| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You 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 org.apache.commons.jexl3; |
| |
| import java.util.concurrent.Callable; |
| |
| /** |
| * Manages variables which can be referenced in a JEXL expression. |
| * |
| * <p>JEXL variable names in their simplest form are 'java-like' identifiers. |
| * JEXL also considers 'ant' inspired variables expressions as valid. |
| * For instance, the expression 'x.y.z' is an 'antish' variable and will be resolved as a whole by the context, |
| * i.e. using the key "x.y.z". This proves to be useful to solve "fully qualified class names".</p> |
| * |
| * <p>The interpreter variable resolution algorithm will try the different sequences of identifiers till it finds |
| * one that exists in the context; if "x" is an object known in the context (JexlContext.has("x") returns true), |
| * "x.y" will <em>not</em> be looked up in the context but will most likely refer to "x.getY()".</p> |
| * |
| * <p>Note that JEXL may use '$jexl' and '$ujexl' variables for internal purpose; setting or getting those |
| * variables may lead to unexpected results unless specified otherwise.</p> |
| * |
| * @since 1.0 |
| */ |
| public interface JexlContext { |
| |
| /** |
| * Gets the value of a variable. |
| * |
| * @param name the variable's name |
| * @return the value |
| */ |
| Object get(String name); |
| |
| /** |
| * Sets the value of a variable. |
| * |
| * @param name the variable's name |
| * @param value the variable's value |
| */ |
| void set(String name, Object value); |
| |
| /** |
| * Checks whether a variable is defined in this context. |
| * |
| * <p>A variable may be defined with a null value; this method checks whether the |
| * value is null or if the variable is undefined.</p> |
| * |
| * @param name the variable's name |
| * @return true if it exists, false otherwise |
| */ |
| boolean has(String name); |
| |
| /** |
| * This interface declares how to resolve a namespace from its name; it is used by the interpreter during |
| * evaluation. |
| * |
| * <p>In JEXL, a namespace is an object that serves the purpose of encapsulating functions; for instance, |
| * the "math" namespace would be the proper object to expose functions like "log(...)", "sinus(...)", etc.</p> |
| * |
| * In expressions like "ns:function(...)", the resolver is called with resolveNamespace("ns"). |
| * |
| * <p>JEXL itself reserves 'jexl' and 'ujexl' as namespaces for internal purpose; resolving those may lead to |
| * unexpected results.</p> |
| * |
| * @since 3.0 |
| */ |
| interface NamespaceResolver { |
| |
| /** |
| * Resolves a namespace by its name. |
| * @param name the name |
| * @return the namespace object |
| */ |
| Object resolveNamespace(String name); |
| } |
| |
| /** |
| * Namespace type that allows creating an instance to delegate namespace methods calls to. |
| * |
| * <p>The functor is created once during the lifetime of a script evaluation.</p> |
| */ |
| interface NamespaceFunctor { |
| /** |
| * Creates the functor object that will be used instead of the namespace. |
| * @param context the context |
| * @return the namespace functor instance |
| */ |
| Object createFunctor(JexlContext context); |
| } |
| |
| /** |
| * A marker interface that indicates the interpreter to put this context in the JexlEngine thread local context |
| * instance during evaluation. |
| * This allows user functions or methods to access the context during a call. |
| * Note that the usual caveats wrt using thread local apply (caching/leaking references, etc.); in particular, |
| * keeping a reference to such a context is to be considered with great care and caution. |
| * It should also be noted that sharing such a context between threads should implicate synchronizing variable |
| * accessing the implementation class. |
| * |
| * @see JexlEngine#setThreadContext(JexlContext.ThreadLocal) |
| * @see JexlEngine#getThreadContext() |
| */ |
| interface ThreadLocal extends JexlContext { |
| // no specific method |
| } |
| |
| /** |
| * This interface declares how to process annotations; it is used by the interpreter during |
| * evaluation. |
| * <p>All annotations are processed through this method; the statement should be |
| */ |
| interface AnnotationProcessor { |
| /** |
| * Processes an annotation. |
| * @param name the annotation name |
| * @param args the arguments |
| * @param statement the statement that was annotated; the processor should invoke this statement 'call' method |
| * @return the result of statement.call() |
| * @throws Exception if annotation processing fails |
| */ |
| Object processAnnotation(String name, Object[] args, Callable<Object> statement) throws Exception; |
| } |
| |
| } |