nepc.l

使用yacc和lex编写的cmm语言的词法分析和语法分析程序.

%{

#include "y.tab.h"
#include "nepc.h"

%}

digit       [0-9]
xdigit      [0-9a-fA-F]
odigit      [0-7]

dec_int     0|[1-9]{digit}*
dec_flt   (0\.{digit}*)|([1-9]{digit}*\.{digit}*)
oct_int     0{odigit}+
hex_int     0(x|X){xdigit}+

letter      [a-zA-Z]
variable    {letter}({letter}|{digit})*

%x          ASTRING
%%
                char *s, *v;
                char tmpstr[MAX_STRLEN];
\"              { BEGIN ASTRING; s = tmpstr; }
<ASTRING>\\n    { *s++ = '\n'; /* CARE BUFFER OVERFLOW HERE!!! */ }
<ASTRING>\\t    { *s++ = '\t'; /* CARE BUFFER OVERFLOW HERE!!! */ }
<ASTRING>\\\"   { *s++ = '\"'; /* CARE BUFFER OVERFLOW HERE!!! */ }
<ASTRING>\"     {
                    *s = '\0';
                    BEGIN 0; 
                    yylval.pStr = tmpstr;
                    return STRING;
                }
<ASTRING>\n     { printf("invalid string"); exit(1); }
<ASTRING>.      { *s++ = *yytext; }

"while"     return WHILE;
"if"        return IF;
"else"      return ELSE;
"print"     return PRINT;

"exit"      return EXIT;
"quit"      return EXIT;
"erase"     return ERASE;
"clear"     return CLEAR;
"cls"       return CLEAR;
"ls"        return LIST;
"list"      return LIST;
"help"      return HELP;
"dec"       return DEC;
"hex"       return HEX;
"oct"       return OCT;

"acos"      return ACOS;
"asin"      return ASIN;
"atan"      return ATAN;
"ceil"      return CEIL;
"cos"       return COS;
"cosh"      return COSH;
"exp"       return EXP;
"fabs"      return FABS;
"floor"     return FLOOR;
"log"       return LOG;
"log10"     return LOG10;
"sin"       return SIN;
"sinh"      return SINH;
"sqrt"      return SQRT;
"tan"       return TAN;
"tanh"      return TANH;

{variable}  {
                v=malloc(yyleng+1);
                strncpy(v, yytext, yyleng);
                v[yyleng]='\0';
                yylval.pStr = v;
                return VARIABLE;
            }

{dec_int}   {
                yylval.iValue = STR_TO_INT(yytext);
                return INTEGER;
            }

{dec_flt}   {
                yylval.fValue = STR_TO_FLT(yytext);
                return FLOAT;
            }

{oct_int}   {
                int i=1; 
                INT val=0;
                while(i<yyleng)
                {
                    val=(val<<3)+yytext[i]-'0';
                    i++;
                }
                yylval.iValue=val;
                return INTEGER;
            }

{hex_int}   {
                int i=2;
                INT val=0;
                while(i<yyleng)
                {
                    if(islower(yytext[i])) val=(val<<4)+yytext[i]-'a'+10;
                    else if(isupper(yytext[i])) val=(val<<4)+yytext[i]-'A'+10;
                    else val=(val<<4)+yytext[i]-'0';
                    i++;
                }
                yylval.iValue=val;
                return INTEGER;
            }

[-()<>=+*/{}.;%] {
                    return *yytext;
                }
">="            return GE;
"<="            return LE;
"=="            return EQ;
"!="            return NE;
"&&"            return AND;
"||"            return OR;
"++"            return PP;
"--"            return SS;

[ \t\n]+          ;       /* ignore whitespace */
.               yyerror("Unknown character");


%%
int yywrap(void) 
{
    return 1;
}