intermediate changes

ref:cde9a383711a11544ce7e107a78147fb96cc4029

1 files changed, 40 insertions, 0 deletions

diff --git a/library/cpp/containers/stack_array/stack_array.h b/library/cpp/containers/stack_array/stack_array.h
new file mode 100644
index 0000000000..28e49bfc3c
--- /dev/null
+++ b/library/cpp/containers/stack_array/stack_array.h
@@ -0,0 +1,40 @@
+#pragma once
+
+#include "range_ops.h"
+
+#include <util/generic/array_ref.h>
+#include <util/system/defaults.h> /* For alloca. */
+
+namespace NStackArray {
+    /**
+     * A stack-allocated array. Should be used instead of � variable length
+     * arrays that are not part of C++ standard.
+     *
+     * Example usage:
+     * @code
+     * void f(int size) {
+     *    // T array[size]; // Wrong!
+     *    TStackArray<T> array(ALLOC_ON_STACK(T, size)); // Right!
+     *    // ...
+     * }
+     * @endcode
+     *
+     * Note that it is generally a *VERY BAD* idea to use this in inline methods
+     * as those might be called from a loop, and then stack overflow is in the cards.
+     */
+    template <class T>
+    class TStackArray: public TArrayRef<T> {
+    public:
+        inline TStackArray(void* data, size_t len)
+            : TArrayRef<T>((T*)data, len)
+        {
+            NRangeOps::InitializeRange(this->begin(), this->end());
+        }
+
+        inline ~TStackArray() {
+            NRangeOps::DestroyRange(this->begin(), this->end());
+        }
+    };
+}
+
+#define ALLOC_ON_STACK(type, n) alloca(sizeof(type) * (n)), (n)