MAIs: minor code simplification in AIs that take both [filter] and id=

These are the AIs that used to use Behavior Candidate Actions (BCA).

data/ai/micro_ais/cas/ca_coward.lua

@@ -4,35 +4,25 @@ local AH = wesnoth.require "ai/lua/ai_helper.lua"
 local ca_coward = {}
 
 function ca_coward:evaluation(ai, cfg)
-    local unit
-    if cfg.filter then
-        unit = wesnoth.get_units({
-            side = wesnoth.current.side,
-            { "and", cfg.filter },
-            formula = '$this_unit.moves > 0' }
-        )[1]
-    else
-        unit = wesnoth.get_units({ id = cfg.id, formula = '$this_unit.moves > 0' })[1]
-    end
+    local filter = cfg.filter or { id = cfg.id }
+    local unit = wesnoth.get_units({
+        side = wesnoth.current.side,
+        { "and", filter },
+        formula = '$this_unit.moves > 0' }
+    )[1]
 
-    -- Check if unit exists as sticky BCAs are not always removed successfully
     if unit then return cfg.ca_score end
     return 0
 end
 
 -- cfg parameters: id, distance, seek_x, seek_y, avoid_x, avoid_y
 function ca_coward:execution(ai, cfg)
-    --print("Coward exec " .. cfg.id)
-    local unit
-    if cfg.filter then
-        unit = wesnoth.get_units({
-            side = wesnoth.current.side,
-            { "and", cfg.filter },
-            formula = '$this_unit.moves > 0' }
-        )[1]
-    else
-        unit = wesnoth.get_units({ id = cfg.id, formula = '$this_unit.moves > 0' })[1]
-    end
+    local filter = cfg.filter or { id = cfg.id }
+    local unit = wesnoth.get_units({
+        side = wesnoth.current.side,
+        { "and", filter },
+        formula = '$this_unit.moves > 0' }
+    )[1]
 
     local reach = wesnoth.find_reach(unit)
 

data/ai/micro_ais/cas/ca_hunter.lua

@@ -39,16 +39,12 @@ local function hunter_attack_weakest_adj_enemy(ai, unit)
 end
 
 function ca_hunter:evaluation(ai, cfg)
-    local unit
-    if cfg.filter then
-        unit = wesnoth.get_units({
-            side = wesnoth.current.side,
-            { "and", cfg.filter },
-            formula = '$this_unit.moves > 0' }
-        )[1]
-    else
-        unit = wesnoth.get_units({ id = cfg.id, formula = '$this_unit.moves > 0' })[1]
-    end
+    local filter = cfg.filter or { id = cfg.id }
+    local unit = wesnoth.get_units({
+        side = wesnoth.current.side,
+        { "and", filter },
+        formula = '$this_unit.moves > 0' }
+    )[1]
 
     if unit then return cfg.ca_score end
     return 0
@@ -60,17 +56,12 @@ function ca_hunter:execution(ai, cfg)
     -- hunting_ground, then retreats to
     -- position given by 'home_x,home_y' for 'rest_turns' turns, or until fully healed
 
-    local unit
-    if cfg.filter then
-        unit = wesnoth.get_units({
-            side = wesnoth.current.side,
-            { "and", cfg.filter },
-            formula = '$this_unit.moves > 0' }
-        )[1]
-    else
-        unit = wesnoth.get_units({ id = cfg.id, formula = '$this_unit.moves > 0' })[1]
-    end
-    --print('Hunter: ', unit.id)
+    local filter = cfg.filter or { id = cfg.id }
+    local unit = wesnoth.get_units({
+        side = wesnoth.current.side,
+        { "and", filter },
+        formula = '$this_unit.moves > 0' }
+    )[1]
 
     -- If hunting_status is not set for the unit -> default behavior -> hunting
     if (not unit.variables.hunting_status) then

data/ai/micro_ais/cas/ca_patrol.lua

@@ -4,33 +4,24 @@ local AH = wesnoth.require "ai/lua/ai_helper.lua"
 local ca_patrol = {}
 
 function ca_patrol:evaluation(ai, cfg)
-    local patrol
-    if cfg.filter then
-        patrol = wesnoth.get_units({
-            side = wesnoth.current.side,
-            { "and", cfg.filter },
-            formula = '$this_unit.moves > 0' }
-        )[1]
-    else
-        patrol = wesnoth.get_units({ id = cfg.id, formula = '$this_unit.moves > 0' })[1]
-    end
+    local filter = cfg.filter or { id = cfg.id }
+    local patrol = wesnoth.get_units({
+        side = wesnoth.current.side,
+        { "and", filter },
+        formula = '$this_unit.moves > 0' }
+    )[1]
 
-    -- Check if unit exists as sticky BCAs are not always removed successfully
     if patrol then return cfg.ca_score end
     return 0
 end
 
 function ca_patrol:execution(ai, cfg, self)
-    local patrol
-    if cfg.filter then
-        patrol = wesnoth.get_units({
-            side = wesnoth.current.side,
-            { "and", cfg.filter },
-            formula = '$this_unit.moves > 0' }
-        )[1]
-    else
-        patrol = wesnoth.get_units({ id = cfg.id, formula = '$this_unit.moves > 0' })[1]
-    end
+    local filter = cfg.filter or { id = cfg.id }
+    local patrol = wesnoth.get_units({
+        side = wesnoth.current.side,
+        { "and", filter },
+        formula = '$this_unit.moves > 0' }
+    )[1]
 
     cfg.waypoint_x = AH.split(cfg.waypoint_x, ",")
     cfg.waypoint_y = AH.split(cfg.waypoint_y, ",")

data/ai/micro_ais/cas/ca_return_guardian.lua

@@ -3,18 +3,13 @@ local AH = wesnoth.require "ai/lua/ai_helper.lua"
 local ca_return_guardian = {}
 
 function ca_return_guardian:evaluation(ai, cfg)
-    local unit
-    if cfg.filter then
-        unit = wesnoth.get_units({
-            side = wesnoth.current.side,
-            { "and", cfg.filter },
-            formula = '$this_unit.moves > 0' }
-        )[1]
-    else
-        unit = wesnoth.get_units({ id = cfg.id, formula = '$this_unit.moves > 0' })[1]
-    end
+    local filter = cfg.filter or { id = cfg.id }
+    local unit = wesnoth.get_units({
+        side = wesnoth.current.side,
+        { "and", filter },
+        formula = '$this_unit.moves > 0' }
+    )[1]
 
-    -- Check if unit exists as sticky BCAs are not always removed successfully
     if unit then
         if ((unit.x ~= cfg.return_x) or (unit.y ~= cfg.return_y)) then
             return cfg.ca_score
@@ -26,17 +21,12 @@ function ca_return_guardian:evaluation(ai, cfg)
 end
 
 function ca_return_guardian:execution(ai, cfg)
-    local unit
-    if cfg.filter then
-        unit = wesnoth.get_units({
-            side = wesnoth.current.side,
-            { "and", cfg.filter },
-            formula = '$this_unit.moves > 0' }
-        )[1]
-    else
-        unit = wesnoth.get_units({ id = cfg.id, formula = '$this_unit.moves > 0' })[1]
-    end
-    --print("Exec guardian move",unit.id)
+    local filter = cfg.filter or { id = cfg.id }
+    local unit = wesnoth.get_units({
+        side = wesnoth.current.side,
+        { "and", filter },
+        formula = '$this_unit.moves > 0' }
+    )[1]
 
     -- In case the return hex is occupied:
     local x, y = cfg.return_x, cfg.return_y

data/ai/micro_ais/cas/ca_stationed_guardian.lua

@@ -4,18 +4,13 @@ local AH = wesnoth.require "ai/lua/ai_helper.lua"
 local ca_stationed_guardian = {}
 
 function ca_stationed_guardian:evaluation(ai, cfg)
-    local unit
-    if cfg.filter then
-        unit = wesnoth.get_units({
-            side = wesnoth.current.side,
-            { "and", cfg.filter },
-            formula = '$this_unit.moves > 0' }
-        )[1]
-    else
-        unit = wesnoth.get_units({ id = cfg.id, formula = '$this_unit.moves > 0' })[1]
-    end
+    local filter = cfg.filter or { id = cfg.id }
+    local unit = wesnoth.get_units({
+        side = wesnoth.current.side,
+        { "and", filter },
+        formula = '$this_unit.moves > 0' }
+    )[1]
 
-    -- Check if unit exists as sticky BCAs are not always removed successfully
     if unit then return cfg.ca_score end
     return 0
 end
@@ -24,16 +19,12 @@ function ca_stationed_guardian:execution(ai, cfg)
     -- (s_x,s_y): coordinates where unit is stationed; tries to move here if there is nobody to attack
     -- (g_x,g_y): location that the unit guards
 
-    local unit
-    if cfg.filter then
-        unit = wesnoth.get_units({
-            side = wesnoth.current.side,
-            { "and", cfg.filter },
-            formula = '$this_unit.moves > 0' }
-        )[1]
-    else
-        unit = wesnoth.get_units({ id = cfg.id, formula = '$this_unit.moves > 0' })[1]
-    end
+    local filter = cfg.filter or { id = cfg.id }
+    local unit = wesnoth.get_units({
+        side = wesnoth.current.side,
+        { "and", filter },
+        formula = '$this_unit.moves > 0' }
+    )[1]
 
     -- find if there are enemies within 'distance'
     local enemies = wesnoth.get_units {

data/ai/micro_ais/cas/ca_zone_guardian.lua

@@ -5,33 +5,24 @@ local LS = wesnoth.require "lua/location_set.lua"
 local ca_zone_guardian = {}
 
 function ca_zone_guardian:evaluation(ai, cfg)
-    local unit
-    if cfg.filter then
-        unit = wesnoth.get_units({
-            side = wesnoth.current.side,
-            { "and", cfg.filter },
-            formula = '$this_unit.moves > 0' }
-        )[1]
-    else
-        unit = wesnoth.get_units({ id = cfg.id, formula = '$this_unit.moves > 0' })[1]
-    end
+    local filter = cfg.filter or { id = cfg.id }
+    local unit = wesnoth.get_units({
+        side = wesnoth.current.side,
+        { "and", filter },
+        formula = '$this_unit.moves > 0' }
+    )[1]
 
-    -- Check if unit exists as sticky BCAs are not always removed successfully
     if unit then return cfg.ca_score end
     return 0
 end
 
 function ca_zone_guardian:execution(ai, cfg)
-    local unit
-    if cfg.filter then
-        unit = wesnoth.get_units({
-            side = wesnoth.current.side,
-            { "and", cfg.filter },
-            formula = '$this_unit.moves > 0' }
-        )[1]
-    else
-        unit = wesnoth.get_units({ id = cfg.id, formula = '$this_unit.moves > 0' })[1]
-    end
+    local filter = cfg.filter or { id = cfg.id }
+    local unit = wesnoth.get_units({
+        side = wesnoth.current.side,
+        { "and", filter },
+        formula = '$this_unit.moves > 0' }
+    )[1]
 
     local reach = wesnoth.find_reach(unit)
     local zone_enemy = cfg.filter_location_enemy or cfg.filter_location