(svn r6057) -Codechange: made a function GetRandomXXX, that _always_ returns a valid XXX, unless there are none to pick from. Then NULL is returned.

7 files changed, 63 insertions, 20 deletions

diff --git a/ai/default/default.c b/ai/default/default.c
index 3de583bf4..08af2b119 100644
--- a/ai/default/default.c
+++ b/ai/default/default.c
@@ -441,14 +441,12 @@ typedef struct FoundRoute {
 
 static Town *AiFindRandomTown(void)
 {
-	Town *t = GetTown(RandomRange(GetTownArraySize()));
-	return IsValidTown(t) ? t : NULL;
+	return GetRandomTown();
 }
 
 static Industry *AiFindRandomIndustry(void)
 {
-	Industry *i = GetIndustry(RandomRange(GetIndustryArraySize()));
-	return IsValidIndustry(i) ? i : NULL;
+	return GetRandomIndustry();
 }
 
 static void AiFindSubsidyIndustryRoute(FoundRoute *fr)
diff --git a/disaster_cmd.c b/disaster_cmd.c
index ea1f3cf97..d44214e17 100644
--- a/disaster_cmd.c
+++ b/disaster_cmd.c
@@ -2,10 +2,10 @@
 
 #include "stdafx.h"
 #include "openttd.h"
+#include "functions.h"
 #include "industry_map.h"
 #include "station_map.h"
 #include "table/strings.h"
-#include "functions.h"
 #include "map.h"
 #include "tile.h"
 #include "vehicle.h"
diff --git a/economy.c b/economy.c
index 19fa8952c..1abdda6d7 100644
--- a/economy.c
+++ b/economy.c
@@ -882,12 +882,11 @@ static void FindSubsidyPassengerRoute(FoundRoute *fr)
 
 	fr->distance = (uint)-1;
 
-	fr->from = from = GetTown(RandomRange(GetTownArraySize()));
-	if (!IsValidTown(from) || from->population < 400)
-		return;
+	fr->from = from = GetRandomTown();
+	if (from == NULL || from->population < 400) return;
 
-	fr->to = to = GetTown(RandomRange(GetTownArraySize()));
-	if (from == to || !IsValidTown(to) || to->population < 400 || to->pct_pass_transported > 42)
+	fr->to = to = GetRandomTown();
+	if (from == to || to == NULL || to->population < 400 || to->pct_pass_transported > 42)
 		return;
 
 	fr->distance = DistanceManhattan(from->xy, to->xy);
@@ -901,8 +900,8 @@ static void FindSubsidyCargoRoute(FoundRoute *fr)
 
 	fr->distance = (uint)-1;
 
-	fr->from = i = GetIndustry(RandomRange(GetIndustryArraySize()));
-	if (!IsValidIndustry(i)) return;
+	fr->from = i = GetRandomIndustry();
+	if (i == NULL) return;
 
 	// Randomize cargo type
 	if (Random()&1 && i->produced_cargo[1] != CT_INVALID) {
@@ -925,19 +924,19 @@ static void FindSubsidyCargoRoute(FoundRoute *fr)
 
 	if (cargo == CT_GOODS || cargo == CT_FOOD) {
 		// The destination is a town
-		Town *t = GetTown(RandomRange(GetTownArraySize()));
+		Town *t = GetRandomTown();
 
 		// Only want big towns
-		if (!IsValidTown(t) || t->population < 900) return;
+		if (t == NULL || t->population < 900) return;
 
 		fr->distance = DistanceManhattan(i->xy, t->xy);
 		fr->to = t;
 	} else {
 		// The destination is an industry
-		Industry *i2 = GetIndustry(RandomRange(GetIndustryArraySize()));
+		Industry *i2 = GetRandomIndustry();
 
 		// The industry must accept the cargo
-		if (i == i2 || !IsValidIndustry(i2) ||
+		if (i == i2 || i == NULL ||
 				(cargo != i2->accepts_cargo[0] &&
 				cargo != i2->accepts_cargo[1] &&
 				cargo != i2->accepts_cargo[2]))
diff --git a/industry.h b/industry.h
index dcd489b95..2b642dece 100644
--- a/industry.h
+++ b/industry.h
@@ -107,6 +107,30 @@ static inline IndustryID GetIndustryArraySize(void)
 	return _total_industries + 1;
 }
 
+/**
+ * Return a random valid town.
+ */
+static inline Industry *GetRandomIndustry(void)
+{
+	uint num = RandomRange(GetIndustryArraySize());
+	uint index = 0;
+
+	if (GetIndustryArraySize() == 0) return NULL;
+
+	while (num > 0) {
+		num--;
+
+		index++;
+		/* Make sure we have a valid industry */
+		while (GetIndustry(index) == NULL) {
+			index++;
+			if (index == GetIndustryArraySize()) index = 0;
+		}
+	}
+
+	return GetIndustry(index);
+}
+
 #define FOR_ALL_INDUSTRIES_FROM(i, start) for (i = GetIndustry(start); i != NULL; i = (i->index + 1 < GetIndustryPoolSize()) ? GetIndustry(i->index + 1) : NULL) if (IsValidIndustry(i))
 #define FOR_ALL_INDUSTRIES(i) FOR_ALL_INDUSTRIES_FROM(i, 0)
 
diff --git a/industry_cmd.c b/industry_cmd.c
index b36f01ff5..215033e13 100644
--- a/industry_cmd.c
+++ b/industry_cmd.c
@@ -3,11 +3,11 @@
 #include "stdafx.h"
 #include "openttd.h"
 #include "clear_map.h"
+#include "functions.h"
 #include "industry_map.h"
 #include "station_map.h"
 #include "table/strings.h"
 #include "table/sprites.h"
-#include "functions.h"
 #include "map.h"
 #include "tile.h"
 #include "viewport.h"
@@ -1879,8 +1879,8 @@ void IndustryMonthlyLoop(void)
 	if (CHANCE16(3, 100)) {
 		MaybeNewIndustry(Random());
 	} else if (!_patches.smooth_economy && GetIndustryArraySize() > 0) {
-		i = GetIndustry(RandomRange(GetIndustryArraySize()));
-		if (IsValidIndustry(i)) ChangeIndustryProduction(i);
+		i = GetRandomIndustry();
+		if (i != NULL) ChangeIndustryProduction(i);
 	}
 
 	_current_player = old_player;
diff --git a/smallmap_gui.c b/smallmap_gui.c
index 337ac4e05..452183c97 100644
--- a/smallmap_gui.c
+++ b/smallmap_gui.c
@@ -2,10 +2,10 @@
 
 #include "stdafx.h"
 #include "openttd.h"
+#include "functions.h"
 #include "bridge_map.h"
 #include "clear_map.h"
 #include "industry_map.h"
-#include "functions.h"
 #include "spritecache.h"
 #include "station_map.h"
 #include "table/strings.h"
diff --git a/town.h b/town.h
index 122a373dc..1ad4a7f04 100644
--- a/town.h
+++ b/town.h
@@ -191,6 +191,28 @@ static inline TownID GetTownArraySize(void)
 	return _total_towns + 1;
 }
 
+/**
+ * Return a random valid town.
+ */
+static inline Town *GetRandomTown(void)
+{
+	uint num = RandomRange(GetTownArraySize());
+	uint index = 0;
+
+	while (num > 0) {
+		num--;
+
+		index++;
+		/* Make sure we have a valid industry */
+		while (GetTown(index) == NULL) {
+			index++;
+			if (index == GetTownArraySize()) index = 0;
+		}
+	}
+
+	return GetTown(index);
+}
+
 static inline bool IsValidTownID(uint index)
 {
 	return index < GetTownPoolSize() && IsValidTown(GetTown(index));