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#ifndef UTIL_STREAM_BLOCK_H
#define UTIL_STREAM_BLOCK_H
#include <cstddef>
#include <stdint.h>
namespace util {
namespace stream {
/**
* Encapsulates a block of memory.
*/
class Block {
public:
/**
* Constructs an empty block.
*/
Block() : mem_(NULL), valid_size_(0) {}
/**
* Constructs a block that encapsulates a segment of memory.
*
* @param[in] mem The segment of memory to encapsulate
* @param[in] size The size of the memory segment in bytes
*/
Block(void *mem, std::size_t size) : mem_(mem), valid_size_(size) {}
/**
* Set the number of bytes in this block that should be interpreted as valid.
*
* @param[in] to Number of bytes
*/
void SetValidSize(std::size_t to) { valid_size_ = to; }
/**
* Gets the number of bytes in this block that should be interpreted as valid.
* This is important because read might fill in less than Allocated at EOF.
*/
std::size_t ValidSize() const { return valid_size_; }
/** Gets a void pointer to the memory underlying this block. */
void *Get() { return mem_; }
/** Gets a const void pointer to the memory underlying this block. */
const void *Get() const { return mem_; }
/**
* Gets a const void pointer to the end of the valid section of memory
* encapsulated by this block.
*/
const void *ValidEnd() const {
return reinterpret_cast<const uint8_t*>(mem_) + valid_size_;
}
/**
* Returns true if this block encapsulates a valid (non-NULL) block of memory.
*
* This method is a user-defined implicit conversion function to boolean;
* among other things, this method enables bare instances of this class
* to be used as the condition of an if statement.
*/
operator bool() const { return mem_ != NULL; }
/**
* Returns true if this block is empty.
*
* In other words, if Get()==NULL, this method will return true.
*/
bool operator!() const { return mem_ == NULL; }
private:
friend class Link;
friend class RewindableStream;
/**
* Points this block's memory at NULL.
*
* This class defines poison as a block whose memory pointer is NULL.
*/
void SetToPoison() {
mem_ = NULL;
}
void *mem_;
std::size_t valid_size_;
};
} // namespace stream
} // namespace util
#endif // UTIL_STREAM_BLOCK_H
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