simpledb.parse
Class Lexer

java.lang.Object
  simpledb.parse.Lexer

public class Lexer
extends Object

The lexical analyzer.

Author:

Edward Sciore

Constructor Summary

Lexer(String s)
Creates a new lexical analyzer for SQL statement s.

Method Summary

void	eatDelim(char d) 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.
int	eatIntConstant() Throws an exception if the current token is not an integer.
void	eatKeyword(String w) Throws an exception if the current token is not the specified keyword.
String	eatStringConstant() Throws an exception if the current token is not a string.
boolean	matchDelim(char d) Returns true if the current token is the specified delimiter character.
boolean	matchId() Returns true if the current token is a legal identifier.
boolean	matchIntConstant() Returns true if the current token is an integer.
boolean	matchKeyword(String w) Returns true if the current token is the specified keyword.
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 SQL statement s.

Parameters:

s - the SQL statement

Method Detail

matchDelim

public boolean matchDelim(char d)

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

Parameters:

d - a character denoting the delimiter

Returns:

true if the delimiter is the current token

matchIntConstant

public boolean matchIntConstant()

Returns true if the current token is an integer.

Returns:

true if the current token is an integer

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 w)

Returns true if the current token is the specified keyword.

Parameters:

w - 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 d)

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

Parameters:

d - a character denoting the delimiter

eatIntConstant

public int eatIntConstant()

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 w)

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

Parameters:

w - 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