A bit of late night work designing the little iterators.

matrix.cpp

@@ -3,23 +3,54 @@
 #include <fmt/core.h>
 
 using namespace fmt;
+using matrix::Matrix;
 
-void matrix_dump(const std::string &msg, Matrix &map, int show_x, int show_y) {
-  println("----------------- {}", msg);
-  for(size_t y = 0; y < map.size(); y++) {
-    for(size_t x = 0; x < map[y].size(); x++) {
-      int col = map[y][x];
+namespace matrix {
 
-      if(int(x) == show_x && int(y) == show_y) {
-        print("{:x}<", col);
-      } else if(col == WALL_PATH_LIMIT) {
+  each_cell::each_cell(Matrix &mat)
+  {
+    height = mat.size();
+    width = mat[0].size();
+  }
+
+  bool each_cell::next() {
+    x++;
+    x *= (x < width);
+    y = y + (x == 0);
+    return y < height;
+  }
+
+  each_row::each_row(Matrix &mat) :
+    $mat(mat)
+  {
+    height = $mat.size();
+    width = $mat[0].size();
+  }
+
+  bool each_row::next() {
+    x++;
+    x *= (x < width);
+    y = y + (x == 0);
+    row = x == width - 1;
+    cell = y < height ? $mat[y][x] : -1;
+    return y < height;
+  }
+
+  void dump(const std::string &msg, Matrix &map, int show_x, int show_y) {
+    println("----------------- {}", msg);
+
+    for(each_row it{map}; it.next();) {
+      if(int(it.x) == show_x && int(it.y) == show_y) {
+        print("{:x}<", it.cell);
+      } else if(it.cell == WALL_PATH_LIMIT) {
         print("# ");
-      } else if(col > 15) {
+      } else if(it.cell > 15) {
         print("* ");
       } else {
-        print("{:x} ", col);
+        print("{:x} ", it.cell);
       }
+
+      if(it.row) print("\n");
     }
-    print("\n");
   }
 }