01: /*
02: * Copyright 1999-2004 The Apache Software Foundation
03: *
04: * Licensed under the Apache License, Version 2.0 (the "License");
05: * you may not use this file except in compliance with the License.
06: * You may obtain a copy of the License at
07: *
08: * http://www.apache.org/licenses/LICENSE-2.0
09: *
10: * Unless required by applicable law or agreed to in writing, software
11: * distributed under the License is distributed on an "AS IS" BASIS,
12: * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13: * See the License for the specific language governing permissions and
14: * limitations under the License.
15: */
16: package org.apache.commons.jxpath;
17:
18: /**
19: * Variables provide access to a global set of values accessible via XPath.
20: * XPath can reference variables using the <code>"$varname"</code> syntax.
21: * To use a custom implementation of this interface, pass it to
22: * {@link JXPathContext#setVariables JXPathContext.setVariables()}
23: *
24: * @author Dmitri Plotnikov
25: * @version $Revision: 1.6 $ $Date: 2004/02/29 14:17:42 $
26: */
27: public interface Variables {
28:
29: /**
30: * Returns true if the specified variable is declared.
31: */
32: boolean isDeclaredVariable(String varName);
33:
34: /**
35: * Returns the value of the specified variable.
36: * Throws IllegalArgumentException if there is no such variable.
37: */
38: Object getVariable(String varName);
39:
40: /**
41: * Defines a new variable with the specified value or modifies
42: * the value of an existing variable.
43: * May throw UnsupportedOperationException.
44: */
45: void declareVariable(String varName, Object value);
46:
47: /**
48: * Removes an existing variable. May throw UnsupportedOperationException.
49: *
50: * @param varName is a variable name without the "$" sign
51: */
52: void undeclareVariable(String varName);
53: }
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