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Java > Open Source Codes > org > apache > jasper > compiler > TextOptimizer


1 /*
2  * Licensed to the Apache Software Foundation (ASF) under one or more
3  * contributor license agreements. See the NOTICE file distributed with
4  * this work for additional information regarding copyright ownership.
5  * The ASF licenses this file to You under the Apache License, Version 2.0
6  * (the "License"); you may not use this file except in compliance with
7  * the License. You may obtain a copy of the License at
8  *
9  * 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.jasper.compiler;
18
19 import org.apache.jasper.JasperException;
20 import org.apache.jasper.Options;
21
22 /**
23  */
24 public class TextOptimizer {
25
26     /**
27      * A visitor to concatenate contiguous template texts.
28      */
29     static class TextCatVisitor extends Node.Visitor {
30
31         private Options options;
32         private int textNodeCount = 0;
33         private Node.TemplateText firstTextNode = null;
34         private StringBuffer JavaDoc textBuffer;
35         private final String JavaDoc emptyText = new String JavaDoc("");
36
37         public TextCatVisitor(Compiler JavaDoc compiler) {
38             options = compiler.getCompilationContext().getOptions();
39         }
40
41         public void doVisit(Node n) throws JasperException {
42             collectText();
43         }
44
45     /*
46          * The following directis are ignored in text concatenation
47          */
48
49         public void visit(Node.PageDirective n) throws JasperException {
50         }
51
52         public void visit(Node.TagDirective n) throws JasperException {
53         }
54
55         public void visit(Node.TaglibDirective n) throws JasperException {
56         }
57
58         public void visit(Node.AttributeDirective n) throws JasperException {
59         }
60
61         public void visit(Node.VariableDirective n) throws JasperException {
62         }
63
64         /*
65          * Don't concatenate text across body boundaries
66          */
67         public void visitBody(Node n) throws JasperException {
68             super.visitBody(n);
69             collectText();
70         }
71
72         public void visit(Node.TemplateText n) throws JasperException {
73
74             if (options.getTrimSpaces() && n.isAllSpace()) {
75                 n.setText(emptyText);
76                 return;
77             }
78
79             if (textNodeCount++ == 0) {
80                 firstTextNode = n;
81                 textBuffer = new StringBuffer JavaDoc(n.getText());
82             } else {
83                 // Append text to text buffer
84 textBuffer.append(n.getText());
85                 n.setText(emptyText);
86             }
87         }
88
89         /**
90          * This method breaks concatenation mode. As a side effect it copies
91          * the concatenated string to the first text node
92          */
93         private void collectText() {
94
95             if (textNodeCount > 1) {
96                 // Copy the text in buffer into the first template text node.
97 firstTextNode.setText(textBuffer.toString());
98             }
99             textNodeCount = 0;
100         }
101
102     }
103
104     public static void concatenate(Compiler JavaDoc compiler, Node.Nodes page)
105             throws JasperException {
106
107         TextCatVisitor v = new TextCatVisitor(compiler);
108         page.visit(v);
109
110     // Cleanup, in case the page ends with a template text
111 v.collectText();
112     }
113 }
114
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