feat(policy): updateed policy system and added new reaction chains

Reacions chains now contain more information and are broken out in a more detailed fashion.

src/include/gridfire/policy/policy_logical.h

@@ -0,0 +1,51 @@
+#pragma once
+
+#include "gridfire/policy/policy_abstract.h"
+
+#include <vector>
+#include <memory>
+
+namespace gridfire::policy {
+    /**
+     * @class MultiReactionChainPolicy
+     * @brief A ReactionChainPolicy composed of multiple child ReactionChainPolicy instances.
+     *
+     * Useful for policies that represent a union of several reaction chains (for example the
+     * `LowMassMainSequenceReactionChainPolicy` composes the proton-proton and CNO chains).
+     *
+     * @par Example
+     * @code
+     * LowMassMainSequenceReactionChainPolicy multi;
+     * const auto &chains = multi.get_chain_policies();
+     * for (const auto &ch : chains) { std::cout << ch->get_reactions().size() << " reactions\n"; }
+     * @endcode
+     */
+    class MultiReactionChainPolicy : public ReactionChainPolicy {
+    public:
+        explicit MultiReactionChainPolicy(std::vector<std::unique_ptr<ReactionChainPolicy>>&& chain_policies);
+
+        [[nodiscard]] const std::vector<std::unique_ptr<ReactionChainPolicy>>& get_chain_policies() const;
+
+        [[nodiscard]] const reaction::ReactionSet& get_reactions() const override;
+
+        [[nodiscard]] bool contains(const std::string &id) const override;
+        [[nodiscard]] bool contains(const reaction::Reaction &reaction) const override;
+
+        [[nodiscard]] std::unique_ptr<ReactionChainPolicy> clone() const override;
+        [[nodiscard]] std::string name() const override;
+        [[nodiscard]] uint64_t hash(uint64_t seed) const override;
+
+        [[nodiscard]] bool operator==(const ReactionChainPolicy& other) const override;
+        [[nodiscard]] bool operator!=(const ReactionChainPolicy& other) const override;
+
+        [[nodiscard]] size_t size() const;
+
+        auto begin() { return m_chain_policies.begin(); }
+        [[nodiscard]] auto begin() const { return m_chain_policies.cbegin(); }
+        auto end() { return m_chain_policies.end(); }
+        [[nodiscard]] auto end() const { return m_chain_policies.cend(); }
+    protected:
+        std::vector<std::unique_ptr<ReactionChainPolicy>> m_chain_policies;
+        reaction::ReactionSet m_reactions;
+    };
+}