com.opengamma.strata.product.Attributes.java Source code

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Here is the source code for com.opengamma.strata.product.Attributes.java

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/*
 * Copyright (C) 2018 - present by OpenGamma Inc. and the OpenGamma group of companies
 *
 * Please see distribution for license.
 */
package com.opengamma.strata.product;

import java.util.Optional;

import com.google.common.collect.ImmutableMap;
import com.opengamma.strata.collect.Messages;

/**
 * Additional attributes that can be associated with a model object.
 */
public interface Attributes {

    /**
     * Obtains an empty instance.
     * <p>
     * The {@link #withAttribute(AttributeType, Object)} method can be used on
     * the instance to add attributes.
     * 
     * @return the empty instance
     */
    public static Attributes empty() {
        return SimpleAttributes.EMPTY;
    }

    /**
     * Obtains an empty instance.
     * <p>
     * The {@link #withAttribute(AttributeType, Object)} method can be used on
     * the instance to add attributes.
     * 
     * @param <T>  the type of the attribute value
     * @param type  the type providing meaning to the value
     * @param value  the value
     * @return the instance
     */
    public static <T> Attributes of(AttributeType<T> type, T value) {
        return new SimpleAttributes(ImmutableMap.of(type, value));
    }

    //-------------------------------------------------------------------------
    /**
     * Gets the attribute associated with the specified type.
     * <p>
     * This method obtains the specified attribute.
     * This allows an attribute to be obtained if available.
     * <p>
     * If the attribute is not found, an exception is thrown.
     * 
     * @param <T>  the type of the attribute value
     * @param type  the type to find
     * @return the attribute value
     * @throws IllegalArgumentException if the attribute is not found
     */
    public default <T> T getAttribute(AttributeType<T> type) {
        return findAttribute(type).orElseThrow(
                () -> new IllegalArgumentException(Messages.format("Attribute not found for type '{}'", type)));
    }

    /**
     * Finds the attribute associated with the specified type.
     * <p>
     * This method obtains the specified attribute.
     * This allows an attribute to be obtained if available.
     * <p>
     * If the attribute is not found, optional empty is returned.
     * 
     * @param <T>  the type of the result
     * @param type  the type to find
     * @return the attribute value
     */
    public abstract <T> Optional<T> findAttribute(AttributeType<T> type);

    /**
     * Returns a copy of this instance with the attribute added.
     * <p>
     * This returns a new instance with the specified attribute added.
     * The attribute is added using {@code Map.put(type, value)} semantics.
     * 
     * @param <T>  the type of the attribute value
     * @param type  the type providing meaning to the value
     * @param value  the value
     * @return a new instance based on this one with the attribute added
     */
    public <T> Attributes withAttribute(AttributeType<T> type, T value);

}