simple.parser
Class SimpleParser

java.lang.Object
  simple.parser.SimpleParser

public class SimpleParser
extends java.lang.Object

This class defines a object that parses a stream of Token generated by Lexer using the following LL(1) grammar:

1. S -> E$
2. E -> TE'
3. E' -> +TE'
4. E' -> -TE'
5. E' -> ε
6. T -> FT'
7. T' -> *T'
8. T' -> /T'
9. T' -> ε
10. F -> r"[0-9]"
11. F -> (E)

Note that the token manipulation itself is encapsulated. The structure of the parser follows a standard recursive descent algorithm, consulting the following parsing table:

	+ or -	* or /	[0-9]	(	)	$
S				(1)	(1)
E				(2)	(2)
E'	(3) or (4)				(5)	(5)
T				(6)	(6)
T'	(9)	(7) or (8)			(9)	(9)
F				(10)	(11)

Author:

Santoso Wijaya

See Also:

Lexer

Constructor Summary

SimpleParser(java.lang.String src)
Creates a parser object, passing it a source expression string.

Method Summary

Stmt	parse() Parses the source string, returning a parse tree rooted with a Stmt node.

Methods inherited from class java.lang.Object

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

Constructor Detail

SimpleParser

public SimpleParser(java.lang.String src)
             throws ParseException

Creates a parser object, passing it a source expression string.

Parameters:

src - the source expression string

Throws:

ParseException - if token lexer analysis throws an exception (unknown character)

Method Detail

parse

public Stmt parse()
           throws ParseException

Parses the source string, returning a parse tree rooted with a Stmt node.

Returns:

a parse tree of the source expression string given to the parser object

Throws:

ParseException

See Also:

ParseNode