Build Your Own Vim Editor

This is a light version of the Vim editor for educational purposes. It implements the basic functionalities of Vim. Now it only support Linux and macOS platforms.

Features

Usage: ./alayavim <file> [<file> ...]

• Normal mode
  • ⬅️⬇️⬆️➡️ to move the cursor
  • BACKSPACE to move to the previous character
  • ENTER to move to the next line
  • i to enter insert mode
  • : to enter command mode
  • h, j, k, l to move left, down, up, and right respectively
  • 0 to move to the beginning of the line
  • $ to move to the end of the line
  • G to move to the end of the file
  • gg to move to the beginning of the file
  • dd to delete the current line
  • yy to copy the current line
  • p to paste the copied line
  • u to undo the last operation
  • ctrl + r to redo the last operation
• Insert mode
  • ESC to switch to normal mode
• Command mode
  • :q to quit (:q! to force quit)
  • :w to save
  • :wq to save and quit
  • :wa to save all files
  • :file to display the file information
  • :n or :next to go to the next file (add ! to override)
  • :p or :prev to go to the previous file (add ! to override)
  • :first to go to the first file
  • :last to go to the last file
  • :set number to display line numbers
  • :set nonumber to hide line numbers
  • :s/old/new/g to replace old with new in the current line
  • :%s/old/new/g to replace old with new in the current file
  • :<number> to go to the line number

Build

mkdir -p build/
cd build/
cmake ..
make -j
./alayavim <file> [<file> ...] 

Project Structure

• main.cpp is the program entry.
• core.cpp implements Core class, which serves as a centralized controller to send commands to different file managers
• filemanager.cpp contains the FileManager class to manage file contents and the corresponding cursor position. It controls the terminal display too.
• log.h contains Log class to record the operations for undo and redo.
• utility.cpp contains utility functions (e.g., ANSI).

Implementation Details

• Support editor-like display style in terminal
  • Forbid buffer (i.e., must press "enter" to complete input) and echo (the character you pressed occurs in the terminal) to capture the key press. It is in <unistd.h>, a POSIX (Portable Operating System Interface) header file.

  void config_set(struct termios &oldt, struct termios &newt) {
    tcgetattr(STDIN_FILENO, &oldt);  // terminal configuration
    newt = oldt;
    newt.c_lflag &= ~ICANON;  // buffer forbidden
    newt.c_lflag &= ~ECHO;    // echo forbidden
    tcsetattr(STDIN_FILENO, TCSANOW, &newt);  // new configuration
  }

  • Distinguish the ESC key (^) from the arrow keys (^[A, ^[B, ^[C, ^[D): switch to nonblocking mode temporarily to read two more characters.

    int switch_to_nonblock(int fd) {
      int flags = fcntl(fd, F_GETFL, 0);
      if (flags == -1) {
        perror("fcntl");
        return -1;
      }
      
      flags |= O_NONBLOCK;
      
      if (fcntl(fd, F_SETFL, flags) == -1) {
        perror("fcntl");
        return -1;
      }
      return 0;
    }

  • ANSI escape sequences are a set of control codes used to control the formatting, color, and behavior of text in command-line interfaces. See utility.h for detailed examples.

• ddd combo should not delete the lines twice.
• Replace
  • The cursor should move to a reasonable position.
    • If the cursor is within one of the replaced patterns, it moves to the start of the new word.
    • If the cursor is beyond the end of this line, it moves to the end of the line.
    • Otherwise, it sticks to the adjacent word, instead of staying in the original position.
• Undo and Redo
  • If two adjacent operations are done within 500ms, they are considered as a single operation in undo and redo.
  • The cursor will move to the original position and the view adjusts accordingly.