add dfhack.items.isRequestedTradeGood

docs/changelog.txt

@@ -50,8 +50,9 @@ changelog.txt uses a syntax similar to RST, with a few special sequences:
 - Price calculations fixed for many item types
 
 ## Lua
-- ``dfhack.items.markForTrade``: new API for marking items for trade
 - ``dfhack.units.getUnitByNobleRole``, ``dfhack.units.getUnitsByNobleRole``: unit lookup API by role
+- ``dfhack.items.markForTrade``: mark items for trade
+- ``dfhack.items.isRequestedTradeGood``: discover whether an item is named in a trade agreement with an active caravan
 - ``dfhack.items.getValue``: gained optional ``caravan`` and ``caravan_buying`` parameters for prices that take trader races and agreements into account
 
 ## Removed

docs/dev/Lua API.rst

@@ -1778,6 +1778,10 @@ Items module
   for the item and ``false`` to get the price that the caravan will sell the
   item for.
 
+* ``dfhack.items.isRequestedTradeGood(item)``
+
+  Returns whether any active caravan will pay extra for the given item.
+
 * ``dfhack.items.createItem(item_type, item_subtype, mat_type, mat_index, unit)``
 
   Creates an item, similar to the `createitem` plugin.

library/LuaApi.cpp

@@ -2020,6 +2020,7 @@ static const LuaWrapper::FunctionReg dfhack_items_module[] = {
     WRAPM(Items, getSubtypeDef),
     WRAPM(Items, getItemBaseValue),
     WRAPM(Items, getValue),
+    WRAPM(Items, isRequestedTradeGood),
     WRAPM(Items, createItem),
     WRAPM(Items, checkMandates),
     WRAPM(Items, canTrade),

library/include/modules/Items.h

@@ -203,6 +203,8 @@ DFHACK_EXPORT bool canTrade(df::item *item);
 DFHACK_EXPORT bool canTradeWithContents(df::item *item);
 /// marks the given item for trade at the given depot
 DFHACK_EXPORT bool markForTrade(df::item *item, df::building_tradedepotst *depot);
+/// Returns true if an active caravan will pay extra for the given item
+DFHACK_EXPORT bool isRequestedTradeGood(df::item *item);
 
 /// Checks whether the item is an assigned hauling vehicle
 DFHACK_EXPORT bool isRouteVehicle(df::item *item);

library/modules/Items.cpp

@@ -1917,6 +1917,19 @@ static int32_t get_trade_agreement_multiplier(df::item *item, const df::caravan_
         : get_sell_request_multiplier(item, caravan);
 }
 
+bool Items::isRequestedTradeGood(df::item *item) {
+    for (auto caravan : df::global::plotinfo->caravans) {
+        auto trade_state = caravan->trade_state;
+        if (caravan->time_remaining <= 0 ||
+                (trade_state != df::caravan_state::T_trade_state::Approaching &&
+                 trade_state != df::caravan_state::T_trade_state::AtDepot))
+            continue;
+        if (get_buy_request_multiplier(item, caravan->buy_prices) > DEFAULT_AGREEMENT_MULTIPLIER)
+            return true;
+    }
+    return false;
+}
+
 int Items::getValue(df::item *item, df::caravan_state *caravan, bool caravan_buying)
 {
     CHECK_NULL_POINTER(item);