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CharStream.java | - | - | - | - |
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1 | /* Generated By:JavaCC: Do not edit this line. CharStream.java Version 4.0 */ | |
2 | package net.sourceforge.pmd.ast; | |
3 | ||
4 | /** | |
5 | * This interface describes a character stream that maintains line and | |
6 | * column number positions of the characters. It also has the capability | |
7 | * to backup the stream to some extent. An implementation of this | |
8 | * interface is used in the TokenManager implementation generated by | |
9 | * JavaCCParser. | |
10 | * <p/> | |
11 | * All the methods except backup can be implemented in any fashion. backup | |
12 | * needs to be implemented correctly for the correct operation of the lexer. | |
13 | * Rest of the methods are all used to get information like line number, | |
14 | * column number and the String that constitutes a token and are not used | |
15 | * by the lexer. Hence their implementation won't affect the generated lexer's | |
16 | * operation. | |
17 | */ | |
18 | ||
19 | public interface CharStream { | |
20 | ||
21 | /** | |
22 | * Returns the next character from the selected input. The method | |
23 | * of selecting the input is the responsibility of the class | |
24 | * implementing this interface. Can throw any java.io.IOException. | |
25 | */ | |
26 | char readChar() throws java.io.IOException; | |
27 | ||
28 | /** | |
29 | * Returns the column position of the character last read. | |
30 | * | |
31 | * @see #getEndColumn | |
32 | * @deprecated | |
33 | */ | |
34 | int getColumn(); | |
35 | ||
36 | /** | |
37 | * Returns the line number of the character last read. | |
38 | * | |
39 | * @see #getEndLine | |
40 | * @deprecated | |
41 | */ | |
42 | int getLine(); | |
43 | ||
44 | /** | |
45 | * Returns the column number of the last character for current token (being | |
46 | * matched after the last call to BeginTOken). | |
47 | */ | |
48 | int getEndColumn(); | |
49 | ||
50 | /** | |
51 | * Returns the line number of the last character for current token (being | |
52 | * matched after the last call to BeginTOken). | |
53 | */ | |
54 | int getEndLine(); | |
55 | ||
56 | /** | |
57 | * Returns the column number of the first character for current token (being | |
58 | * matched after the last call to BeginTOken). | |
59 | */ | |
60 | int getBeginColumn(); | |
61 | ||
62 | /** | |
63 | * Returns the line number of the first character for current token (being | |
64 | * matched after the last call to BeginTOken). | |
65 | */ | |
66 | int getBeginLine(); | |
67 | ||
68 | /** | |
69 | * Backs up the input stream by amount steps. Lexer calls this method if it | |
70 | * had already read some characters, but could not use them to match a | |
71 | * (longer) token. So, they will be used again as the prefix of the next | |
72 | * token and it is the implemetation's responsibility to do this right. | |
73 | */ | |
74 | void backup(int amount); | |
75 | ||
76 | /** | |
77 | * Returns the next character that marks the beginning of the next token. | |
78 | * All characters must remain in the buffer between two successive calls | |
79 | * to this method to implement backup correctly. | |
80 | */ | |
81 | char BeginToken() throws java.io.IOException; | |
82 | ||
83 | /** | |
84 | * Returns a string made up of characters from the marked token beginning | |
85 | * to the current buffer position. Implementations have the choice of returning | |
86 | * anything that they want to. For example, for efficiency, one might decide | |
87 | * to just return null, which is a valid implementation. | |
88 | */ | |
89 | String GetImage(); | |
90 | ||
91 | /** | |
92 | * Returns an array of characters that make up the suffix of length 'len' for | |
93 | * the currently matched token. This is used to build up the matched string | |
94 | * for use in actions in the case of MORE. A simple and inefficient | |
95 | * implementation of this is as follows : | |
96 | * <p/> | |
97 | * { | |
98 | * String t = GetImage(); | |
99 | * return t.substring(t.length() - len, t.length()).toCharArray(); | |
100 | * } | |
101 | */ | |
102 | char[] GetSuffix(int len); | |
103 | ||
104 | /** | |
105 | * The lexer calls this function to indicate that it is done with the stream | |
106 | * and hence implementations can free any resources held by this class. | |
107 | * Again, the body of this function can be just empty and it will not | |
108 | * affect the lexer's operation. | |
109 | */ | |
110 | void Done(); | |
111 | ||
112 | } |
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