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1   /* Generated By:JavaCC: Do not edit this line. CharStream.java Version 4.1 */
2   /* JavaCCOptions:STATIC=false */
3   package net.sourceforge.pmd.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 interface CharStream {
21  
22    /**
23     * Returns the next character from the selected input.  The method
24     * of selecting the input is the responsibility of the class
25     * implementing this interface.  Can throw any java.io.IOException.
26     */
27    char readChar() throws java.io.IOException;
28  
29    /**
30     * Returns the column position of the character last read.
31     * @deprecated
32     * @see #getEndColumn
33     */
34    int getColumn();
35  
36    /**
37     * Returns the line number of the character last read.
38     * @deprecated
39     * @see #getEndLine
40     */
41    int getLine();
42  
43    /**
44     * Returns the column number of the last character for current token (being
45     * matched after the last call to BeginTOken).
46     */
47    int getEndColumn();
48  
49    /**
50     * Returns the line number of the last character for current token (being
51     * matched after the last call to BeginTOken).
52     */
53    int getEndLine();
54  
55    /**
56     * Returns the column number of the first character for current token (being
57     * matched after the last call to BeginTOken).
58     */
59    int getBeginColumn();
60  
61    /**
62     * Returns the line number of the first character for current token (being
63     * matched after the last call to BeginTOken).
64     */
65    int getBeginLine();
66  
67    /**
68     * Backs up the input stream by amount steps. Lexer calls this method if it
69     * had already read some characters, but could not use them to match a
70     * (longer) token. So, they will be used again as the prefix of the next
71     * token and it is the implemetation's responsibility to do this right.
72     */
73    void backup(int amount);
74  
75    /**
76     * Returns the next character that marks the beginning of the next token.
77     * All characters must remain in the buffer between two successive calls
78     * to this method to implement backup correctly.
79     */
80    char BeginToken() throws java.io.IOException;
81  
82    /**
83     * Returns a string made up of characters from the marked token beginning
84     * to the current buffer position. Implementations have the choice of returning
85     * anything that they want to. For example, for efficiency, one might decide
86     * to just return null, which is a valid implementation.
87     */
88    String GetImage();
89  
90    /**
91     * Returns an array of characters that make up the suffix of length 'len' for
92     * the currently matched token. This is used to build up the matched string
93     * for use in actions in the case of MORE. A simple and inefficient
94     * implementation of this is as follows :
95     *
96     *   {
97     *      String t = GetImage();
98     *      return t.substring(t.length() - len, t.length()).toCharArray();
99     *   }
100    */
101   char[] GetSuffix(int len);
102 
103   /**
104    * The lexer calls this function to indicate that it is done with the stream
105    * and hence implementations can free any resources held by this class.
106    * Again, the body of this function can be just empty and it will not
107    * affect the lexer's operation.
108    */
109   void Done();
110 
111 }
112 /* JavaCC - OriginalChecksum=ee07529224d9f56bc326274129aba6aa (do not edit this line) */