--- CBOR-XS/XS.xs	2020/11/30 20:38:25	1.69
+++ CBOR-XS/XS.xs	2021/10/23 03:00:31	1.73
@@ -30,6 +30,9 @@
 # define SvREFCNT_dec_NN(sv) SvREFCNT_dec (sv)
 #endif
 
+// perl's is_utf8_string interprets len=0 as "calculate len", but we want it to mean 0
+#define cbor_is_utf8_string(str,len) (!(len) || is_utf8_string ((str), (len)))
+
 // known major and minor types
 enum cbor_type
 {
@@ -111,6 +114,7 @@
   AS_FLOAT16 = 4,
   AS_FLOAT32 = 5,
   AS_FLOAT64 = 6,
+  AS_MAP     = 7,
   // possibly future enhancements: (generic) float, (generic) string
 };
 
@@ -202,7 +206,7 @@
 }
 
 // minimum length of a string to be registered for stringref
-ecb_inline int
+ecb_inline STRLEN
 minimum_string_length (UV idx)
 {
   return idx <=          23 ?  3
@@ -241,6 +245,8 @@
     }
 }
 
+static void encode_sv (enc_t *enc, SV *sv);
+
 ecb_inline void
 encode_ch (enc_t *enc, char ch)
 {
@@ -425,6 +431,38 @@
   encode_ch (enc, istrue ? MAJOR_MISC | SIMPLE_TRUE : MAJOR_MISC | SIMPLE_FALSE);
 }
 
+// encodes an arrayref containing key-value pairs as CBOR map
+ecb_inline void
+encode_array_as_map (enc_t *enc, SV *sv)
+{
+  if (enc->depth >= enc->cbor.max_depth)
+    croak (ERR_NESTING_EXCEEDED);
+
+  ++enc->depth;
+
+  // as_map does error checking for us, but we re-check in case
+  // things have changed.
+
+  if (!SvROK (sv) || SvTYPE (SvRV (sv)) != SVt_PVAV)
+    croak ("CBOR::XS::as_map requires an array reference (did you change the array after calling as_map?)");
+
+  AV *av = (AV *)SvRV (sv);
+  int i, len = av_len (av);
+
+  if (!(len & 1))
+    croak ("CBOR::XS::as_map requires an even number of elements (did you change the array after calling as_map?)");
+
+  encode_uint (enc, MAJOR_MAP, (len + 1) >> 1);
+
+  for (i = 0; i <= len; ++i)
+    {
+      SV **svp = av_fetch (av, i, 0);
+      encode_sv (enc, svp ? *svp : &PL_sv_undef);
+    }
+
+  --enc->depth;
+}
+
 ecb_inline void
 encode_forced (enc_t *enc, UV type, SV *sv)
 {
@@ -463,13 +501,13 @@
       case AS_FLOAT32: encode_float32 (enc, SvNV (sv)); break;
       case AS_FLOAT64: encode_float64 (enc, SvNV (sv)); break;
 
+      case AS_MAP: encode_array_as_map (enc, sv); break;
+
       default:
         croak ("encountered malformed CBOR::XS::Tagged object");
     }
 }
 
-static void encode_sv (enc_t *enc, SV *sv);
-
 static void
 encode_av (enc_t *enc, AV *av)
 {
@@ -954,7 +992,7 @@
         dec->cur += len;
 
         if (ecb_expect_false (dec->cbor.flags & F_VALIDATE_UTF8))
-          if (!is_utf8_string (key, len))
+          if (!cbor_is_utf8_string ((U8 *)key, len))
             ERR ("corrupted CBOR data (invalid UTF-8 in map key)");
 
         hv_store (hv, key, -len, decode_sv (dec), 0);
@@ -1093,7 +1131,7 @@
   if (utf8)
     {
       if (ecb_expect_false (dec->cbor.flags & F_VALIDATE_UTF8))
-        if (!is_utf8_string (SvPVX (sv), SvCUR (sv)))
+        if (!cbor_is_utf8_string (SvPVX (sv), SvCUR (sv)))
           ERR ("corrupted CBOR data (invalid UTF-8 in text string)");
 
       SvUTF8_on (sv);
@@ -1536,6 +1574,7 @@
 
                       case MAJOR_MAP     >> MAJOR_SHIFT:
                         len <<= 1;
+                        /* FALLTHROUGH */
                       case MAJOR_ARRAY   >> MAJOR_SHIFT:
                         if (len)
                           {