public final class

FastCharStream

extends Object
implements CharStream
java.lang.Object
   ↳ org.apache.lucene.queryParser.FastCharStream

Class Overview

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 Token API.

Summary

Public Constructors
FastCharStream(Reader r)
Constructs from a Reader.
Public Methods
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 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 void backup(int amount)
Backs up the input stream by amount steps.
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 getColumn()
Returns the column position of the character last read.@deprecated
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 int getLine()
Returns the line number of the character last read.@deprecated
final char readChar()
Returns the next character from the selected input.
[Expand]
Inherited Methods
From class java.lang.Object
From interface org.apache.lucene.queryParser.CharStream

Public Constructors

public FastCharStream (Reader r)

Constructs from a Reader.

Public Methods

public final char BeginToken ()

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.

Throws
IOException

public 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. Again, the body of this function can be just empty and it will not affect the lexer's operation.

public final String GetImage ()

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.

public final char[] GetSuffix (int len)

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(); }

public final void backup (int amount)

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.

public final int getBeginColumn ()

Returns the column number of the first character for current token (being matched after the last call to BeginTOken).

public final int getBeginLine ()

Returns the line number of the first character for current token (being matched after the last call to BeginTOken).

public final int getColumn ()

Returns the column position of the character last read.@deprecated

public final int getEndColumn ()

Returns the column number of the last character for current token (being matched after the last call to BeginTOken).

public final int getEndLine ()

Returns the line number of the last character for current token (being matched after the last call to BeginTOken).

public final int getLine ()

Returns the line number of the character last read.@deprecated

public final char readChar ()

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.

Throws
IOException