Replace coral::fixed_buffer with coral::ring_buffer

source/coral/io.cpp

@@ -4,34 +4,76 @@ import coral;
 
 export namespace coral {
 	/**
-	 * Multiplexing byte-based ring buffer of `capacity` size that may be used for memory-backed I/O operations and
-	 * lightweight data construction.
+	 * Multiplexing byte-based ring buffer that may be used for memory-backed I/O operations and fast data (re)-
+	 * construction.
 	 */
-	template<usize capacity> struct fixed_buffer : public writer, public reader {
-		fixed_buffer() = default;
+	struct ring_buffer : public writer, public reader {
+		/**
+		 * Potential results from attempting to allocate a ring buffer dynamically.
+		 *
+		 * [allocate_result::ok] means nothing went wrong and the allocation was successful.
+		 *
+		 * [allocate_result::out_of_memory] indicates that there is not enough memory available in the provided
+		 * allocator to create a buffer of the requested size.
+		 */
+		enum class [[nodiscard]] allocate_result {
+			ok,
+			out_of_memory,
+		};
+
+		ring_buffer() = default;
+
+		ring_buffer(ring_buffer const &) = delete;
+
+		~ring_buffer() override {
+			if (this->data_allocator != nullptr) this->data_allocator->deallocate(this->data.pointer);
+		}
+
+		/**
+		 * Attempts to allocate memory for the ring buffer `capacity` number of bytes large with `data_allocator` as the
+		 * allocation strategy.
+		 *
+		 * See [allocate_result] for more information on error handling.
+		 *
+		 * *Note*: calling allocate will wipe out the contents of the current buffer.
+		 */
+		allocate_result allocate(allocator & data_allocator, usize capacity) {
+			if (this->data_allocator != nullptr) this->data_allocator->deallocate(this->data.pointer);
+
+			this->clear();
+
+			u8 * const data {this->data_allocator->reallocate(nullptr, capacity)};
+
+			if (data == nullptr) {
+				this->data_allocator = nullptr;
+				this->data = {};
+
+				return allocate_result::out_of_memory;
+			}
+
+			this->data_allocator = &data_allocator;
+			this->data = {data, capacity};
+
+			return allocate_result::ok;
+		}
 
 		/**
 		 * Returns a mutable [slice] ranging from the head to the last-filled element.
 		 *
 		 * *Note*: The lifetime and validity of the returned slice is only guaranteed for as long as the source
-		 * [fixed_buffer] is not mutated or out-of-scope.
+		 * [ring_buffer] is not mutated or out-of-scope.
 		 */
 		slice<u8 const> as_slice() const {
-			return {this->data, this->data_filled};
-		}
-
-		/**
-		 * Returns the base pointer of the buffer data.
-		 */
-		u8 const * begin() const {
 			return this->data;
 		}
 
 		/**
-		 * Returns the tail pointer of the buffer data.
+		 * Clears all written elements from the buffer.
 		 */
-		u8 const * end() const {
-			return this->data + this->cursor;
+		void clear() {
+			this->data_filled = 0;
+			this->read_index = 0;
+			this->write_index = 0;
 		}
 
 		/**
@@ -45,14 +87,14 @@ export namespace coral {
 		 * Returns `true` if the buffer is completely empty of data, otherwise `false`.
 		 */
 		bool is_empty() const {
-			return this->data_filled == capacity;
+			return this->data_filled == this->data.length;
 		}
 
 		/**
 		 * Returns `true` if the buffer has been completely filled with data, otherwise `false`.
 		 */
 		bool is_full() const {
-			return this->data_filled == capacity;
+			return this->data_filled == this->data.length;
 		}
 
 		/**
@@ -64,7 +106,7 @@ export namespace coral {
 
 			this->data_filled += 1;
 			this->data[this->write_index] = data;
-			this->write_index = (this->write_index + 1) % capacity;
+			this->write_index = (this->write_index + 1) % this->data.length;
 
 			return true;
 		}
@@ -73,13 +115,13 @@ export namespace coral {
 		 * Reads whatever data is in the buffer into `data`, returning the number of bytes read from the buffer.
 		 */
 		expected<usize, io_error> read(slice<u8> const & data) override {
-			slice const readable_data {this->data, min(this->data_filled, data.length)};
+			slice const readable_data {this->data.sliced(0, min(this->data_filled, data.length))};
 
 			this->data_filled -= readable_data.length;
 
 			for (usize index = 0; index < readable_data.length; index += 1) {
 				data[index] = this->data[this->read_index];
-				this->read_index = (this->read_index + 1) % capacity;
+				this->read_index = (this->read_index + 1) % this->data.length;
 			}
 
 			return readable_data.length;
@@ -89,23 +131,20 @@ export namespace coral {
 		 * Returns the remaining unfilled buffer space in bytes.
 		 */
 		usize remaining() const {
-			return capacity - this->data_filled;
+			return this->data.length - this->data_filled;
 		}
 
 		/**
-		 * Attempts to write `data` to the buffer, returning the number of bytes written or [io_error::unavailable] if
-		 * it has been completely filled and no more bytes can be written.
+		 * Write `data` to the buffer, returning the number of bytes written to the buffer.
 		 */
 		expected<usize, io_error> write(slice<u8 const> const & data) override {
-			if (this->is_full()) return io_error::unavailable;
-
 			slice const writable_data {data.sliced(0, min(data.length, this->remaining()))};
 
 			this->data_filled += writable_data.length;
 
 			for (usize index = 0; index < writable_data.length; index += 1) {
 				this->data[this->write_index] = data[index];
-				this->write_index = (this->write_index + 1) % capacity;
+				this->write_index = (this->write_index + 1) % this->data.length;
 			}
 
 			return writable_data.length;
@@ -118,7 +157,9 @@ export namespace coral {
 
 		usize write_index {0};
 
-		u8 data[capacity]{0};
+		allocator * data_allocator {nullptr};
+
+		slice<u8> data {};
 	};
 
 	/**