mirror of
https://github.com/python/cpython
synced 2024-09-04 15:56:13 +00:00
169 lines
5.9 KiB
Python
169 lines
5.9 KiB
Python
r"""Utilities to compile possibly incomplete Python source code.
|
|
|
|
This module provides two interfaces, broadly similar to the builtin
|
|
function compile(), which take program text, a filename and a 'mode'
|
|
and:
|
|
|
|
- Return code object if the command is complete and valid
|
|
- Return None if the command is incomplete
|
|
- Raise SyntaxError, ValueError or OverflowError if the command is a
|
|
syntax error (OverflowError and ValueError can be produced by
|
|
malformed literals).
|
|
|
|
Approach:
|
|
|
|
First, check if the source consists entirely of blank lines and
|
|
comments; if so, replace it with 'pass', because the built-in
|
|
parser doesn't always do the right thing for these.
|
|
|
|
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 from Python 1.4
|
|
through 2.2, at least.
|
|
|
|
Caveat:
|
|
|
|
It is possible (but not likely) that the parser stops parsing with a
|
|
successful outcome before reaching the end of the source; in this
|
|
case, trailing symbols may be ignored instead of causing an error.
|
|
For example, a backslash followed by two newlines may be followed by
|
|
arbitrary garbage. This will be fixed once the API for the parser is
|
|
better.
|
|
|
|
The two interfaces are:
|
|
|
|
compile_command(source, filename, symbol):
|
|
|
|
Compiles a single command in the manner described above.
|
|
|
|
CommandCompiler():
|
|
|
|
Instances of this class have __call__ methods identical in
|
|
signature to compile_command; the difference is that if the
|
|
instance compiles program text containing a __future__ statement,
|
|
the instance 'remembers' and compiles all subsequent program texts
|
|
with the statement in force.
|
|
|
|
The module also provides another class:
|
|
|
|
Compile():
|
|
|
|
Instances of this class act like the built-in function compile,
|
|
but with 'memory' in the sense described above.
|
|
"""
|
|
|
|
import __future__
|
|
|
|
_features = [getattr(__future__, fname)
|
|
for fname in __future__.all_feature_names]
|
|
|
|
__all__ = ["compile_command", "Compile", "CommandCompiler"]
|
|
|
|
PyCF_DONT_IMPLY_DEDENT = 0x200 # Matches pythonrun.h
|
|
|
|
def _maybe_compile(compiler, source, filename, symbol):
|
|
# Check for source consisting of only blank lines and comments
|
|
for line in source.split("\n"):
|
|
line = line.strip()
|
|
if line and line[0] != '#':
|
|
break # Leave it alone
|
|
else:
|
|
if symbol != "eval":
|
|
source = "pass" # Replace it with a 'pass' statement
|
|
|
|
err = err1 = err2 = None
|
|
code = code1 = code2 = None
|
|
|
|
try:
|
|
code = compiler(source, filename, symbol)
|
|
except SyntaxError as err:
|
|
pass
|
|
|
|
try:
|
|
code1 = compiler(source + "\n", filename, symbol)
|
|
except SyntaxError as e:
|
|
err1 = e
|
|
|
|
try:
|
|
code2 = compiler(source + "\n\n", filename, symbol)
|
|
except SyntaxError as e:
|
|
err2 = e
|
|
|
|
if code:
|
|
return code
|
|
if not code1 and repr(err1) == repr(err2):
|
|
raise SyntaxError(err1)
|
|
|
|
def _compile(source, filename, symbol):
|
|
return compile(source, filename, symbol, PyCF_DONT_IMPLY_DEDENT)
|
|
|
|
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 / exceptions raised:
|
|
|
|
- Return a code object if the command is complete and valid
|
|
- Return None if the command is incomplete
|
|
- Raise SyntaxError, ValueError or OverflowError if the command is a
|
|
syntax error (OverflowError and ValueError can be produced by
|
|
malformed literals).
|
|
"""
|
|
return _maybe_compile(_compile, source, filename, symbol)
|
|
|
|
class Compile:
|
|
"""Instances of this class behave much like the built-in compile
|
|
function, but if one is used to compile text containing a future
|
|
statement, it "remembers" and compiles all subsequent program texts
|
|
with the statement in force."""
|
|
def __init__(self):
|
|
self.flags = PyCF_DONT_IMPLY_DEDENT
|
|
|
|
def __call__(self, source, filename, symbol):
|
|
codeob = compile(source, filename, symbol, self.flags, 1)
|
|
for feature in _features:
|
|
if codeob.co_flags & feature.compiler_flag:
|
|
self.flags |= feature.compiler_flag
|
|
return codeob
|
|
|
|
class CommandCompiler:
|
|
"""Instances of this class have __call__ methods identical in
|
|
signature to compile_command; the difference is that if the
|
|
instance compiles program text containing a __future__ statement,
|
|
the instance 'remembers' and compiles all subsequent program texts
|
|
with the statement in force."""
|
|
|
|
def __init__(self,):
|
|
self.compiler = Compile()
|
|
|
|
def __call__(self, 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 / exceptions raised:
|
|
|
|
- Return a code object if the command is complete and valid
|
|
- Return None if the command is incomplete
|
|
- Raise SyntaxError, ValueError or OverflowError if the command is a
|
|
syntax error (OverflowError and ValueError can be produced by
|
|
malformed literals).
|
|
"""
|
|
return _maybe_compile(self.compiler, source, filename, symbol)
|