org.vanilladb.core.query.parse

Class Lexer

java.lang.Object

org.vanilladb.core.query.parse.Lexer

public class Lexer
extends Object

The lexical analyzer.

Constructor Summary

Constructors

Constructor and Description
Lexer(String s) Creates a new lexical analyzer for the specified SQL statement.

Method Summary

Modifier and Type	Method and Description
void	eatDelim(char delimiter) Throws an exception if the current token is not the specified delimiter.
String	eatId() Throws an exception if the current token is not an identifier.
void	eatKeyword(String keyword) Throws an exception if the current token is not the specified keyword.
double	eatNumericConstant() Throws an exception if the current token is not an integer.
String	eatStringConstant() Throws an exception if the current token is not a string.
boolean	matchDelim(char delimiter) Returns true if the current token is the specified delimiter character.
boolean	matchId() Returns true if the current token is a legal identifier.
boolean	matchKeyword(String keyword) Returns true if the current token is the specified keyword.
boolean	matchNumericConstant() Returns true if the current token is a numeric value.
boolean	matchStringConstant() Returns true if the current token is a string.

Methods inherited from class java.lang.Object

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

Constructor Detail

Lexer

public Lexer(String s)

Creates a new lexical analyzer for the specified SQL statement.

Parameters:

s - the SQL statement

Method Detail

matchDelim

public boolean matchDelim(char delimiter)

Returns true if the current token is the specified delimiter character.

Parameters:

delimiter - a character denoting the delimiter

Returns:

true if the delimiter is the current token

matchNumericConstant

public boolean matchNumericConstant()

Returns true if the current token is a numeric value.

Returns:

true if the current token is a numeric value

matchStringConstant

public boolean matchStringConstant()

Returns true if the current token is a string.

Returns:

true if the current token is a string

matchKeyword

public boolean matchKeyword(String keyword)

Returns true if the current token is the specified keyword.

Parameters:

keyword - the keyword string

Returns:

true if that keyword is the current token

matchId

public boolean matchId()

Returns true if the current token is a legal identifier.

Returns:

true if the current token is an identifier

eatDelim

public void eatDelim(char delimiter)

Throws an exception if the current token is not the specified delimiter. Otherwise, moves to the next token.

Parameters:

delimiter - a character denoting the delimiter

eatNumericConstant

public double eatNumericConstant()

Throws an exception if the current token is not an integer. Otherwise, returns that integer and moves to the next token.

Returns:

the integer value of the current token

eatStringConstant

public String eatStringConstant()

Throws an exception if the current token is not a string. Otherwise, returns that string and moves to the next token.

Returns:

the string value of the current token

eatKeyword

public void eatKeyword(String keyword)

Throws an exception if the current token is not the specified keyword. Otherwise, moves to the next token.

Parameters:

keyword - the keyword string

eatId

public String eatId()

Throws an exception if the current token is not an identifier. Otherwise, returns the identifier string and moves to the next token.

Returns:

the string value of the current token