From: Perl 5 Porters <perl5-porters@africa.nicoh.com>
Date: Sun, 7 Jul 1996 20:45:42 +0000 (+0000)
Subject: Add default UNIVERSAL methods to core
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=6d4a7be2b18d1674acf2ccc0da715a204e2d1ed0;p=p5sagit%2Fp5-mst-13.2.git

Add default UNIVERSAL methods to core
---

diff --git a/universal.c b/universal.c
new file mode 100644
index 0000000..830e206
--- /dev/null
+++ b/universal.c
@@ -0,0 +1,232 @@
+#include "EXTERN.h"
+#include "perl.h"
+#include "XSUB.h"
+
+/*
+ * Contributed by Graham Barr  <Graham.Barr@tiuk.ti.com>
+ * The main guts of traverse_isa was actually copied from gv_fetchmeth
+ */
+
+static SV *
+isa_lookup(stash, name, len, level)
+HV *stash;
+char *name;
+int len;
+int level;
+{
+    AV* av;
+    GV* gv;
+    GV** gvp;
+    HV* hv = Nullhv;
+
+    if (!stash)
+	return &sv_undef;
+
+    if(strEQ(HvNAME(stash), name))
+	return &sv_yes;
+
+    if (level > 100)
+	croak("Recursive inheritance detected");
+
+    gvp = (GV**)hv_fetch(stash, "::ISA::CACHE::", 14, FALSE);
+
+    if (gvp && (gv = *gvp) != (GV*)&sv_undef && (hv = GvHV(gv))) {
+	SV* sv;
+	SV** svp = (SV**)hv_fetch(hv, name, len, FALSE);
+	if (svp && (sv = *svp) != (SV*)&sv_undef)
+	    return sv;
+    }
+
+    gvp = (GV**)hv_fetch(stash,"ISA",3,FALSE);
+    
+    if (gvp && (gv = *gvp) != (GV*)&sv_undef && (av = GvAV(gv))) {
+	if(!hv) {
+	    gvp = (GV**)hv_fetch(stash, "::ISA::CACHE::", 14, TRUE);
+
+	    gv = *gvp;
+
+	    if (SvTYPE(gv) != SVt_PVGV)
+		gv_init(gv, stash, "::ISA::CACHE::", 14, TRUE);
+
+	    hv = GvHVn(gv);
+	}
+	if(hv) {
+	    SV** svp = AvARRAY(av);
+	    I32 items = AvFILL(av) + 1;
+	    while (items--) {
+		SV* sv = *svp++;
+		HV* basestash = gv_stashsv(sv, FALSE);
+		if (!basestash) {
+		    if (dowarn)
+			warn("Can't locate package %s for @%s::ISA",
+			    SvPVX(sv), HvNAME(stash));
+		    continue;
+		}
+		if(&sv_yes == isa_lookup(basestash, name, len, level + 1)) {
+		    (void)hv_store(hv,name,len,&sv_yes,0);
+		    return &sv_yes;
+		}
+	    }
+	    (void)hv_store(hv,name,len,&sv_no,0);
+	}
+    }
+
+    return &sv_no;
+}
+
+static
+XS(XS_UNIVERSAL_isa)
+{
+    dXSARGS;
+    SV *sv, *rv;
+    char *name;
+
+    if (items != 2)
+	croak("Usage: UNIVERSAL::isa(reference, kind)");
+
+    sv = ST(0);
+    name = (char *)SvPV(ST(1),na);
+
+    if (!SvROK(sv)) {
+        rv = &sv_no;
+    }
+    else if((sv = (SV*)SvRV(sv)) && SvOBJECT(sv) &&
+     &sv_yes == isa_lookup(SvSTASH(sv), name, strlen(name), 0)) {
+	rv = &sv_yes;
+    }
+    else {
+        char *s;
+
+        switch (SvTYPE(sv)) {
+            case SVt_NULL:
+    	    case SVt_IV:
+	    case SVt_NV:
+	    case SVt_RV:
+	    case SVt_PV:
+	    case SVt_PVIV:
+	    case SVt_PVNV:
+	    case SVt_PVBM:
+	    case SVt_PVMG:  s = "SCALAR";       break;
+	    case SVt_PVLV:  s = "LVALUE";       break;
+	    case SVt_PVAV:  s = "ARRAY";        break;
+	    case SVt_PVHV:  s = "HASH";         break;
+	    case SVt_PVCV:  s = "CODE";         break;
+	    case SVt_PVGV:  s = "GLOB";         break;
+	    case SVt_PVFM:  s = "FORMATLINE";   break;
+	    case SVt_PVIO:  s = "FILEHANDLE";   break;
+	    default:        s = "UNKNOWN";      break;
+        }
+        rv = strEQ(s,name) ? &sv_yes : &sv_no;
+    }
+
+    ST(0) = rv;
+    XSRETURN(1);
+}
+
+static
+XS(XS_UNIVERSAL_can)
+{
+    dXSARGS;
+    SV   *sv;
+    char *name;
+    SV   *rv;
+    GV   *gv;
+    CV   *cvp;
+
+    if (items != 2)
+	croak("Usage: UNIVERSAL::can(object-ref, method)");
+
+    sv = ST(0);
+    name = (char *)SvPV(ST(1),na);
+    rv = &sv_undef;
+
+    if(SvROK(sv) && (sv = (SV*)SvRV(sv)) && SvOBJECT(sv)) {
+        gv = gv_fetchmethod(SvSTASH(sv), name);
+
+        if(gv && GvCV(gv)) {
+            /* If the sub is only a stub then we may have a gv to AUTOLOAD */
+            GV **gvp = (GV**)hv_fetch(GvSTASH(gv), name, strlen(name), TRUE);
+            if(gvp && (cvp = GvCV(*gvp))) {
+                rv = sv_newmortal();
+                sv_setsv(rv, newRV((SV*)cvp));
+            }
+        }
+    }
+
+    ST(0) = rv;
+    XSRETURN(1);
+}
+
+static
+XS(XS_UNIVERSAL_is_instance)
+{
+    dXSARGS;
+    ST(0) = SvROK(ST(0)) ? &sv_yes : &sv_no;
+    XSRETURN(1);
+}
+
+static
+XS(XS_UNIVERSAL_class)
+{
+    dXSARGS;
+    if(SvROK(ST(0))) {
+        SV *sv = sv_newmortal();
+        sv_setpv(sv, HvNAME(SvSTASH(ST(0))));
+        ST(0) = sv;
+    }
+    XSRETURN(1);
+}
+
+static
+XS(XS_UNIVERSAL_VERSION)
+{
+    dXSARGS;
+    HV *pkg;
+    GV **gvp;
+    GV *gv;
+    SV *sv;
+    char *undef;
+
+    if(SvROK(ST(0))) {
+        sv = (SV*)SvRV(ST(0));
+        if(!SvOBJECT(sv))
+            croak("Cannot find version of an unblessed reference");
+        pkg = SvSTASH(sv);
+    }
+    else {
+        pkg = gv_stashsv(ST(0), FALSE);
+    }
+
+    gvp = pkg ? (GV**)hv_fetch(pkg,"VERSION",7,FALSE) : Null(GV**);
+
+    if (gvp && (gv = *gvp) != (GV*)&sv_undef && (sv = GvSV(gv))) {
+        SV *nsv = sv_newmortal();
+        sv_setsv(nsv, sv);
+        sv = nsv;
+        undef = Nullch;
+    }
+    else {
+        sv = (SV*)&sv_undef;
+        undef = "(undef)";
+    }
+
+    if(items > 1 && (undef || SvNV(ST(1)) > SvNV(sv)))
+	croak("%s version %s required--this is only version %s",
+	    HvNAME(pkg),SvPV(ST(1),na),undef ? undef : SvPV(sv,na));
+
+    ST(0) = sv;
+
+    XSRETURN(1);
+}
+
+void
+boot_core_UNIVERSAL()
+{
+    char *file = __FILE__;
+
+    newXS("UNIVERSAL::isa",             XS_UNIVERSAL_isa,         file);
+    newXS("UNIVERSAL::can",             XS_UNIVERSAL_can,         file);
+    newXS("UNIVERSAL::class",           XS_UNIVERSAL_class,       file);
+    newXS("UNIVERSAL::is_instance",     XS_UNIVERSAL_is_instance, file);
+    newXS("UNIVERSAL::VERSION", 	XS_UNIVERSAL_VERSION, 	  file);
+}