Stop putting dsfs in existing scratch int arrays.

I'm going to work towards turning 'dsf' into an opaque type, so that I
can improve its implementation without breaking clients. The first
step is to deal manually with puzzles that currently reuse a single
array of ints for multiple purposes, some of which are dsf and some
are not.

In divvy_rectangle_attempt, 'tmp' was used as an int array and later a
dsf, and I've made a new 'tmpdsf' to be the latter.

In Dominosa, solver->pc_scratch2 was sometimes a dsf, and now there's
a new solver->dsf_scratch.

In Map, parse_edge_list() needed a dsf internally and then never
exported it; it expected to be passed an array of 2*w*h ints and used
the second half as a dsf. Now it expects only w*h ints, and allocates
its own dsf internally, freeing it again before returning.

And in Tents, find_errors() was allocating a single block of 2*w*h
ints and using the second half of it as a dsf, apparently just to save
one malloc. Now we malloc and free the dsf separately.

1 files changed, 25 insertions, 14 deletions

diff --git a/map.c b/map.c
index fff4486..1122466 100644
--- a/map.c
+++ b/map.c
@@ -1724,8 +1724,8 @@ static const char *parse_edge_list(const game_params *params,
     int i, k, pos;
     bool state;
     const char *p = *desc;
-
-    dsf_init(map+wh, wh);
+    const char *err = NULL;
+    int *dsf = snew_dsf(wh);
 
     pos = -1;
     state = false;
@@ -1736,8 +1736,10 @@ static const char *parse_edge_list(const game_params *params,
      * pairs of squares whenever the edge list shows a non-edge).
      */
     while (*p && *p != ',') {
-	if (*p < 'a' || *p > 'z')
-	    return "Unexpected character in edge list";
+	if (*p < 'a' || *p > 'z') {
+            err = "Unexpected character in edge list";
+            goto out;
+        }
 	if (*p == 'z')
 	    k = 25;
 	else
@@ -1760,10 +1762,12 @@ static const char *parse_edge_list(const game_params *params,
 		y = (pos - w*(h-1)) % h;
 		dx = 1;
 		dy = 0;
-	    } else
-		return "Too much data in edge list";
+	    } else {
+                err = "Too much data in edge list";
+                goto out;
+            }
 	    if (!state)
-		dsf_merge(map+wh, y*w+x, (y+dy)*w+(x+dx));
+		dsf_merge(dsf, y*w+x, (y+dy)*w+(x+dx));
 
 	    pos++;
 	}
@@ -1772,8 +1776,10 @@ static const char *parse_edge_list(const game_params *params,
 	p++;
     }
     assert(pos <= 2*wh-w-h);
-    if (pos < 2*wh-w-h)
-	return "Too little data in edge list";
+    if (pos < 2*wh-w-h) {
+        err = "Too little data in edge list";
+        goto out;
+    }
 
     /*
      * Now go through again and allocate region numbers.
@@ -1782,17 +1788,22 @@ static const char *parse_edge_list(const game_params *params,
     for (i = 0; i < wh; i++)
 	map[i] = -1;
     for (i = 0; i < wh; i++) {
-	k = dsf_canonify(map+wh, i);
+	k = dsf_canonify(dsf, i);
 	if (map[k] < 0)
 	    map[k] = pos++;
 	map[i] = map[k];
     }
-    if (pos != n)
-	return "Edge list defines the wrong number of regions";
+    if (pos != n) {
+        err = "Edge list defines the wrong number of regions";
+        goto out;
+    }
 
     *desc = p;
+    err = NULL; /* no error */
 
-    return NULL;
+  out:
+    sfree(dsf);
+    return err;
 }
 
 static const char *validate_desc(const game_params *params, const char *desc)
@@ -1802,7 +1813,7 @@ static const char *validate_desc(const game_params *params, const char *desc)
     int *map;
     const char *ret;
 
-    map = snewn(2*wh, int);
+    map = snewn(wh, int);
     ret = parse_edge_list(params, &desc, map);
     sfree(map);
     if (ret)