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/**
* Copyright (C) 2011-2012 Typesafe Inc.
*/
package com.crashnote.core.config.helper;
import java.util.Map;
/**
* Subtype of {@link ConfigValue} representing an object (dictionary, map)
* value, as in JSON's { "a" : 42 } syntax.
*
*
* {@code ConfigObject} implements {@code java.util.Map} so
* you can use it like a regular Java map. Or call {@link #unwrapped()} to
* unwrap the map to a map with plain Java values rather than
* {@code ConfigValue}.
*
*
* Like all {@link ConfigValue} subtypes, {@code ConfigObject} is immutable.
* This makes it threadsafe and you never have to create "defensive copies." The
* mutator methods from {@link java.util.Map} all throw
* {@link java.lang.UnsupportedOperationException}.
*
*
* The {@link ConfigValue#valueType} method on an object returns
* {@link ConfigValueType#OBJECT}.
*
*
* In most cases you want to use the {@link Config} interface rather than this
* one. Call {@link #toConfig()} to convert a {@code ConfigObject} to a
* {@code Config}.
*
*
* The API for a {@code ConfigObject} is in terms of keys, while the API for a
* {@link Config} is in terms of path expressions. Conceptually,
* {@code ConfigObject} is a tree of maps from keys to values, while a
* {@code Config} is a one-level map from paths to values.
*
*
* Use {@link ConfigUtil#joinPath} and {@link ConfigUtil#splitPath} to convert
* between path expressions and individual path elements (keys).
*
*
* A {@code ConfigObject} may contain null values, which will have
* {@link ConfigValue#valueType()} equal to {@link ConfigValueType#NULL}. If
* {@code get()} returns Java's null then the key was not present in the parsed
* file (or wherever this value tree came from). If {@code get()} returns a
* {@link ConfigValue} with type {@code ConfigValueType#NULL} then the key was
* set to null explicitly in the config file.
*
*
* Do not implement {@code ConfigObject}; it should only be implemented
* by the config library. Arbitrary implementations will not work because the
* library internals assume a specific concrete implementation. Also, this
* interface is likely to grow new methods over time, so third-party
* implementations will break.
*/
public interface ConfigObject extends ConfigValue, Map {
/**
* Converts this object to a {@link Config} instance, enabling you to use
* path expressions to find values in the object. This is a constant-time
* operation (it is not proportional to the size of the object).
*
* @return a {@link Config} with this object as its root
*/
Config toConfig();
/**
* Recursively unwraps the object, returning a map from String to whatever
* plain Java values are unwrapped from the object's values.
*
* @return a {@link java.util.Map} containing plain Java objects
*/
@Override
Map unwrapped();
@Override
ConfigObject withFallback(ConfigMergeable other);
/**
* Gets a {@link ConfigValue} at the given key, or returns null if there is
* no value. The returned {@link ConfigValue} may have
* {@link ConfigValueType#NULL} or any other type, and the passed-in key
* must be a key in this object, rather than a path expression.
*
* @param key
* key to look up
*
* @return the value at the key or null if none
*/
@Override
ConfigValue get(Object key);
/**
* Clone the object with only the given key (and its children) retained; all
* sibling keys are removed.
*
* @param key
* key to keep
* @return a copy of the object minus all keys except the one specified
*/
ConfigObject withOnlyKey(String key);
/**
* Clone the object with the given key removed.
*
* @param key
* key to remove
* @return a copy of the object minus the specified key
*/
ConfigObject withoutKey(String key);
}