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Ok, this is a bit of a cheeky question. I want to build a simple text editor (using my own text mode screen handling). I just want a good example of data structures that can be used to represent the text buffer, and some simple examples of char/text insertion/deletion. I can handle all the rest of the code myself (file i/o, console i/o etc). A link to a nice simple editor source would be great (C or C++).
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A buffer is the basic unit of text being edited. It can be any size, from zero characters to the largest item that can be manipulated on the computer system. This limit on size is usually set by such factors as address space, amount of real and/or virtual memory, and mass storage capacity.
The emacs editing mode is entered when you enable either the emacs or gmacs option. The only difference between these two modes is the way each handles the Ctrl-T edit command. To edit, move the cursor to the point needing correction and insert or delete characters or words, as needed.
To insert text into a buffer, place the cursor where you want to start inserting text, and start typing away. If you want to insert the contents of another file into the current buffer, place the cursor at the desired insertion point, and type Control-X-I. Emacs will ask you for the name of the file you wish to insert.
I used to work for a company whose main product was a text editor. While I mainly worked on the scripting language for it, the internal design of the editor itself was naturally a major topic of discussion.
It seemed like it broke down into two general trains of thought. One was that you stored each line by itself, and then link them together in a linked list or other overall data structure that you were happy with. The advantage was that any line-oriented editing actions (such as deleting an entire line, or moving a line block within a file) were beyond trivial to implement and therefore lightning fast. The down side was that loading and saving the file took a bit more work, because you'd have to traverse the entire file and build these data structures.
The other train of thought at that time was to try to keep hunks of text together regardless of line breaks when they hadn't been changed, breaking them up only as required by editing. The advantage was that an unedited hunk of the file could be blasted out to a file very easily. So simple edits where you load a file, change one line, and save the file, were super fast. The disadvantage was that line-oriented or column-block operations were very time consuming to execute because you would have to parse through these hunks of text and move alot of data around.
We always stuck with the line-oriented design, for whatever that is worth, and our product was considered one of the fastest editors at the time.
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The "Gang of Four" book (Design Patterns) has a GUI-based text editor as it's main source of examples and is a worthwhile book to own.
The general "pure text" editor probably uses ropes, which SGI's STL has an implementation of. Basically, they are a linked list of character buffers. That way, inserting/deleting characters involves changing smaller buffers and a few pointers, instead of storing the entire document in a single buffer and having to shift everything.
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This is 2008. Don't write a text editor; you're reinventing fire.
Still here? I'm not sure if this applies or what platforms you plan to support, but the Neatpad series of tutorials is a great place to start thinking about writing a text editor. They focus on Win32 as the basic platform, but many of the lessons learned will apply anywhere.
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