gristlabs_grist-core/sandbox/grist/repl.py

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"""
This module implements an interpreter for a REPL. It subclasses Python's
code.InteractiveInterpreter class, implementing most of its methods, but with
slight changes in order to be convenient for Grist's purposes
"""
import code
import sys
from StringIO import StringIO
from collections import namedtuple
SUCCESS = 0
INCOMPLETE = 1
ERROR = 2
EvalTuple = namedtuple("EvalTuple", ("output", "error", "status"))
#pylint: disable=exec-used, bare-except
class REPLInterpreter(code.InteractiveInterpreter):
def __init__(self):
code.InteractiveInterpreter.__init__(self)
self.error_text = ""
def runsource(self, source, filename="<input>", symbol="single"):
"""
Compiles and executes source. Returns an EvalTuple with a status
INCOMPLETE if the code is incomplete,
ERROR if it encountered a compilation or run-time error,
SUCCESS otherwise.
an output, which gives all of the output of the user's program
(with stderr piped to stdout, essentially, though mock-file objects are used)
an error, which reports a syntax error at compilation or a runtime error with a
Traceback.
"""
old_stdout = sys.stdout
old_stderr = sys.stderr
user_output = StringIO()
self.error_text = ""
try:
code = self.compile(source, filename, symbol)
except (OverflowError, SyntaxError, ValueError):
self.showsyntaxerror(filename)
status = ERROR
else:
status = INCOMPLETE if code is None else SUCCESS
if status == SUCCESS:
try:
# We use temproray variables to access stdio/stdout
# to make sure the client can't do funky things
# like get/set attr and have that hurt us
sys.stdout = user_output
sys.stderr = user_output
exec code in self.locals
except:
# bare except to catch absolutely all things the user can throw
self.showtraceback()
status = ERROR
finally:
sys.stdout = old_stdout
sys.stderr = old_stderr
program_output = user_output.getvalue()
user_output.close()
return EvalTuple(program_output, self.error_text, status)
def write(self, txt):
"""
Used by showsyntaxerror and showtraceback
"""
self.error_text += txt
def runcode(self, code):
"""
This would normally do the part of runsource after compiling the code, but doesn't quite
make sense as its own function for our purposes because it couldn't support an INCOMPLETE
return value, etc. We explicitly hide it here to make sure the base class's version isn't
called by accident.
"""
raise NotImplementedError("REPLInterpreter.runcode not implemented, use runsource instead")