cmm语言的bnf表示.txt

来自「参照清华大学《编译原理》写的cmm语言词法分析程序」· 文本 代码 · 共 44 行

<DIGIT>				::= 	0|1|2|3|4|6|6|7|8|9
<LETTER>				::=	a|b|c…|X|Y|Z
<AddOp>				::=	+|-
<MulOp>				::=	*|/
<AssignOp>			::=	=
<RelationOp>			::=	==|!=|<|<=|>|>=
<Underline>			::=	_
<Type>				::=	int|real
<Identifier>			::= 	{<LETTER>(<DIGIT>|<LETTER>|<UNDERLINE>}
<IntNumber>			::=	<DIGIT>{<DIGIT>}
<RealNumber>			::=	{<DIGIT>}<DOT><DIGIT>{<DIGIT>}|<DIGIT>{<DIGIT>}<DOT>{<DIGIT>}
<Factor>				::=	Identifier()
					|	Number()
					|	<MINUS>Factor()
					|	<LPAREN>Expression()<RPAREN>	
<Item>				::=	<Factor>{<MultOp> <Factor>}
<Expression>			::=	<Item>{<AddOp><Item>}

<VarDeclaration>		::=	<Type> <VarDeclarationId> [ <AssignOp> <VarInitializer>]

<VarDeclarationId>		::=	<Identifier> {‘[‘’]’}

<VarInitializer>			::=	<ArrayInitializer>|<Expression>

<ArrayInitializer>			::=	‘{‘[<VarInitializer> {‘,’<VarInitializer>}]’}’

<AssignStatement>		::=	<Identifier>{‘[‘<Expression>’]’} <AssignOp> <Expression>

<Condition>			::=	<Expression>	<RelationOp>	<Expression>
<ConditionStatement>	::=	‘if’’(‘ <Condition>’)’<Statement>
						 { ‘else’’if’’(‘<Condition>’)’ <Statement>} 
						 [‘else’<Statement>]
<WhileStatement>		::=	‘while’’(‘<Condition>’)’<Statement>
<ReadStatement>		::=	‘read’’(‘<Identifier>{‘,’<Identifier>}’)’
<WriteStatement>		::=	  ‘write’’(‘<Expression>{‘,’<Expression>}’)’
<CompoundStatement>	::=	‘{‘<Statement>{<Statement>}’}’
<Statement>			::=	<AssignStatement>
					|	<ConditionStatement>
					|	<WhileStatement>
					|	<ReadStatement>
					|	<WriteStatement>
					|	<CompoundStatement>
<Program>               ::=     {ConstDeclaration}{VarDeclaration}{Statement}