Azhng / viw

VI Worsened, a lightweight and fun VI clone.

Viw, the ghetto editor

VI Worsened, a lightweight and fun VI clone. Inspired by the 6-domino-cascade from the React world.

DEMO

https://vimeo.com/205701269

Dependencies

• gcc
• ncurses

# Fedora
sudo dnf install ncurses-devel

# Debian/Ubuntu
sudo apt-get install libncurses5-dev

Installation & usage

$ git clone https://github.com/lpan/viw
$ cd viw/
$ make build
$ ./viw [filename]

Supported keybindings

• j Cursor down
• k Cursor up
• h Cursor left
• l Curosr right
• 0 Cursor to the beginning of the line
• $ Cursor to the end of the line
• i Insert before
• I Insert at the beginning of the line
• a Insert after
• A Insert at the end of the line
• o Append line then insert
• O Prepend line then insert
• dd Delete line under the cursor
• gg Go to the first line of the file
• G Go the last line of the file

Supported EX mode commands

• :q quit
• :w save
• :wq save then quit

Hacking

Feel free to contribute! :)

How does it work

1. initiate the state

• Read file to buffer.
• Set up interface with ncurses

2. Listen to keyboard events.

• Each supported keybinding is mapped to a method that mutates the buffer

3. Run update_state(st) and render_update(st)

• Similar to selectors in redux, update_state(state_t *st) will update all the computed properties (such as cursor position, rows to be displayed on the screen, etc) according to the new mutated buffer state.
• render_update(state_t *st) will actually render everything on the screen according to the result from update_state().

4. Goto step 2

Hierarchy of the states

Our main state object has two children states, namely buffer and screen. This seperation makes it easier to perform unit tests against the buffer. It also facilitates the migration to a different rendering library in the future.

The State

• The parent state stores computed states that depend on the buffer and/or screen. Those states include cursor positions, aount of space reserved for line numbers, etc.

The Buffer

• The buffer is represented as a two dimensional doubly linked list. This allows conatant time line/char deletion and insertion. Go to buffer.h for more information.
• Buffer is only allowed to be modified by the methods declared in buffer.h

The Screen

• The screen is the state of the interface between viw and GNU ncurses. It stores information such as pointers to the ncurses windows, etc. You can learn more about it at screen.h.