[Freeciv-Dev] (PR#13366) get_invention and A_FUTURE

["Mateusz Stefek" <mstefek@xxxxxxxxx>]

<URL: http://bugs.freeciv.org/Ticket/Display.html?id=13366 >

Get invention doesn't work well with A_FUTURE and update_research()
doesn't mark A_FUTURE as TECH_RESEARCHABLE when it should.

This patch cleans up this part of tech code.
--
mateusz

Index: common/tech.c
===================================================================
RCS file: /home/freeciv/CVS/freeciv/common/tech.c,v
retrieving revision 1.96
diff -u -r1.96 tech.c
--- common/tech.c       27 Jun 2005 14:30:18 -0000      1.96
+++ common/tech.c       28 Jun 2005 20:49:05 -0000
@@ -49,12 +49,15 @@
    in common/tech.h */
 
 /**************************************************************************
-...
+  Returns state of the tech for current pplayer.
+  This can be: TECH_KNOW, TECH_UNKNOWN or TECH_REACHABLE
+  Should be called with existing techs or A_FUTURE
 **************************************************************************/
 enum tech_state get_invention(const struct player *pplayer,
                              Tech_type_id tech)
 {
-  assert(tech >= 0 || tech < game.control.num_tech_types);
+  assert(tech == A_FUTURE ||
+         (tech >= 0 && tech < game.control.num_tech_types));
 
   return get_player_research(pplayer)->inventions[tech].state;
 }
@@ -191,12 +194,17 @@
 }
 
 /**************************************************************************
-  Marks reachable techs. Calls build_required_techs to update the
-  cache of requirements.
+  Mark as TECH_REACHABLE each tech which is available, not known and
+  which has all requirements fullfiled.
+  If there is no such a tech mark A_FUTURE as researchable.
+  
+  Recalculate research->num_known_tech_with_flag
+  Should be called always after set_invention()
 **************************************************************************/
 void update_research(struct player *pplayer)
 {
   enum tech_flag_id flag;
+  int researchable = 0;
 
   tech_type_iterate(i) {
     if (i == A_NONE) {
@@ -214,10 +222,16 @@
          && get_invention(pplayer, advances[i].req[0]) == TECH_KNOWN
          && get_invention(pplayer, advances[i].req[1]) == TECH_KNOWN) {
        set_invention(pplayer, i, TECH_REACHABLE);
+       researchable++;
       }
     }
     build_required_techs(pplayer, i);
   } tech_type_iterate_end;
+  
+  /* No techs we can research? Mark A_FUTURE as researchable */
+  if (researchable == 0) {
+    set_invention(pplayer, A_FUTURE, TECH_REACHABLE);
+  }
 
   for (flag = 0; flag < TF_LAST; flag++) {
     get_player_research(pplayer)->num_known_tech_with_flag[flag] = 0;
Index: ai/aihand.c
===================================================================
RCS file: /home/freeciv/CVS/freeciv/ai/aihand.c,v
retrieving revision 1.117
diff -u -r1.117 aihand.c
--- ai/aihand.c 14 May 2005 15:38:49 -0000      1.117
+++ ai/aihand.c 28 Jun 2005 20:49:06 -0000
@@ -390,7 +390,8 @@
   }
 
   /* Crank up tech want */
-  if (get_invention(pplayer, ai->goal.govt.req) == TECH_KNOWN) {
+  if (ai->goal.govt.req == A_UNSET ||
+      get_invention(pplayer, ai->goal.govt.req) == TECH_KNOWN) {
     return; /* already got it! */
   } else if (ai->goal.govt.val > 0) {
     /* We have few cities in the beginning, compensate for this to ensure