gnu.prolog.io.parser
Class ReaderCharStream

java.lang.Object
  gnu.prolog.io.parser.ReaderCharStream

All Implemented Interfaces:

CharStream

public final class ReaderCharStream
extends Object
implements CharStream

An implementation of interface CharStream, where the stream is assumed to contain only ASCII characters (without unicode processing). TODO: add unicode support.

Field Summary

int

bufpos

Constructor Summary

ReaderCharStream(Reader dstream, int startline, int startcolumn)

ReaderCharStream(Reader dstream, int startline, int startcolumn, int buffersize)

Method Summary

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	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).
String	GetImage() Returns a string made up of characters from the marked token beginning to the current buffer position.
int	getLine() Deprecated.
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.
void	reInit(Reader dstream, int startline, int startcolumn)
void	reInit(Reader dstream, int startline, int startcolumn, int buffersize)

Methods inherited from class java.lang.Object

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

Field Detail

bufpos

public int bufpos

Constructor Detail

ReaderCharStream

public ReaderCharStream(Reader dstream,
                        int startline,
                        int startcolumn,
                        int buffersize)

ReaderCharStream

public ReaderCharStream(Reader dstream,
                        int startline,
                        int startcolumn)

Method Detail

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

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

getColumn

@Deprecated
public final int getColumn()

Deprecated.

Description copied from interface: CharStream

Returns the column position of the character last read.

Specified by:

getColumn in interface CharStream

See Also:

getEndColumn()

getLine

@Deprecated
public final int getLine()

Deprecated.

Description copied from interface: CharStream

Returns the line number of the character last read.

Specified by:

getLine in interface CharStream

See Also:

getEndLine()

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

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 implemetation's responsibility to do this right.

Specified by:

backup in interface CharStream

reInit

public void reInit(Reader dstream,
                   int startline,
                   int startcolumn,
                   int buffersize)

reInit

public void reInit(Reader dstream,
                   int startline,
                   int startcolumn)

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 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