aima.core.logic.common

Class Lexer

java.lang.Object

aima.core.logic.common.Lexer

Direct Known Subclasses:

FOLLexer, PLLexer

public abstract class Lexer
extends java.lang.Object

An abstract base class for constructing lexical analyzers for knowledge representation languages. It provides a mechanism for converting a sequence of characters to a sequence of tokens that are meaningful in the representation language of interest.

Author:

Ravi Mohan, Ciaran O'Reilly, Mike Stampone

Field Summary

Fields

Modifier and Type	Field and Description
protected int	lookAheadBufferSize

Constructor Summary

Constructors

Constructor and Description
Lexer()

Method Summary

Modifier and Type	Method and Description
protected void	consume() Consume 1 character from the input.
protected int	getCurrentPositionInInput()
protected char	lookAhead(int position)
abstract Token	nextToken() To be implemented by concrete implementations
void	setInput(java.io.Reader inputReader) Set the character stream reader of the lexical analyzer.
void	setInput(java.lang.String inputString) Sets the character stream of the lexical analyzer.

Methods inherited from class java.lang.Object

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

Field Detail

lookAheadBufferSize

protected int lookAheadBufferSize

Constructor Detail

Lexer

public Lexer()

Method Detail

setInput

public void setInput(java.lang.String inputString)

Sets the character stream of the lexical analyzer.

Parameters:

inputString - a sequence of characters to be converted into a sequence of tokens.

setInput

public void setInput(java.io.Reader inputReader)

Set the character stream reader of the lexical analyzer.

Parameters:

inputReader - a reader on a sequence of characters to be converted into a sequence of tokens.

nextToken

public abstract Token nextToken()

To be implemented by concrete implementations

Returns:

the next token from the input.

getCurrentPositionInInput

protected int getCurrentPositionInInput()

lookAhead

protected char lookAhead(int position)

consume

protected void consume()

Consume 1 character from the input.