editor.h

Editor C++ 源程序 用链表实现

class Editor:public List<String> {
public:
   Editor(ifstream *file_in, ofstream *file_out);
   bool get_command();
   void run_command();
private:
   ifstream *infile;
   ofstream *outfile;
   char user_command;

//  auxiliary functions
   Error_code next_line();
   Error_code previous_line();
   Error_code goto_line();
   Error_code insert_line();
   Error_code substitute_line();
   Error_code change_line();
   void read_file();
   void write_file();
   void find_string();
   bool user_says_yes();
};


Editor::Editor(ifstream *file_in, ofstream *file_out)
/*
Post: Initialize the Editor members infile and outfile with the parameters.
*/
{
   infile = file_in;
   outfile = file_out;
}


bool Editor::get_command()
/*
Post: Sets member user_command; returns true unless the user's command is q.
Uses: C library function tolower.
*/
{
   if (current!=NULL)
      cout << current_position << " : "
           << current->entry.c_str() << "\n??" << flush;
   else
      cout << "File buffer is empty(please use command r to read file to buffer). \n??" << flush;

   cin >> user_command;    //  ignores white space and gets command
   user_command = tolower(user_command);
   while (cin.get() != '\n')
      ;                       //  ignore user's enter key
   if (user_command == 'q')
      return false;
   else
      return true;
}


void Editor::run_command()
/*
Post: The command in user_command has been performed.
Uses: methods and auxiliary functions of the class Editor,
      the class String, and the String processing functions.
*/
{
   String temp_string;
   switch (user_command) {
   case 'b':
      if (empty())
         cout << " Warning: empty buffer " << endl;
      else
         while (previous_line() == success)
            ;
      break;

   case 'c':
      if (empty())
         cout << " Warning: Empty file" << endl;
      else if (change_line() != success)
         cout << " Error: Substitution failed " << endl;
      break;

   case 'd':
      if (remove(current_position, temp_string) != success)
         cout << " Error: Deletion failed " << endl;
      break;

   case 'e':
      if (empty())
         cout << " Warning: empty buffer " << endl;
      else
         while (next_line() == success)
            ;
      break;

   case 'f':
      if (empty())
         cout << " Warning: Empty file" << endl;
      else
         find_string();
      break;

   case 'g':
      if (goto_line() != success)
         cout << " Warning: No such line" << endl;
      break;

   case '?':
   case 'h':
      cout << "Valid commands are: b(egin) c(hange) d(el) e(nd)" << endl
           << "f(ind) g(o) h(elp) i(nsert) l(ength) n(ext) p(rior) " << endl
           << "q(uit) r(ead) s(ubstitute) v(iew) w(rite) " << endl;
      break;

   case 'i':
      if (insert_line() != success)
         cout << " Error: Insertion failed " << endl;
      break;

   case 'l':
      cout << "There are " << size() << " lines in the file." << endl;
      if (!empty())
         cout << "Current line length is "
              << strlen((current->entry).c_str()) << endl;
      break;

   case 'n':
      if (next_line() != success)
         cout << " Warning: at end of buffer" << endl;
      break;

   case 'p':
      if (previous_line() != success)
         cout << " Warning: at start of buffer" << endl;
      break;

   case 'r':
      read_file();
      break;

   case 's':
      if (substitute_line() != success)
         cout << " Error: Substitution failed " << endl;
      break;

   case 'v':
      traverse(write);
      break;

   case 'w':
      if (empty())
         cout << " Warning: Empty file" << endl;
      else
         write_file();
      break;

   default :
      cout << "Press h or ? for help or enter a valid command: ";
   }
}


Error_code Editor::next_line()
{
	if(current==NULL || current->next==NULL)return fail;
	else{
		current=current->next;
		current_position++;
		return success;
	}
}


Error_code Editor::previous_line()
{
	if(current==NULL || current->back==NULL)return fail;
	else{
		current=current->back;
		current_position--;
		return success;
	}
}


Error_code Editor::goto_line()
{
   int line_number;
   cout << " Goto what line number? " << flush;
   cin  >> line_number;
   if(line_number < 0 || line_number > count-1)return range_error;
   else{
	   set_position(line_number);
	   return success;
   }
}


Error_code Editor::insert_line()
/*
Post: A string entered by the user is inserted as a user-selected line number.
Uses: String and Editor methods and functions.
*/
{
   int line_number;
   cout << " Insert what line number? " << flush;
   cin  >> line_number;
   while (cin.get() != '\n');
   cout << " What is the new line to insert? " << flush;
   String to_insert = read_in(cin);
   return insert(line_number, to_insert);
}


Error_code Editor::substitute_line()
{
   int line_number;
   char ch;
   String new_line;
   cout << " Substitute what line number? " << flush;
   cin  >> line_number;
   if(line_number < 0 || line_number > count-1)return range_error;
   else{
	   set_position(line_number);
	   cout<<" What is the new line to substitute? "<<endl<< flush;
	   while((ch=cin.get())!='\n');  //skip exchange line character
	   new_line=read_in(cin);
	   current->entry=new_line;
	   return success;
   }
}


Error_code Editor::change_line()
/*
Pre:  The Editor is not empty.
Post: If a user-specified string appears in the
      current line, it is replaced by a new user-selected string.
      Else: an Error_code is returned.
Uses: String and Editor methods and functions.
*/
{
   Error_code result = success;
   cout << " What text segment do you want to replace? " << flush;
   String old_text = read_in(cin);
   cout << " What new text segment do you want to add in? " << flush;
   String new_text = read_in(cin);

   int index = strstr(current->entry, old_text);
   if (index == -1) result = fail;
   else {
      String new_line;
      strncpy(new_line, current->entry, index);
      strcat(new_line, new_text);
      const char *old_line = (current->entry).c_str();
      strcat(new_line, (String)(old_line + index + strlen(old_text.c_str())));
      current->entry = new_line;
   }
   return result;
}


bool Editor::user_says_yes()
{
	char answer;
	cin>>answer;
	answer=tolower(answer);
	if(answer=='y'||answer=='t'||answer=='o')return true;
	else return false;
}

   
void Editor::read_file()
/*
Pre:  Either the Editor is empty or the user authorizes the command.
Post: The contents of *infile are read to the Editor.
      Any prior contents of the Editor are overwritten.
Uses: String and Editor methods and functions.
*/
{
   bool proceed = true;
   if (!empty()) {
      cout << "Buffer is not empty; the read will destroy it." << endl;
      cout << " OK to proceed? " << endl<< flush;
      if (proceed = user_says_yes()) clear();
   }

  int line_number = 0;
  char terminal_char;
  while (proceed) {
      String in_string = read_in(*infile, terminal_char);
      if (terminal_char == EOF) {
         proceed = false;
         if (strlen(in_string.c_str()) > 0) insert(line_number , in_string);
      }
      else insert(line_number++, in_string);
   }
}


void Editor::write_file()
{
	String curr_line;
    int line_number;
	for(line_number=0;line_number<size();line_number++){
		retrieve(line_number, curr_line);
		*outfile<<curr_line.c_str()<<endl;
	}
}


void Editor::find_string()
/*
Pre:  The Editor is not empty.
Post: The current line is advanced until either it contains a copy
      of a user-selected string or it reaches the end of the Editor.
      If the selected string is found, the corresponding line is
      printed with the string highlighted.
Uses: String and Editor methods and functions.
*/
{
   int index;
   cout << "Enter string to search for:" << endl;
   String search_string = read_in(cin);
   while ((index = strstr(current->entry, search_string)) == -1)
      if (next_line() != success) break;
   if (index == -1) cout << "String was not found.";
   else {
      cout << (current->entry).c_str() << endl;
      for (int i = 0; i < index; i++)
         cout << " ";
      for (int j = 0; j < strlen(search_string.c_str()); j++)
         cout << "^";
   }
   cout << endl;
}