Make encode_ui() and decode_ui() optional in back-ends

The majority of back-ends define encode_ui() to return NULL and
decode_ui() to do nothing.  This commit allows them to instead specify
the relevant function pointers as NULL, in which case the mid-end won't
try to call them.

I'm planning to add a parameter to decode_ui(), and if I'm going to have
to touch every back-end's version of decode_ui(), I may as well ensure
that most of them never need to be touched again.  And obviously
encode_ui() should go the same way for symmetry.

4 files changed, 8 insertions, 44 deletions

diff --git a/unfinished/group.c b/unfinished/group.c
index bbac220..7a2ffe6 100644
--- a/unfinished/group.c
+++ b/unfinished/group.c
@@ -1272,15 +1272,6 @@ static void free_ui(game_ui *ui)
     sfree(ui);
 }
 
-static char *encode_ui(const game_ui *ui)
-{
-    return NULL;
-}
-
-static void decode_ui(game_ui *ui, const char *encoding)
-{
-}
-
 static void game_changed_state(game_ui *ui, const game_state *oldstate,
                                const game_state *newstate)
 {
@@ -2332,8 +2323,8 @@ const struct game thegame = {
     true, game_can_format_as_text_now, game_text_format,
     new_ui,
     free_ui,
-    encode_ui,
-    decode_ui,
+    NULL, /* encode_ui */
+    NULL, /* decode_ui */
     NULL, /* game_request_keys */
     game_changed_state,
     current_key_label,
diff --git a/unfinished/separate.c b/unfinished/separate.c
index d3423de..324a966 100644
--- a/unfinished/separate.c
+++ b/unfinished/separate.c
@@ -705,15 +705,6 @@ static void free_ui(game_ui *ui)
 {
 }
 
-static char *encode_ui(const game_ui *ui)
-{
-    return NULL;
-}
-
-static void decode_ui(game_ui *ui, const char *encoding)
-{
-}
-
 static void game_changed_state(game_ui *ui, const game_state *oldstate,
                                const game_state *newstate)
 {
@@ -845,8 +836,8 @@ const struct game thegame = {
     false, game_can_format_as_text_now, game_text_format,
     new_ui,
     free_ui,
-    encode_ui,
-    decode_ui,
+    NULL, /* encode_ui */
+    NULL, /* decode_ui */
     NULL, /* game_request_keys */
     game_changed_state,
     NULL, /* current_key_label */
diff --git a/unfinished/slide.c b/unfinished/slide.c
index 115230f..fe573e8 100644
--- a/unfinished/slide.c
+++ b/unfinished/slide.c
@@ -1217,15 +1217,6 @@ static void free_ui(game_ui *ui)
     sfree(ui);
 }
 
-static char *encode_ui(const game_ui *ui)
-{
-    return NULL;
-}
-
-static void decode_ui(game_ui *ui, const char *encoding)
-{
-}
-
 static void game_changed_state(game_ui *ui, const game_state *oldstate,
                                const game_state *newstate)
 {
@@ -2337,8 +2328,8 @@ const struct game thegame = {
     true, game_can_format_as_text_now, game_text_format,
     new_ui,
     free_ui,
-    encode_ui,
-    decode_ui,
+    NULL, /* encode_ui */
+    NULL, /* decode_ui */
     NULL, /* game_request_keys */
     game_changed_state,
     NULL, /* current_key_label */
diff --git a/unfinished/sokoban.c b/unfinished/sokoban.c
index bef7d72..65d1fa6 100644
--- a/unfinished/sokoban.c
+++ b/unfinished/sokoban.c
@@ -927,15 +927,6 @@ static void free_ui(game_ui *ui)
 {
 }
 
-static char *encode_ui(const game_ui *ui)
-{
-    return NULL;
-}
-
-static void decode_ui(game_ui *ui, const char *encoding)
-{
-}
-
 static void game_changed_state(game_ui *ui, const game_state *oldstate,
                                const game_state *newstate)
 {
@@ -1459,8 +1450,8 @@ const struct game thegame = {
     false, game_can_format_as_text_now, game_text_format,
     new_ui,
     free_ui,
-    encode_ui,
-    decode_ui,
+    NULL, /* encode_ui */
+    NULL, /* decode_ui */
     NULL, /* game_request_keys */
     game_changed_state,
     NULL, /* current_key_label */