file_iterator.h

#pragma once

#include <cassert>
#include "file.h"
#include "page.h"
#include "types.h"

namespace wiscdb {

class FileIterator {
 public:
  FileIterator()
      : file_(NULL),
        current_page_number_(Page::INVALID_NUMBER) {
  }

  FileIterator(File* file)
      : file_(file) {
    assert(file_ != NULL);
    const FileHeader& header = file_->readHeader();
    current_page_number_ = header.first_used_page;
  }

  FileIterator(File* file, PageId page_number)
      : file_(file),
        current_page_number_(page_number) {
  }

  inline FileIterator& operator++() {
    assert(file_ != NULL);
    const PageHeader& header = file_->readPageHeader(current_page_number_);
    current_page_number_ = header.next_page_number;

    return *this;
  }

  //postfix
  inline FileIterator operator++(int)
  {
    FileIterator tmp = *this;   // copy ourselves

    assert(file_ != NULL);
    const PageHeader& header = file_->readPageHeader(current_page_number_);
    current_page_number_ = header.next_page_number;

    return tmp;
  }

  inline bool operator==(const FileIterator& rhs) const {
    return file_->filename() == rhs.file_->filename() &&
        current_page_number_ == rhs.current_page_number_;
  }

  inline bool operator!=(const FileIterator& rhs) const {
    return (file_->filename() != rhs.file_->filename()) ||
        (current_page_number_ != rhs.current_page_number_);
  }

  inline Page operator*() const
  { return file_->readPage(current_page_number_); }

 private:
  File* file_;

  PageId current_page_number_;
};

}