Added "pre-sort only" mode as Robert suggested.

[libucw.git] / lib / sorter.h

diff --git a/lib/sorter.h b/lib/sorter.h
index 9611e08279fef9ef45599bc06e5ec5275f9ea843..b61d630d9454cb22466592562a8c40824011c0ef 100644 (file)
--- a/lib/sorter.h
+++ b/lib/sorter.h
@@ -18,10 +18,14 @@
  *  SORT_KEY       [*] data type capable of storing a single key
  *  SORT_PREFIX(x)  [*] add a name prefix (used on all global names
  *                     defined by the sorter)
- *  SORT_PRESORT       include an in-core presorting pass. Beware, when in
+ *  SORT_PRESORT       include an in-core pre-sorting pass. Beware, when in
  *                     the pre-sorting mode, it's quite possible that the
  *                     comparison function will be called with both arguments
  *                     identical.
+ *  SORT_PRESORT_ONLY  a C expression which, if evaluated to non-zero, makes
+ *                     the sorter stop after the pre-sorting pass, resulting
+ *                     in a file which is not necessarily sorted, but which
+ *                     contains long runs. Implies SORT_PRESORT.
  *  SORT_UNIFY         merge items with identical keys
  *  SORT_UNIQUE                all items have distinct keys (checked in debug mode)
  *  SORT_REGULAR       all items are equally long and they don't contain
@@ -120,6 +124,13 @@ extern uns sorter_pass_counter;
 #define SORT_ASSERT_UNIQUE
 #endif
 
+#ifdef SORT_PRESORT_ONLY
+#undef SORT_PRESORT
+#define SORT_PRESORT
+#else
+#define SORT_PRESORT_ONLY 0
+#endif
+
 #ifdef SORT_REGULAR
 
 static inline int
@@ -152,10 +163,7 @@ static struct fastbuf *
 P(flush_out)(struct fastbuf *out)
 {
   if (out)
-    {
-      bflush(out);
-      bsetpos(out, 0);
-    }
+    brewind(out);
   return out;
 }
 
@@ -388,7 +396,8 @@ P(presort)(struct fastbuf **fb1, struct fastbuf **fb2)
   leftover = NULL;
   while (cont)
     {
-      SWAP(out1, out2, tbuf);
+      if (!(SORT_PRESORT_ONLY))
+       SWAP(out1, out2, tbuf);
       if (!out1)
        out1 = bopen_tmp(sorter_stream_bufsize);
       current = buffer;
@@ -542,5 +551,7 @@ struct fastbuf *fb1, struct fastbuf *fb2
 #undef SORT_INPUT_FBPAIR
 #undef SORT_OUTPUT_FILE
 #undef SORT_OUTPUT_FB
+#undef SORT_PRESORT
+#undef SORT_PRESORT_ONLY
 
 #endif         /* !SORT_DECLARE_ONLY */