org.apache.lucene.queryParser.surround.parser

Class FastCharStream

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 Token API.

Constructor Summary

FastCharStream(Reader r)
Constructs from a Reader.

Method Summary

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.
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.
void
backup(int amount)
Backs up the input stream by amount steps.
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).
int
getLine()
Deprecated.
char
readChar()
Returns the next character from the selected input.

Constructor Details

FastCharStream

public FastCharStream(Reader r)
Constructs from a Reader.

Method Details

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.
Specified by:
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.
Specified by:
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.
Specified by:
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(); }
Specified by:
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.
Specified by:
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).
Specified by:
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).
Specified by:
getBeginLine in interface CharStream

getColumn

public final int getColumn()

Deprecated.

Returns the column position of the character last read.
Specified by:
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).
Specified by:
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).
Specified by:
getEndLine in interface CharStream

getLine

public final int getLine()

Deprecated.

Returns the line number of the character last read.
Specified by:
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.
Specified by:
readChar in interface CharStream

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