mirror of https://github.com/python/cpython
389 lines
13 KiB
Python
389 lines
13 KiB
Python
"""Utilities needed to emulate Python's interactive interpreter.
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"""
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# Inspired by similar code by Jeff Epler and Fredrik Lundh.
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import builtins
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import sys
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import traceback
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from codeop import CommandCompiler, compile_command
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__all__ = ["InteractiveInterpreter", "InteractiveConsole", "interact",
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"compile_command"]
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class InteractiveInterpreter:
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"""Base class for InteractiveConsole.
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This class deals with parsing and interpreter state (the user's
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namespace); it doesn't deal with input buffering or prompting or
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input file naming (the filename is always passed in explicitly).
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"""
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def __init__(self, locals=None):
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"""Constructor.
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The optional 'locals' argument specifies a mapping to use as the
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namespace in which code will be executed; it defaults to a newly
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created dictionary with key "__name__" set to "__console__" and
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key "__doc__" set to None.
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"""
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if locals is None:
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locals = {"__name__": "__console__", "__doc__": None}
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self.locals = locals
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self.compile = CommandCompiler()
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def runsource(self, source, filename="<input>", symbol="single"):
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"""Compile and run some source in the interpreter.
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Arguments are as for compile_command().
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One of several things can happen:
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1) The input is incorrect; compile_command() raised an
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exception (SyntaxError or OverflowError). A syntax traceback
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will be printed by calling the showsyntaxerror() method.
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2) The input is incomplete, and more input is required;
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compile_command() returned None. Nothing happens.
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3) The input is complete; compile_command() returned a code
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object. The code is executed by calling self.runcode() (which
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also handles run-time exceptions, except for SystemExit).
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The return value is True in case 2, False in the other cases (unless
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an exception is raised). The return value can be used to
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decide whether to use sys.ps1 or sys.ps2 to prompt the next
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line.
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"""
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try:
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code = self.compile(source, filename, symbol)
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except (OverflowError, SyntaxError, ValueError):
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# Case 1
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self.showsyntaxerror(filename)
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return False
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if code is None:
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# Case 2
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return True
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# Case 3
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self.runcode(code)
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return False
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def runcode(self, code):
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"""Execute a code object.
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When an exception occurs, self.showtraceback() is called to
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display a traceback. All exceptions are caught except
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SystemExit, which is reraised.
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A note about KeyboardInterrupt: this exception may occur
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elsewhere in this code, and may not always be caught. The
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caller should be prepared to deal with it.
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"""
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try:
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exec(code, self.locals)
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except SystemExit:
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raise
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except:
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self.showtraceback()
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def showsyntaxerror(self, filename=None, **kwargs):
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"""Display the syntax error that just occurred.
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This doesn't display a stack trace because there isn't one.
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If a filename is given, it is stuffed in the exception instead
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of what was there before (because Python's parser always uses
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"<string>" when reading from a string).
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The output is written by self.write(), below.
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"""
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colorize = kwargs.pop('colorize', False)
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type, value, tb = sys.exc_info()
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sys.last_exc = value
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sys.last_type = type
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sys.last_value = value
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sys.last_traceback = tb
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if filename and type is SyntaxError:
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# Work hard to stuff the correct filename in the exception
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try:
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msg, (dummy_filename, lineno, offset, line) = value.args
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except ValueError:
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# Not the format we expect; leave it alone
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pass
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else:
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# Stuff in the right filename
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value = SyntaxError(msg, (filename, lineno, offset, line))
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sys.last_exc = sys.last_value = value
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if sys.excepthook is sys.__excepthook__:
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lines = traceback.format_exception_only(type, value, colorize=colorize)
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self.write(''.join(lines))
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else:
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# If someone has set sys.excepthook, we let that take precedence
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# over self.write
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self._call_excepthook(type, value, tb)
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def showtraceback(self, **kwargs):
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"""Display the exception that just occurred.
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We remove the first stack item because it is our own code.
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The output is written by self.write(), below.
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"""
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colorize = kwargs.pop('colorize', False)
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sys.last_type, sys.last_value, last_tb = ei = sys.exc_info()
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sys.last_traceback = last_tb
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sys.last_exc = ei[1]
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try:
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if sys.excepthook is sys.__excepthook__:
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lines = traceback.format_exception(ei[0], ei[1], last_tb.tb_next, colorize=colorize)
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self.write(''.join(lines))
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else:
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# If someone has set sys.excepthook, we let that take precedence
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# over self.write
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self._call_excepthook(ei[0], ei[1], last_tb)
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finally:
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last_tb = ei = None
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def _call_excepthook(self, typ, value, tb):
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try:
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sys.excepthook(typ, value, tb)
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except SystemExit:
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raise
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except BaseException as e:
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e.__context__ = None
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print('Error in sys.excepthook:', file=sys.stderr)
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sys.__excepthook__(type(e), e, e.__traceback__.tb_next)
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print(file=sys.stderr)
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print('Original exception was:', file=sys.stderr)
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sys.__excepthook__(typ, value, tb)
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def write(self, data):
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"""Write a string.
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The base implementation writes to sys.stderr; a subclass may
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replace this with a different implementation.
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"""
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sys.stderr.write(data)
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class InteractiveConsole(InteractiveInterpreter):
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"""Closely emulate the behavior of the interactive Python interpreter.
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This class builds on InteractiveInterpreter and adds prompting
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using the familiar sys.ps1 and sys.ps2, and input buffering.
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"""
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def __init__(self, locals=None, filename="<console>", *, local_exit=False):
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"""Constructor.
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The optional locals argument will be passed to the
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InteractiveInterpreter base class.
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The optional filename argument should specify the (file)name
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of the input stream; it will show up in tracebacks.
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"""
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InteractiveInterpreter.__init__(self, locals)
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self.filename = filename
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self.local_exit = local_exit
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self.resetbuffer()
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def resetbuffer(self):
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"""Reset the input buffer."""
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self.buffer = []
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def interact(self, banner=None, exitmsg=None):
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"""Closely emulate the interactive Python console.
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The optional banner argument specifies the banner to print
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before the first interaction; by default it prints a banner
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similar to the one printed by the real Python interpreter,
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followed by the current class name in parentheses (so as not
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to confuse this with the real interpreter -- since it's so
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close!).
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The optional exitmsg argument specifies the exit message
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printed when exiting. Pass the empty string to suppress
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printing an exit message. If exitmsg is not given or None,
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a default message is printed.
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"""
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try:
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sys.ps1
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except AttributeError:
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sys.ps1 = ">>> "
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try:
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sys.ps2
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except AttributeError:
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sys.ps2 = "... "
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cprt = 'Type "help", "copyright", "credits" or "license" for more information.'
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if banner is None:
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self.write("Python %s on %s\n%s\n(%s)\n" %
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(sys.version, sys.platform, cprt,
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self.__class__.__name__))
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elif banner:
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self.write("%s\n" % str(banner))
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more = 0
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# When the user uses exit() or quit() in their interactive shell
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# they probably just want to exit the created shell, not the whole
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# process. exit and quit in builtins closes sys.stdin which makes
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# it super difficult to restore
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#
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# When self.local_exit is True, we overwrite the builtins so
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# exit() and quit() only raises SystemExit and we can catch that
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# to only exit the interactive shell
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_exit = None
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_quit = None
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if self.local_exit:
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if hasattr(builtins, "exit"):
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_exit = builtins.exit
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builtins.exit = Quitter("exit")
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if hasattr(builtins, "quit"):
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_quit = builtins.quit
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builtins.quit = Quitter("quit")
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try:
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while True:
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try:
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if more:
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prompt = sys.ps2
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else:
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prompt = sys.ps1
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try:
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line = self.raw_input(prompt)
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except EOFError:
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self.write("\n")
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break
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else:
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more = self.push(line)
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except KeyboardInterrupt:
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self.write("\nKeyboardInterrupt\n")
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self.resetbuffer()
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more = 0
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except SystemExit as e:
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if self.local_exit:
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self.write("\n")
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break
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else:
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raise e
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finally:
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# restore exit and quit in builtins if they were modified
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if _exit is not None:
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builtins.exit = _exit
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if _quit is not None:
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builtins.quit = _quit
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if exitmsg is None:
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self.write('now exiting %s...\n' % self.__class__.__name__)
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elif exitmsg != '':
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self.write('%s\n' % exitmsg)
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def push(self, line, filename=None, _symbol="single"):
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"""Push a line to the interpreter.
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The line should not have a trailing newline; it may have
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internal newlines. The line is appended to a buffer and the
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interpreter's runsource() method is called with the
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concatenated contents of the buffer as source. If this
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indicates that the command was executed or invalid, the buffer
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is reset; otherwise, the command is incomplete, and the buffer
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is left as it was after the line was appended. The return
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value is 1 if more input is required, 0 if the line was dealt
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with in some way (this is the same as runsource()).
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"""
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self.buffer.append(line)
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source = "\n".join(self.buffer)
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if filename is None:
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filename = self.filename
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more = self.runsource(source, filename, symbol=_symbol)
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if not more:
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self.resetbuffer()
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return more
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def raw_input(self, prompt=""):
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"""Write a prompt and read a line.
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The returned line does not include the trailing newline.
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When the user enters the EOF key sequence, EOFError is raised.
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The base implementation uses the built-in function
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input(); a subclass may replace this with a different
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implementation.
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"""
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return input(prompt)
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class Quitter:
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def __init__(self, name):
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self.name = name
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if sys.platform == "win32":
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self.eof = 'Ctrl-Z plus Return'
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else:
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self.eof = 'Ctrl-D (i.e. EOF)'
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def __repr__(self):
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return f'Use {self.name} or {self.eof} to exit'
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def __call__(self, code=None):
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raise SystemExit(code)
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def interact(banner=None, readfunc=None, local=None, exitmsg=None, local_exit=False):
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"""Closely emulate the interactive Python interpreter.
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This is a backwards compatible interface to the InteractiveConsole
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class. When readfunc is not specified, it attempts to import the
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readline module to enable GNU readline if it is available.
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Arguments (all optional, all default to None):
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banner -- passed to InteractiveConsole.interact()
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readfunc -- if not None, replaces InteractiveConsole.raw_input()
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local -- passed to InteractiveInterpreter.__init__()
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exitmsg -- passed to InteractiveConsole.interact()
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local_exit -- passed to InteractiveConsole.__init__()
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"""
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console = InteractiveConsole(local, local_exit=local_exit)
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if readfunc is not None:
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console.raw_input = readfunc
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else:
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try:
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import readline
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except ImportError:
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pass
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console.interact(banner, exitmsg)
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if __name__ == "__main__":
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import argparse
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parser = argparse.ArgumentParser()
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parser.add_argument('-q', action='store_true',
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help="don't print version and copyright messages")
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args = parser.parse_args()
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if args.q or sys.flags.quiet:
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banner = ''
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else:
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banner = None
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interact(banner)
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