Codechange: Store custom station layouts in a map instead of nested vectors. (#12898)

The map key is the platforms and length combined. This simplifies allocation and searching for layouts.

(cherry picked from commit ff972ec4ff)

# Conflicts:
#	src/newgrf.cpp
#	src/newgrf_station.h

src/newgrf.cpp

@@ -2029,14 +2029,14 @@ static ChangeInfoResult StationChangeInfo(uint stid, int numinfo, int prop, cons
 
 					if (length == 0 || number == 0) break;
 
-					if (statspec->layouts.size() < length) statspec->layouts.resize(length);
-					if (statspec->layouts[length - 1].size() < number) statspec->layouts[length - 1].resize(number);
+					const uint8_t *buf_layout = buf->ReadBytes(length * number);
 
-					const uint8_t *layout = buf->ReadBytes(length * number);
-					statspec->layouts[length - 1][number - 1].assign(layout, layout + length * number);
+					/* Create entry in layouts and assign the layout to it. */
+					auto &layout = statspec->layouts[GetStationLayoutKey(number, length)];
+					layout.assign(buf_layout, buf_layout + length * number);
 
 					/* Ensure the first bit, axis, is zero. The rest of the value is validated during rendering, as we don't know the range yet. */
-					for (auto &tile : statspec->layouts[length - 1][number - 1]) {
+					for (auto &tile : layout) {
 						if ((tile & ~1U) != tile) {
 							GrfMsg(1, "StationChangeInfo: Invalid tile {} in layout {}x{}", tile, length, number);
 							tile &= ~1U;

src/newgrf_station.h

@@ -21,6 +21,7 @@
 #include "newgrf_spritegroup.h"
 #include "newgrf_town.h"
 #include <vector>
+#include <unordered_map>
 
 /** Scope resolver for stations. */
 struct StationScopeResolver : public ScopeResolver {
@@ -191,15 +192,8 @@ struct StationSpec : NewGRFSpecBase<StationClassID> {
 
 	uint8_t internal_flags; ///< Bitmask of internal spec flags (StationSpecIntlFlags)
 
-	/**
-	 * Custom platform layouts.
-	 * This is a 2D array containing an array of tiles.
-	 * 1st layer is platform lengths.
-	 * 2nd layer is tracks (width).
-	 * These can be sparsely populated, and the upper limit is not defined but
-	 * limited to 255.
-	 */
-	std::vector<std::vector<std::vector<uint8_t>>> layouts;
+	/** Custom platform layouts, keyed by platform and length combined. */
+	std::unordered_map<uint16_t, std::vector<uint8_t>> layouts;
 };
 DECLARE_ENUM_AS_BIT_SET(StationSpec::TileFlags);
 
@@ -208,6 +202,17 @@ using StationClass = NewGRFClass<StationSpec, StationClassID, STAT_CLASS_MAX>;
 
 const StationSpec *GetStationSpec(TileIndex t);
 
+/**
+ * Get the station layout key for a given station layout size.
+ * @param platforms Number of platforms.
+ * @param length Length of platforms.
+ * @returns Key of station layout.
+ */
+inline uint16_t GetStationLayoutKey(uint8_t platforms, uint8_t length)
+{
+	return (length << 8U) | platforms;
+}
+
 /**
  * Test if a StationClass is the waypoint class.
  * @param cls StationClass to test.

src/station_cmd.cpp

@@ -1325,14 +1325,14 @@ static inline uint8_t *CreateMulti(uint8_t *layout, int n, uint8_t b)
  */
 void GetStationLayout(uint8_t *layout, uint numtracks, uint plat_len, const StationSpec *statspec)
 {
-	if (statspec != nullptr && statspec->layouts.size() >= plat_len &&
-			statspec->layouts[plat_len - 1].size() >= numtracks &&
-			!statspec->layouts[plat_len - 1][numtracks - 1].empty()) {
-		/* Custom layout defined, follow it. */
-		memcpy(layout, statspec->layouts[plat_len - 1][numtracks - 1].data(),
-			static_cast<size_t>(plat_len) * numtracks);
+	if (statspec != nullptr) {
+		auto found = statspec->layouts.find(GetStationLayoutKey(numtracks, plat_len));
+		if (found != std::end(statspec->layouts)) {
+			/* Custom layout defined, copy to buffer. */
+			std::copy(std::begin(found->second), std::end(found->second), layout);
 			return;
 		}
+	}
 
 	if (plat_len == 1) {
 		CreateSingle(layout, numtracks);