feat(cpp-object-oriented-modular-refactoring): step 18 - load-hierarchy

include/fesa/loads/load.h

@@ -0,0 +1,48 @@
+#ifndef FESA_LOADS_LOAD_H_
+#define FESA_LOADS_LOAD_H_
+
+#include <cstddef>
+#include <functional>
+#include <vector>
+
+#include "fesa/core/status.h"
+
+namespace fesa {
+
+class DofManager;
+class Domain;
+class SourceTargetResolver;
+
+/// @brief Describes one ordered contribution to the full load vector.
+struct LoadContribution {
+  std::size_t source_order;
+  std::size_t full_dof_index;
+  double value;
+};
+
+/// @brief Provides immutable semantic and equation context to a Load.
+/// @note Every referenced object must outlive a contribution request.
+struct LoadContext {
+  const Domain& domain;
+  const DofManager& dof_manager;
+  const SourceTargetResolver& target_resolver;
+};
+
+/// @brief Produces local ordered load contributions without global mutation.
+class Load {
+ public:
+  virtual ~Load() = default;
+
+  /// @brief Computes finite full-DOF contributions in stable target order.
+  /// @param context Non-owning semantic and equation context for this call.
+  /// @return Ordered contributions or a structured model failure.
+  virtual Result<std::vector<LoadContribution>> ComputeContributions(
+      const LoadContext& context) const = 0;
+};
+
+/// @brief Holds non-owning loads in an explicitly supplied source order.
+using LoadView = std::vector<std::reference_wrapper<const Load>>;
+
+}  // namespace fesa
+
+#endif  // FESA_LOADS_LOAD_H_