Took the plunge and converted my 'shaperators' into templates so they'll work on any 'matrix-like' thing.

matrix.cpp

@@ -8,122 +8,8 @@
 using namespace fmt;
 using std::min, std::max;
 
-inline size_t next_x(size_t x, size_t width) {
-  return (x + 1) * ((x + 1) < width);
-}
-
-inline size_t next_y(size_t x, size_t y) {
-  return y + (x == 0);
-}
-
-inline bool at_end(size_t y, size_t height) {
-  return y < height;
-}
-
-inline bool end_row(size_t x, size_t width) {
-  return x == width - 1;
-}
-
-
 namespace matrix {
 
-  each_cell::each_cell(Matrix &mat)
-  {
-    height = mat.size();
-    width = mat[0].size();
-  }
-
-  bool each_cell::next() {
-    x = next_x(x, width);
-    y = next_y(x, y);
-    return at_end(y, height);
-  }
-
-  each_row::each_row(Matrix &mat) :
-    $mat(mat)
-  {
-    height = $mat.size();
-    width = $mat[0].size();
-  }
-
-  bool each_row::next() {
-    x = next_x(x, width);
-    y = next_y(x, y);
-    row = end_row(x, width);
-    return at_end(y, height);
-  }
-
-  in_box::in_box(Matrix &mat, size_t at_x, size_t at_y, size_t size) :
-    from_x(at_x), from_y(at_y)
-  {
-    size_t h = matrix::height(mat);
-    size_t w = matrix::width(mat);
-
-    // keeps it from going below zero
-    // need extra -1 to compensate for the first next()
-    left = max(from_x, size) - size;
-    x = left - 1;  // must be -1 for next()
-    // keeps it from going above width
-    right = min(from_x + size + 1, w);
-
-    // same for these two
-    top = max(from_y, size) - size;
-    y = top - (left == 0);
-    bottom = min(from_y + size + 1, h);
-  }
-
-  bool in_box::next() {
-    // calc next but allow to go to 0 for next
-    x = next_x(x, right);
-    // x will go to 0, which signals new line
-    y = next_y(x, y);  // this must go here
-    // if x==0 then this moves it to min_x
-    x = max(x, left);
-    // and done
-
-    return at_end(y, bottom);
-  }
-
-  float in_box::distance() {
-    int dx = from_x - x;
-    int dy = from_y - y;
-
-    return sqrt((dx * dx) + (dy * dy));
-  }
-
-  void in_box::dump() {
-    println("BOX: x={},y={}; left={},right={}; top={},bottom={}",
-        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),
      x(start.x), y(start.y), dirs{mat, start.x, start.y}
@@ -189,31 +75,6 @@ namespace matrix {
     }
   }
 
-
-  circle::circle(Matrix &mat, Point center, float radius) :
-    center_x(center.x), center_y(center.y), radius(radius)
-  {
-    width = matrix::width(mat);
-    height = matrix::height(mat);
-    top = max(int(floor(center_y - radius)), 0);
-    bottom = min(int(floor(center_y + radius)), height - 1);
-
-    y = top;
-  }
-
-  bool circle::next() {
-    y++;
-    if(y <= bottom) {
-      dy = y - center_y;
-      dx = floor(sqrt(radius * radius - dy * dy));
-      left = max(0, int(center_x) - dx);
-      right = min(width, int(center_x) + dx + 1);
-      return true;
-    } else {
-      return false;
-    }
-  }
-
   void dump(const std::string &msg, Matrix &map, int show_x, int show_y) {
     println("----------------- {}", msg);