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StringFormat.xs  view on Meta::CPAN

/*
	StringFormat.xs
*/

#define PERL_NO_GET_CONTEXT
#include <EXTERN.h>
#include <perl.h>
#include <XSUB.h>

#define HINT_KEY "Acme::StringFormat"

#define my_SvPOK(sv) (SvFLAGS(sv) & (SVf_POK | SVp_POK))

static U32 sf_hash = 0;
static SV* sf_hint_key = NULL;

static UV sf_depth = 0;

typedef OP* (*ck_t)(pTHX_ OP*);
static ck_t sf_old_ck_modulo = NULL;

static OP*
sf_pp_modulo(pTHX){
	dVAR; dSP;
	SV* lhs = TOPm1s; /* top minus 1 scalar */
	SV* rhs = TOPs;

	if( my_SvPOK(lhs) ){
		dTARGET;
		STRLEN len;
		const char* start = SvPV_const(lhs, len);
		register const char* p     = start;
		register const char* end   = start + len;

		bool maybe_tainted = FALSE; /* maybe not used */

		/* start of formatter */
		while(p < end){
			if(*p == '%'){
				p++;
				if(*p != '%'){
					break;
				}
			}
			p++;
		}
		if(p == end && ckWARN(WARN_PRINTF)){
			Perl_warner(aTHX_ packWARN(WARN_PRINTF), "Arguments mismatch for %s", HINT_KEY);
		}

		/* end of formatter */
		while(p < end){
			if(*p == '%'){
				if(*(p+1) == '%'){
					p++;
				}
				else{
					break;
				}
			}
			p++;
		}

#if 0
		printf("#%s\n#", start);
		{
			int i;
			for(i = 0; i < (p - start); i++){
				printf(" ");
			}
			printf("^\n");
		}
#endif

		sv_vsetpvfn(TARG, start, (STRLEN)(p - start), NULL, &rhs, 1, &maybe_tainted);

		if(end != p) sv_catpvn(TARG, p, (STRLEN)(end - p));

		if(SvTAINTED(lhs)) SvTAINTED_on(TARG);
		if(SvUTF8(lhs))    SvUTF8_on(TARG);

		if(opASSIGN){
			sv_setsv(lhs, TARG);
			TARG = lhs;
		}

		SP--;
		SETs(TARG);
		RETURN;
	}

	return PL_ppaddr[OP_MODULO](aTHX);
}

static OP*
sf_ck_modulo(pTHX_ OP* o){
	HE* he = hv_fetch_ent(GvHV(PL_hintgv), sf_hint_key, FALSE, sf_hash);

	if( he && SvTRUE(HeVAL(he)) ){

		o->op_flags |= OPf_SPECIAL;
		o->op_ppaddr = sf_pp_modulo;
	}
	return sf_old_ck_modulo(aTHX_ o);
}

MODULE = Acme::StringFormat		PACKAGE = Acme::StringFormat

PROTOTYPES: DISABLE

BOOT:
	sf_hint_key = newSVpvs(HINT_KEY);
	PERL_HASH(sf_hash, HINT_KEY, sizeof(HINT_KEY)-1);

SV*
_enter(...)
CODE:
	PERL_UNUSED_ARG(items);
	if(sf_depth == 0){
		sf_old_ck_modulo = PL_check[OP_MODULO];
		PL_check[OP_MODULO] = sf_ck_modulo;
	}
	sf_depth++;
	RETVAL = newSV(0);
	sv_setref_uv(RETVAL, HINT_KEY, sf_depth);
OUTPUT:
	RETVAL

void
DESTROY(...)
CODE:
	PERL_UNUSED_ARG(items);
	if(sf_depth == 0){
		Perl_croak(aTHX_ "panic: %s scope underflow", HINT_KEY);
	}