01: /*
02: * Licensed to the Apache Software Foundation (ASF) under one or more
03: * contributor license agreements. See the NOTICE file distributed with
04: * this work for additional information regarding copyright ownership.
05: * The ASF licenses this file to You under the Apache License, Version 2.0
06: * (the "License"); you may not use this file except in compliance with
07: * the License. You may obtain a copy of the License at
08: *
09: * http://www.apache.org/licenses/LICENSE-2.0
10: *
11: * Unless required by applicable law or agreed to in writing, software
12: * distributed under the License is distributed on an "AS IS" BASIS,
13: * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14: * See the License for the specific language governing permissions and
15: * limitations under the License.
16: *
17: * $Header:$
18: */
19: package org.apache.beehive.netui.script;
20:
21: import java.util.List;
22:
23: /**
24: * This class implements support for an Expression object.
25: * It provides access to metadata about the parsed expression
26: * including the data binding context and tokens that constitute
27: * the expression.
28: */
29: public abstract class Expression {
30:
31: /**
32: * Get the expression's data binding context.
33: * @return the implicit object that this expression references
34: */
35: public abstract String getContext();
36:
37: /**
38: * Get the expression's token list. For an expression that looks like
39: * "actionForm.customer.name", this will include the tokens "actionForm",
40: * "customer", and "name".
41: * @return the list of tokens contained in the expression
42: */
43: public abstract List getTokens();
44:
45: /**
46: * Return an expression that is created starting with the
47: * token at the given index.
48: *
49: * @param start the token index at which to build the sub-expression
50: * @return a sub-expression starting with the token referenced by <code>start</code>
51: * @throws java.lang.IllegalStateException if the provided start token is out of bounds
52: * given the number of tokens in the expression.
53: */
54: public abstract String getExpression(int start);
55: }
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