Pg: Support custom type overrides with callbacks

c/pgtypes.c

@@ -32,6 +32,7 @@ struct fupg_tio {
             const fupg_record *info;
             fupg_tio *tio;
         } record;
+        SV *cb;
     };
 };
 
@@ -416,6 +417,52 @@ SENDFN(record) {
 }
 
 
+RECVFN(perlcb) {
+    dSP;
+
+    ENTER;
+    SAVETMPS;
+
+    PUSHMARK(SP);
+    mXPUSHs(newSVpvn(buf, len));
+    PUTBACK;
+    call_sv(ctx->cb, G_SCALAR);
+    SPAGAIN;
+
+    SV *ret = newSV(0);
+    sv_setsv(ret, POPs);
+    PUTBACK;
+
+    FREETMPS;
+    LEAVE;
+    return ret;
+}
+
+SENDFN(perlcb) {
+    dSP;
+
+    ENTER;
+    SAVETMPS;
+
+    PUSHMARK(SP);
+    XPUSHs(val);
+
+    PUTBACK;
+    call_sv(ctx->cb, G_SCALAR);
+    SPAGAIN;
+
+    SV *ret = POPs;
+    PUTBACK;
+
+    STRLEN len;
+    const char *buf = SvPV(ret, len);
+    fustr_write(out, buf, len);
+
+    FREETMPS;
+    LEAVE;
+}
+
+
 RECVFN(inet) { /* Also works for cidr */
     char tmp[128];
     if (len < 8) RERR("input data too short");
@@ -726,6 +773,8 @@ static const fupg_type fupg_builtin[] = {
 
 #define FUPG_BUILTIN (sizeof(fupg_builtin) / sizeof(fupg_type))
 
+static const fupg_type fupg_type_perlcb = { 0, 0, {"$perl_cb"}, fupg_send_perlcb, fupg_recv_perlcb };
+
 
 static const fupg_type *fupg_type_byoid(const fupg_type *list, int len, Oid oid) {
     int i, b = 0, e = len-1;