From 9cf016e1a6ae5d4a9ba9191b97b872965056941a Mon Sep 17 00:00:00 2001
From: Justin Ethier <justin.ethier@gmail.com>
Date: Wed, 29 Jun 2016 22:55:18 -0400
Subject: [PATCH] More cleanup, generalize apply_va logic

---
 runtime.c | 88 +++++++++++++++++++++++++++++--------------------------
 1 file changed, 46 insertions(+), 42 deletions(-)

diff --git a/runtime.c b/runtime.c
index ebd38297..df82f4f9 100644
--- a/runtime.c
+++ b/runtime.c
@@ -3230,24 +3230,6 @@ void _call_95cc(void *data, object cont, object args)
   return_closcall2(data, __glo_call_95cc_scheme_base, cont, car(args));
 }
 
-void apply_va(void *data, object cont, int argc, object func, ...)
-{
-  object tmp = NULL;
-  int i;
-  va_list ap;
-  va_start(ap, func);
-  for (i = 1; i < argc; i++) {
-    tmp = va_arg(ap, object);
-  }
-  va_end(ap);
-//  fprintf(stdout, "DEBUG applying argc %d, func ", argc);
-//  Cyc_display(func, stdout);
-//  fprintf(stdout, " to values ");
-//  Cyc_display(tmp, stdout);
-//  fprintf(stdout, "\n");
-  apply(data, cont, func, tmp);
-}
-
 // Prepend value to the given list
 #define stack_prepend(lis, value) { \
   pair_type *tmp2 = alloca(sizeof(pair_type)); \
@@ -3265,38 +3247,60 @@ void apply_va(void *data, object cont, int argc, object func, ...)
   } \
 }
 
+// Front-end to apply
+//
+// Core of va processing is done here, because we need different
+// functions for apply_va and dispatch_apply_va, and those functions
+// need to start and end va. BUT, we need to allocate new objects
+// so this stuff can't be returned, so a workaround is to put it in
+// this macro.
+//
+// Fast path is just to take list, if we only have func and 1 arg.
+// Otherwise append all args together into a single list, per r7rs.
+#define do_apply_va \
+  va_start(ap, func); \
+  if (argc == 2) { \
+    lis = va_arg(ap, object); \
+    Cyc_check_pair_or_null(data, lis); \
+  } else { \
+    for (i = 1; i < argc; i++) { \
+      tmp = va_arg(ap, object); \
+      if (tmp == NULL){ \
+        continue; \
+      } else if (is_object_type(tmp) && type_of(tmp) == pair_tag) { \
+        l = tmp; \
+        stack_list_prepend(l, lis); \
+      } else { \
+        stack_prepend(lis, tmp); \
+      } \
+    } \
+    l = lis; \
+    lis = NULL; \
+    stack_list_prepend(l, lis); \
+  } \
+  va_end(ap);
+
 void dispatch_apply_va(void *data, int argc, object clo, object cont, object func, ...)
 {
-  list lis = NULL, tmp, l;
+  list lis = NULL, l;
+  object tmp;
   int i;
   va_list ap;
   argc = argc - 1; // Required for "dispatch" function
-  va_start(ap, func);
-  if (argc == 2) {
-    // Fast path, nothing to append
-    lis = va_arg(ap, object);
-    Cyc_check_pair_or_null(data, lis);
-  } else {
-    for (i = 1; i < argc; i++) {
-      tmp = va_arg(ap, object);
-      if (tmp == NULL){
-        continue;
-      } else if (is_object_type(tmp) && type_of(tmp) == pair_tag) {
-        l = tmp;
-        stack_list_prepend(l, lis);
-      } else {
-        stack_prepend(lis, tmp);
-      }
-    }
-    // Reverse lis
-    l = lis;
-    lis = NULL;
-    stack_list_prepend(l, lis);
-  }
-  va_end(ap);
+  do_apply_va
   apply(data, cont, func, lis);
 }
 
+void apply_va(void *data, object cont, int argc, object func, ...)
+{
+  list lis = NULL, l;
+  object tmp;
+  int i;
+  va_list ap;
+  do_apply_va
+  apply(data, cont, func, tmp);
+}
+
 /*
  * @param cont - Continuation for the function to call into
  * @param func - Function to execute