1 /* Generated By:JavaCC: Do not edit this line. CharStream.java Version 5.0 */
2 /* JavaCCOptions:STATIC=true,SUPPORT_CLASS_VISIBILITY_PUBLIC=true */
3 package net.sourceforge.pmd.lang.ast;
4
5 /**
6 * This interface describes a character stream that maintains line and
7 * column number positions of the characters. It also has the capability
8 * to backup the stream to some extent. An implementation of this
9 * interface is used in the TokenManager implementation generated by
10 * JavaCCParser.
11 *
12 * All the methods except backup can be implemented in any fashion. backup
13 * needs to be implemented correctly for the correct operation of the lexer.
14 * Rest of the methods are all used to get information like line number,
15 * column number and the String that constitutes a token and are not used
16 * by the lexer. Hence their implementation won't affect the generated lexer's
17 * operation.
18 */
19
20 public
21 interface CharStream {
22
23 /**
24 * Returns the next character from the selected input. The method
25 * of selecting the input is the responsibility of the class
26 * implementing this interface. Can throw any java.io.IOException.
27 */
28 char readChar() throws java.io.IOException;
29
30 @Deprecated
31 /**
32 * Returns the column position of the character last read.
33 * @deprecated
34 * @see #getEndColumn
35 */
36 int getColumn();
37
38 @Deprecated
39 /**
40 * Returns the line number of the character last read.
41 * @deprecated
42 * @see #getEndLine
43 */
44 int getLine();
45
46 /**
47 * Returns the column number of the last character for current token (being
48 * matched after the last call to BeginTOken).
49 */
50 int getEndColumn();
51
52 /**
53 * Returns the line number of the last character for current token (being
54 * matched after the last call to BeginTOken).
55 */
56 int getEndLine();
57
58 /**
59 * Returns the column number of the first character for current token (being
60 * matched after the last call to BeginTOken).
61 */
62 int getBeginColumn();
63
64 /**
65 * Returns the line number of the first character for current token (being
66 * matched after the last call to BeginTOken).
67 */
68 int getBeginLine();
69
70 /**
71 * Backs up the input stream by amount steps. Lexer calls this method if it
72 * had already read some characters, but could not use them to match a
73 * (longer) token. So, they will be used again as the prefix of the next
74 * token and it is the implemetation's responsibility to do this right.
75 */
76 void backup(int amount);
77
78 /**
79 * Returns the next character that marks the beginning of the next token.
80 * All characters must remain in the buffer between two successive calls
81 * to this method to implement backup correctly.
82 */
83 char BeginToken() throws java.io.IOException;
84
85 /**
86 * Returns a string made up of characters from the marked token beginning
87 * to the current buffer position. Implementations have the choice of returning
88 * anything that they want to. For example, for efficiency, one might decide
89 * to just return null, which is a valid implementation.
90 */
91 String GetImage();
92
93 /**
94 * Returns an array of characters that make up the suffix of length 'len' for
95 * the currently matched token. This is used to build up the matched string
96 * for use in actions in the case of MORE. A simple and inefficient
97 * implementation of this is as follows :
98 *
99 * {
100 * String t = GetImage();
101 * return t.substring(t.length() - len, t.length()).toCharArray();
102 * }
103 */
104 char[] GetSuffix(int len);
105
106 /**
107 * The lexer calls this function to indicate that it is done with the stream
108 * and hence implementations can free any resources held by this class.
109 * Again, the body of this function can be just empty and it will not
110 * affect the lexer's operation.
111 */
112 void Done();
113
114 }
115 /* JavaCC - OriginalChecksum=50902730f941726c1dc428c106b9f5a3 (do not edit this line) */