A slightly working flood iterator and a working compass iterator.

matrix.cpp

@@ -1,5 +1,6 @@
 #include "matrix.hpp"
 #include "constants.hpp"
+#include "dbc.hpp"
 #include <fmt/core.h>
 
 using namespace fmt;
@@ -83,6 +84,89 @@ namespace matrix {
         x, y, left, right, top, bottom);
   }
 
+  compass::compass(Matrix &mat, size_t x, size_t y) :
+    x(x), y(y)
+  {
+    array<int, 4> x_in{0, 1, 0, -1};
+    array<int, 4> y_in{-1, 0, 1, 0};
+
+    for(size_t i = 0; i < 4; i++) {
+      int nx = x + x_in[i];
+      int ny = y + y_in[i];
+      if(matrix::inbounds(mat, nx, ny)) {
+        x_dirs[max_dirs] = nx;
+        y_dirs[max_dirs] = ny;
+        max_dirs++;
+      }
+    }
+  }
+
+  bool compass::next() {
+    dir++;
+    if(dir < max_dirs) {
+      x = x_dirs[dir];
+      y = y_dirs[dir];
+      return true;
+    } else {
+      return false;
+    }
+  }
+
+  flood::flood(Matrix &mat, Point start, int old_val, int new_val) :
+    mat(mat), start(start), old_val(old_val), new_val(new_val),
+    dirs{mat, start.x, start.y}
+  {
+    dbc::check(old_val != new_val, "what you doing?");
+    current_loc = start;
+    q.push(start);
+  }
+
+  bool flood::next() {
+    if(!q.empty()) {
+      if(!dirs.next()) {
+        // box is done reset it
+        auto current_loc = q.front();
+        q.pop();
+
+        dirs = matrix::compass{mat, current_loc.x, current_loc.y};
+        dirs.next();
+      }
+
+      // get the next thing
+      if(mat[dirs.y][dirs.x] == old_val) {
+        mat[dirs.y][dirs.x] += new_val;
+        x = dirs.x;
+        y = dirs.y;
+
+        q.push({.x=dirs.x, .y=dirs.y});
+      }
+
+      return true;
+    } else {
+      return false;
+    }
+  }
+
+  bool flood::next_working() {
+    if(!q.empty()) {
+      auto current_loc = q.front();
+      q.pop();
+
+      for(matrix::in_box box{mat, current_loc.x, current_loc.y, 1};
+          box.next();)
+      {
+        if(mat[box.y][box.x] == old_val) {
+          mat[box.y][box.x] += new_val;
+          q.push({.x=box.x, .y=box.y});
+        }
+      }
+
+      return true;
+    } else {
+      return false;
+    }
+  }
+
   void dump(const std::string &msg, Matrix &map, int show_x, int show_y) {
     println("----------------- {}", msg);
 
@@ -102,4 +186,5 @@ namespace matrix {
       if(it.row) print("\n");
     }
   }
+
 }