swd2 frontend for line editing and history

swd-readline.py

#! /usr/bin/python -u

import subprocess
import selectors
import os
import time
import readline
import sys
import atexit
import threading

# set this to true to clear the line you just typed, as it is echoed by mecrisp anyway
clear_line = True

history_file = ".swdhistory"

process = None


def write2proc(line):
    global process
    process.stdin.write(f"{line}\n")
    process.stdin.flush()


def sendchar(ch):
    global process
    process.stdin.write(ch)
    process.stdin.flush()


def run(cmd):
    global process

    # stdout and stderr go straight to the terminal, but we pipe stdin so we can send commands
    with subprocess.Popen(cmd, stdin=subprocess.PIPE, stdout=None, stderr=None, shell=False, universal_newlines=True, bufsize=0, encoding='utf-8', errors='replace') as p:
        process = p
        p.wait()

    print('command complete')


# tab completion for forth words here
# we could add all known words, or just have a file with common words we want easy access to.
def completer(text, state):
    # TODO read in a list of common forth words here
    options = [word for word in ["words", "compiletoram", "dup", "swap"] if word.startswith(text)]
    if state < len(options):
        return options[state]
    return None


def delete_last_line():
    # cursor up one line
    sys.stdout.write('\x1b[1A')
    # delete last line
    sys.stdout.write('\x1b[2K')


def main():
    global process
    try:
        readline.read_history_file(history_file)
        readline.set_history_length(1000)
    except FileNotFoundError:
        pass  # No history file yet

    readline.set_completer(completer)
    readline.parse_and_bind("tab: complete")

    t = threading.Thread(target=run, daemon=True, args=("swd2", ))
    t.start()

    print("SWD2 frontend with line editing and history. Type 'ctrl-D' to quit.")

    while True:
        try:
            line = input()
            if len(line) > 0 and clear_line:
                delete_last_line()
            write2proc(line)
        except EOFError:
            sendchar("\x04")
            process.kill()
            break  # Handle Ctrl+D for exit
        except KeyboardInterrupt:
            sendchar("\x03")

    print("Goodbye!")
    t.join()


atexit.register(readline.write_history_file, history_file)

if __name__ == '__main__':
    main()

'''
BSD 2-Clause License

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this
   list of conditions and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright notice,
   this list of conditions and the following disclaimer in the documentation
   and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
'''


'''
This Python script provides a frontend for interacting with the `swd2` command-line tool. It incorporates features like line editing, command history,
and tab completion for specific Forth words. Here's a summary of the code:

1. **Imports**: The script imports several modules including `subprocess`, `selectors`, `os`, `time`, `readline`, `sys`, `atexit`, and `threading`.

2. **Global Variables**:
   - `history_file`: Specifies the file to store command history.
   - `process`: Holds a reference to the subprocess running `swd2`.

3. **Functions**:
   - `write2proc(line)`: Sends a line of input to the `swd2` process's standard input and flushes it.
   - `sendchar(ch)`: Sends a single character to the `swd2` process's standard input and flushes it.
   - `run(cmd)`: Starts a subprocess with the given command, waits for it to complete, and prints 'command complete' when done.
   - `completer(text, state)`: Provides tab completion for a list of predefined Forth words.

4. **Main Function**:
   - Loads command history from `history_file` if it exists.
   - Sets up the completer function for readline to provide tab completion.
   - Starts the `swd2` process in a separate thread so that the main program can continue running and handle user input.
   - Enters an infinite loop where it reads lines of input from the user, sends them to the `swd2` process, and handles `EOFError` (Ctrl+D) or
`KeyboardInterrupt` (Ctrl+C).
   - Registers a function to save command history when the program exits.

5. **Exit Handling**:
   - Uses `atexit.register` to ensure that the command history is written to `history_file` when the script terminates.

6. **Execution**:
   - The `main()` function is called if the script is executed as the main module, starting the interaction with the `swd2` tool.

This script enhances the user experience by providing a more interactive and convenient way to use the `swd2` command-line tool through features like
command history and tab completion.
'''

Updated to be better at catching all output

Significantly simplified the popen stuff, now works properly with control-C etc, and doesn't drop output. may need to run with python -u though to make sure nothing is buffered