Add a variant of closest_points_first that takes a predicate

src/activity_item_handling.cpp

@@ -3809,8 +3809,7 @@ int get_auto_consume_moves( Character &you, const bool food )
 bool try_fuel_fire( player_activity &act, Character &you, const bool starting_fire )
 {
     const tripoint_bub_ms pos = you.pos_bub();
-    std::vector<tripoint_bub_ms> adjacent = closest_points_first( pos, PICKUP_RANGE );
-    adjacent.erase( adjacent.begin() );
+    std::vector<tripoint_bub_ms> adjacent = closest_points_first( pos, 1, PICKUP_RANGE );
 
     map &here = get_map();
     std::optional<tripoint_bub_ms> best_fire =

src/map.cpp

@@ -5160,8 +5160,7 @@ std::pair<item *, tripoint_bub_ms> map::_add_item_or_charges( const tripoint_bub
     if( overflow && copies_remaining > 0 ) {
         // ...otherwise try to overflow to adjacent tiles (if permitted)
         const int max_dist = 2;
-        std::vector<tripoint_bub_ms> tiles = closest_points_first( pos, max_dist );
-        tiles.erase( tiles.begin() ); // we already tried this position
+        std::vector<tripoint_bub_ms> tiles = closest_points_first( pos, 1, max_dist );
         const int max_path_length = 4 * max_dist;
         const pathfinding_settings setting( 0, max_dist, max_path_length, 0, false, false, true, false,
                                             false, false );

src/monattack.cpp

@@ -2153,9 +2153,7 @@ bool mattack::formblob( monster *z )
     }
 
     bool didit = false;
-    std::vector<tripoint_bub_ms> pts = closest_points_first( z->pos_bub(), 1 );
-    // Don't check own tile
-    pts.erase( pts.begin() );
+    std::vector<tripoint_bub_ms> pts = closest_points_first( z->pos_bub(), 1, 1 );
     creature_tracker &creatures = get_creature_tracker();
     for( const tripoint_bub_ms &dest : pts ) {
         Creature *critter = creatures.creature_at( dest );

src/monmove.cpp

@@ -41,6 +41,7 @@
 #include "options.h"
 #include "pathfinding.h"
 #include "pimpl.h"
+#include "point.h"
 #include "rng.h"
 #include "scent_map.h"
 #include "sounds.h"
@@ -1800,11 +1801,14 @@ bool monster::attack_at( const tripoint_bub_ms &p )
 static tripoint_bub_ms find_closest_stair( const tripoint_bub_ms &near_this,
         const ter_furn_flag stair_type )
 {
-    map &here = get_map();
-    for( const tripoint_bub_ms &candidate : closest_points_first( near_this, 10 ) ) {
-        if( here.has_flag( stair_type, candidate ) ) {
-            return candidate;
-        }
+    const map &here = get_map();
+    std::optional<tripoint_bub_ms> candidate = find_point_closest_first( near_this, 0, 10, [&here,
+    stair_type]( const tripoint_bub_ms & candidate ) {
+        return here.has_flag( stair_type, candidate );
+    } );
+
+    if( candidate != std::nullopt ) {
+        return *candidate;
     }
     // we didn't find it
     return near_this;

src/npc.cpp

@@ -1175,9 +1175,9 @@ void npc::place_on_map( map *here )
         return;
     }
 
-    for( const tripoint_abs_ms &p : closest_points_first( pos_abs(), SEEX + 1 ) ) {
-        if( g->is_empty( here, p ) ) {
-            setpos( here, here->get_bub( p ) );
+    for( const tripoint_bub_ms &p : closest_points_first( pos_bub(), 1, SEEX + 1 ) ) {
+        if( g->is_empty( p ) ) {
+            setpos( p );
             return;
         }
     }

src/npcmove.cpp

@@ -3176,8 +3176,7 @@ void npc::avoid_friendly_fire()
 
     tripoint_bub_ms center = midpoint_round_to_nearest( fr_pts );
 
-    std::vector<tripoint_bub_ms> candidates = closest_points_first( pos_bub(), 1 );
-    candidates.erase( candidates.begin() );
+    std::vector<tripoint_bub_ms> candidates = closest_points_first( pos_bub(), 1, 1 );
     std::sort( candidates.begin(), candidates.end(),
     [&tar, &center]( const tripoint_bub_ms & l, const tripoint_bub_ms & r ) {
         return ( rl_dist( l, tar ) - rl_dist( l, center ) ) <

src/point.cpp

@@ -117,21 +117,42 @@ std::istream &operator>>( std::istream &is, tripoint &pos )
     return is;
 }
 
+std::optional<int> rectangle_size( int min_dist, int max_dist )
+{
+    min_dist = std::max( min_dist, 0 );
+    max_dist = std::max( max_dist, 0 );
+
+    if( min_dist > max_dist ) {
+        return std::nullopt;
+    }
+
+    const int min_edge = min_dist * 2 + 1;
+    const int max_edge = max_dist * 2 + 1;
+
+    const int n = max_edge * max_edge - ( min_edge - 2 ) * ( min_edge - 2 ) + ( min_dist == 0 ? 1 : 0 );
+    return n;
+}
+
 std::vector<tripoint> closest_points_first( const tripoint &center, int max_dist )
 {
     return closest_points_first( center, 0, max_dist );
 }
 
 std::vector<tripoint> closest_points_first( const tripoint &center, int min_dist, int max_dist )
 {
-    const std::vector<point> points = closest_points_first( center.xy(), min_dist, max_dist );
+    std::optional<int> n = rectangle_size( min_dist, max_dist );
+
+    if( n == std::nullopt ) {
+        return {};
+    }
 
     std::vector<tripoint> result;
-    result.reserve( points.size() );
+    result.reserve( *n );
 
-    for( const point &p : points ) {
-        result.emplace_back( p, center.z );
-    }
+    find_point_closest_first( center, min_dist, max_dist, [&result]( const tripoint & p ) {
+        result.push_back( p );
+        return false;
+    } );
 
     return result;
 }
@@ -143,42 +164,26 @@ std::vector<point> closest_points_first( const point &center, int max_dist )
 
 std::vector<point> closest_points_first( const point &center, int min_dist, int max_dist )
 {
-    min_dist = std::max( min_dist, 0 );
-    max_dist = std::max( max_dist, 0 );
+    std::optional<int> n = rectangle_size( min_dist, max_dist );
 
-    if( min_dist > max_dist ) {
+    if( n == std::nullopt ) {
         return {};
     }
 
-    const int min_edge = min_dist * 2 + 1;
-    const int max_edge = max_dist * 2 + 1;
-
-    const int n = max_edge * max_edge - ( min_edge - 2 ) * ( min_edge - 2 );
-    const bool is_center_included = min_dist == 0;
-
     std::vector<point> result;
-    result.reserve( n + ( is_center_included ? 1 : 0 ) );
-
-    if( is_center_included ) {
-        result.push_back( center );
-    }
+    result.reserve( *n );
 
-    int x_init = std::max( min_dist, 1 );
-    point p( x_init, 1 - x_init );
-
-    point d( point::east );
-
-    for( int i = 0; i < n; i++ ) {
-        result.push_back( center + p );
-
-        if( p.x == p.y || ( p.x < 0 && p.x == -p.y ) || ( p.x > 0 && p.x == 1 - p.y ) ) {
-            std::swap( d.x, d.y );
-            d.x = -d.x;
-        }
-
-        p.x += d.x;
-        p.y += d.y;
-    }
+    find_point_closest_first( center, min_dist, max_dist, [&result]( const point & p ) {
+        result.push_back( p );
+        return false;
+    } );
 
     return result;
 }
+
+template <typename PredicateFn, typename Point>
+std::optional<Point> find_point_closest_first( const Point &center, int max_dist,
+        PredicateFn &&fn )
+{
+    return find_point_closest_first( center, 0, max_dist, fn );
+}

src/point.h

@@ -8,6 +8,7 @@
 #include <cstdint>
 #include <cstdlib>
 #include <functional>
+#include <optional>
 #include <ostream>
 #include <vector>
 
@@ -358,6 +359,18 @@ std::vector<tripoint> closest_points_first( const tripoint &center, int min_dist
 std::vector<point> closest_points_first( const point &center, int max_dist );
 std::vector<point> closest_points_first( const point &center, int min_dist, int max_dist );
 
+template <typename PredicateFn, typename Point>
+std::optional<Point> find_point_closest_first( const Point &center, int min_dist, int max_dist,
+        PredicateFn &&fn );
+
+template <typename PredicateFn, typename Point>
+std::optional<Point> find_point_closest_first( const Point &center, int max_dist,
+        PredicateFn &&fn );
+
+
+// Calculate the number of tiles in a square from min_dist to max_dist about an arbitrary centre.
+std::optional<int> rectangle_size( int min_dist, int max_dist );
+
 // Make point hashable so it can be used as an unordered_set or unordered_map key,
 // or a component of one.
 namespace std
@@ -442,4 +455,56 @@ inline constexpr const std::array<tripoint, 8> eight_horizontal_neighbors = { {
     }
 };
 
+/* Return points in a clockwise spiral from min_dist to max_dist, inclusive, ordered by
+ * the closest points first. The distance is calculated using roguelike distances, so
+ * movement in any direction only counts as 1.
+ *
+ * The predicate function is evaluated on each point. If the function returns true, the
+ * point is returned. If the predicate function never returns true then std::nullopt is
+ * returned once max_dist is reached.
+ *
+ * @param center The center of the spiral.
+ * @param min_dist minimum distance to start the spiral from.
+ * @param max_dist greatest distance from the centre that the spiral will go to.
+ * @returns std::nullopt if min_dist > max_dist or predicate_fn evaluated to true for
+ *      no points.
+ */
+template <typename PredicateFn, typename Point>
+std::optional<Point> find_point_closest_first( const Point &center, int min_dist, int max_dist,
+        PredicateFn &&predicate_fn )
+{
+    const std::optional<int> n = rectangle_size( min_dist, max_dist );
+
+    if( n == std::nullopt ) {
+        return {};
+    }
+
+    const bool is_center_included = min_dist == 0;
+
+    if( is_center_included && predicate_fn( center ) ) {
+        return center;
+    }
+
+    int x_init = std::max( min_dist, 1 );
+    point p {x_init, 1 - x_init};
+
+    point d = point::east;
+
+    for( int i = is_center_included; i < *n; i++ ) {
+        const Point next = Point{ center.raw() + p.raw() };
+        if( predicate_fn( next ) ) {
+            return next;
+        }
+
+        if( p.x == p.y || ( p.x < 0 && p.x == -p.y ) || ( p.x > 0 && p.x == 1 - p.y ) ) {
+            std::swap( d.x, d.y );
+            d.x = -d.x;
+        }
+
+        p += d;
+    }
+
+    return std::nullopt;
+}
+
 #endif // CATA_SRC_POINT_H

src/ranged.cpp

@@ -2238,6 +2238,7 @@ static void cycle_action( item &weap, const itype_id &ammo, const tripoint_bub_m
     } ), tiles.end() );
     tripoint_bub_ms eject{ tiles.empty() ? pos : random_entry( tiles ) };
 
+
     // for turrets try and drop casings or linkages directly to any CARGO part on the same tile
     const std::optional<vpart_reference> ovp_cargo = weap.has_flag( flag_VEHICLE )
             ? here.veh_at( pos ).cargo()
@@ -3156,12 +3157,12 @@ tripoint_bub_ms target_ui::choose_initial_target()
 
     // Try closest practice target
     map &here = get_map();
-    const std::vector<tripoint_bub_ms> nearby = closest_points_first( src, range );
-    const auto target_spot = std::find_if( nearby.begin(), nearby.end(),
-    [this, &here]( const tripoint_bub_ms & pt ) {
+    std::optional<tripoint_bub_ms> target_spot = find_point_closest_first( src, 0, range, [this,
+    &here]( const tripoint_bub_ms & pt ) {
         return here.tr_at( pt ).id == tr_practice_target && this->you->sees( pt );
     } );
-    if( target_spot != nearby.end() ) {
+
+    if( target_spot != std::nullopt ) {
         return *target_spot;
     }