ylex.c

/*
    module  : ylex.c
    version : 1.10
    date    : 03/21/24
*/
#include "globals.h"

static void dumptok(Token tok)
{
    switch (tok.symb) {
    case CHAR_	  : printf("'%d", (int)tok.yylval.num);
		    break;
    case STRING_  : printf("\"%s\"", tok.yylval.str);
		    break;
    case FLOAT_	  : printf("%g", tok.yylval.dbl);
		    break;
    case INTEGER_ : printf("%" PRId64, tok.yylval.num);
		    break;
    case USR_	  : printf("%s", tok.yylval.str);
		    break;
    case '['	  : printf("LBRACK");
		    break;
    case '{'	  : printf("LBRACE");
		    break;
    case '('	  : printf("LPAREN");
		    break;
    case ']'	  : printf("RBRACK");
		    break;
    case '}'	  : printf("RBRACE");
		    break;
    case ')'	  : printf("RPAREN");
		    break;
    case ';'	  : printf("SEMICOL");
		    break;
    case EQDEF	  : printf("EQUAL");
		    break;
    case END	  : printf("END");
		    break;
    case MODULE_  : printf("MODULE");
		    break;
    case PRIVATE  : printf("PRIVATE");
		    break;
    case PUBLIC   : printf("PUBLIC");
		    break;
    case CONST_   : printf("CONST");
		    break;
    }
    printf("\n");
}

/*
 * Push a symbol into the tokenlist.
 */
static void push_symb(pEnv env, Symbol symb)
{
    Token tok;

    tok.symb = symb;
    tok.yylval = yylval;
    vec_push(env->tokens, tok);
}

/*
 * yylex - wrapper around my_yylex, storing tokens read, reading from the
 *	   store or just calling my_yylex itself. This allows tokens to be
 *	   read twice.
 *
 * After reading MODULE or PRIVATE, read all tokens upto END, and include
 * them in the tokenlist. All symbols preceding "==" are declared.
 */
int yylex(pEnv env)
{
    Token tok;
    Symbol symb;
    int module = 0, private = 0, hide = 0, modl = 0, hcnt = 0;

/*
 * If there is a tokenlist, extract tokens from there.
 */
    if (vec_size(env->tokens)) {
begin:	    
	tok = vec_pop(env->tokens);
	if (env->printing)
	    dumptok(tok);
	symb = tok.symb;
	yylval = tok.yylval;
	return symb;
    }
/*
 * There is no tokenlist, use the normal procedure to get one.
 */
    symb = my_yylex(env);
/*
 * There is a token available, do some extra processing, in case the token is
 * MODULE or PRIVATE: MODULE .. END or HIDE .. END.
 */
    if (symb == MODULE_ || symb == PRIVATE) {
/*
 * Copy the global variables of modl.c into local variables.
 */
	tok.symb = symb;
	savemod(&hide, &modl, &hcnt);
	do {
	    switch (symb) {
	    case MODULE_  : push_symb(env, symb);
			    symb = my_yylex(env);
			    if (symb == USR_) {
				initmod(env, yylval.str);
				module++;
			    } else
				yyerror(env, "atom expected as name of module");
			    break;
	    case PRIVATE  : initpriv(env);
			    if (!module)
				private++;
			    break;
	    case PUBLIC   : stoppriv();
			    break;
	    case EQDEF	  : if (tok.symb == USR_) {
				if (strchr(yylval.str, '.') == 0)
				    yylval.str = classify(env, yylval.str);
				enteratom(env, yylval.str, 0);
			    }
			    break;
	    case END	  : if (module) {
				exitmod();
				module--;
			    } else if (private) {
				exitpriv();
				private--;
			    }
			    if (!module && !private)
				goto done;
			    break;
	    }
	    tok.symb = symb;	/* previous symbol */
	    push_symb(env, symb);
	    symb = my_yylex(env);
	} while (1);
/*
 * Restore the global variables in modl.c from the local copies.
 */
done:	undomod(hide, modl, hcnt);
	push_symb(env, symb);	/* store the last symbol that was read */
	push_symb(env, symb);	/* extra sym for the benefit of reverse */
	vec_reverse(env->tokens);
    }
/*
 * If there is a tokenlist, extract tokens from there.
 */
    if (vec_size(env->tokens))
	goto begin;
    if (env->printing) {
	tok.symb = symb;
	tok.yylval = yylval;
	dumptok(tok);
    }
    return symb;
}