CS 215 Fundamentals of Programming II Spring 2010 Project 6. Dnode<T> structure. Specifications for Document Class. 30 points

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1 CS 215 Fundamentals of Programming II Spring 2010 Project 6 30 points Out: March 26, 2010 Due: April 14, 2010 A line editor is a text editor that operates on lines of a textfile. A line editor manipulates text one line at a time. The editor keeps track of a "current line" at all times, and the commands of the editor are performed relative to this current line. In the past, this type of editor was necessary for printing terminals and dumb video terminals where one could not move around on a screen. Now such editors are used in batch mode where editing commands are read from a file and applied to a target file. For example, source code patches often are distributed this way. Your assignment is to write a Document class (specification given below) that supports line editing of a textfile and to write a (main) program that allows a user to interactively edit a textfile. Dnode<T> structure This project assumes the Dnode<T> structure definition of Chapter 9.5 of the textbook (pages ) for doubly linked nodes as used in lecture. Since it is a template, the definition should be placed outside and before the Document class definition in the document.h header file. Specifications for Document Class Note: this is not a template class, though it does use the Dnode structure template from the textbook. Attributes Object Type Name pointer to list of lines Dnode<string>* front pointer to current line Dnode<string>* curr The Document class stores a document as a doubly linked list of lines (strings) with front pointing to the (front of the) list. It uses a pointer, curr, to keep track of the current line that its operations may act upon. Minimally, a document might look like the following: front "" "" "" curr Document doc; This document consists of the three lines: 03/25/2010 Page 1 of 7

2 and the current line is "". You may want to add other attributes or special nodes to aid in implementing the Document operations. Operations Default constructor creates an empty document. no objects Explicit value constructor creates a document from an input stream. Assumes the input stream is open and valid. Each line of the stream is stored as a line of the document. The current line is set to the. input stream istream variable received & passed back in Copy constructor creates a copy of the original Document. Note this includes setting the current line to the line corresponding to the current line in the original. original document Document variable received original Destructor deletes a Document's nodes no objects operator= assignment operator, make this Document the same as the original Document. Note this includes setting the current line to the line corresponding to the current line in the original. Returns a reference to this object. original document Document variable received original this document Document & variable returned *this Insert inserts a line in front of the current line; the current line remains the same. If the document is empty, then inserts the line as the first one in the document and makes it the current line. 03/25/2010 Page 2 of 7

3 line to insert string variable received line Append inserts a line at the end of the document making it the current line. line to insert string variable received line Replace replaces the contents of the current line. If the document is empty, throws a UnderflowError exception. replacement line string variable received line Delete deletes the line at the current position; the current line becomes the next line after the deleted line unless the is deleted, then the becomes the current line. If the document is empty, throws a UnderflowError exception. No objects Find finds the in the document containing the target string (as a substring) and makes it the current line. If no line contains the target string, then throw a NotFoundError exception, and the current line remains the same. target string string variable received target SetCurrent sets the current line to the nth line from the top of the document with the numbered 1. If the document has fewer than n lines or n < 1, throws a RangeError exception and the current line remains the same. line number of the new current line int variable received n MoveCurrent moves the current line n places. If n > 0, move in the forward direction (toward the end). If n < 0, move in the backward direction (toward the beginning). If there are fewer than n lines in the appropriate direction, throws a RangeError exception and the current line remains the same. 03/25/2010 Page 3 of 7

4 number of lines to move the current line int variable received n WriteLine writes the current line to an output stream. If the document is empty, throws a UnderflowError exception. output stream ostream variable received & passed back out WriteAll writes all the lines in the document starting with the to an output stream; the current line remains the same. output stream ostream variable received & passed back out Assignment (20 points) Write the implementation of the Document class. The Dnode structure definition and the Document class definition should be put in header file document.h with suitable compilation guards (the Dnode structure first, then the Document class). The implementations of the Document class functions should be put in source file document.cpp. This project must be implemented using a doubly linked list. Projects that do not so will be returned for resubmission with late penalties. (10 points) Write a (main) program in file editor.cpp that has one command line argument, the name of a textfile to edit. The program should construct a Document object using the given textfile with the current line set to the (if the file is not empty), then allow the user to interactively edit the file by using the following command set. Commands may be entered in upper or lower case. An example run is shown below. Command I line A line R line D F target Description Insert a line in front of the current line. If the document is empty, this line becomes the current line. Append a line to end of the document making it the current line. Replace the current line. If the document is empty, an error message is displayed. Delete the current line. The next line becomes the current line unless the is deleted, then the current line becomes the (new). If the document is empty, an error message is displayed. Find the in the document containing target, making it the current line. If not found, a message is displayed and the current line remains the same. 03/25/2010 Page 4 of 7

5 Command S n M n C L W filename H Q Description Set the current line to the nth line from the top of the document with the numbered 1. If the document has fewer than n lines or n < 1, an error message is displayed and the current line remains the same. Move the current line n places. If n > 0, move in the forward direction (toward the bottom). If n < 0, move in the backward direction (toward the top). If there are fewer than n lines in the appropriate direction, an error message is displayed and the current line remains the same. Display the current line to the screen. If the document is empty, display an error message Display the entire document to the screen. Write the entire document to file named filename. Display command menu (i.e., help) Quit the editor without saving any changes Implementation notes: A reminder that strings and their operations are covered in Chapter 1.8 (pages 28 36) of the textbook. Also, string operations that return an index use the value string::npos to indicate end of string or not found. Since operator>> stops at the first whitespace, for commands I, A, R, and F, there will be at least one space left in the stream before the argument. For the purposes of this assignment, we will assume that the argument will follow the command letter after exactly one space and any other leading spaces are intended to be part of the line. To get rid of the separating space, use inputstream.ignore(); which will remove one character from the input stream. Error conditions in the main program must be determined by handling any exceptions thrown by Document operations. All exception types are defined in the file /home/hwang/cs215/project6/except.h on csserver. Note that this version of the header file contains new definitions, so be sure to get a copy of this version. You must submit a makefile named Makefile.project6 that creates an executable named editor for your project. Submissions without working makefiles will be assessed up to a 3 point penalty as indicated in the syllabus. It should conform to the examples given in the handout Very Basic make and demonstrated in class. REMINDER: Your project must compile for it to be graded. Submissions that do not compile will be returned for resubmission and assessed a late penalty. Submissions that do not substantially work also will be returned for resubmission and assessed a late penalty. Follow the guidelines in the C++ Programming Style Guideline handout. As stated in the syllabus, part of the grade on a programming project depends on how well you adhere to the guidelines. The grader will look at your code listing and grade it according to the guidelines. 03/25/2010 Page 5 of 7

6 What to submit Electronically submit a tarfile containing Makefile.project6, document.h, document.cpp, and editor.cpp as explained in the handout Submission Instructions for CS 215. Do not submit object files, executable files, or except.h. Turn in a hardcopy of your Makefile.project6, document.h, document.cpp, and editor.cpp. The submission system will compile and test the Document implementation against a test driver program. It will compile the project main program, but will not run it. Example Run user@csserver:~/cs215/projects$ more sampleedit.txt user@csserver:~/cs215/projects$./editor sampleedit.txt > h This line editor can do the following commands: I line insert line in front of current line A line append line to end of document R line replace current line D delete the current line F target makes line containing target current line S n set current line to nth line M n move current line n places C display current line to screen L display entire document to screen W file write document to file Q quit the editor (does not save changes) > i > a > m 2 > r 03/25/2010 Page 6 of 7

7 > s 1 > d > f mid > w sample2.txt > q user@csserver:~/cs215/projects$ more sample2.txt user@csserver:~/cs215/projects$ 03/25/2010 Page 7 of 7