mirror of
https://github.com/python/cpython.git
synced 2024-11-29 21:05:33 +08:00
1557a7314c
Currently, contains one function: compile_command(), which helps determining whether a source string is complete, incomplete or in error. This is useful when writing your own version of the Python read-eval-print loop.
53 lines
1.5 KiB
Python
53 lines
1.5 KiB
Python
"""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
|
|
if not code1 and err1 == err2:
|
|
raise SyntaxError, err1
|