001 /* Generated By:JavaCC: Do not edit this line. CharStream.java Version 5.0 */
002 /* JavaCCOptions:STATIC=false,SUPPORT_CLASS_VISIBILITY_PUBLIC=true */
003 package org.w3c.flute.parser;
004
005 /**
006 * This interface describes a character stream that maintains line and
007 * column number positions of the characters. It also has the capability
008 * to backup the stream to some extent. An implementation of this
009 * interface is used in the TokenManager implementation generated by
010 * JavaCCParser.
011 *
012 * All the methods except backup can be implemented in any fashion. backup
013 * needs to be implemented correctly for the correct operation of the lexer.
014 * Rest of the methods are all used to get information like line number,
015 * column number and the String that constitutes a token and are not used
016 * by the lexer. Hence their implementation won't affect the generated lexer's
017 * operation.
018 */
019
020 public
021 interface CharStream {
022
023 /**
024 * Returns the next character from the selected input. The method
025 * of selecting the input is the responsibility of the class
026 * implementing this interface. Can throw any java.io.IOException.
027 */
028 char readChar() throws java.io.IOException;
029
030 @Deprecated
031 /**
032 * Returns the column position of the character last read.
033 * @deprecated
034 * @see #getEndColumn
035 */
036 int getColumn();
037
038 @Deprecated
039 /**
040 * Returns the line number of the character last read.
041 * @deprecated
042 * @see #getEndLine
043 */
044 int getLine();
045
046 /**
047 * Returns the column number of the last character for current token (being
048 * matched after the last call to BeginTOken).
049 */
050 int getEndColumn();
051
052 /**
053 * Returns the line number of the last character for current token (being
054 * matched after the last call to BeginTOken).
055 */
056 int getEndLine();
057
058 /**
059 * Returns the column number of the first character for current token (being
060 * matched after the last call to BeginTOken).
061 */
062 int getBeginColumn();
063
064 /**
065 * Returns the line number of the first character for current token (being
066 * matched after the last call to BeginTOken).
067 */
068 int getBeginLine();
069
070 /**
071 * Backs up the input stream by amount steps. Lexer calls this method if it
072 * had already read some characters, but could not use them to match a
073 * (longer) token. So, they will be used again as the prefix of the next
074 * token and it is the implemetation's responsibility to do this right.
075 */
076 void backup(int amount);
077
078 /**
079 * Returns the next character that marks the beginning of the next token.
080 * All characters must remain in the buffer between two successive calls
081 * to this method to implement backup correctly.
082 */
083 char BeginToken() throws java.io.IOException;
084
085 /**
086 * Returns a string made up of characters from the marked token beginning
087 * to the current buffer position. Implementations have the choice of returning
088 * anything that they want to. For example, for efficiency, one might decide
089 * to just return null, which is a valid implementation.
090 */
091 String GetImage();
092
093 /**
094 * Returns an array of characters that make up the suffix of length 'len' for
095 * the currently matched token. This is used to build up the matched string
096 * for use in actions in the case of MORE. A simple and inefficient
097 * implementation of this is as follows :
098 *
099 * {
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=9e13eaf20bbd60d420d5d89177ab64a7 (do not edit this line) */