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我们有作为编译器的任务。我们已经做了词汇和语法分析,但是我们坚持生成中间代码。我们意识到我们必须实现一个符号表以进行中间代码生成,我们不知道,如何去做以及它包含什么。如何制作符号表
给定下面的代码,符号表应该包含什么? (该代码是用下面描述的教育语言编写的)
另外我们如何在符号表中实现范围?
<PROGRAM> ::= PROGRAM ID <BLOCK> ENDPROGRAM <BLOCK> ::= {<DECLARATIONS> <SUBPROGRAMS> <SEQUENCE>} <DECLARATIONS> ::= ε | DECLARE <VARLIST> ENDDECLARE <VARLIST> ::= ε | ID (, ID)* <SUBPROGRAMS> ::= (<PROCORFUNC>) * <PROCORFUNC> ::= PROCEDURE ID <PROCORFUNCBODY> ENDPROCEDURE | FUNCTION ID <PROCORFUNCBODY> ENDFUNCTION <PROCORFUNCBODY> ::= <FORMALPARS> <BLOCK> <FORMALPARS> ::= ε | (<FORMALPARLIST>) <FORMALPARLIST> ::= <FORMALPARITEM> (, <FORMALPARITEM>)* <FORMALPARITEM> ::= IN ID | INOUT ID <SEQUENCE> ::= <STATEMENT> (; <STATEMENT>)* <STATEMENT> ::= ε | <ASSIGNMENT-STAT> | <IF-STAT> | <WHILE-STAT> | <FOR-STAT> | <EXIT-STAT> | <CALL-STAT> | <RETURN-STAT> <ASSIGNMENT-STAT> ::= ID := <EXPRESSION> <IF-STAT> ::= IF <CONDITION> THEN <SEQUENCE> <ELSEPART> ENDIF <ELSEPART> ::= ε | ELSE <SEQUENCE> <WHILE-STAT> ::= DO {<SEQUENCE>} WHILE (<CONDITION>) <FOR-STAT> ::= (<ASSIGNMENT-STAT>; <CONDITION>;<ASSIGNMENT-STAT>;) {<SEQUENCE>} <EXIT-STAT> ::= EXIT <CALL-STAT> ::= CALL ID <ACTUALPARS> <ACTUALPARS> ::= (<ACTUALPARLIST>) | ε <ACTUALPARLIST> ::= <ACTUALPARITEM> (, <ACTUALPARITEM>)* <ACTUALPARITEM> ::= IN <EXPRESSION> | INOUT ID <RETURN-STAT> ::= RETURN <EXPRESSION> <CONDITION> ::= <BOOLTERM> (OR <BOOLTERM>)* <BOOLTERM> ::= <BOOLFACTOR> (AND <BOOLFACTOR>)* <BOOLFACTOR> ::= NOT [<CONDITION>] | [<CONDITION>] | <EXPRESSION> <RELATIONAL-OPER> <EXPRESSION> | TRUE | FALSE <EXPRESSION> ::= <OPTIONAL-SIGN> <TERM> (<ADD-OPER> <TERM>)* <TERM> ::= <FACTOR> (<MUL-OPER> <FACTOR>)* <FACTOR> ::= CONSTANT | (<EXPRESSION>) | ID <IDTAIL> <IDTAIL> ::= ε | <ACTUALPARS> <RELATIONAL-OPER> ::= = | < (ε | = | >) | > (ε | =) <ADD-OPER> ::= + | - <MUL-OPER> ::= * |/ <OPTIONAL-SIGN> ::= ε | <ADD-OPER>
PROGRAM MULTIPLY
{
DECLARE
A, B, C
ENDDECLARE
PROCEDURE Aop(INOUT A)
{
A=A+1;
}
ENDPROCEDURE
FUNCTION Bop(IN B){
IF [NOT[[TRUE AND FALSE]OR[TRUE]]] THEN B := 100/2;
ELSE B := 100;
ENDIF;
RETURN B;
}
ENDFUNCTION
CALL Aop(INOUT A);
CALL Bop(IN B);
A := 40;
C := A * B;
}
ENDPROGRAM
我讨厌它,如果我的编程语言总是喊回我... – Bobby 2011-12-16 13:26:34