Add memory-streams to list of features

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## 0.35.0 - TBD
 
+Features
+
+- Add `memory-streams` to the list of symbols that `(features)` can return, indicating that the current installation supports in-memory streams.
+
 Bug Fixes
 
 - Enforce a maximum recursion depth when printing an object via `display` and `write`, and when comparing objects via `equal?`. This prevents segmentation faults when working with circular data structures.

include/cyclone/runtime.h

@@ -375,6 +375,7 @@ object Cyc_io_peek_u8(void *data, object cont, object port);
 object Cyc_write_bytevector(void *data, object bvec, object port, object start, object end);
 object Cyc_io_read_line(void *data, object cont, object port);
 void Cyc_io_read_token(void *data, object cont, object port);
+int Cyc_have_mstreams();
 /**@}*/
 
 

mstreams.c

@@ -32,6 +32,15 @@ if (obj_is_not_closure(clo)) { \
  } \
 }
 
+int Cyc_have_mstreams()
+{
+#if CYC_HAVE_FMEMOPEN && CYC_HAVE_OPEN_MEMSTREAM
+  return 1;
+#else
+  return 0;
+#endif
+}
+
 object Cyc_heap_alloc_port(void *data, port_type *p);
 port_type *Cyc_io_open_input_string(void *data, object str)
 {

runtime.c

@@ -2942,6 +2942,13 @@ object Cyc_compilation_environment(void *data, object cont, object var)
       snprintf(buf, sizeof(buf), "%s", CYC_PLATFORM);
       make_utf8_string(data, str, buf);
       _return_closcall1(data, cont, &str);
+    } else if (strncmp(((symbol) var)->desc, "memory-streams", 9) == 0) {
+      char buf[] = "memory-streams";
+      if (!Cyc_have_mstreams()) {
+        buf[0] = '\0';
+      }
+      make_utf8_string(data, str, buf);
+      _return_closcall1(data, cont, &str);
     }
   }
   Cyc_rt_raise2(data, 

scheme/base.sld

@@ -235,6 +235,9 @@
   (begin
     ;; Features implemented by this Scheme
     (define (features) 
+      (let ((feats *other-features*))
+        (if (> (string-length (Cyc-compilation-environment 'memory-streams)) 0)
+          (set! feats (cons 'memory-streams feats)))
         (cons 
           'cyclone
           (cons
@@ -242,7 +245,7 @@
               (string-append "version-" *version-number*))
             (cons
               (string->symbol (Cyc-compilation-environment 'platform))
-            *other-features*))))
+              feats)))))
 
     (define *other-features* 
             '(r7rs