DataContext.java revision 712c262ddf6790c16a8567053f616c71da7e1856 
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.data;
18
19import com.google.clearsilver.jsilver.autoescape.EscapeMode;
20
21/**
22 * Manages the global Data object and local variable mappings during rendering.
23 */
24public interface DataContext {
25
26  /**
27   * Returns the main Data object this RenderingContext was defined with.
28   */
29  Data getRootData();
30
31  /**
32   * Creates a new Data object to hold local references, pushes it onto the variable map stack. This
33   * is used to hold macro parameters after a call command, and local variables defined for 'each'
34   * and 'with'.
35   */
36  void pushVariableScope();
37
38  /**
39   * Removes the most recent Data object added to the local variable map stack.
40   */
41  void popVariableScope();
42
43  /**
44   * Creates and sets a local variable in the current scope equal to the given value.
45   *
46   * @param name the name of the local variable to fetch or create.
47   * @param value The String value to store at the local variable.
48   */
49  void createLocalVariableByValue(String name, String value);
50
51  /**
52   * Creates and sets a local variable in the current scope equal to the given value. Also set the
53   * EscapeMode that was applied to its value. This may be used by the template renderer to decide
54   * whether to autoescape the variable.
55   *
56   * @param name the name of the local variable to fetch or create.
57   * @param value The String value to store at the local variable.
58   * @param mode EscapeMode that describes the escaping this variable has. {@code
59   *        EscapeMode.ESCAPE_NONE} if the variable was not escaped. {@code
60   *        EscapeMode.ESCAPE_IS_CONSTANT} if the variable was populated with a string or numeric
61   *        literal.
62   */
63  void createLocalVariableByValue(String name, String value, EscapeMode mode);
64
65  /**
66   * Creates and sets a local variable in the current scope equal to the given value.
67   * <p>
68   * This method is a helper method for supporting the first() and last() functions on loops without
69   * requiring loops create a full Data tree.
70   *
71   * @param name the name of the local variable to fetch or create.
72   * @param value The String value to store at the local variable.
73   * @param isFirst What the local variable should return for
74   *        {@link com.google.clearsilver.jsilver.data.Data#isFirstSibling}
75   * @param isLast What the local variable should return for
76   *        {@link com.google.clearsilver.jsilver.data.Data#isLastSibling}
77   */
78  void createLocalVariableByValue(String name, String value, boolean isFirst, boolean isLast);
79
80  /**
81   * Creates a local variable that references a (possibly non-existent) Data node. When the Data
82   * object for this variable is requested, it will return the Data object at the path location or
83   * {@code null}, if it does not exist. If {@link #findVariable} is called with {@code create ==
84   * true}, then if no Data object exists at the path location, it will be created.
85   *
86   * @param name the name of the local variable to fetch or create.
87   * @param path The path to the Data object
88   */
89  void createLocalVariableByPath(String name, String path);
90
91  /**
92   * Searches the variable map stack for the specified variable name. If not found, it then searches
93   * the root Data object. If not found then and create is {@code true}, then a new node is created
94   * with the given name in the root Data object and that node is returned.
95   * <p>
96   * Note: This only creates nodes in the root Data object, not in any local variable map. To do
97   * that, use the Data node returned by {@link #pushVariableScope()}.
98   *
99   * @param name the name of the variable to find and/or create.
100   * @param create if {@link true} then a new node will be created if an existing Data node with the
101   *        given name does not exist.
102   * @return The first Data node in the variable map stack that matches the given name, or a Data
103   *         node in the root Data object matching the given name, or {@code null} if no such node
104   *         exists and {@code create} is {@code false}.
105   */
106  Data findVariable(String name, boolean create);
107
108  /**
109   * Searches the variable map stack for the specified variable name, and returns its
110   * {@link EscapeMode}.
111   *
112   * @return If the variable is found, returns its {@link EscapeMode}, otherwise returns {@code
113   *         EscapeMode.ESCAPE_NONE}.
114   */
115  EscapeMode findVariableEscapeMode(String name);
116}
117