com.google.api.tools.framework.model.Element Maven / Gradle / Ivy
/*
* Copyright (C) 2016 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.api.tools.framework.model;
import com.google.common.base.Preconditions;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
import com.google.inject.Key;
import java.util.List;
import java.util.Map;
import javax.annotation.Nullable;
/**
* Base class for all model elements.
*
*
* Elements allow to attach dynamic attributes based on a typed key, which are typically established
* by a {@link Processor}. The decision whether to use a dynamic attribute or a plain getter/setter
* which is hard-wired into the object model depends on whether the expressed information is
* globally relevant for many processor or only used locally by a tool. For example, derived type
* information is considered to be globally relevant and hard-wired into the object model, so it is
* easy discoverable.
*/
public abstract class Element {
private final Map, Object> attributes = Maps.newHashMap();
/**
* Returns the model associated with this element.
*/
public abstract Model getModel();
/**
* Returns the location associated with this element.
*/
public abstract Location getLocation();
/**
* Returns a fully qualified name for the element.
*/
public abstract String getFullName();
/**
* Returns a simple name for the element.
*/
public abstract String getSimpleName();
/**
* Puts an attribute value, returning the old one.
*/
@SuppressWarnings("unchecked")
@Nullable
public T putAttribute(Key key, T value) {
return (T) attributes.put(key, Preconditions.checkNotNull(value));
}
/**
* Adds an attribute value.
*/
@SuppressWarnings("unchecked")
public void addAttribute(Key> key, T value) {
List list = getAttribute(key);
if (list == null) {
list = Lists.newArrayList();
putAttribute(key, list);
}
list.add(value);
}
/**
* Removes an attribute value, returning the old one.
*/
@SuppressWarnings("unchecked")
@Nullable
public T removeAttribute(Key key) {
return (T) attributes.remove(key);
}
/**
* Gets an attribute value.
*/
@SuppressWarnings("unchecked")
public T getAttribute(Key key) {
return (T) attributes.get(key);
}
/**
* Gets an attribute value if it exists, otherwise the given default value.
*/
@SuppressWarnings("unchecked")
public T getAttributeOrDefault(Key key, T defaultValue) {
T value = (T) attributes.get(key);
if (value != null) {
return value;
}
return defaultValue;
}
/**
* Checks whether an attribute is present.
*/
@Nullable
public boolean hasAttribute(Key key) {
return attributes.containsKey(key);
}
}