weka.core.expressionlanguage.parser

Class Scanner

java.lang.Object

weka.core.expressionlanguage.parser.Scanner

All Implemented Interfaces:

java_cup.runtime.Scanner

public class Scanner
extends java.lang.Object
implements java_cup.runtime.Scanner

A lexical scanner for an expression language. It emerged as a superset of the weka.core.mathematicalexpression package, the weka.filers.unsupervised.instance.subsetbyexpression package and the weka.core.AttributeExpression class. Warning: This file (Scanner.java) has been auto generated by jflex.

Version:

$Revision: 1000 $

Author:

Benjamin Weber ( benweber at student dot ethz dot ch )

Field Summary

Fields

Modifier and Type	Field and Description
static int	STRING1
static int	STRING2
static int	YYEOF This character denotes the end of file.
static int	YYINITIAL

Constructor Summary

Constructors

Constructor and Description
Scanner(java.io.Reader in) Creates a new scanner

Method Summary

Modifier and Type	Method and Description
java_cup.runtime.Symbol	next_token() Resumes scanning until the next regular expression is matched, the end of input is encountered or an I/O-Error occurs.
boolean	yyatEOF() Returns whether the scanner has reached the end of the reader it reads from.
void	yybegin(int newState) Enters a new lexical state.
char	yycharat(int position) Returns the character at the given position from the matched text.
void	yyclose() Closes the input reader.
int	yylength() How many characters were matched.
void	yypushback(int number) Pushes the specified amount of characters back into the input stream.
void	yyreset(java.io.Reader reader) Resets the scanner to read from a new input stream.
int	yystate() Returns the current lexical state.
java.lang.String	yytext() Returns the text matched by the current regular expression.

Methods inherited from class java.lang.Object

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

Field Detail

YYEOF

public static final int YYEOF

This character denotes the end of file.

See Also:

Constant Field Values

YYINITIAL

public static final int YYINITIAL

See Also:

Constant Field Values

STRING1

public static final int STRING1

See Also:

Constant Field Values

STRING2

public static final int STRING2

See Also:

Constant Field Values

Constructor Detail

Scanner

public Scanner(java.io.Reader in)

Creates a new scanner

Parameters:

in - the java.io.Reader to read input from.

Method Detail

yyclose

public final void yyclose()
                   throws java.io.IOException

Closes the input reader.

Throws:

java.io.IOException - if the reader could not be closed.

yyreset

public final void yyreset(java.io.Reader reader)

Resets the scanner to read from a new input stream.

Does not close the old reader.

All internal variables are reset, the old input stream cannot be reused (internal buffer is discarded and lost). Lexical state is set to ZZ_INITIAL.

Internal scan buffer is resized down to its initial length, if it has grown.

Parameters:

reader - The new input stream.

yyatEOF

public final boolean yyatEOF()

Returns whether the scanner has reached the end of the reader it reads from.

Returns:

whether the scanner has reached EOF.

yystate

public final int yystate()

Returns the current lexical state.

Returns:

the current lexical state.

yybegin

public final void yybegin(int newState)

Enters a new lexical state.

Parameters:

newState - the new lexical state

yytext

public final java.lang.String yytext()

Returns the text matched by the current regular expression.

Returns:

the matched text.

yycharat

public final char yycharat(int position)

Returns the character at the given position from the matched text.

It is equivalent to yytext().charAt(pos), but faster.

Parameters:

position - the position of the character to fetch. A value from 0 to yylength()-1.

Returns:

the character at position.

yylength

public final int yylength()

How many characters were matched.

Returns:

the length of the matched text region.

yypushback

public void yypushback(int number)
                throws SyntaxException

Pushes the specified amount of characters back into the input stream.

They will be read again by then next call of the scanning method.

Parameters:

number - the number of characters to be read again. This number must not be greater than yylength().

Throws:

SyntaxException

next_token

public java_cup.runtime.Symbol next_token()
                                   throws java.io.IOException,
                                          SyntaxException

Resumes scanning until the next regular expression is matched, the end of input is encountered or an I/O-Error occurs.

Specified by:

next_token in interface java_cup.runtime.Scanner

Returns:

the next token.

Throws:

java.io.IOException - if any I/O-Error occurs.

SyntaxException