1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
|
/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
/* Generated By:JavaCC: Do not edit this line. CharStream.java Version 2.1 */
package org.apache.velocity.runtime.parser;
/**
* This interface describes a character stream that maintains line and
* column number positions of the characters. It also has the capability
* to backup the stream to some extent. An implementation of this
* interface is used in the TokenManager implementation generated by
* JavaCCParser.
*
* All the methods except backup can be implemented in any fashion. backup
* needs to be implemented correctly for the correct operation of the lexer.
* Rest of the methods are all used to get information like line number,
* column number and the String that constitutes a token and are not used
* by the lexer. Hence their implementation won't affect the generated lexer's
* operation.
*/
public interface CharStream
{
/**
* Returns the next character from the selected input. The method
* of selecting the input is the responsibility of the class
* implementing this interface. Can throw any java.io.IOException.
* @return read char
* @throws java.io.IOException
*/
char readChar() throws java.io.IOException;
/**
* Returns the column number of the last character for current token (being
* matched after the last call to BeginTOken).
* @return ending column number
*/
int getEndColumn();
/**
* Returns the line number of the last character for current token (being
* matched after the last call to BeginTOken).
* @return ending line number
*/
int getEndLine();
/**
* Returns the column number of the first character for current token (being
* matched after the last call to BeginTOken).
* @return starting column number
*/
int getBeginColumn();
/**
* Returns the line number of the first character for current token (being
* matched after the last call to BeginTOken).
* @return starting line number
*/
int getBeginLine();
/**
* Backs up the input stream by amount steps. Lexer calls this method if it
* had already read some characters, but could not use them to match a
* (longer) token. So, they will be used again as the prefix of the next
* token and it is the implemetation's responsibility to do this right.
* @param amount
*/
void backup(int amount);
/**
* Returns the next character that marks the beginning of the next token.
* All characters must remain in the buffer between two successive calls
* to this method to implement backup correctly.
* @return next token start char
* @throws java.io.IOException
*/
char BeginToken() throws java.io.IOException;
/**
* Returns a string made up of characters from the marked token beginning
* to the current buffer position. Implementations have the choice of returning
* anything that they want to. For example, for efficiency, one might decide
* to just return null, which is a valid implementation.
* @return token image
*/
String GetImage();
/**
* <p>Returns an array of characters that make up the suffix of length 'len' for
* the currently matched token. This is used to build up the matched string
* for use in actions in the case of MORE. A simple and inefficient
* implementation of this is as follows :</p>
* <pre><code>
* {
* String t = GetImage();
* return t.substring(t.length() - len, t.length()).toCharArray();
* }
* </code></pre>
* @param len suffix len
* @return suffix
*/
char[] GetSuffix(int len);
/**
* The lexer calls this function to indicate that it is done with the stream
* and hence implementations can free any resources held by this class.
* Again, the body of this function can be just empty and it will not
* affect the lexer's operation.
*/
void Done();
}
|
