public interface ExpressionEngine
Definition of an interface for evaluating keys for hierarchical configurations.
An expression engine knows how to map a key for a configuration's
property to a single or a set of configuration nodes. Thus it defines the way
how properties are addressed in this configuration. Methods of a
configuration that have to handle property key (e.g.
addProperty() do not interpret
the passed in keys on their own, but delegate this task to an associated
expression engine. This expression engine will then find out, which
configuration nodes are addressed by the key.
Separating the task of evaluating property keys from the configuration object has the advantage that many different expression languages (i.e. ways for querying or setting properties) can be supported. Just set a suitable implementation of this interface as the configuration's expression engine, and you can use the syntax provided by this implementation.
|Modifier and Type||Method and Description|
Returns the key for the specified node in the expression language supported by an implementation.
Returns information needed for an add operation.
Finds the node(s) that is (are) matched by the specified key.
List<ConfigurationNode> query(ConfigurationNode root, String key)
root- the root node of a hierarchy of configuration nodes
key- the key to be evaluated
String nodeKey(ConfigurationNode node, String parentKey)
node- the node, for which the key must be constructed
parentKey- the key of this node's parent (can be null for the root node)
NodeAddData prepareAdd(ConfigurationNode root, String key)
root- the root node
key- the key for the new property
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