Add ParmParse.to_dict()

src/Base/ParmParse.cpp

@@ -9,8 +9,10 @@
 #include <AMReX_IntVect.H>
 #include <AMReX_ParmParse.H>
 
+#include <functional>
 #include <iostream>
 #include <string>
+#include <string_view>
 #include <vector>
 
 
@@ -103,5 +105,91 @@ void init_ParmParse(py::module &m)
         )
 
         // TODO: dumpTable, hasUnusedInputs, getUnusedInputs, getEntries
+
+        .def(
+            "to_dict",
+            [](ParmParse &pp) {
+                py::dict d;
+
+                auto g_table = pp.table();
+
+                // sort all keys
+                std::vector<std::string> sorted_names;
+                sorted_names.reserve(g_table.size());
+                for (auto const& [name, entry] : g_table) {
+                    sorted_names.push_back(name);
+                }
+                std::sort(sorted_names.begin(), sorted_names.end());
+
+                // helper function to unroll any nested parameter.sub.options into dict of dict of value
+                auto add_nested = [&d](auto && value, std::string_view s) {
+                    py::dict d_inner = d;  // just hold a handle to the current dict
+
+                    while (true) {
+                        auto pos = s.find('.');
+                        bool last = pos == std::string_view::npos;
+                        py::str key(s.substr(0, pos));
+
+                        if (last) {
+                            d_inner[key] = value;
+                            break;
+                        } else {
+                            // Create nested dict if missing or wrong type
+                            if (!d_inner.contains(key) ||
+                                !py::isinstance<py::dict>(d_inner[key])) {
+                                d_inner[key] = py::dict();
+                            }
+
+                            // Move one level deeper (safe, keeps reference alive)
+                            d_inner = d_inner[key].cast<py::dict>();
+                        }
+                        s.remove_prefix(pos + 1);
+                    }
+                };
+
+                for (auto const& name : sorted_names) {
+                    auto const& entry = g_table[name];
+                    for (auto const & vals : entry.m_vals) {
+                        if (vals.size() == 1) {
+                            std::visit(
+                                [&](auto&& arg) {
+                                    using T = std::remove_pointer_t<std::decay_t<decltype(arg)>>;
+                                    T v;
+                                    pp.get(name.c_str(), v);
+                                    add_nested(v, name);
+                                },
+                                entry.m_typehint
+                            );
+                        } else {
+                            std::visit(
+                                [&](auto&& arg) {
+                                    using T = std::remove_pointer_t<std::decay_t<decltype(arg)>>;
+                                    if constexpr (!std::is_same_v<T, bool>) {
+                                        std::vector<T> valarr;
+                                        pp.getarr(name.c_str(), valarr);
+                                        add_nested(valarr, name);
+                                    }
+                                },
+                                entry.m_typehint
+                            );
+                        }
+                    }
+                }
+
+                return d;
+            },
+            R"(Convert to a nested Python dictionary.
+
+.. code-block:: python
+
+    # Example: dump all ParmParse entries to YAML or TOML
+    import toml
+    import yaml
+
+    pp = amr.ParmParse("").to_dict()
+    yaml_string = yaml.dump(d)
+    toml_string = toml.dumps(d)
+)"
+        )
     ;
 }

tests/test_parmparse.py

@@ -15,8 +15,42 @@ def test_parmparse():
     dt = pp_param.get_real("dt")
     dopml = pp_param.get_bool("do_pml")
 
+    pp_param.add("ncell", 42)  # overwrite file
+    pp_param.add(
+        "question", "What is the answer to life, the universe, and everything?"
+    )
+    pp_param.add("answer", 41)
+    pp_param.add("answer", 42)  # last wins
+    pp_param.add("pi_approx", 3.1415)
+    pp_param.addarr("floats", [1.0, 2.0, 3.0])
+    pp_param.addarr("ints", [4, 5, 6])
+    pp_param.addarr("strs", ["Who", "Where", "What", "When", "How"])
+
     assert dopml
     assert np.isclose(dt, 1.0e-5)
     assert ncell == 100
 
+    # printing
     pp.pretty_print_table()
+
+    # type hints
+    d = pp.to_dict()
+    assert isinstance(d["param"]["ncell"], int)  # overwritten
+    assert isinstance(d["param"]["dt"], str)  # file
+    assert isinstance(d["param"]["do_pml"], str)  # file
+    assert isinstance(d["param"]["question"], str)
+    assert isinstance(d["param"]["answer"], int)
+    assert d["param"]["answer"] == 42  # last wins
+    assert isinstance(d["param"]["pi_approx"], float)
+    assert isinstance(d["param"]["floats"], list)
+    assert isinstance(d["param"]["ints"], list)
+    assert isinstance(d["param"]["strs"], list)
+    assert d["param"]["floats"] == [1.0, 2.0, 3.0]
+    assert d["param"]["ints"] == [4, 5, 6]
+    assert d["param"]["strs"] == ["Who", "Where", "What", "When", "How"]
+
+    # You can now dump to YAML or TOML or any other format
+    # import toml
+    # import yaml
+    # yaml_string = yaml.dump(d)
+    # toml_string = toml.dumps(d)