a little interpreter wrote by java for CMM language

• program -> statement// 外部（全局）声明

• statement -> declare | block_sta | if_sta | while_sta | for_sta | print_sta | scan_sta | assign_sta | break_sta | continue_sta | conditionTop | statement

• //声明语句 declare -> (INT|REAL|BOOL|CHAR|STRING) declare_sub (COMI declare_sub)* SEMI

• declare_sub -> (ID (ASSIGN condition)?) | (ID array (ASSIGN LBRACE arrayDeclare RBRACE)?)

• array -> LBRACKET expression RBRACKET

• arrayDeclare -> (INTNUM|REALNUM|CHAR_S|STR|TRUE|FALSE|ID) (COMI (INTNUM|REALNUM|CHAR_S|STR|TRUE|FALSE|ID))*

• //{}代码段语句 block_sta -> LBRACE (statement)* RBRACE

• //if语句

• if_sta -> IF LPAREN condition RPAREN (LBRACE (statement)* RBRACE | (statement)?) (ELSE IF elseif_sta)* ELSE(LBRACE (statement)* RBRACE | (statement)?)

• elseif_sta -> LPAREN condition RPAREN (LBRACE (statement)* RBRACE | (statement)?)

• //while语句 while_sta -> WHILE LPAREN condition RPAREN LBRACE (statement)* RBRACE

• //for语句 for_sta -> FOR LPAREN (declare | assign_sta) condition assign_sta RPAREN (LBRACE (statement)* RBRACE | (statement)?)

• //赋值语句 assign -> ID (array)? ASSIGN condition SEMI

• //print语句 print_sta -> PRINT LPAREN (condition | ID) RPAREN SEMI

• //scan语句 scan_sta -> SCAN LPAREN (STR | ID)? RPAREN (SEMI)?

• //break break_sta -> BREAK SEMI

• //continue continue_sta -> CONTINUE SEMI

• //声明，赋值之外直接出现算术式情况 eg：1+2； conditionTop -> condition (SEMI)+

• //条件语句 解决符号优先级问题

• condition -> firstCondition (OR firstCondition)*

• firstCondition -> secondCondition (AND secondCondition)*

• secondCondition -> thirdCondition (BAND thirdCondition)*

• thirdCondition -> fourCondition (BOR fourCondition)*

• fourCondition -> expression (comparsion expression)*

• expression -> mdexpression ((ADD|SUB) mdexpression)*

• mdexpression -> factor ((MUL|DEVIDE) factor)*

• //单个因子式 factor->INTNUM|REALNUM|CHAR_S|STR|TRUE|FALSE|(ID(array)?)|((NEG|POS) factor)|( LPAREN condition RPAREN ) | scan_sta comparsion -> EQ | GREATER | UE | GE | LE | LESS

• //注解
  < LPARENT: ( > < RPARENT: ) > < LBRACE: { > < RBRACE: } > < LBRACKET: [ > < RBRACKET: ] > < SEMI: ; > < COMI: , >