cpython/Lib/code.py at 3.15 · python/cpython · GitHub

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"""Utilities needed to emulate Python's interactive interpreter.

"""

# Inspired by similar code by Jeff Epler and Fredrik Lundh.

import builtins

import sys

import traceback

from codeop import CommandCompiler, compile_command

__all__ = ["InteractiveInterpreter", "InteractiveConsole", "interact",

"compile_command"]

class InteractiveInterpreter:

"""Base class for InteractiveConsole.

This class deals with parsing and interpreter state (the user's

namespace); it doesn't deal with input buffering or prompting or

input file naming (the filename is always passed in explicitly).

"""

def __init__(self, locals=None):

"""Constructor.

The optional 'locals' argument specifies a mapping to use as the

namespace in which code will be executed; it defaults to a newly

created dictionary with key "__name__" set to "__console__" and

key "__doc__" set to None.

"""

if locals is None:

locals = {"__name__": "__console__", "__doc__": None}

self.locals = locals

self.compile = CommandCompiler()

def runsource(self, source, filename="<input>", symbol="single"):

"""Compile and run some source in the interpreter.

Arguments are as for compile_command().

One of several things can happen:

1) The input is incorrect; compile_command() raised an

exception (usually SyntaxError). A syntax traceback will be

printed by calling the showsyntaxerror() method.

2) The input is incomplete, and more input is required;

compile_command() returned None. Nothing happens.

3) The input is complete; compile_command() returned a code

object. The code is executed by calling self.runcode() (which

also handles run-time exceptions, except for SystemExit).

The return value is True in case 2, False in the other cases (unless

an exception is raised). The return value can be used to

decide whether to use sys.ps1 or sys.ps2 to prompt the next

line.

"""

try:

code = self.compile(source, filename, symbol)

except Exception:

# Case 1

self.showsyntaxerror(filename, source=source)

return False

if code is None:

# Case 2

return True

# Case 3

self.runcode(code)

return False

def runcode(self, code):

"""Execute a code object.

When an exception occurs, self.showtraceback() is called to

display a traceback. All exceptions are caught except

SystemExit, which is reraised.

A note about KeyboardInterrupt: this exception may occur

elsewhere in this code, and may not always be caught. The

caller should be prepared to deal with it.

"""

try:

exec(code, self.locals)

except SystemExit:

raise

except:

self.showtraceback()

def showsyntaxerror(self, filename=None, **kwargs):

"""Display the syntax error that just occurred.

This doesn't display a stack trace because there isn't one.

If a filename is given, it is stuffed in the exception instead

of what was there before (because Python's parser always uses

"<string>" when reading from a string).

The output is written by self.write(), below.

"""

try:

typ, value, tb = sys.exc_info()

if filename and issubclass(typ, SyntaxError):

value.filename = filename

source = kwargs.pop('source', "")

self._showtraceback(typ, value, None, source)

finally:

typ = value = tb = None

def showtraceback(self):

"""Display the exception that just occurred.

We remove the first stack item because it is our own code.

The output is written by self.write(), below.

"""

try:

typ, value, tb = sys.exc_info()

self._showtraceback(typ, value, tb.tb_next, "")

finally:

typ = value = tb = None

def _showtraceback(self, typ, value, tb, source):

sys.last_type = typ

sys.last_traceback = tb

value = value.with_traceback(tb)

# Set the line of text that the exception refers to

lines = source.splitlines()

if (source and typ is SyntaxError

and not value.text and value.lineno is not None

and len(lines) >= value.lineno):

value.text = lines[value.lineno - 1]

sys.last_exc = sys.last_value = value

if sys.excepthook is sys.__excepthook__:

self._excepthook(typ, value, tb)

else:

# If someone has set sys.excepthook, we let that take precedence

# over self.write

try:

sys.excepthook(typ, value, tb)

except SystemExit:

raise

except BaseException as e:

e.__context__ = None

e = e.with_traceback(e.__traceback__.tb_next)

print('Error in sys.excepthook:', file=sys.stderr)

sys.__excepthook__(type(e), e, e.__traceback__)

print(file=sys.stderr)

print('Original exception was:', file=sys.stderr)

sys.__excepthook__(typ, value, tb)

def _excepthook(self, typ, value, tb):

# This method is being overwritten in

# _pyrepl.console.InteractiveColoredConsole

lines = traceback.format_exception(typ, value, tb)

self.write(''.join(lines))

def write(self, data):

"""Write a string.

The base implementation writes to sys.stderr; a subclass may

replace this with a different implementation.

"""

sys.stderr.write(data)

class InteractiveConsole(InteractiveInterpreter):

"""Closely emulate the behavior of the interactive Python interpreter.

This class builds on InteractiveInterpreter and adds prompting

using the familiar sys.ps1 and sys.ps2, and input buffering.

"""

def __init__(self, locals=None, filename="<console>", *, local_exit=False):

"""Constructor.

The optional locals argument will be passed to the

InteractiveInterpreter base class.

The optional filename argument should specify the (file)name

of the input stream; it will show up in tracebacks.

"""

InteractiveInterpreter.__init__(self, locals)

self.filename = filename

self.local_exit = local_exit

self.resetbuffer()

def resetbuffer(self):

"""Reset the input buffer."""

self.buffer = []

def interact(self, banner=None, exitmsg=None):

"""Closely emulate the interactive Python console.

The optional banner argument specifies the banner to print

before the first interaction; by default it prints a banner

similar to the one printed by the real Python interpreter,

followed by the current class name in parentheses (so as not

to confuse this with the real interpreter -- since it's so

close!).

The optional exitmsg argument specifies the exit message

printed when exiting. Pass the empty string to suppress

printing an exit message. If exitmsg is not given or None,

a default message is printed.

"""

try:

sys.ps1

delete_ps1_after = False

except AttributeError:

sys.ps1 = ">>> "

delete_ps1_after = True

try:

sys.ps2

delete_ps2_after = False

except AttributeError:

sys.ps2 = "... "

delete_ps2_after = True

cprt = 'Type "help", "copyright", "credits" or "license" for more information.'

if banner is None:

self.write("Python %s on %s\n%s\n(%s)\n" %

(sys.version, sys.platform, cprt,

self.__class__.__name__))

elif banner:

self.write("%s\n" % str(banner))

more = 0

# When the user uses exit() or quit() in their interactive shell

# they probably just want to exit the created shell, not the whole

# process. exit and quit in builtins closes sys.stdin which makes

# it super difficult to restore

# When self.local_exit is True, we overwrite the builtins so

# exit() and quit() only raises SystemExit and we can catch that

# to only exit the interactive shell

_exit = None

_quit = None

if self.local_exit:

if hasattr(builtins, "exit"):

_exit = builtins.exit

builtins.exit = Quitter("exit")

if hasattr(builtins, "quit"):

_quit = builtins.quit

builtins.quit = Quitter("quit")

try:

while True:

try:

if more:

prompt = sys.ps2

else:

prompt = sys.ps1

try:

line = self.raw_input(prompt)

except EOFError:

self.write("\n")

break

else:

more = self.push(line)

except KeyboardInterrupt:

self.write("\nKeyboardInterrupt\n")

self.resetbuffer()

more = 0

except SystemExit as e:

if self.local_exit:

self.write("\n")

break

else:

raise e

finally:

# restore exit and quit in builtins if they were modified

if _exit is not None:

builtins.exit = _exit

if _quit is not None:

builtins.quit = _quit

if delete_ps1_after:

del sys.ps1

if delete_ps2_after:

del sys.ps2

if exitmsg is None:

self.write('now exiting %s...\n' % self.__class__.__name__)

elif exitmsg != '':

self.write('%s\n' % exitmsg)

def push(self, line, filename=None, _symbol="single"):

"""Push a line to the interpreter.

The line should not have a trailing newline; it may have

internal newlines. The line is appended to a buffer and the

interpreter's runsource() method is called with the

concatenated contents of the buffer as source. If this

indicates that the command was executed or invalid, the buffer

is reset; otherwise, the command is incomplete, and the buffer

is left as it was after the line was appended. The return

value is 1 if more input is required, 0 if the line was dealt

with in some way (this is the same as runsource()).

"""

self.buffer.append(line)

source = "\n".join(self.buffer)

if filename is None:

filename = self.filename

more = self.runsource(source, filename, symbol=_symbol)

if not more:

self.resetbuffer()

return more

def raw_input(self, prompt=""):

"""Write a prompt and read a line.

The returned line does not include the trailing newline.

When the user enters the EOF key sequence, EOFError is raised.

The base implementation uses the built-in function

input(); a subclass may replace this with a different

implementation.

"""

return input(prompt)

class Quitter:

def __init__(self, name):

self.name = name

if sys.platform == "win32":

self.eof = 'Ctrl-Z plus Return'

else:

self.eof = 'Ctrl-D (i.e. EOF)'

def __repr__(self):

return f'Use {self.name} or {self.eof} to exit'

def __call__(self, code=None):

raise SystemExit(code)

def interact(banner=None, readfunc=None, local=None, exitmsg=None, local_exit=False):

"""Closely emulate the interactive Python interpreter.

This is a backwards compatible interface to the InteractiveConsole

class. When readfunc is not specified, it attempts to import the

readline module to enable GNU readline if it is available.

Arguments (all optional, all default to None):

banner -- passed to InteractiveConsole.interact()

readfunc -- if not None, replaces InteractiveConsole.raw_input()

local -- passed to InteractiveInterpreter.__init__()

exitmsg -- passed to InteractiveConsole.interact()

local_exit -- passed to InteractiveConsole.__init__()

"""

console = InteractiveConsole(local, local_exit=local_exit)

if readfunc is not None:

console.raw_input = readfunc

else:

try:

import readline # noqa: F401

except ImportError:

pass

console.interact(banner, exitmsg)

if __name__ == "__main__":

import argparse

parser = argparse.ArgumentParser()

parser.add_argument('-q', action='store_true',

help="don't print version and copyright messages")

args = parser.parse_args()

if args.q or sys.flags.quiet:

banner = ''

else:

banner = None

interact(banner)

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