From c5134a9ddba4fd14703d506b0cccd51d823e013e Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Sat, 30 May 2020 07:38:12 -0700
Subject: quasistrings: reduce consing.

Quasistrings compile to code that requires on the sys:fmt-join
function to glue strings together. Rewriting that function to
avoid converting its arguments from struct args * to a list.

* eval.c (fmt_join): Static function removed.

* lib.c (cat_str_measure, cat_str_append): more_p parameter
changed to int type, which better matches the C style Boolean
values it takes.
(fmt_join): New external function.

* lib.h: Declared.

* args.h (args_more_nozap, args_get_nozap): New inline
functions allowing multiple iterations over arguments without
making a copy.
---
 lib.c | 40 ++++++++++++++++++++++++++++++++++------
 1 file changed, 34 insertions(+), 6 deletions(-)

(limited to 'lib.c')

diff --git a/lib.c b/lib.c
index 6180d87a..ef3d511c 100644
--- a/lib.c
+++ b/lib.c
@@ -4101,7 +4101,7 @@ static void cat_str_init(struct cat_str *cs, val sep, wchar_t *onech)
   }
 }
 
-static void cat_str_measure(struct cat_str *cs, val item, val more_p)
+static void cat_str_measure(struct cat_str *cs, val item, int more_p)
 {
   if (!item)
     return;
@@ -4143,7 +4143,7 @@ static void cat_str_alloc(struct cat_str *cs)
   cs->ptr = cs->str = chk_wmalloc(cs->total);
 }
 
-static void cat_str_append(struct cat_str *cs, val item, val more_p)
+static void cat_str_append(struct cat_str *cs, val item, int more_p)
 {
   if (!item)
     return;
@@ -4176,12 +4176,12 @@ val cat_str(val list, val sep)
   cat_str_init(&cs, sep, onech);
 
   for (iter = list; iter != nil; iter = cdr(iter))
-    cat_str_measure(&cs, car(iter), cdr(iter));
+    cat_str_measure(&cs, car(iter), cdr(iter) != nil);
 
   cat_str_alloc(&cs);
 
   for (iter = list; iter != nil; iter = cdr(iter))
-    cat_str_append(&cs, car(iter), cdr(iter));
+    cat_str_append(&cs, car(iter), cdr(iter) != nil);
 
   return cat_str_get(&cs);
 }
@@ -4197,7 +4197,7 @@ static val vscat(val sep, va_list vl1, va_list vl2)
   for (item = va_arg(vl1, val); item != nao; item = next)
   {
     next = va_arg(vl1, val);
-    cat_str_measure(&cs, item, tnil(next != nao));
+    cat_str_measure(&cs, item, next != nao);
   }
 
   cat_str_alloc(&cs);
@@ -4205,7 +4205,7 @@ static val vscat(val sep, va_list vl1, va_list vl2)
   for (item = va_arg(vl2, val); item != nao; item = next)
   {
     next = va_arg(vl2, val);
-    cat_str_append(&cs, item, tnil(next != nao));
+    cat_str_append(&cs, item, next != nao);
   }
 
   return cat_str_get(&cs);
@@ -4223,6 +4223,34 @@ val scat(val sep, ...)
   return ret;
 }
 
+val fmt_join(struct args *args)
+{
+  cnum index;
+  val iter;
+  int more;
+  struct cat_str cs;
+
+  cat_str_init(&cs, nil, 0);
+
+  for (index = 0, iter = args->list, more = args_more_nozap(args, index, iter);
+       more;)
+  {
+    val item = args_get_nozap(args, &index, &iter);
+    cat_str_measure(&cs, item, more = args_more_nozap(args, index, iter));
+  }
+
+  cat_str_alloc(&cs);
+
+  for (index = 0, iter = args->list, more = args_more_nozap(args, index, iter);
+       more;)
+  {
+    val item = args_get_nozap(args, &index, &iter);
+    cat_str_append(&cs, item, more = args_more_nozap(args, index, iter));
+  }
+
+  return cat_str_get(&cs);
+}
+
 val split_str_keep(val str, val sep, val keep_sep)
 {
   keep_sep = default_null_arg(keep_sep);
-- 
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