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: package org.apache.cocoon.forms.formmodel;
18:
19: import java.util.Iterator;
20:
21: import org.apache.cocoon.forms.datatype.Datatype;
22:
23: /**
24: * Common interface for an algorithm to calculate the value of a
25: * {@link org.apache.cocoon.forms.formmodel.CalculatedField}.
26: *
27: * @version $Id: CalculatedFieldAlgorithm.java 449149 2006-09-23 03:58:05Z crossley $
28: */
29: public interface CalculatedFieldAlgorithm {
30:
31: /**
32: * Checks wether this algorithm is able to return the given datatype. For example,
33: * an arithmetic algorithm like sum should check that the given datatype is a number.
34: * @param dataType The target datatype.
35: * @return true if this algorithm can return a compatible value, false otherwise.
36: */
37: public boolean isSuitableFor(Datatype dataType);
38:
39: /**
40: * Performs the actual calculation.
41: * @param form The form.
42: * @param parent The parent widget of the {@link CalculatedField} widget (may be the same as form)
43: * @param datatype The target datatype.
44: * @return the calculated value for the {@link CalculatedField}.
45: */
46: public Object calculate(Form form, Widget parent, Datatype datatype);
47:
48: /**
49: * Returns an iterator on trigger widget paths. When the value of a trigger widget changes,
50: * then the {@link CalculatedField} value must be recalculated.
51: * @return An iterator of Strings representing widget paths as interpreted by {@link org.apache.cocoon.forms.util.WidgetFinder}.
52: */
53: public Iterator getTriggerWidgets();
54:
55: }
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