Introduce routines in each game module to encode a set of game

parameters as a string, and decode it again. This is used in
midend.c to prepend the game parameters to the game seed, so that
copying out of the Specific box is sufficient to completely specify
the game you were playing.
Throughout development of these games I have referred to `seed'
internally, and `game ID' externally. Now there's a measurable
difference between them! :-)

[originally from svn r4231]

cube.c

@@ -6,6 +6,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <assert.h>
+#include <ctype.h>
 #include <math.h>
 
 #include "puzzles.h"
@@ -276,6 +277,37 @@ game_params *dup_params(game_params *params)
     return ret;
 }
 
+game_params *decode_params(char const *string)
+{
+    game_params *ret = default_params();
+
+    switch (*string) {
+      case 't': ret->solid = TETRAHEDRON; string++; break;
+      case 'c': ret->solid = CUBE;        string++; break;
+      case 'o': ret->solid = OCTAHEDRON;  string++; break;
+      case 'i': ret->solid = ICOSAHEDRON; string++; break;
+      default: break;
+    }
+    ret->d1 = ret->d2 = atoi(string);
+    while (*string && isdigit(*string)) string++;
+    if (*string == 'x') {
+        string++;
+        ret->d2 = atoi(string);
+    }
+
+    return ret;
+}
+
+char *encode_params(game_params *params)
+{
+    char data[256];
+
+    assert(params->solid >= 0 && params->solid < 4);
+    sprintf(data, "%c%dx%d", "tcoi"[params->solid], params->d1, params->d2);
+
+    return dupstr(data);
+}
+
 static void enum_grid_squares(game_params *params,
                               void (*callback)(void *, struct grid_square *),
                               void *ctx)
@@ -653,7 +685,7 @@ char *new_game_seed(game_params *params, random_state *rs)
     /*
      * Choose a non-blue square for the polyhedron.
      */
-    sprintf(p, ":%d", data.gridptrs[0][random_upto(rs, m)]);
+    sprintf(p, ",%d", data.gridptrs[0][random_upto(rs, m)]);
 
     sfree(data.gridptrs[0]);
     sfree(flags);
@@ -824,13 +856,13 @@ char *validate_seed(game_params *params, char *seed)
 	/* NB if seed[j]=='\0' that will also be caught here, so we're safe */
     }
 
-    if (seed[i] != ':')
+    if (seed[i] != ',')
-	return "Expected ':' after hex digits";
+	return "Expected ',' after hex digits";
 
     i++;
     do {
 	if (seed[i] < '0' || seed[i] > '9')
-	    return "Expected decimal integer after ':'";
+	    return "Expected decimal integer after ','";
 	i++;
     } while (seed[i]);
 
@@ -883,7 +915,7 @@ game_state *new_game(game_params *params, char *seed)
 		j = 8;
 	}
 
-	if (*p == ':')
+	if (*p == ',')
 	    p++;
 
 	state->current = atoi(p);

fifteen.c

@@ -6,6 +6,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <assert.h>
+#include <ctype.h>
 #include <math.h>
 
 #include "puzzles.h"
@@ -72,6 +73,29 @@ game_params *dup_params(game_params *params)
     return ret;
 }
 
+game_params *decode_params(char const *string)
+{
+    game_params *ret = default_params();
+
+    ret->w = ret->h = atoi(string);
+    while (*string && isdigit(*string)) string++;
+    if (*string == 'x') {
+        string++;
+        ret->h = atoi(string);
+    }
+
+    return ret;
+}
+
+char *encode_params(game_params *params)
+{
+    char data[256];
+
+    sprintf(data, "%dx%d", params->w, params->h);
+
+    return dupstr(data);
+}
+
 config_item *game_configure(game_params *params)
 {
     config_item *ret;

midend.c

@@ -333,7 +333,7 @@ int midend_wants_statusbar(midend_data *me)
 
 config_item *midend_get_config(midend_data *me, int which, char **wintitle)
 {
-    char *titlebuf;
+    char *titlebuf, *parstr;
     config_item *ret;
 
     titlebuf = snewn(40 + strlen(game_name), char);
@@ -352,7 +352,15 @@ config_item *midend_get_config(midend_data *me, int which, char **wintitle)
 	ret[0].type = C_STRING;
 	ret[0].name = "Game ID";
 	ret[0].ival = 0;
-	ret[0].sval = dupstr(me->seed);
+        /*
+         * The text going in here will be a string encoding of the
+         * parameters, plus a colon, plus the game seed. This is a
+         * full game ID.
+         */
+        parstr = encode_params(me->params);
+        ret[0].sval = snewn(strlen(parstr) + strlen(me->seed) + 2, char);
+        sprintf(ret[0].sval, "%s:%s", parstr, me->seed);
+        sfree(parstr);
 
 	ret[1].type = C_END;
 	ret[1].name = ret[1].sval = NULL;
@@ -367,7 +375,7 @@ config_item *midend_get_config(midend_data *me, int which, char **wintitle)
 
 char *midend_set_config(midend_data *me, int which, config_item *cfg)
 {
-    char *error;
+    char *error, *p;
     game_params *params;
 
     switch (which) {
@@ -385,12 +393,34 @@ char *midend_set_config(midend_data *me, int which, config_item *cfg)
 	break;
 
       case CFG_SEED:
-	error = validate_seed(me->params, cfg[0].sval);
+
+        /*
+         * The game ID will often (in fact, mostly) have a prefix
+         * containing a string-encoded parameter specification
+         * followed by a colon. So first find the colon, and then
+         * split the string up.
+         */
+        p = strchr(cfg[0].sval, ':');
+
+        if (p) {
+            *p++ = '\0';               /* p now points to game seed */
+            params = decode_params(cfg[0].sval);
+            error = validate_params(params);
+            if (error) {
+                free_params(params);
+                return error;
+            }
+            free_params(me->params);
+            me->params = params;
+        } else
+            p = cfg[0].sval;
+
+	error = validate_seed(me->params, p);
 	if (error)
 	    return error;
 
 	sfree(me->seed);
-	me->seed = dupstr(cfg[0].sval);
+	me->seed = dupstr(p);
 	me->fresh_seed = TRUE;
 
 	break;

net.c

@@ -6,6 +6,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <assert.h>
+#include <ctype.h>
 #include <math.h>
 
 #include "puzzles.h"
@@ -183,6 +184,44 @@ game_params *dup_params(game_params *params)
     return ret;
 }
 
+game_params *decode_params(char const *string)
+{
+    game_params *ret = default_params();
+    char const *p = string;
+
+    ret->width = atoi(p);
+    while (*p && isdigit(*p)) p++;
+    if (*p == 'x') {
+        p++;
+        ret->height = atoi(p);
+        while (*p && isdigit(*p)) p++;
+        if ( (ret->wrapping = (*p == 'w')) != 0 )
+            p++;
+        if (*p == 'b')
+            ret->barrier_probability = atof(p+1);
+    } else {
+        ret->height = ret->width;
+    }
+
+    return ret;
+}
+
+char *encode_params(game_params *params)
+{
+    char ret[400];
+    int len;
+
+    len = sprintf(ret, "%dx%d", params->width, params->height);
+    if (params->wrapping)
+        ret[len++] = 'w';
+    if (params->barrier_probability)
+        len += sprintf(ret+len, "b%g", params->barrier_probability);
+    assert(len < lenof(ret));
+    ret[len] = '\0';
+
+    return dupstr(ret);
+}
+
 config_item *game_configure(game_params *params)
 {
     config_item *ret;

nullgame.c

@@ -15,6 +15,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <assert.h>
+#include <ctype.h>
 #include <math.h>
 
 #include "puzzles.h"
@@ -61,6 +62,20 @@ game_params *dup_params(game_params *params)
     return ret;
 }
 
+game_params *decode_params(char const *string)
+{
+    game_params *ret = snew(game_params);
+
+    ret->FIXME = 0;
+
+    return ret;
+}
+
+char *encode_params(game_params *params)
+{
+    return dupstr("FIXME");
+}
+
 config_item *game_configure(game_params *params)
 {
     return NULL;

puzzles.h

@@ -162,6 +162,8 @@ extern const char *const game_name;
 const int game_can_configure;
 game_params *default_params(void);
 int game_fetch_preset(int i, char **name, game_params **params);
+game_params *decode_params(char const *string);
+char *encode_params(game_params *);
 void free_params(game_params *params);
 game_params *dup_params(game_params *params);
 config_item *game_configure(game_params *params);

rect.c

@@ -34,6 +34,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <assert.h>
+#include <ctype.h>
 #include <math.h>
 
 #include "puzzles.h"
@@ -129,6 +130,29 @@ game_params *dup_params(game_params *params)
     return ret;
 }
 
+game_params *decode_params(char const *string)
+{
+    game_params *ret = default_params();
+
+    ret->w = ret->h = atoi(string);
+    while (*string && isdigit(*string)) string++;
+    if (*string == 'x') {
+        string++;
+        ret->h = atoi(string);
+    }
+
+    return ret;
+}
+
+char *encode_params(game_params *params)
+{
+    char data[256];
+
+    sprintf(data, "%dx%d", params->w, params->h);
+
+    return dupstr(data);
+}
+
 config_item *game_configure(game_params *params)
 {
     config_item *ret;

sixteen.c

@@ -8,6 +8,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <assert.h>
+#include <ctype.h>
 #include <math.h>
 
 #include "puzzles.h"
@@ -92,6 +93,29 @@ game_params *dup_params(game_params *params)
     return ret;
 }
 
+game_params *decode_params(char const *string)
+{
+    game_params *ret = default_params();
+
+    ret->w = ret->h = atoi(string);
+    while (*string && isdigit(*string)) string++;
+    if (*string == 'x') {
+        string++;
+        ret->h = atoi(string);
+    }
+
+    return ret;
+}
+
+char *encode_params(game_params *params)
+{
+    char data[256];
+
+    sprintf(data, "%dx%d", params->w, params->h);
+
+    return dupstr(data);
+}
+
 config_item *game_configure(game_params *params)
 {
     config_item *ret;