Package org.apache.lucene.queryparser.charstream

Class FastCharStream

  • All Implemented Interfaces:
    CharStream
    public final class FastCharStream
extends Object
implements CharStream
    An efficient implementation of JavaCC's CharStream interface.

    Note that this does not do line-number counting, but instead keeps track of the character position of the token in the input, as required by Lucene's OffsetAttribute API.

    • Constructor Summary

      Constructors 
      Constructor Description
      FastCharStream​(Reader r)
      Constructs from a Reader.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      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 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).
      String GetImage()
      Returns a string made up of characters from the marked token beginning to the current buffer position.
      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 selected input.

    • Constructor Detail

      • FastCharStream

        public FastCharStream​(Reader r)
        Constructs from a Reader.

    • Method Detail

      • readChar

        public final char readChar()
                    throws IOException
        Description copied from interface: CharStream
        Returns the next character from the selected input. The method of selecting the input is the responsibility of the class implementing this interface. Can throw any java.io.IOException.
        Specified by:
        readChar in interface CharStream
        Throws:
        IOException

      • BeginToken

        public final char BeginToken()
                      throws 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:
        IOException

      • 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 implementation's responsibility to do this right.
        Specified by:
        backup in interface CharStream

      • GetImage

        public final 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 final 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

      • 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