How to Use a Stack-Based Vector in C ?

Using STL Vector with Stack Storage

Problem:

Finding a C vector-like class that utilizes stack storage instead of the heap.

Solution:

Chromium's stack_container.h provides a StackVector class that perfectly fits the requirement. It behaves almost identically to an ordinary vector but allocates data on the stack.

Usage:

• Create a buffer with a specified size:

<code class="cpp">char buffer[4096];</code>

• Create the StackVector object:

<code class="cpp">stack_vector<match_item> matches(buffer, sizeof(buffer));</code>

Alternatively, the buffer can be allocated internally by the class:

<code class="cpp">stack_vector<match_item, 256> matches;</code>

• Customize the allocator's size:

<code class="cpp">typedef std::pair<const char *, const char *> comp_list_item;
static const size_t comp_list_alloc_size = 128;
typedef StackAllocator<comp_list_item, comp_list_alloc_size> comp_list_alloc_type;</code>

• Instantiate the allocator and construct the vector:

<code class="cpp">comp_list_alloc_type::Source match_list_buffer;
comp_list_alloc_type match_list_alloc(&match_list_buffer);
comp_list_type match_list(match_list_alloc);</code>

• Reserve memory for the vector:

<code class="cpp">match_list.reserve(comp_list_alloc_size);</code>

Benefits:

• Drop-in replacement for STL vectors
• Allocates data on the stack, improving efficiency
• Customizable allocator size
• Option for automatic fallback to heap allocation in case of overflow

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