feat: implement core term, symbol, and clause storage logic with canonicalization support

1 files changed, 33 insertions, 5 deletions

diff --git a/include/atp/core/term_bank.h b/include/atp/core/term_bank.h
index a121f8a..f909e2f 100644
--- a/include/atp/core/term_bank.h
+++ b/include/atp/core/term_bank.h
@@ -16,42 +16,70 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
-
 #pragma once
 
 /// @file term_bank.h
 /// @brief Hash-consing term pool — guarantees structural sharing.
 
+#include "atp/core/symbol_table.h"
 #include "atp/core/term.h"
 #include "atp/core/types.h"
 
 #include <span>
+#include <unordered_map>
+#include <vector>
 
 namespace atp {
 
 /// Global term pool with hash-consing.
 /// Every structurally identical term maps to the same TermId.
+///
+/// Holds a reference to SymbolTable for variable detection.
 class TermBank {
   public:
-    TermBank() = default;
+    /// TermBank needs the SymbolTable to distinguish variables from constants
+    /// (both have 0 args, but SymbolKind differs).
+    explicit TermBank(const SymbolTable& symbols) : symbols_(symbols) {}
 
     /// Create or retrieve a term. Returns the canonical TermId.
     TermId makeTerm(SymbolId symbol, std::span<const TermId> args);
 
-    /// Create a variable term.
+    /// Create a variable term. Convenience for makeTerm(var, {}).
     TermId makeVar(SymbolId var_symbol);
 
     /// Look up a term by its ID.
     [[nodiscard]] const Term& getTerm(TermId id) const;
 
-    /// Check if a TermId represents a variable.
+    /// Check if a TermId represents a variable (delegates to SymbolTable).
     [[nodiscard]] bool isVariable(TermId id) const;
 
     /// Total number of unique terms stored.
     [[nodiscard]] size_t size() const;
 
+    /// Access the underlying SymbolTable.
+    [[nodiscard]] const SymbolTable& symbols() const { return symbols_; }
+
   private:
-    // TODO: Phase 1 implementation — flat arena + hash index
+    struct TermKey {
+        SymbolId symbol;
+        std::vector<TermId> args;
+
+        bool operator==(const TermKey& other) const = default;
+    };
+
+    struct TermKeyHash {
+        size_t operator()(const TermKey& key) const {
+            size_t seed = std::hash<uint32_t>{}(key.symbol);
+            for (TermId arg : key.args) {
+                seed ^= std::hash<uint32_t>{}(arg) + 0x9e3779b9 + (seed << 6) + (seed >> 2);
+            }
+            return seed;
+        }
+    };
+
+    const SymbolTable& symbols_;
+    std::vector<Term> terms_;
+    std::unordered_map<TermKey, TermId, TermKeyHash> term_to_id_;
 };
 
 }  // namespace atp