Package org.apache.lucene.queryparser.charstream

Class FastCharStream

java.lang.Object
org.apache.lucene.queryparser.charstream.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

    Modifier and Type
    Method
    Description
    final void
    backup(int amount)
    Backs up the input stream by amount steps.
    final char
    BeginToken()
    Returns the next character that marks the beginning of the next token.
    final 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.
    final int
    getBeginColumn()
    Returns the column number of the first character for current token (being matched after the last call to BeginTOken).
    final int
    getBeginLine()
    Returns the line number of the first character for current token (being matched after the last call to BeginTOken).
    final int
    getEndColumn()
    Returns the column number of the last character for current token (being matched after the last call to BeginTOken).
    final int
    getEndLine()
    Returns the line number of the last character for current token (being matched after the last call to BeginTOken).
    final String
    GetImage()
    Returns a string made up of characters from the marked token beginning to the current buffer position.
    final char[]
    GetSuffix(int len)
    Returns an array of characters that make up the suffix of length 'len' for the currently matched token.
    final char
    readChar()
    Returns the next character from the selected input.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • FastCharStream

      public FastCharStream(Reader r)
      Constructs from a Reader.

  • Method Details

    • 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