Add back missing file lost in rebase

Former-commit-id: b5512d77a1299cf6ff960229cd47776b82eaba4b

src/compactvector.h

@@ -0,0 +1,153 @@
+#pragma once
+
+#include <type_traits>
+#include <assert.h>
+
+/*************************************************
+ * compactvector - similar to std::vector but optimized for minimal memory
+ *  
+ *  Notable differences:
+ *      - Limited to 2^32 elements
+ *      - Grows linearly not exponentially
+ * 
+ *************************************************/
+
+template<typename T, bool MEMMOVE_SAFE=false>
+class compactvector
+{
+    static_assert(MEMMOVE_SAFE || std::is_trivially_copyable<T>::value, "compactvector requires trivially copyable types");
+    T *m_data = nullptr;
+    unsigned m_celem = 0;
+    unsigned m_max = 0;
+
+public:
+    typedef T* iterator;
+
+    compactvector() noexcept = default;
+    ~compactvector() noexcept
+    {
+        clear();    // call dtors
+        zfree(m_data);
+    }
+
+    compactvector(compactvector &) noexcept = delete;
+
+    compactvector(compactvector &&src) noexcept
+    {
+        m_data = src.m_data;
+        m_celem = src.m_celem;
+        m_max = src.m_max;
+        src.m_data = nullptr;
+        src.m_celem = 0;
+        src.m_max = 0;
+    }
+
+    compactvector &operator=(const compactvector&) noexcept = delete;
+    compactvector &operator=(compactvector &&src) noexcept
+    {
+        zfree(m_data);
+        m_data = src.m_data;
+        m_celem = src.m_celem;
+        m_max = src.m_max;
+        src.m_data = nullptr;
+        src.m_celem = 0;
+        src.m_max = 0;
+        return *this;
+    }
+
+    inline T* begin() { return m_data; }
+    inline const T* begin() const { return m_data; }
+
+    inline T* end() { return m_data + m_celem; }
+    inline const T* end() const { return m_data + m_celem; }
+
+    T* insert(T* where, T &val)
+    {
+        assert(where >= m_data);
+        size_t idx = where - m_data;
+        if (m_celem >= m_max)
+        {
+            if (m_max < 2)
+                m_max = 2;
+            else
+                m_max = m_max + 4;
+            
+            m_data = (T*)zrealloc(m_data, sizeof(T) * m_max, MALLOC_LOCAL);
+            m_max = zmalloc_usable(m_data) / sizeof(T);
+        }
+        assert(idx < m_max);
+        where = m_data + idx;
+        memmove(m_data + idx + 1, m_data + idx, (m_celem - idx)*sizeof(T));
+        new(m_data + idx) T(std::move(val));
+        ++m_celem;
+        return where;
+    }
+
+    T &operator[](size_t idx)
+    {
+        assert(idx < m_celem);
+        return m_data[idx];
+    }
+    const T &operator[](size_t idx) const
+    {
+        assert(idx < m_celem);
+        return m_data[idx];
+    }
+
+    T& back() { assert(m_celem > 0); return m_data[m_celem-1]; }
+    const T& back() const { assert(m_celem > 0); return m_data[m_celem-1]; }
+
+    void erase(T* where)
+    {
+        assert(where >= m_data);
+        size_t idx = where - m_data;
+        assert(idx < m_celem);
+        where->~T();
+        memmove(where, where+1, ((m_celem - idx - 1)*sizeof(T)));
+        --m_celem;
+
+        if (m_celem == 0)
+        {
+            zfree(m_data);
+            m_data = nullptr;
+            m_max = 0;
+        }
+    }
+
+    void shrink_to_fit()
+    {
+        if (m_max == m_celem)
+            return;
+        m_data = (T*)zrealloc(m_data, sizeof(T) * m_celem, MALLOC_LOCAL);
+        m_max = m_celem;    // NOTE: We do not get the usable size here, because this could cause us to continually realloc
+    }
+
+    size_t bytes_used() const
+    {
+        return sizeof(this) + (m_max * sizeof(T));
+    }
+
+    void clear()
+    {
+        for (size_t idx = 0; idx < m_celem; ++idx)
+            m_data[idx].~T();
+        zfree(m_data);
+        m_data = nullptr;
+        m_celem = 0;
+        m_max = 0;
+    }
+
+    bool empty() const noexcept
+    {
+        return m_celem == 0;
+    }
+
+    size_t size() const noexcept
+    {
+        return m_celem;
+    }
+
+    T* data() noexcept { return m_data; }
+    const T* data() const noexcept { return m_data; }
+};
+static_assert(sizeof(compactvector<void*>) <= 16, "not compact");