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* Copyright 2001-2008 Codehaus Foundation.
* 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
* 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.
* Logs expressions before resolution is attempted, and clears them
* after resolution is complete (or, fails all strategies). In between,
* if the value of an expression contains more expressions, RecursionInterceptor
* implementations ensure that those expressions don't reference an expression
* which is in the process of being resolved. If that happens, the expression
* references are cyclical, and would otherwise result in an infinite loop.
public interface RecursionInterceptor
* Log the intention to start resolving the given expression. This signals
* the interceptor to start tracking that expression to make sure it doesn't
* come up again until after it has been resolved (or, fails to resolve).
* @param expression The expression to be resolved.
void expressionResolutionStarted( String expression );
* Signal to the interceptor that the all efforts to resolve the given
* expression have completed - whether successfully or not is irrelevant -
* and that the expression should not be tracked for recursion any longer.
* @param expression The expression to stop tracking.
void expressionResolutionFinished( String expression );
* Check whether the given value contains an expression that is currently
* being tracked by this interceptor. If so, that expression is still in
* the process of being resolved, and this constitutes an expression cycle.
* @param value The value to check for expression cycles.
* @return True if the value contains tracked expressions; false otherwise.
boolean hasRecursiveExpression( String value );
* @return The list of expressions that participate in the cycle caused by
* the given expression.
* @param expression the expression to start with.
List getExpressionCycle( String expression );
* Reset the interceptor
public void clear();