Copy infrastructure from tc

include/ml/meshlib_json.hpp

@@ -0,0 +1,68 @@
+#pragma once
+
+#include "meshlib.hpp"
+
+#include <Eigen/Eigen>
+#include <nlohmann/json.hpp>
+
+namespace Eigen {
+    template<class Derived>
+    void to_json(nlohmann::json &json, const Eigen::PlainObjectBase<Derived> &mat) {
+        using Scalar = typename Derived::Scalar;
+
+        auto rows = mat.rows();
+        auto cols = mat.cols();
+
+        std::vector<Scalar> vals(mat.size());
+        Map<Derived>(vals.data(), rows, cols) = mat;
+
+        json = {
+            {"rows", rows},
+            {"cols", cols},
+            {"vals", vals},
+        };
+    }
+
+    template<class Derived>
+    void from_json(const nlohmann::json &j, Derived &d) {
+        using Scalar = typename Derived::Scalar;
+
+        auto rows = j["rows"].get<Index>();
+        auto cols = j["cols"].get<Index>();
+        auto vals = j["vals"].get<std::vector<Scalar>>();
+
+        d = Map<Derived>(vals.data(), rows, cols);
+    }
+}
+
+namespace nlohmann {
+    template<typename PT_, typename CT_>
+    struct adl_serializer<ml::Mesh<PT_, CT_>> {
+        static void to_json(json &j, const ml::Mesh<PT_, CT_> &m) {
+            j = {
+                {"points", m.points},
+                {"cells",  m.cells},
+            };
+        }
+
+        static ml::Mesh<PT_, CT_> from_json(const json &j) {
+            return ml::Mesh<PT_, CT_>(
+                j["points"].get<PT_>(),
+                j["cells"].get<CT_>()
+            );
+        }
+    };
+}
+
+namespace ml {
+    template<typename PT_, typename CT_>
+    void write(const ml::Mesh<PT_, CT_> &mesh, std::ostream &&out) {
+        nlohmann::json json = mesh;
+        nlohmann::json::to_msgpack(json, out);
+    }
+
+    template<typename M_>
+    M_ read(std::istream &&in) {
+        return nlohmann::json::from_msgpack(in).get<M_>();
+    }
+}