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.ri.compiler;
17:
18: import java.util.Arrays;
19:
20: import org.apache.commons.jxpath.Function;
21: import org.apache.commons.jxpath.JXPathException;
22: import org.apache.commons.jxpath.ri.EvalContext;
23: import org.apache.commons.jxpath.ri.QName;
24:
25: /**
26: * Represents an element of the parse tree representing an extension function
27: * call.
28: *
29: * @author Dmitri Plotnikov
30: * @version $Revision: 1.13 $ $Date: 2004/03/25 05:42:01 $
31: */
32: public class ExtensionFunction extends Operation {
33:
34: private QName functionName;
35:
36: public ExtensionFunction(QName functionName, Expression args[]) {
37: super (args);
38: this .functionName = functionName;
39: }
40:
41: public QName getFunctionName() {
42: return functionName;
43: }
44:
45: /**
46: * An extension function gets the current context, therefore it MAY be
47: * context dependent.
48: */
49: public boolean computeContextDependent() {
50: return true;
51: }
52:
53: public String toString() {
54: StringBuffer buffer = new StringBuffer();
55: buffer.append(functionName);
56: buffer.append('(');
57: Expression args[] = getArguments();
58: if (args != null) {
59: for (int i = 0; i < args.length; i++) {
60: if (i > 0) {
61: buffer.append(", ");
62: }
63: buffer.append(args[i]);
64: }
65: }
66: buffer.append(')');
67: return buffer.toString();
68: }
69:
70: public Object compute(EvalContext context) {
71: return computeValue(context);
72: }
73:
74: public Object computeValue(EvalContext context) {
75: Object[] parameters = null;
76: if (args != null) {
77: parameters = new Object[args.length];
78: for (int i = 0; i < args.length; i++) {
79: parameters[i] = convert(args[i].compute(context));
80: }
81: }
82:
83: Function function = context.getRootContext().getFunction(
84: functionName, parameters);
85: if (function == null) {
86: throw new JXPathException("No such function: "
87: + functionName + Arrays.asList(parameters));
88: }
89:
90: return function.invoke(context, parameters);
91: }
92:
93: private Object convert(Object object) {
94: if (object instanceof EvalContext) {
95: return ((EvalContext) object).getValue();
96: }
97: return object;
98: }
99: }
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