Allow mission descriptions to refer to the effects of the mission.

src/dialogue.h

@@ -86,6 +86,7 @@ struct talk_topic {
 struct talk_effect_fun_t {
     private:
         std::function<void( const dialogue &d )> function;
+        std::vector<std::pair<int, std::string>> likely_rewards;
 
     public:
         talk_effect_fun_t() = default;
@@ -121,6 +122,7 @@ struct talk_effect_fun_t {
         void set_bulk_trade_accept( bool is_trade, bool is_npc = false );
         void set_npc_gets_item( bool to_use );
         void set_add_mission( std::string mission_id );
+        std::vector<std::pair<int, std::string>> get_likely_rewards();
 
         void operator()( const dialogue &d ) const {
             if( !function ) {

src/mission.cpp

@@ -593,6 +593,11 @@ character_id mission::get_npc_id() const
     return npc_id;
 }
 
+std::vector<std::pair<int, std::string>> mission::get_likely_rewards()
+{
+    return type->likely_rewards;
+}
+
 void mission::set_target( const tripoint &p )
 {
     target = p;

src/mission.h

@@ -222,6 +222,9 @@ struct mission_type {
         // If true, the NPC will press this mission!
         bool urgent = false;
 
+        // A limited subset of the talk_effects on the mission
+        std::vector<std::pair<int, std::string>> likely_rewards;
+
         // Points of origin
         std::vector<mission_origin> origins;
         itype_id item_id = "null";
@@ -371,6 +374,7 @@ class mission
         int get_id() const;
         const std::string &get_item_id() const;
         character_id get_npc_id() const;
+        std::vector<std::pair<int, std::string>> get_likely_rewards();
         /**
          * Whether the mission is assigned to a player character. If not, the mission is free and
          * can be assigned.

src/mission_ui.cpp

@@ -4,6 +4,7 @@
 #include <string>
 #include <vector>
 #include <algorithm>
+#include <regex>
 
 #include "avatar.h"
 #include "mission.h"
@@ -123,10 +124,21 @@ void game::list_missions()
             y += fold_and_print( w_missions, point( 31, y ), getmaxx( w_missions ) - 33, col,
                                  miss->name() + for_npc );
 
+            auto format_tokenized_description = []( const std::string description,
+            std::vector<std::pair<int, std::string>> rewards ) {
+                std::string formatted_description = description;
+                for( size_t i = 0; i < rewards.size(); i++ ) {
+                    std::regex token("<reward_count:" + rewards[i].second + ">");
+                    formatted_description = std::regex_replace( formatted_description, token, string_format( "%d",
+                                            rewards[i].first ) );
+                }
+                return formatted_description;
+            };
+
             y++;
             if( !miss->get_description().empty() ) {
                 y += fold_and_print( w_missions, point( 31, y ), getmaxx( w_missions ) - 33, c_white,
-                                     miss->get_description() );
+                                     format_tokenized_description( miss->get_description(), miss->get_likely_rewards() ) );
             }
             if( miss->has_deadline() ) {
                 const time_point deadline = miss->get_deadline();

src/mission_util.cpp

@@ -14,6 +14,7 @@
 #include "mapgen_functions.h"
 #include "messages.h"
 #include "npc.h"
+#include "npctalk.h"
 #include "overmap.h"
 #include "overmapbuffer.h"
 #include "rng.h"
@@ -527,5 +528,13 @@ bool mission_type::parse_funcs( JsonObject &jo, std::function<void( mission * )>
             mission_function( miss );
         }
     };
+
+    for( talk_effect_fun_t &effect : talk_effects.effects ) {
+        auto rewards = effect.get_likely_rewards();
+        if( !rewards.empty() ) {
+            likely_rewards.insert( likely_rewards.end(), rewards.begin(), rewards.end() );
+        }
+    }
+
     return true;
 }

src/npctalk.cpp

@@ -1807,6 +1807,12 @@ void talk_effect_fun_t::set_u_buy_item( const std::string &item_name, int cost,
             popup( _( "%1$s gives you a %2$s." ), p.name, container.tname() );
         }
     };
+
+    // Update structure used by mission descriptions.
+    if (cost <= 0)
+    {
+        likely_rewards.push_back(std::pair<int, std::string>(count, item_name));
+    }
 }
 
 void talk_effect_fun_t::set_u_sell_item( const std::string &item_name, int cost, int count )
@@ -2097,6 +2103,11 @@ void talk_effect_fun_t::set_add_mission( const std::string mission_id )
     };
 }
 
+std::vector<std::pair<int, std::string>> talk_effect_fun_t::get_likely_rewards()
+{
+    return likely_rewards;
+}
+
 void talk_effect_t::set_effect_consequence( const talk_effect_fun_t &fun, dialogue_consequence con )
 {
     effects.push_back( fun );