I had implemented python shell using code.InteractiveConsole to execute the commands for a project. Below is a simplified version, though still quite long because I had written bindings for special keys (like Return, Tab ...) to behave like in the python console. It is possible to add more features such as autocompletion with jedi and syntax highighting with pygments.
The main idea is that I use the push() method of the code.InteractiveConsole to execute the commands. This method returns True if it is a partial command, e.g. def test(x):, and I use this feedback to insert a ... prompt, otherwise, the output is displayed and a new >>> prompt is displayed. I capture the output using contextlib.redirect_stdout.
Also there is a lot of code involving marks and comparing indexes because I prevent the user from inserting text inside previously executed commands. The idea is that I created a mark 'input' which tells me where the start of the active prompt is and with self.compare('insert', '<', 'input') I can know when the user is trying to insert text above the active prompt.
import tkinter as tk
import sys
import re
from code import InteractiveConsole
from contextlib import redirect_stderr, redirect_stdout
from io import StringIO
class History(list):
def __getitem__(self, index):
try:
return list.__getitem__(self, index)
except IndexError:
return
class TextConsole(tk.Text):
def __init__(self, master, **kw):
kw.setdefault('width', 50)
kw.setdefault('wrap', 'word')
kw.setdefault('prompt1', '>>> ')
kw.setdefault('prompt2', '... ')
banner = kw.pop('banner', 'Python %s\n' % sys.version)
self._prompt1 = kw.pop('prompt1')
self._prompt2 = kw.pop('prompt2')
tk.Text.__init__(self, master, **kw)
# --- history
self.history = History()
self._hist_item = 0
self._hist_match = ''
# --- initialization
self._console = InteractiveConsole() # python console to execute commands
self.insert('end', banner, 'banner')
self.prompt()
self.mark_set('input', 'insert')
self.mark_gravity('input', 'left')
# --- bindings
self.bind('<Control-Return>', self.on_ctrl_return)
self.bind('<Shift-Return>', self.on_shift_return)
self.bind('<KeyPress>', self.on_key_press)
self.bind('<KeyRelease>', self.on_key_release)
self.bind('<Tab>', self.on_tab)
self.bind('<Down>', self.on_down)
self.bind('<Up>', self.on_up)
self.bind('<Return>', self.on_return)
self.bind('<BackSpace>', self.on_backspace)
self.bind('<Control-c>', self.on_ctrl_c)
self.bind('<<Paste>>', self.on_paste)
def on_ctrl_c(self, event):
"""Copy selected code, removing prompts first"""
sel = self.tag_ranges('sel')
if sel:
txt = self.get('sel.first', 'sel.last').splitlines()
lines = []
for i, line in enumerate(txt):
if line.startswith(self._prompt1):
lines.append(line[len(self._prompt1):])
elif line.startswith(self._prompt2):
lines.append(line[len(self._prompt2):])
else:
lines.append(line)
self.clipboard_clear()
self.clipboard_append('\n'.join(lines))
return 'break'
def on_paste(self, event):
"""Paste commands"""
if self.compare('insert', '<', 'input'):
return "break"
sel = self.tag_ranges('sel')
if sel:
self.delete('sel.first', 'sel.last')
txt = self.clipboard_get()
self.insert("insert", txt)
self.insert_cmd(self.get("input", "end"))
return 'break'
def prompt(self, result=False):
"""Insert a prompt"""
if result:
self.insert('end', self._prompt2, 'prompt')
else:
self.insert('end', self._prompt1, 'prompt')
self.mark_set('input', 'end-1c')
def on_key_press(self, event):
"""Prevent text insertion in command history"""
if self.compare('insert', '<', 'input') and event.keysym not in ['Left', 'Right']:
self._hist_item = len(self.history)
self.mark_set('insert', 'input lineend')
if not event.char.isalnum():
return 'break'
def on_key_release(self, event):
"""Reset history scrolling"""
if self.compare('insert', '<', 'input') and event.keysym not in ['Left', 'Right']:
self._hist_item = len(self.history)
return 'break'
def on_up(self, event):
"""Handle up arrow key press"""
if self.compare('insert', '<', 'input'):
self.mark_set('insert', 'end')
return 'break'
elif self.index('input linestart') == self.index('insert linestart'):
# navigate history
line = self.get('input', 'insert')
self._hist_match = line
hist_item = self._hist_item
self._hist_item -= 1
item = self.history[self._hist_item]
while self._hist_item >= 0 and not item.startswith(line):
self._hist_item -= 1
item = self.history[self._hist_item]
if self._hist_item >= 0:
index = self.index('insert')
self.insert_cmd(item)
self.mark_set('insert', index)
else:
self._hist_item = hist_item
return 'break'
def on_down(self, event):
"""Handle down arrow key press"""
if self.compare('insert', '<', 'input'):
self.mark_set('insert', 'end')
return 'break'
elif self.compare('insert lineend', '==', 'end-1c'):
# navigate history
line = self._hist_match
self._hist_item += 1
item = self.history[self._hist_item]
while item is not None and not item.startswith(line):
self._hist_item += 1
item = self.history[self._hist_item]
if item is not None:
self.insert_cmd(item)
self.mark_set('insert', 'input+%ic' % len(self._hist_match))
else:
self._hist_item = len(self.history)
self.delete('input', 'end')
self.insert('insert', line)
return 'break'
def on_tab(self, event):
"""Handle tab key press"""
if self.compare('insert', '<', 'input'):
self.mark_set('insert', 'input lineend')
return "break"
# indent code
sel = self.tag_ranges('sel')
if sel:
start = str(self.index('sel.first'))
end = str(self.index('sel.last'))
start_line = int(start.split('.')[0])
end_line = int(end.split('.')[0]) + 1
for line in range(start_line, end_line):
self.insert('%i.0' % line, ' ')
else:
txt = self.get('insert-1c')
if not txt.isalnum() and txt != '.':
self.insert('insert', ' ')
return "break"
def on_shift_return(self, event):
"""Handle Shift+Return key press"""
if self.compare('insert', '<', 'input'):
self.mark_set('insert', 'input lineend')
return 'break'
else: # execute commands
self.mark_set('insert', 'end')
self.insert('insert', '\n')
self.insert('insert', self._prompt2, 'prompt')
self.eval_current(True)
def on_return(self, event=None):
"""Handle Return key press"""
if self.compare('insert', '<', 'input'):
self.mark_set('insert', 'input lineend')
return 'break'
else:
self.eval_current(True)
self.see('end')
return 'break'
def on_ctrl_return(self, event=None):
"""Handle Ctrl+Return key press"""
self.insert('insert', '\n' + self._prompt2, 'prompt')
return 'break'
def on_backspace(self, event):
"""Handle delete key press"""
if self.compare('insert', '<=', 'input'):
self.mark_set('insert', 'input lineend')
return 'break'
sel = self.tag_ranges('sel')
if sel:
self.delete('sel.first', 'sel.last')
else:
linestart = self.get('insert linestart', 'insert')
if re.search(r' $', linestart):
self.delete('insert-4c', 'insert')
else:
self.delete('insert-1c')
return 'break'
def insert_cmd(self, cmd):
"""Insert lines of code, adding prompts"""
input_index = self.index('input')
self.delete('input', 'end')
lines = cmd.splitlines()
if lines:
indent = len(re.search(r'^( )*', lines[0]).group())
self.insert('insert', lines[0][indent:])
for line in lines[1:]:
line = line[indent:]
self.insert('insert', '\n')
self.prompt(True)
self.insert('insert', line)
self.mark_set('input', input_index)
self.see('end')
def eval_current(self, auto_indent=False):
"""Evaluate code"""
index = self.index('input')
lines = self.get('input', 'insert lineend').splitlines() # commands to execute
self.mark_set('insert', 'insert lineend')
if lines: # there is code to execute
# remove prompts
lines = [lines[0].rstrip()] + [line[len(self._prompt2):].rstrip() for line in lines[1:]]
for i, l in enumerate(lines):
if l.endswith('?'):
lines[i] = 'help(%s)' % l[:-1]
cmds = '\n'.join(lines)
self.insert('insert', '\n')
out = StringIO() # command output
err = StringIO() # command error traceback
with redirect_stderr(err): # redirect error traceback to err
with redirect_stdout(out): # redirect command output
# execute commands in interactive console
res = self._console.push(cmds)
# if res is True, this is a partial command, e.g. 'def test():' and we need to wait for the rest of the code
errors = err.getvalue()
if errors: # there were errors during the execution
self.insert('end', errors) # display the traceback
self.mark_set('input', 'end')
self.see('end')
self.prompt() # insert new prompt
else:
output = out.getvalue() # get output
if output:
self.insert('end', output, 'output')
self.mark_set('input', 'end')
self.see('end')
if not res and self.compare('insert linestart', '>', 'insert'):
self.insert('insert', '\n')
self.prompt(res)
if auto_indent and lines:
# insert indentation similar to previous lines
indent = re.search(r'^( )*', lines[-1]).group()
line = lines[-1].strip()
if line and line[-1] == ':':
indent = indent + ' '
self.insert('insert', indent)
self.see('end')
if res:
self.mark_set('input', index)
self._console.resetbuffer() # clear buffer since the whole command will be retrieved from the text widget
elif lines:
self.history.append(lines) # add commands to history
self._hist_item = len(self.history)
out.close()
err.close()
else:
self.insert('insert', '\n')
self.prompt()
if __name__ == '__main__':
root = tk.Tk()
console = TextConsole(root)
console.pack(fill='both', expand=True)
root.mainloop()
