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#ifndef QUICHE_SPDY_CORE_SPDY_HEADER_STORAGE_H_
#define QUICHE_SPDY_CORE_SPDY_HEADER_STORAGE_H_
#include "absl/strings/string_view.h"
#include "quiche/common/platform/api/quiche_export.h"
#include "quiche/spdy/core/spdy_simple_arena.h"
namespace spdy {
// This class provides a backing store for absl::string_views. It previously
// used custom allocation logic, but now uses an UnsafeArena instead. It has the
// property that absl::string_views that refer to data in SpdyHeaderStorage are
// never invalidated until the SpdyHeaderStorage is deleted or Clear() is
// called.
//
// Write operations always append to the last block. If there is not enough
// space to perform the write, a new block is allocated, and any unused space
// is wasted.
class QUICHE_EXPORT_PRIVATE SpdyHeaderStorage {
public:
SpdyHeaderStorage();
SpdyHeaderStorage(const SpdyHeaderStorage&) = delete;
SpdyHeaderStorage& operator=(const SpdyHeaderStorage&) = delete;
SpdyHeaderStorage(SpdyHeaderStorage&& other) = default;
SpdyHeaderStorage& operator=(SpdyHeaderStorage&& other) = default;
absl::string_view Write(absl::string_view s);
// If |s| points to the most recent allocation from arena_, the arena will
// reclaim the memory. Otherwise, this method is a no-op.
void Rewind(absl::string_view s);
void Clear() { arena_.Reset(); }
// Given a list of fragments and a separator, writes the fragments joined by
// the separator to a contiguous region of memory. Returns a absl::string_view
// pointing to the region of memory.
absl::string_view WriteFragments(
const std::vector<absl::string_view>& fragments,
absl::string_view separator);
size_t bytes_allocated() const { return arena_.status().bytes_allocated(); }
private:
SpdySimpleArena arena_;
};
// Writes |fragments| to |dst|, joined by |separator|. |dst| must be large
// enough to hold the result. Returns the number of bytes written.
QUICHE_EXPORT_PRIVATE size_t
Join(char* dst, const std::vector<absl::string_view>& fragments,
absl::string_view separator);
} // namespace spdy
#endif // QUICHE_SPDY_CORE_SPDY_HEADER_STORAGE_H_
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