Getters for config content

config_utilities/include/config_utilities/config.h

@@ -42,6 +42,7 @@
 #include <vector>
 
 #include "config_utilities/internal/checks.h"
+#include "config_utilities/internal/logger.h"
 #include "config_utilities/internal/namespacing.h"
 #include "config_utilities/internal/visitor.h"
 #include "config_utilities/traits.h"
@@ -94,6 +95,61 @@ void field(T& field, const std::string& field_name, const std::string& unit = ""
   internal::Visitor::visitField<Conversion>(field, field_name, unit);
 }
 
+
+/**
+ * @brief Lists all the fields of the given configuration.
+ *
+ * This function retrieves metadata from the provided configuration object
+ * and extracts the names of all fields, returning them in a vector.
+ *
+ * @tparam ConfigT The type of the configuration.
+ * @param config The configuration object whose fields are to be listed.
+ * @return A vector containing the names of all fields in the configuration.
+ */
+template <typename ConfigT>
+std::vector<std::string> listFields(const ConfigT& config) {
+  internal::MetaData data = internal::Visitor::getValues(config);
+  std::vector<std::string> fields;
+  for (const auto& field_info : data.field_infos) {
+    fields.emplace_back(field_info.name);
+  }
+  return fields;
+}
+
+/**
+ * @brief Retrieves the value of a specified field from the given configuration.
+ *
+ * This function searches for a field with the specified name in the provided
+ * configuration object and attempts to convert its value to the requested type.
+ * If the field is found and the conversion is successful, the value is returned
+ * as an optional. If the field is not found or the conversion fails, a warning
+ * is logged and an empty optional is returned.
+ *
+ * @tparam ConfigT The type of the configuration.
+ * @tparam T The type to which the field value should be converted.
+ * @param config The configuration object from which the field value is to be retrieved.
+ * @param field_name The name of the field whose value is to be retrieved.
+ * @return An optional containing the value of the field if found and successfully converted,
+ *         otherwise an empty optional.
+ */
+template <typename ConfigT, typename T>
+std::optional<T> getField(const ConfigT& config, const std::string& field_name) {
+  internal::MetaData data = internal::Visitor::getValues(config);
+  for (const auto& field_info : data.field_infos) {
+    if (field_info.name == field_name) {
+      try {
+        return field_info.value.as<T>();
+      } catch (const YAML::BadConversion& e) {
+        internal::Logger::logWarning("Field " + field_name + " could not be converted to the requested type.");
+
+        return std::nullopt;
+      }
+    }
+  }
+  internal::Logger::logWarning("Field " + field_name + " not found in config.");
+  return std::nullopt;
+}
+
 /**
  * @brief Declare that this config inherits from a base config. Note that this call typically requires explicit
  * template declaration or explicit casting for argument dependent look-up. E.g. 'base<BaseT>(config)' or '

config_utilities/test/CMakeLists.txt

@@ -19,6 +19,7 @@ add_executable(
   tests/enums.cpp
   tests/external_registry.cpp
   tests/factory.cpp
+  tests/getters.cpp
   tests/inheritance.cpp
   tests/missing_fields.cpp
   tests/namespacing.cpp

config_utilities/test/tests/getters.cpp

@@ -0,0 +1,86 @@
+/** -----------------------------------------------------------------------------
+ * Copyright (c) 2023 Massachusetts Institute of Technology.
+ * All Rights Reserved.
+ *
+ * AUTHORS:     Lukas Schmid <[email protected]>, Nathan Hughes <[email protected]>
+ * AFFILIATION: MIT-SPARK Lab, Massachusetts Institute of Technology
+ * YEAR:        2023
+ * LICENSE:     BSD 3-Clause
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ * list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ *
+ * 3. Neither the name of the copyright holder nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ * -------------------------------------------------------------------------- */
+
+#include <gtest/gtest.h>
+
+#include "config_utilities/config.h"
+#include "config_utilities/parsing/yaml.h"
+#include "config_utilities/test/default_config.h"
+
+namespace config::test {
+
+struct GetterStruct {
+  int some_number;
+  std::string some_string;
+};
+
+void declare_config(GetterStruct& config) {
+  name("GetterStruct");
+  field(config.some_number, "some_number");
+  field(config.some_string, "some_string");
+}
+
+TEST(ConfigGetters, Getters) {
+  const std::string yaml_string = R"yaml(
+some_number: 5
+some_string: "Hello"
+)yaml";
+  const auto node = YAML::Load(yaml_string);
+
+  const auto config = fromYaml<GetterStruct>(node);
+  EXPECT_EQ(config.some_number, 5);
+  EXPECT_EQ(config.some_string, "Hello");
+
+  const auto fields = listFields(config);
+  EXPECT_EQ(fields.size(), 2);
+  EXPECT_EQ(fields[0], "some_number");
+  EXPECT_EQ(fields[1], "some_string");
+
+  const auto number = getField<GetterStruct, int>(config, "some_number");
+  EXPECT_TRUE(number.has_value());
+  EXPECT_EQ(number.value(), 5);
+
+  const auto string = getField<GetterStruct, std::string>(config, "some_string");
+  EXPECT_TRUE(string.has_value());
+  EXPECT_EQ(string.value(), "Hello");
+
+  const auto wrong = getField<GetterStruct, int>(config, "some_string");
+  EXPECT_FALSE(wrong.has_value());
+
+  const auto wrong2 = getField<GetterStruct, std::string>(config, "non_existent_field");
+  EXPECT_FALSE(wrong2.has_value());
+}
+
+}  // namespace config::test