t-deckard/app/ed.py

# A simple line-oriented text editor for MicroPython/CircuitPython
# implementing the POSIX 'ed' subset
# Usage: from app.ed import edit
# Created by Luxferre in 2025, released into public domain

from deck.input import input

class Ed:
  def __init__(self, filename=None):
    self.filename = filename
    self.buffer = []
    self.current_line = 0  # 1-indexed for the user, 0 means empty or before first line
    self.dirty = False
    self.last_error = ""

    if filename:
      try:
        with open(filename, "r") as f:
          self.buffer = [line.rstrip("\n\r") for line in f.readlines()]
        self.current_line = len(self.buffer)
        print(len("".join(self.buffer)) + len(self.buffer)) # Print byte count
      except OSError:
        print(f"cannot open input file {filename}")

  def _parse_address(self, addr_str):
    """Simple address parser for line numbers, '.', and '$'."""
    if not addr_str:
      return self.current_line
    if addr_str == ".":
      return self.current_line
    if addr_str == "$":
      return len(self.buffer)
    try:
      return int(addr_str)
    except ValueError:
      return None

  def _get_range(self, addr_range):
    """Parses ranges like '1,5' or '%'."""
    if not addr_range:
      return self.current_line, self.current_line
    if addr_range == ",":
      return 1, len(self.buffer)
    if addr_range == "%":
      return 1, len(self.buffer)
    
    parts = addr_range.split(",")
    if len(parts) == 1:
      addr = self._parse_address(parts[0])
      return addr, addr
    else:
      return self._parse_address(parts[0]), self._parse_address(parts[1])

  def run(self):
    while True:
      try:
        cmd_line = input(":").strip()
      except EOFError:
        break

      if not cmd_line:
        # A null command (just newline) prints the current line
        if self.buffer:
          print(self.buffer[self.current_line - 1])
        continue

      # Basic command regex-like split
      # Format: [address]command[parameters]
      cmd_char = ""
      addr_part = ""
      for i, char in enumerate(cmd_line):
        if char.isalpha():
          addr_part = cmd_line[:i]
          cmd_char = char
          params = cmd_line[i+1:].strip()
          break
      else:
        # If no alpha command found, try interpreting as address only
        addr = self._parse_address(cmd_line)
        if addr is not None and 0 <= addr <= len(self.buffer):
          self.current_line = addr
          if self.current_line > 0:
            print(self.buffer[self.current_line - 1])
          continue
        else:
          print("?")
          continue

      try:
        start, end = self._get_range(addr_part)
        
        if cmd_char == 'q':
          if self.dirty and params != "!":
            print("?")
            self.dirty = False # Standard ed behavior: second q forces exit
            continue
          break

        elif cmd_char == 'p' or cmd_char == 'n':
          if not self.buffer:
            print("?")
            continue
          start = max(1, start)
          end = min(len(self.buffer), end)
          for i in range(start - 1, end):
            if cmd_char == 'n':
              print(f"{i + 1}\t{self.buffer[i]}")
            else:
              print(self.buffer[i])
          self.current_line = end

        elif cmd_char == 'a':
          idx = start
          while True:
            line = input("")
            if line == ".":
              break
            self.buffer.insert(idx, line)
            idx += 1
            self.dirty = True
          self.current_line = idx

        elif cmd_char == 'i':
          idx = max(0, start - 1)
          while True:
            line = input("")
            if line == ".":
              break
            self.buffer.insert(idx, line)
            idx += 1
            self.dirty = True
          self.current_line = idx

        elif cmd_char == 'c':
          if not self.buffer:
            print("?")
            continue
          del self.buffer[start-1 : end]
          idx = start - 1
          while True:
            line = input("")
            if line == ".":
              break
            self.buffer.insert(idx, line)
            idx += 1
            self.dirty = True
          self.current_line = idx

        elif cmd_char == 'd':
          if not self.buffer:
            print("?")
            continue
          del self.buffer[start-1 : end]
          self.current_line = min(start, len(self.buffer))
          self.dirty = True

        elif cmd_char == 's':
          if not self.buffer or not params:
            print("?")
            continue
          # Simple s/old/new/ parser
          sep = params[0]
          parts = params.split(sep)
          if len(parts) < 3:
            print("?")
            continue
          old, new = parts[1], parts[2]
          start = max(1, start)
          end = min(len(self.buffer), end)
          for i in range(start - 1, end):
            if old in self.buffer[i]:
              self.buffer[i] = self.buffer[i].replace(old, new)
              self.dirty = True
          self.current_line = end

        elif cmd_char == 'w':
          target = params if params else self.filename
          if not target:
            print("?")
            continue
          with open(target, "w") as f:
            for line in self.buffer:
              f.write(line + "\n")
          print(len("".join(self.buffer)) + len(self.buffer))
          self.dirty = False
          self.filename = target

        elif cmd_char == 'f':
          if params:
            self.filename = params
          print(self.filename if self.filename else "No current filename")

        else:
          print("?")

      except Exception:
        print("?")

def edit(fname):
  editor = Ed(fname)
  editor.run()