VariableValue.java revision 56ed4167b942ec265f9cee70ac4d71d10b3835ce 
1/*
2 * Copyright (C) 2010 Google Inc.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
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
17package com.google.clearsilver.jsilver.values;
18
19import com.google.clearsilver.jsilver.autoescape.EscapeMode;
20import com.google.clearsilver.jsilver.data.Data;
21import com.google.clearsilver.jsilver.data.DataContext;
22import com.google.clearsilver.jsilver.data.TypeConverter;
23
24/**
25 * A value linked to a variable reference. When this value is evaluated in an expression a Data
26 * object will be fetched from the provided DataContext and and its value returned or {@code null}
27 * if there is no Data object associated with the given name.
28 *
29 * @see Value
30 * @see Data
31 */
32public class VariableValue extends VariantValue {
33  // TODO: Make this non-public and come up with a smarter way
34  // for it to be used elsewhere without having to be used in a cast.
35
36  private final String name;
37  private final DataContext dataContext;
38
39  private boolean gotRef = false;
40  private Data reference;
41
42  public VariableValue(String name, DataContext dataContext) {
43    // VariableValues always have partiallyEscaped=false since they represent
44    // a Data object, not a compound expression containing escaping functions.
45    // We override getEscapeMode() to return the Data object's escape mode,
46    // so the mode we pass here is just ignored.
47    super(EscapeMode.ESCAPE_NONE, false);
48    this.dataContext = dataContext;
49    this.name = name;
50  }
51
52  public String getName() {
53    return name;
54  }
55
56  public Data getReference() {
57    if (!gotRef) {
58      reference = dataContext.findVariable(name, false);
59      gotRef = true;
60    }
61    return reference;
62  }
63
64  @Override
65  protected String value() {
66    Data data = getReference();
67    return data == null ? null : data.getValue();
68  }
69
70  @Override
71  public boolean exists() {
72    return TypeConverter.exists(getReference());
73  }
74
75  // Note we are not overriding asString as we want that to return the value
76  // of the node located at this address.
77  @Override
78  public String toString() {
79    return name;
80  }
81
82  @Override
83  public EscapeMode getEscapeMode() {
84    Data data = getReference();
85    if (data == null) {
86      return super.getEscapeMode();
87    }
88    return data.getEscapeMode();
89  }
90
91}
92