mini-c文法规则

以下是一种简单的Mini-C文法规则：

<program> ::= <declaration-list>

<declaration-list> ::= <declaration> | <declaration> <declaration-list>

<declaration> ::= <var-declaration> | <fun-declaration>

<var-declaration> ::= <type-specifier> <id-list> ;

<id-list> ::= <identifier> | <identifier>, <id-list>

<fun-declaration> ::= <type-specifier> <identifier> ( <params> ) <compound-stmt>

<params> ::= <param-list> | VOID

<param-list> ::= <param> | <param>, <param-list>

<param> ::= <type-specifier> <identifier>

<compound-stmt> ::= { <local-declarations> <statement-list> }

<local-declarations> ::= <var-declaration> | <local-declarations> <var-declaration>

<statement-list> ::= <statement> | <statement> <statement-list>

<statement> ::= <expression-stmt> | <compound-stmt> | <selection-stmt> | <iteration-stmt> | <return-stmt>

<expression-stmt> ::= <expression> ;

<selection-stmt> ::= if ( <expression> ) <statement> | if ( <expression> ) <statement> else <statement>

<iteration-stmt> ::= while ( <expression> ) <statement>

<return-stmt> ::= return ; | return <expression> ;

<expression> ::= <var> = <expression> | <simple-expression>

<var> ::= <identifier> | <identifier> [ <expression> ]

<simple-expression> ::= <additive-expression> <relop> <additive-expression> | <additive-expression>

<additive-expression> ::= <term> <addop> <term> | <term>

<term> ::= <factor> <mulop> <factor> | <factor>

<factor> ::= ( <expression> ) | <var> | <call> | NUM

<call> ::= <identifier> ( <args> )

<args> ::= <arg-list> | ε

<arg-list> ::= <expression> | <expression>, <arg-list>

<relop> ::= <= | < | > | >= | == | !=

<addop> ::= + | -

<mulop> ::= * | /

其中，`<identifier>`代表变量名，`NUM`代表数字常量，`<type-specifier>`代表数据类型（如int、float等）。这个文法规则支持函数定义、变量声明、复合语句、选择语句、循环语句和返回语句等基本语法结构。