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c-compiler

c compiler with lex and yacc

q1

q2

Note: There are 1 shift/reduce conflicts, correctly resolved by default: IF '(' expression ')' statement _ ELSE statement

Solve unary via %prec

Solve ++ with lexer INC_OP

union define tokens, pass yylval.str from lex to yacc

%option yylineno use linenon

yacc recursive $$ $1

TODO

lineno

c0 tokens

public enum TokenType 
{
	//关键字
	IF,ELSE,WHILE,RETURN,VOID,INT, 
	//运算符 + - * /  =  <  <=  >  >=  !=  … 
	PLUS,MINUS,STAR,SLASH, LT,LTEQ,GT,GTEQ,EQ,NEQ,ASSIGN,
	//界符 ;  ,  (  )  [  ]  {  }  /*  */
	SEMI,COMMA,LPAREN,RPAREN,LSQUAR,RSQUAR,LBRACE,RBRACE,
	LCOMMENT,RCOMMENT,
	ID, 				//标识符
	NUMBER, 			//数字常量

『 ID→letter(letter|didit)* NUMBER→digit digit * letter→a|b|…|z|A|B|…|Z digit→0|…|9 』 NONTOKEN,ERROR,ENDFILE // 其它 };

c0 pattern

program→ { var-declaration | fun-declaration } var-declaration→ int ID { , ID }
fun-declaration→ ( int | void ) ID ( params ) compound-stmt params → int ID { , int ID } | void | empty compound-stmt→ { { var-declaration } { statement } } statement→ expression-stmt∣compound-stmt ∣if-stmt ∣while-stmt |return-stmt expression-stmt→ [ expression ] ; if-stmt→ if( expression ) statement [ else statement ] while-stmt→ while( expression ) statement return-stmt→ return [ expression ] ; expression→ ID = expression | simple-expression simple-expression→ additive-expression [ relop additive-expression ] relop → < | <= | > | >= | == | != additive-expression→ term [( + | - ) term ] term→ factor [ ( * | / ) factor ] factor→ ( expression )| ID | call | NUM call→ ID( args ) args→ expression { , expression } | empty ID →… ;参见C语言标识符定义 NUM →… ;参见C语言数的定义

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