From 89e094d3f832467cacb586f739bd3793c52d2803 Mon Sep 17 00:00:00 2001
From: cdemeyer-teachx <cdemeyer@teachx.ai>
Date: Fri, 29 Aug 2025 16:24:15 +0900
Subject: [PATCH] ability to enable/disable allocator

---
 include/nd-wfc/wfc_allocator.hpp | 68 +++++++++++++++++++++++++++++++-
 1 file changed, 67 insertions(+), 1 deletion(-)

diff --git a/include/nd-wfc/wfc_allocator.hpp b/include/nd-wfc/wfc_allocator.hpp
index a74a911..fd64e04 100644
--- a/include/nd-wfc/wfc_allocator.hpp
+++ b/include/nd-wfc/wfc_allocator.hpp
@@ -10,7 +10,10 @@
 #include <cstdlib>
 #include <memory>
 
+//#define WFC_USE_STACK_ALLOCATOR
+
 inline void* allocate_aligned_memory(size_t alignment, size_t size) {
+#ifdef WFC_USE_STACK_ALLOCATOR
     void* ptr = nullptr;
 
 #ifdef _MSC_VER
@@ -30,9 +33,25 @@ inline void* allocate_aligned_memory(size_t alignment, size_t size) {
 #endif
 
     return ptr;
+#else
+    // When not using stack allocator, use standard malloc with manual alignment
+    void* ptr = std::malloc(size + alignment - 1 + sizeof(void*));
+    if (!ptr) return nullptr;
+
+    void* aligned_ptr = static_cast<char*>(ptr) + sizeof(void*) +
+                       (alignment - (reinterpret_cast<uintptr_t>(static_cast<char*>(ptr) + sizeof(void*)) % alignment)) % alignment;
+
+    // Store original pointer for free
+    *(static_cast<void**>(aligned_ptr) - 1) = ptr;
+
+    return aligned_ptr;
+#endif
 }
 
 inline void free_aligned_memory(void* ptr) {
+    if (!ptr) return;
+
+#ifdef WFC_USE_STACK_ALLOCATOR
 #ifdef _MSC_VER
     _aligned_free(ptr);
 #elif defined(__GNUC__) || defined(__clang__)
@@ -50,13 +69,19 @@ inline void free_aligned_memory(void* ptr) {
     free(ptr);
 #endif
 #endif
+#else
+    // When not using stack allocator, free the original pointer
+    void* original_ptr = *(static_cast<void**>(ptr) - 1);
+    std::free(original_ptr);
+#endif
 }
 
 namespace WFC {
 
+#ifdef WFC_USE_STACK_ALLOCATOR
 /**
  * @brief Stack allocator specifically designed for WFC branching operations
- * 
+ *
  * This allocator uses a stack-based approach where memory is allocated in chunks
  * and automatically deallocated when branches go out of scope. It's optimized
  * for the recursive branching pattern used in the WFC algorithm.
@@ -268,6 +293,47 @@ private:
     std::vector<Block> m_allocations;
 };
 
+#else // WFC_USE_STACK_ALLOCATOR not defined
+/**
+ * @brief Simplified allocator using standard malloc/free
+ */
+class WFCStackAllocator {
+public:
+    explicit WFCStackAllocator(size_t = 1024 * 1024) {}
+    ~WFCStackAllocator() = default;
+
+    // Non-copyable, non-movable for consistency
+    WFCStackAllocator(const WFCStackAllocator&) = delete;
+    WFCStackAllocator& operator=(const WFCStackAllocator&) = delete;
+    WFCStackAllocator(WFCStackAllocator&&) = delete;
+    WFCStackAllocator& operator=(WFCStackAllocator&&) = delete;
+
+    void* allocate(size_t size, size_t alignment = 8) {
+        return allocate_aligned_memory(alignment, size);
+    }
+
+    void deallocate(void* ptr) {
+        free_aligned_memory(ptr);
+    }
+
+    class StackFrame {
+    public:
+        StackFrame(WFCStackAllocator&) {}
+        ~StackFrame() = default;
+        StackFrame(const StackFrame&) = delete;
+        StackFrame& operator=(const StackFrame&) = delete;
+        StackFrame(StackFrame&&) = default;
+        StackFrame& operator=(StackFrame&&) = default;
+    };
+
+    StackFrame createFrame() { return StackFrame(*this); }
+    size_t getUsed() const { return 0; }
+    size_t getCapacity() const { return 0; }
+    size_t getAllocationCount() const { return 0; }
+    void reset() {}
+};
+#endif // WFC_USE_STACK_ALLOCATOR
+
 /**
  * @brief Custom allocator adapter for STL containers using WFCStackAllocator
  */