3.grm

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//这是一个小型pascal文法

[nonterminal]
	statement
	procedure_statement
	compound_statement
 	variable expression
	expression_list
	simple_expression
	term factor sign
[terminal]
	if then else while do
	assignop relop addop mulop
	num not + -
[production]
	statement => variable assignop expression |
				 procedure_statement |
				 compound_statement |
				 if expression then statement else statement |
				 while expression do statement ;
	variable => id | id [ expression ] ;
	procedure_statement => id | id ( expression_list ) ;
	expression_list => expression | expression_list , expression ;
	expression => simple_expression |
				  simple_expression relop simple_expression ;
	simple_expression => term | sign term |
						 simple_expression addop term ;
	term => factor | term mulop factor ;
	factor => id | id ( expression_list ) | num | ( expression ) | not factor ;
	sign => + | - ;