Function capacity

Libraries/Http/Internal/HttpFixedBufferWriter.h:22–22

    [[nodiscard]] Span<const char> written() const { return {buffer.data(), size}; }
    [[nodiscard]] size_t           writtenBytes() const { return size; }
    [[nodiscard]] size_t           capacity() const { return buffer.sizeInBytes(); }

    Result append(Span<const char> value, const char* outOfSpaceError);
    Result append(StringSpan value, const char* outOfSpaceError) { return append(value.toCharSpan(), outOfSpaceError); }