oracle.javatools.parser
Class AbstractLexer

java.lang.Object
  oracle.javatools.parser.AbstractLexer

All Implemented Interfaces:

Lexer

Direct Known Subclasses:

GenericLexer

public abstract class AbstractLexer

extends java.lang.Object

implements Lexer

The AbstractLexer is a basic abstract implementation which takes care of common functionality across all Lexers, such as the buffer and offset issues, and for providing a basic LexerToken object which just stores token and offset information.

See Also:

Lexer, AbstractLexer.DefaultLexerToken

Nested Class Summary

protected static class

AbstractLexer.DefaultLexerToken The DefaultLexerToken just implements a basic LexerToken which stores a token and start/end offsets.

Field Summary

protected int	currentPos The current position in the buffer where the next lex operation will occur (assuming that backup() has not been called.)
protected ReadTextBuffer	textBuffer The underlying text buffer we are lexing.

Fields inherited from interface oracle.javatools.parser.Lexer

TK_EOF, TK_NOT_FOUND

Constructor Summary

AbstractLexer()

Method Summary

abstract void	backup() Unlexes the last found token.
LexerToken	createLexerToken() Creates an empty LexerToken for a specific Lexer implementation to be passed in to the lex() call to be filled in.
ReadTextBuffer	getTextBuffer() Gets the text buffer that is being used by this Lexer.
abstract int	lex(LexerToken lexedToken) Scans the text buffer at the current position and returns the token that was found.
void	setPosition(int offset) Sets the current lex (read) position to the given offset in the buffer.
void	setTextBuffer(ReadTextBuffer buffer) Sets the text buffer that is to be used by this Lexer.

Methods inherited from class java.lang.Object

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

Field Detail

textBuffer

protected ReadTextBuffer textBuffer

The underlying text buffer we are lexing.

currentPos

protected int currentPos

The current position in the buffer where the next lex operation will occur (assuming that backup() has not been called.)

Constructor Detail

AbstractLexer

public AbstractLexer()

Method Detail

setTextBuffer

public void setTextBuffer(ReadTextBuffer buffer)

Sets the text buffer that is to be used by this Lexer.

Specified by:

setTextBuffer in interface Lexer

Parameters:

buffer - the text buffer to use

getTextBuffer

public ReadTextBuffer getTextBuffer()

Gets the text buffer that is being used by this Lexer.

Specified by:

getTextBuffer in interface Lexer

Returns:

the text buffer being used

setPosition

public void setPosition(int offset)

Sets the current lex (read) position to the given offset in the buffer. It is the clients responsibility to ensure that this offset corresponds to the start of a token, otherwise unexpected (and incorrect) results may occur.

Specified by:

setPosition in interface Lexer

Parameters:

offset - the offset for the next lex() operation.

createLexerToken

public LexerToken createLexerToken()

Creates an empty LexerToken for a specific Lexer implementation to be passed in to the lex() call to be filled in.

Specified by:

createLexerToken in interface Lexer

Returns:

a newly created LexerToken

lex

public abstract int lex(LexerToken lexedToken)

Scans the text buffer at the current position and returns the token that was found. The token and offset information is also stored in the lexedToken instance passed in to the call.

Specified by:

lex in interface Lexer

Parameters:

lexedToken - the instance passed in where token info is stored

Returns:

the token that was found, same as calling lexedToken.getToken() (for convenience)

backup

public abstract void backup()

Unlexes the last found token. The next call to lex() will return the last token and offset information found.

Specified by:

backup in interface Lexer