cpython/Lib/code.py

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"""Utilities dealing with code objects."""
def compile_command(source, filename="<input>", symbol="single"):
r"""Compile a command and determine whether it is incomplete.
Arguments:
source -- the source string; may contain \n characters
filename -- optional filename from which source was read; default "<input>"
symbol -- optional grammar start symbol; "single" (default) or "eval"
Return value / exception raised:
- Return a code object if the command is complete and valid
- Return None if the command is incomplete
- Raise SyntaxError if the command is a syntax error
Approach:
Compile three times: as is, with \n, and with \n\n appended. If
it compiles as is, it's complete. If it compiles with one \n
appended, we expect more. If it doesn't compile either way, we
compare the error we get when compiling with \n or \n\n appended.
If the errors are the same, the code is broken. But if the errors
are different, we expect more. Not intuitive; not even guaranteed
to hold in future releases; but this matches the compiler's
behavior in Python 1.4 and 1.5.
"""
err = err1 = err2 = None
code = code1 = code2 = None
try:
code = compile(source, filename, symbol)
except SyntaxError, err:
pass
try:
code1 = compile(source + "\n", filename, symbol)
except SyntaxError, err1:
pass
try:
code2 = compile(source + "\n\n", filename, symbol)
except SyntaxError, err2:
pass
if code:
return code
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try:
e1 = err1.__dict__
except AttributeError:
e1 = err1
try:
e2 = err2.__dict__
except AttributeError:
e2 = err2
if not code1 and e1 == e2:
raise SyntaxError, err1
def interact(banner=None, readfunc=raw_input, local=None):
# Due to Jeff Epler, with changes by Guido:
"""Closely emulate the interactive Python console."""
try: import readline # Enable GNU readline if available
except: pass
local = local or {}
import sys, string, traceback
sys.ps1 = '>>> '
sys.ps2 = '... '
if banner:
print banner
else:
print "Python Interactive Console", sys.version
print sys.copyright
buf = []
while 1:
if buf: prompt = sys.ps2
else: prompt = sys.ps1
try: line = readfunc(prompt)
except KeyboardInterrupt:
print "\nKeyboardInterrupt"
buf = []
continue
except EOFError: break
buf.append(line)
try: x = compile_command(string.join(buf, "\n"))
except SyntaxError:
traceback.print_exc(0)
buf = []
continue
if x == None: continue
else:
try: exec x in local
except:
exc_type, exc_value, exc_traceback = \
sys.exc_type, sys.exc_value, \
sys.exc_traceback
l = len(traceback.extract_tb(sys.exc_traceback))
try: 1/0
except:
m = len(traceback.extract_tb(
sys.exc_traceback))
traceback.print_exception(exc_type,
exc_value, exc_traceback, l-m)
buf = []
if __name__ == '__main__':
interact()