string_view_vector.h

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#ifndef GRAPHSCOPE_UTILS_STRING_VIEW_VECTOR_H_
#define GRAPHSCOPE_UTILS_STRING_VIEW_VECTOR_H_
 
#include <stdlib.h>
#include <string.h>
 
#include <string_view>
#include <vector>
 
namespace gs {
 
class StringViewVector {
 public:
  StringViewVector() { offsets_.push_back(0); }
  ~StringViewVector() {}
 
  void push_back(const std::string_view& val) {
    size_t old_size = buffer_.size();
    buffer_.resize(old_size + val.size());
    memcpy(&buffer_[old_size], val.data(), val.size());
    offsets_.push_back(buffer_.size());
  }
 
  void emplace_back(const std::string_view& val) {
    size_t old_size = buffer_.size();
    buffer_.resize(old_size + val.size());
    memcpy(&buffer_[old_size], val.data(), val.size());
    offsets_.push_back(buffer_.size());
  }
 
  size_t size() const {
    assert(offsets_.size() > 0);
    return offsets_.size() - 1;
  }
 
  std::string_view operator[](size_t index) const {
    size_t from = offsets_[index];
    size_t len = offsets_[index + 1] - from;
    return std::string_view(&buffer_[from], len);
  }
 
  std::vector<char>& content_buffer() { return buffer_; }
 
  const std::vector<char>& content_buffer() const { return buffer_; }
 
  std::vector<size_t>& offset_buffer() { return offsets_; }
 
  const std::vector<size_t>& offset_buffer() const { return offsets_; }
 
  void clear() {
    buffer_.clear();
    offsets_.clear();
    offsets_.push_back(0);
  }
 
  void swap(StringViewVector& rhs) {
    buffer_.swap(rhs.buffer_);
    offsets_.swap(rhs.offsets_);
  }
 
 private:
  std::vector<char> buffer_;
  std::vector<size_t> offsets_;
};
 
}  // namespace gs
 
#endif  // GRAPHSCOPE_UTILS_STRING_VIEW_VECTOR_H_