Signature.java

package eu.stratosphere.util.reflect;

import java.io.Serializable;
import java.util.Arrays;

/**
 * General signature of a method that handles exactly the specified argument types.
 * 
 * @author Arvid Heise
 */
public class Signature implements Serializable {
	/**
	 * Constant that is returned by {@link #getDistance(MethodSignature)} if the given actual signature is incompatible
	 * with the declared signature.
	 */
	public static final int INCOMPATIBLE = -1;

	/**
	 * 
	 */
	private static final long serialVersionUID = -3618253913777961043L;

	private final Class<?>[] parameterTypes;

	/**
	 * Initializes MethodSignature with the given, declared parameter types.
	 * 
	 * @param parameterTypes
	 *        the parameter types
	 */
	public Signature(final Class<?>[] parameterTypes) {
		this.parameterTypes = parameterTypes;
	}

	@Override
	public boolean equals(final Object obj) {
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (this.getClass() != obj.getClass())
			return false;
		final Signature other = (Signature) obj;
		return Arrays.equals(this.parameterTypes, other.parameterTypes);
	}

	/**
	 * Returns the distance between this signature and the given signature by summing up the hierarchical distance
	 * between the actual and the declared type with {@link ReflectUtil#getDistance(Class, Class)}.
	 * 
	 * @param actualSignature
	 *        the actual signature that should have equal or more specific types than this declared signature
	 * @return the distance or {@link #INCOMPATIBLE}
	 */
	public int getDistance(final Signature actualSignature) {
		final Class<?>[] actualParamTypes = actualSignature.parameterTypes;
		if (this.parameterTypes.length != actualParamTypes.length)
			return INCOMPATIBLE;

		int distance = 0;
		for (int index = 0; index < this.parameterTypes.length; index++) {
			final Class<?> paramType = actualParamTypes[index];
			if (paramType != null) {
				final int actualDistance = ReflectUtil.getDistance(this.parameterTypes[index], paramType);
				if (actualDistance < 0)
					return INCOMPATIBLE;
				distance += actualDistance;
			}
		}

		return distance;
	}

	/**
	 * Returns the declared parameter types of a method.
	 * 
	 * @return the parameter types
	 */
	public Class<?>[] getParameterTypes() {
		return this.parameterTypes;
	}

	@Override
	public int hashCode() {
		final int prime = 31;
		int result = 1;
		result = prime * result + Arrays.hashCode(this.parameterTypes);
		return result;
	}

	/*
	 * (non-Javadoc)
	 * @see eu.stratosphere.sopremo.SopremoType#toString(java.lang.StringBuilder)
	 */
	public void toString(final StringBuilder builder) {
		builder.append("(").append(Arrays.toString(this.parameterTypes)).append(")");
	}

	/*
	 * (non-Javadoc)
	 * @see java.lang.Object#toString()
	 */
	@Override
	public String toString() {
		final StringBuilder builder = new StringBuilder();
		this.toString(builder);
		return builder.toString();
	}

	public Object[] adjustParameters(final Object[] params) {
		return params;
	}
}