A first exploration of doing a matrix iterator.

tests/matrix.cpp

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+#include <catch2/catch_test_macros.hpp>
+#include <fmt/core.h>
+#include <string>
+#include "config.hpp"
+#include "matrix.hpp"
+#include "components.hpp"
+#include <nlohmann/json.hpp>
+#include <fstream>
+
+using namespace nlohmann;
+using namespace fmt;
+using std::string;
+
+
+
+#include <algorithm>
+#include <iostream>
+
+struct ItStep {
+  int cell;
+  size_t x;
+  size_t y;
+  bool row;
+};
+
+class MatrixIterator1 {
+  public:
+    class iterator
+    {
+    public:
+      Matrix &mat;
+      size_t x = 0;
+      size_t y = 0;
+
+      using iterator_category = std::input_iterator_tag;
+      using value_type = ItStep;
+      using difference_type = ItStep;
+      using pointer = ItStep *;
+      using reference = ItStep;
+
+      explicit iterator(Matrix &_mat)
+        : mat(_mat) {}
+
+      iterator& operator++() {
+        x++;
+        if(x < mat[0].size()) {
+          return *this;
+        } else {
+          x = 0;
+          y++;
+          return *this;
+        }
+      }
+
+      iterator operator++(int) {
+        iterator retval = *this;
+        ++(*this);
+        return retval;
+      }
+
+      bool operator==(iterator other) const {
+        return x == other.x && y == other.y;
+      }
+
+      reference operator*() const {
+        return {
+          .cell = mat[y][x],
+          .x = x,
+          .y = y,
+          .row = x >= mat[0].size() - 1
+        };
+      }
+  };
+
+  Matrix &mat;
+
+  MatrixIterator1(Matrix &mat_) :
+    mat(mat_)
+  {
+  }
+
+  iterator begin() {
+    return iterator(mat);
+  }
+
+  iterator end() {
+    iterator it(mat);
+    it.y = mat.size();
+    it.x = 0;
+    return it;
+  }
+};
+
+struct MatrixIterator2 {
+  Matrix &$mat;
+  size_t x = ~0;
+  size_t y = ~0;
+  size_t width = 0;
+  size_t height = 0;
+  int cell = 0;
+  bool row = false;
+
+  MatrixIterator2(Matrix &mat) :
+    $mat(mat)
+  {
+    height = $mat.size();
+    width = $mat[0].size();
+  }
+
+  bool next() {
+    x++;
+    x *= (x < width);
+    y = y + (x == 0);
+    row = x == width - 1;
+
+    if(y < height) {
+      cell = $mat[y][x];
+      return true;
+    } else {
+      return false;
+    }
+  }
+};
+
+TEST_CASE("basic matrix iterator", "[matrix]") {
+  std::ifstream infile("./tests/dijkstra.json");
+  json data = json::parse(infile);
+  auto test = data[0];
+
+  Matrix walls = test["walls"];
+
+  matrix_dump("ITERATOR DUMP", walls);
+
+  println("VS Matrix1 ------");
+
+  for(auto [cell, x, y, row] : MatrixIterator1(walls)) {
+    REQUIRE(walls[y][x] == cell);
+    print("{} ", cell);
+    if(row) print("\n");
+  }
+
+  println("VS Matrix2------");
+
+  for(MatrixIterator2 mit{walls}; mit.next();) {
+    REQUIRE(walls[mit.y][mit.x] == mit.cell);
+    print("{} ", mit.cell);
+    if(mit.row) print("\n");
+  }
+
+  println("END TEST=============");
+}
+
+
+template<long FROM, long TO>
+class Range {
+  public:
+    class iterator
+    {
+      long num = FROM;
+
+    public:
+      using iterator_category = std::input_iterator_tag;
+      using value_type = long;
+      using difference_type = long;
+      using pointer = const long *;
+      using reference = long;
+
+      explicit iterator(long _num = 0) : num(_num) {}
+
+      iterator& operator++() {
+        num = TO >= FROM ? num + 1 : num - 1;
+        return *this;
+      }
+
+      iterator operator++(int) {
+        iterator retval = *this;
+        ++(*this);
+        return retval;
+      }
+
+      bool operator==(iterator other) const {
+        return num == other.num;
+      }
+
+      bool operator!=(iterator other) const {
+        return !(*this == other);
+      }
+
+      reference operator*() const {
+        return num;
+      }
+  };
+
+  iterator begin() {
+    return iterator(FROM);
+  }
+
+  iterator end() {
+    return iterator(TO >= FROM ? TO + 1 : TO - 1);
+  }
+};
+
+TEST_CASE("basic matrix example", "[matrix]") {
+  auto range = Range<15, 25>();
+  auto itr = std::find(range.begin(), range.end(), 18);
+  std::cout << *itr << '\n';
+
+  for(long l : Range<3, 5>()) {
+    std::cout << l << ' ';
+  }
+
+  std::cout << '\n';
+}
+
+TEST_CASE("matrix_assign works", "[matrix]") {
+
+}
+
+TEST_CASE("matrix_dump works", "[matrix]") {
+
+}