Merge pull request scp-fs2open#5811 from Goober5000/perform_on_missio…

…n_skip

implement on-mission-skip SEXP

code/mission/missioncampaign.cpp

@@ -1642,19 +1642,19 @@ void mission_campaign_end_close()
 
 /**
  * Skip to the next mission in the campaign
- * this also posts the state change by default.  pass 0 to override that
+ * this also posts the state change
  */
-void mission_campaign_skip_to_next(int start_game)
+void mission_campaign_skip_to_next()
 {
+	// mark mission as skipped
+	Campaign.missions[Campaign.current_mission].flags |= CMISSION_FLAG_SKIPPED;
+
 	// mark all goals/events complete
 	// these do not really matter, since is-previous-event-* and is-previous-goal-* sexps check
 	// to see if the mission was skipped, and use defaults accordingly.
 	mission_goal_mark_objectives_complete();
 	mission_goal_mark_events_complete();
 
-	// mark mission as skipped
-	Campaign.missions[Campaign.current_mission].flags |= CMISSION_FLAG_SKIPPED;
-
 	// store
 	mission_campaign_store_goals_and_events_and_variables();
 
@@ -1665,22 +1665,20 @@ void mission_campaign_skip_to_next(int start_game)
 	Player->failures_this_session = 0;
 	Player->show_skip_popup = 1;
 
-	if (start_game) {
-		// proceed to next mission or main hall
-		if ((Campaign.missions[Campaign.current_mission].flags & CMISSION_FLAG_HAS_LOOP) && (Campaign.loop_mission != -1)) {
-			// go to loop solicitation
-			gameseq_post_event(GS_EVENT_LOOP_BRIEF);
-		} else {
-			// closes out mission stuff, sets up next one
-			mission_campaign_mission_over();
+	// proceed to next mission or main hall
+	if ((Campaign.missions[Campaign.current_mission].flags & CMISSION_FLAG_HAS_LOOP) && (Campaign.loop_mission != -1)) {
+		// go to loop solicitation
+		gameseq_post_event(GS_EVENT_LOOP_BRIEF);
+	} else {
+		// closes out mission stuff, sets up next one
+		mission_campaign_mission_over();
 
-			if ( Campaign.next_mission == -1 || (The_mission.flags[Mission::Mission_Flags::End_to_mainhall]) ) {
-				// go to main hall, either the campaign is over or the FREDer requested it.
-				gameseq_post_event(GS_EVENT_MAIN_MENU);
-			} else {
-				// go to next mission
-				gameseq_post_event(GS_EVENT_START_GAME);
-			}
+		if ( Campaign.next_mission == -1 || (The_mission.flags[Mission::Mission_Flags::End_to_mainhall]) ) {
+			// go to main hall, either the campaign is over or the FREDer requested it.
+			gameseq_post_event(GS_EVENT_MAIN_MENU);
+		} else {
+			// go to next mission
+			gameseq_post_event(GS_EVENT_START_GAME);
 		}
 	}
 }

code/mission/missioncampaign.h

@@ -239,7 +239,7 @@ void mission_campaign_eval_next_mission();
 int mission_campaign_previous_mission();
 
 // proceeds to next mission in campaign
-void mission_campaign_skip_to_next(int start_game = 1);
+void mission_campaign_skip_to_next();
 
 // break out of loop
 void mission_campaign_exit_loop();

code/mission/missiongoals.cpp

@@ -1280,21 +1280,24 @@ void mission_goal_fail_incomplete()
 // to skip past training misisons
 void mission_goal_mark_objectives_complete()
 {
-	int i;
-
-	for (i = 0; i < (int)Mission_goals.size(); i++ ) {
-		Mission_goals[i].satisfied = GOAL_COMPLETE;
+	for (auto &g: Mission_goals) {
+		g.satisfied = GOAL_COMPLETE;
 	}
 }
 
 // small function used to mark all events as completed.  Used in the skipping of missions.
 void mission_goal_mark_events_complete()
 {
-	int i;
+	for (auto &e: Mission_events) {
+		// Handle on-mission-skip SEXPs if we have any.  We could search the entire
+		// SEXP tree, but requiring the operator to be at the root limits potential
+		// unexpected side-effects.
+		if ((e.formula >= 0) && (get_operator_const(e.formula) == OP_ON_MISSION_SKIP)) {
+			eval_sexp(e.formula);
+		}
 
-	for (i = 0; i < (int)Mission_events.size(); i++ ) {
-		Mission_events[i].result = 1;
-		Mission_events[i].flags |= MEF_EVENT_IS_DONE;	// in lieu of setting formula to -1
+		e.result = 1;
+		e.flags |= MEF_EVENT_IS_DONE;	// in lieu of setting formula to -1
 	}
 }
 

code/parse/sexp.cpp

@@ -383,6 +383,7 @@ SCP_vector<sexp_oper> Operators = {
 	{ "when-argument",					OP_WHEN_ARGUMENT,						3,	INT_MAX,	SEXP_CONDITIONAL_OPERATOR,},	// Goober5000
 	{ "every-time",						OP_EVERY_TIME,							2,	INT_MAX,	SEXP_CONDITIONAL_OPERATOR,},	// Goober5000
 	{ "every-time-argument",			OP_EVERY_TIME_ARGUMENT,					3,	INT_MAX,	SEXP_CONDITIONAL_OPERATOR,},	// Goober5000
+	{ "on-mission-skip",				OP_ON_MISSION_SKIP,						1,	INT_MAX,	SEXP_CONDITIONAL_OPERATOR, },	// Goober5000
 	{ "functional-when",				OP_FUNCTIONAL_WHEN,						4,	INT_MAX,	SEXP_CONDITIONAL_OPERATOR, },	// Goober5000
 	{ "if-then-else",					OP_IF_THEN_ELSE,						3,	INT_MAX,	SEXP_CONDITIONAL_OPERATOR,},	// Goober5000
 	{ "functional-if-then-else",		OP_FUNCTIONAL_IF_THEN_ELSE,				3,	3,			SEXP_CONDITIONAL_OPERATOR, },	// Goober5000
@@ -10522,6 +10523,24 @@ int eval_perform_actions(int n, int op_num)
 
 		actions = n;
 	}
+	else if (op_num == OP_ON_MISSION_SKIP)
+	{
+		retval_first = true;
+		actions = n;
+
+		// if the player is skipping the mission, we'll unconditionally perform the actions
+		if ((Game_mode & GM_CAMPAIGN_MODE) && (Campaign.current_mission >= 0) && (Campaign.missions[Campaign.current_mission].flags & CMISSION_FLAG_SKIPPED))
+		{
+			return_cond = Locked_sexp_true;
+			actions_cond = Locked_sexp_true;
+		}
+		// if the player isn't skipping the mission (which is most of the time), we'll return false
+		else
+		{
+			return_cond = Locked_sexp_false;
+			actions_cond = Locked_sexp_false;
+		}
+	}
 	else
 	{
 		UNREACHABLE("Unsupported SEXP %d!", op_num);
@@ -27294,6 +27313,7 @@ int eval_sexp(int cur_node, int referenced_node)
 			case OP_PERFORM_ACTIONS_BOOL_FIRST:
 			case OP_PERFORM_ACTIONS_BOOL_LAST:
 			case OP_FUNCTIONAL_WHEN:
+			case OP_ON_MISSION_SKIP:
 				sexp_val = eval_perform_actions( node, op_num );
 				break;
 
@@ -30045,6 +30065,7 @@ int query_operator_return_type(int op)
 		case OP_WHEN_ARGUMENT:
 		case OP_EVERY_TIME:
 		case OP_EVERY_TIME_ARGUMENT:
+		case OP_ON_MISSION_SKIP:
 		case OP_IF_THEN_ELSE:
 		case OP_SWITCH:
 		case OP_INVALIDATE_ARGUMENT:
@@ -31293,6 +31314,7 @@ int query_operator_argument_type(int op, int argnum)
 				return OPF_NULL;
 
 		case OP_DO_FOR_VALID_ARGUMENTS:
+		case OP_ON_MISSION_SKIP:
 			return OPF_NULL;
 
 		case OP_RANDOM_OF:
@@ -35034,6 +35056,7 @@ int get_category(int op_id)
 		case OP_WHEN_ARGUMENT:
 		case OP_EVERY_TIME:
 		case OP_EVERY_TIME_ARGUMENT:
+		case OP_ON_MISSION_SKIP:
 		case OP_ANY_OF:
 		case OP_EVERY_OF:
 		case OP_RANDOM_OF:
@@ -37045,6 +37068,15 @@ SCP_vector<sexp_help_struct> Sexp_help = {
 		"\t2:\tBoolean expression that must be true for actions to take place.\r\n"
 		"\tRest:\tActions to take when the boolean expression becomes true." },
 
+	// Goober5000
+	{ OP_ON_MISSION_SKIP, "on-mission-skip (Conditional operator)\r\n"
+		"\tThis is a special operator that performs its actions when, and only when, the player chooses to skip the current mission.  "
+		"Since the player may do this in the debriefing, mission designers should limit these actions to campaign-specific things like "
+		"adding entries to the tech room, allowing ships and weapons, and calling scripts.  Note that this operator must be the top-level "
+		"operator in its event in order to work.\r\n\r\n"
+		"Takes 1 or more arguments...\r\n"
+		"\tAll:\tActions to take if the player chooses to skip the current mission.\r\n" },
+
 	// Goober5000
 	{ OP_IF_THEN_ELSE, "If-then-else (Conditional operator)\r\n"
 		"\tPerforms one action if a condition is true (like \"when\"), or another action (or set of actions) if the condition is false.  "

code/parse/sexp.h

@@ -512,7 +512,8 @@ enum : int {
 	OP_FUNCTIONAL_WHEN,	// Goober5000
 	OP_FOR_CONTAINER_DATA,	// jg18
 	OP_FOR_MAP_CONTAINER_KEYS,	// jg18
-
+	OP_ON_MISSION_SKIP,	// Goober5000
+
 	// OP_CATEGORY_CHANGE
 	// sexpressions with side-effects