org.apache.lucene.queryParser
Class FastCharStream
- CharStream
public final class FastCharStream
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.
char | BeginToken() - Returns the next character that marks the beginning of the next token.
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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.
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String | GetImage() - Returns a string made up of characters from the marked token beginning
to the current buffer position.
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char[] | GetSuffix(int len) - Returns an array of characters that make up the suffix of length 'len' for
the currently matched token.
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void | backup(int amount) - Backs up the input stream by amount steps.
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int | getBeginColumn() - Returns the column number of the first character for current token (being
matched after the last call to BeginTOken).
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int | getBeginLine() - Returns the line number of the first character for current token (being
matched after the last call to BeginTOken).
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int | getColumn()
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int | getEndColumn() - Returns the column number of the last character for current token (being
matched after the last call to BeginTOken).
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int | getEndLine() - Returns the line number of the last character for current token (being
matched after the last call to BeginTOken).
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int | getLine()
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char | readChar() - Returns the next character from the selected input.
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FastCharStream
public FastCharStream(Reader r)
Constructs from a Reader.
BeginToken
public final char BeginToken()
throws IOException
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.
- BeginToken in interface CharStream
Done
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.
- Done in interface CharStream
GetImage
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.
- GetImage in interface CharStream
GetSuffix
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();
}
- GetSuffix in interface CharStream
backup
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.
- backup in interface CharStream
getBeginColumn
public final int getBeginColumn()
Returns the column number of the first character for current token (being
matched after the last call to BeginTOken).
- getBeginColumn in interface CharStream
getBeginLine
public final int getBeginLine()
Returns the line number of the first character for current token (being
matched after the last call to BeginTOken).
- getBeginLine in interface CharStream
getColumn
public final int getColumn()
Returns the column position of the character last read.
- getColumn in interface CharStream
getEndColumn
public final int getEndColumn()
Returns the column number of the last character for current token (being
matched after the last call to BeginTOken).
- getEndColumn in interface CharStream
getEndLine
public final int getEndLine()
Returns the line number of the last character for current token (being
matched after the last call to BeginTOken).
- getEndLine in interface CharStream
getLine
public final int getLine()
Returns the line number of the character last read.
- getLine in interface CharStream
readChar
public final char readChar()
throws IOException
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.
- readChar in interface CharStream
Copyright © 2000-2006 Apache Software Foundation. All Rights Reserved.