Class InputCharStream

  • All Implemented Interfaces:
    CharStream

    public final class InputCharStream
    extends java.lang.Object
    implements CharStream
    An implementation of interface CharStream. Implements input character stream that maintains line and column number positions of the characters. It also has the capability to backup the stream to some extent.
    The object of this class is constructed using java.io.Reader reader and it is left to constructor of the reader to set up character encoding correctly. This means that method read of the reader is used to get next characters, assuming it returns appropriate values. It is recommended to use class java.io.InputStreamReader as a reader, which allows to set desired character encoding. This class is an intermediate component between input character reader and the parser.
    The code of this class is based on the class ASCII_CharStream - implementation of interface CharStream, that JavaCC would have generated with the following options set in a JavaCC grammar file:
        JAVA_UNICODE_ESCAPE = false;
        UNICODE_INPUT = false;
        USER_CHAR_STREAM = false; 
    Note that this class is not fully JavaCC generated.
    Version:
    $Revision: 5962 $ $Date: 2003-03-03 00:05:44 -0700 (Mon, 03 Mar 2003) $
    Author:
    JavaCC, Alexander Totok
    • Constructor Summary

      Constructors 
      Constructor Description
      InputCharStream​(java.io.Reader dstream)
      Constructor, instantiating the char stream to begin at 1-st line and 1-st column of dstream.
      InputCharStream​(java.io.Reader dstream, int startline, int startcolumn)
      Constructor, allowing to specify start line and start column of the char stream.
      InputCharStream​(java.io.Reader dstream, int startline, int startcolumn, int buffersize)
      Constructor, allowing to specify start line and start column of the char stream, and buffer size as well.
    • Method Summary

      All Methods Instance Methods Concrete Methods Deprecated Methods 
      Modifier and Type Method Description
      void adjustBeginLineColumn​(int newLine, int newCol)
      Method to adjust line and column numbers for the start of a token.
      void backup​(int amount)
      Backs up the input stream by amount steps.
      char BeginToken()
      Returns the next character that marks the beginning of the next token.
      void Done()
      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.
      int getBeginColumn()
      Returns the column number of the first character for current token (being matched after the last call to BeginTOken).
      int getBeginLine()
      Returns the line number of the first character for current token (being matched after the last call to BeginTOken).
      int getColumn()
      Deprecated. 
      int getEndColumn()
      Returns the column number of the last character for current token (being matched after the last call to BeginTOken).
      int getEndLine()
      Returns the line number of the last character for current token (being matched after the last call to BeginTOken).
      java.lang.String GetImage()
      Returns a string made up of characters from the marked token beginning to the current buffer position.
      int getLine()
      Deprecated. 
      char[] GetSuffix​(int len)
      Returns an array of characters that make up the suffix of length 'len' for the currently matched token.
      char readChar()
      Returns the next character from the input stream.
      void ReInit​(java.io.Reader dstream)
      Reinitialization of the char stream, instantiating the char stream to begin at 1-st line and 1-st column of dstream.
      void ReInit​(java.io.Reader dstream, int startline, int startcolumn)
      Reinitialization of the char stream, allowing to specify start line and start column of the char stream.
      void ReInit​(java.io.Reader dstream, int startline, int startcolumn, int buffersize)
      Reinitialization of the char stream, allowing to specify start line and start column of the char stream, and buffer size as well.
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Field Detail

      • bufsize

        int bufsize
      • available

        int available
      • tokenBegin

        int tokenBegin
      • bufpos

        public int bufpos
    • Constructor Detail

      • InputCharStream

        public InputCharStream​(java.io.Reader dstream,
                               int startline,
                               int startcolumn,
                               int buffersize)
        Constructor, allowing to specify start line and start column of the char stream, and buffer size as well.
      • InputCharStream

        public InputCharStream​(java.io.Reader dstream,
                               int startline,
                               int startcolumn)
        Constructor, allowing to specify start line and start column of the char stream.
      • InputCharStream

        public InputCharStream​(java.io.Reader dstream)
        Constructor, instantiating the char stream to begin at 1-st line and 1-st column of dstream.
    • Method Detail

      • BeginToken

        public final char BeginToken()
                              throws java.io.IOException
        Description copied from interface: CharStream
        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.
        Specified by:
        BeginToken in interface CharStream
        Throws:
        java.io.IOException
      • readChar

        public final char readChar()
                            throws java.io.IOException
        Returns the next character from the input stream. The only method whose implementation is different from its original in the ASCII_CharStream class.
        Specified by:
        readChar in interface CharStream
        Throws:
        java.io.IOException
      • getColumn

        public final int getColumn()
        Deprecated.
        Description copied from interface: CharStream
        Returns the column position of the character last read.
        Specified by:
        getColumn in interface CharStream
        See Also:
        getEndColumn()
      • getLine

        public final int getLine()
        Deprecated.
        Description copied from interface: CharStream
        Returns the line number of the character last read.
        Specified by:
        getLine in interface CharStream
        See Also:
        getEndLine()
      • getEndColumn

        public final int getEndColumn()
        Description copied from interface: CharStream
        Returns the column number of the last character for current token (being matched after the last call to BeginTOken).
        Specified by:
        getEndColumn in interface CharStream
      • getEndLine

        public final int getEndLine()
        Description copied from interface: CharStream
        Returns the line number of the last character for current token (being matched after the last call to BeginTOken).
        Specified by:
        getEndLine in interface CharStream
      • getBeginColumn

        public final int getBeginColumn()
        Description copied from interface: CharStream
        Returns the column number of the first character for current token (being matched after the last call to BeginTOken).
        Specified by:
        getBeginColumn in interface CharStream
      • getBeginLine

        public final int getBeginLine()
        Description copied from interface: CharStream
        Returns the line number of the first character for current token (being matched after the last call to BeginTOken).
        Specified by:
        getBeginLine in interface CharStream
      • backup

        public final void backup​(int amount)
        Description copied from interface: CharStream
        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.
        Specified by:
        backup in interface CharStream
      • ReInit

        public void ReInit​(java.io.Reader dstream,
                           int startline,
                           int startcolumn,
                           int buffersize)
        Reinitialization of the char stream, allowing to specify start line and start column of the char stream, and buffer size as well.
      • ReInit

        public void ReInit​(java.io.Reader dstream,
                           int startline,
                           int startcolumn)
        Reinitialization of the char stream, allowing to specify start line and start column of the char stream.
      • ReInit

        public void ReInit​(java.io.Reader dstream)
        Reinitialization of the char stream, instantiating the char stream to begin at 1-st line and 1-st column of dstream.
      • GetImage

        public final java.lang.String GetImage()
        Description copied from interface: CharStream
        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.
        Specified by:
        GetImage in interface CharStream
      • GetSuffix

        public final char[] GetSuffix​(int len)
        Description copied from interface: CharStream
        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 :
           {
              String t = GetImage();
              return t.substring(t.length() - len, t.length()).toCharArray();
           }
         
        Specified by:
        GetSuffix in interface CharStream
      • Done

        public void Done()
        Description copied from interface: CharStream
        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.
        Specified by:
        Done in interface CharStream
      • adjustBeginLineColumn

        public void adjustBeginLineColumn​(int newLine,
                                          int newCol)
        Method to adjust line and column numbers for the start of a token.