Create method signature
     * @param name - Method name
     * @param returnType - Return type descriptor
     * @param argumentTypes - Argument type descriptors
     */
    public Signature(String name, String returnType, String[] argumentTypes);
    
    /**
     * Get method name
     * @return Method name
     */
    public String getName();
    
    /**
     * Get return type descriptor
     * @return Return type descriptor string
     */
    public String getReturnType();
    
    /**
     * Get argument type descriptors
     * @return Array of argument type descriptor strings
     */
    public String[] getArgumentTypes();
    
    /**
     * Get method descriptor string
     * @return Complete method descriptor
     */
    public String getDescriptor();
    
    /**
     * Check equality with another signature
     * @param obj - Object to compare
     * @return true if signatures are equal
     */
    @Override
    public boolean equals(Object obj);
    
    /**
     * Get hash code for signature
     * @return Hash code
     */
    @Override
    public int hashCode();
    
    /**
     * Get string representation
     * @return String representation of signature
     */
    @Override
    public String toString();
}

import net.sf.cglib.core.Signature;

// Create signature for method: String getName()
Signature getterSig = new Signature("getName", "Ljava/lang/String;", new String[0]);

// Create signature for method: void setAge(int age)
Signature setterSig = new Signature("setAge", "V", new String[]{"I"});

// Create signature for method: List<String> findItems(String query, int limit)
Signature findSig = new Signature("findItems", 
    "Ljava/util/List;", 
    new String[]{"Ljava/lang/String;", "I"});

// Compare signatures
boolean isEqual = getterSig.equals(otherSignature);

// Use in collections (implements proper hashCode/equals)
Set<Signature> methodSignatures = new HashSet<>();
methodSignatures.add(getterSig);
methodSignatures.add(setterSig);

/**
 * Low-level class generation utilities
 */
public abstract class ClassGenerator extends AbstractClassGenerator {
    /**
     * Generate class bytecode
     * @param strategy - Generation strategy
     * @return Generated class
     * @throws Exception - If generation fails
     */
    protected abstract Class generate(ClassLoaderData data) throws Exception;
    
    /**
     * Get default ClassLoader
     * @return Default ClassLoader
     */
    protected ClassLoader getDefaultClassLoader();
    
    /**
     * Generate class name
     * @return Generated class name
     */
    protected String generateClassName();
    
    /**
     * Create class generator
     * @param source - Source object for generation context
     */
    protected ClassGenerator(Source source);
}

/**
 * Base class for all CGLib class generators
 */
public abstract class AbstractClassGenerator implements ClassGenerator {
    /**
     * Set class loader for generated classes
     * @param classLoader - ClassLoader to use
     */
    public void setClassLoader(ClassLoader classLoader);
    
    /**
     * Get class loader for generated classes
     * @return ClassLoader being used
     */
    public ClassLoader getClassLoader();
    
    /**
     * Set naming policy for generated classes
     * @param namingPolicy - NamingPolicy implementation
     */
    public void setNamingPolicy(NamingPolicy namingPolicy);
    
    /**
     * Get naming policy
     * @return Current NamingPolicy
     */
    public NamingPolicy getNamingPolicy();
    
    /**
     * Set generation strategy
     * @param strategy - GeneratorStrategy implementation
     */
    public void setStrategy(GeneratorStrategy strategy);
    
    /**
     * Get generation strategy
     * @return Current GeneratorStrategy
     */
    public GeneratorStrategy getStrategy();
    
    /**
     * Create instance of generated class
     * @param key - Cache key for class generation
     * @return Generated class instance
     */
    protected Object create(Object key);
}

/**
 * Policy interface for generating names of dynamically created classes
 */
public interface NamingPolicy {
    /**
     * Generate class name
     * @param prefix - Prefix for class name
     * @param source - Source class name
     * @param key - Generation key object
     * @param names - Predicate to check for name conflicts
     * @return Generated class name
     */
    String getClassName(String prefix, String source, Object key, Predicate names);
    
    /**
     * Default naming policy instance
     */
    NamingPolicy DEFAULT = new DefaultNamingPolicy();
}

import net.sf.cglib.core.NamingPolicy;
import net.sf.cglib.core.Predicate;

// Custom naming policy
NamingPolicy customPolicy = new NamingPolicy() {
    @Override
    public String getClassName(String prefix, String source, Object key, Predicate names) {
        return "com.mycompany.generated." + prefix + "$$" + source + "$$" + key.hashCode();
    }
};

// Use with Enhancer
Enhancer enhancer = new Enhancer();
enhancer.setSuperclass(MyClass.class);
enhancer.setNamingPolicy(customPolicy);
enhancer.setCallback(interceptor);
Object proxy = enhancer.create();

/**
 * Runtime exception for undeclared checked exceptions in proxy methods
 */
public class UndeclaredThrowableException extends RuntimeException {
    /**
     * Create exception with undeclared throwable
     * @param undeclaredThrowable - The undeclared exception
     */
    public UndeclaredThrowableException(Throwable undeclaredThrowable);
    
    /**
     * Get the undeclared throwable
     * @return Undeclared throwable cause
     */
    public Throwable getUndeclaredThrowable();
}

/**
 * Exception thrown when code generation fails
 */
public class CodeGenerationException extends RuntimeException {
    /**
     * Create exception with message
     * @param message - Error message
     */
    public CodeGenerationException(String message);
    
    /**
     * Create exception with message and cause
     * @param message - Error message
     * @param cause - Underlying cause
     */
    public CodeGenerationException(String message, Throwable cause);
}

import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.ClassVisitor;

/**
 * Strategy interface for generating classes
 */
public interface GeneratorStrategy {
    /**
     * Generate class bytecode
     * @param cg - ClassGenerator instance
     * @return Generated class bytecode
     * @throws Exception - If generation fails
     */
    byte[] generate(ClassGenerator cg) throws Exception;
    
    /**
     * Default strategy instance
     */
    GeneratorStrategy DEFAULT = new DefaultGeneratorStrategy();
}

/**
 * Predicate interface for filtering operations
 */
public interface Predicate {
    /**
     * Evaluate predicate
     * @param arg - Argument to evaluate
     * @return true if predicate matches, false otherwise
     */
    boolean evaluate(Object arg);
}