There are two copies of the grammar -- the one used by Python itself as
Grammar/Grammar, and the one used by lib2to3 which has necessarily diverged at
Lib/lib2to3/Grammar.txt because it needs to support older syntax an we want it
to be reasonable stable to avoid requiring fixer rewrites.
This brings suport for syntax like `if x:= foo():` to match what the live
Python grammar does.
This should've been added at the time of the walrus operator itself, but lib2to3 being
independent is often overlooked. So we do consider this a bugfix rather than enhancement.
New tests also added.
I also made the comments in line with the builtin Grammar/Grammar. PEP 306 was
withdrawn, Kees Blom's railroad program has been lost to the sands of time for
at least 16 years now (I found a python-dev post from people looking for it).
Fix two (in my opinion) spurious failure conditions in the lib2to3.tests.test_parser.TestParserIdempotency test_parser test.
Use the same encoding found in the initial file to write a temp file for a diff. This retains the BOM if the encoding was initially utf-8-sig.
If the file cannot be parsed using the normal grammar, try again with no print statement which should succeed for valid files using future print_function
For case (1), the driver was correctly handling a BOM in a utf-8 file, but then the test was not writing a comparison file using 'utf-8-sig' to diff against, so the BOM got removed. I don't think that is the fault of the parser, and lib2to3 will retain the BOM.
For case (2), lib2to3 pre-detects the use of from __future__ import print_function or allows the user to force this interpretation with a -p flag, and then selects a different grammar with the print statement removed. That makes the test cases unfair to this test as the driver itself doesn't know which grammar to use. As a minimal fix, the test will try using a grammar with the print statement, and if that fails fall back on a grammar without it. A more thorough handling of the idempotency test would to be to parse all files using both grammars and ignore if one of the two failed but otherwise check both. I didn't think this was necessary but can change.
This is more complicated than it should be because we need to preserve the
useful mtime-based regeneration feature that lib2to3.pgen2.driver.load_grammar
has. We only look for the pickled grammar file with pkgutil.get_data and only if
the source file does not exist.
Note: this doesn't unpack f-strings into the underlying JoinedStr AST.
Ideally we'd fully implement JoinedStr here but given its additional
complexity, I think this is worth bandaiding as is. This unblocks tools like
https://github.com/google/yapf to format 3.6 syntax using f-strings.
This commit simplifies async/await tokenization in tokenizer.c,
tokenize.py & lib2to3/tokenize.py. Previous solution was to keep
a stack of async-def & def blocks, whereas the new approach is just
to remember position of the outermost async-def block.
This change won't bring any parsing performance improvements, but
it makes the code much easier to read and validate.
with line feeds. This was ported from the sandbox to the 3.3 branch, but
didn't make it into 3.2.
- Re-enable lib2to3's test_parser.py tests, though with an expected failure
(see issue 13125).
svn+ssh://pythondev@svn.python.org/python/trunk
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r76062 | benjamin.peterson | 2009-11-02 12:12:12 -0600 (Mon, 02 Nov 2009) | 70 lines
Merged revisions 74359,75081,75088,75213,75278,75303,75427-75428,75734-75736,75865,76059-76061 via svnmerge from
svn+ssh://pythondev@svn.python.org/sandbox/trunk/2to3/lib2to3
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r74359 | benjamin.peterson | 2009-08-12 17:23:13 -0500 (Wed, 12 Aug 2009) | 1 line
don't pass the deprecated print_function option
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r75081 | benjamin.peterson | 2009-09-26 22:02:57 -0500 (Sat, 26 Sep 2009) | 1 line
let 2to3 work with extended iterable unpacking
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r75088 | benjamin.peterson | 2009-09-27 11:25:21 -0500 (Sun, 27 Sep 2009) | 1 line
look on the type only for __call__
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r75213 | benjamin.peterson | 2009-10-03 10:09:46 -0500 (Sat, 03 Oct 2009) | 5 lines
revert 75212; it's not correct
People can use isinstance(x, collections.Callable) if they expect objects with
__call__ in their instance dictionaries.
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r75278 | benjamin.peterson | 2009-10-07 16:25:56 -0500 (Wed, 07 Oct 2009) | 4 lines
fix whitespace problems with fix_idioms #3563
Patch by Joe Amenta.
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r75303 | benjamin.peterson | 2009-10-09 16:59:11 -0500 (Fri, 09 Oct 2009) | 1 line
port latin-1 and utf-8 cookie improvements
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r75427 | benjamin.peterson | 2009-10-14 20:35:57 -0500 (Wed, 14 Oct 2009) | 1 line
force floor division
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r75428 | benjamin.peterson | 2009-10-14 20:39:21 -0500 (Wed, 14 Oct 2009) | 1 line
silence -3 warnings about __hash__
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r75734 | benjamin.peterson | 2009-10-26 16:25:53 -0500 (Mon, 26 Oct 2009) | 2 lines
warn on map(None, ...) with more than 2 arguments #7203
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r75735 | benjamin.peterson | 2009-10-26 16:28:25 -0500 (Mon, 26 Oct 2009) | 1 line
remove unused result
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r75736 | benjamin.peterson | 2009-10-26 16:29:02 -0500 (Mon, 26 Oct 2009) | 1 line
using get() here is a bit pointless
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r75865 | benjamin.peterson | 2009-10-27 15:49:00 -0500 (Tue, 27 Oct 2009) | 1 line
explain reason for warning
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r76059 | benjamin.peterson | 2009-11-02 11:43:47 -0600 (Mon, 02 Nov 2009) | 1 line
tuples are no longer used for children
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r76060 | benjamin.peterson | 2009-11-02 11:55:40 -0600 (Mon, 02 Nov 2009) | 1 line
revert r76059; apparently some fixers rely on Leaf no () for children
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r76061 | benjamin.peterson | 2009-11-02 12:06:17 -0600 (Mon, 02 Nov 2009) | 1 line
make fix_tuple_params keep the tree valid #7253
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svn+ssh://pythondev@svn.python.org/python/trunk
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r72494 | benjamin.peterson | 2009-05-08 20:01:14 -0500 (Fri, 08 May 2009) | 21 lines
Merged revisions 72491-72493 via svnmerge from
svn+ssh://pythondev@svn.python.org/sandbox/trunk/2to3/lib2to3
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r72491 | benjamin.peterson | 2009-05-08 19:33:27 -0500 (Fri, 08 May 2009) | 7 lines
make 2to3 use unicode internally on 2.x
This started out as a fix for #2660, but became this large refactoring
when I realized the dire state this was in. 2to3 now uses
tokenize.detect_encoding to decode the files correctly into unicode.
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r72492 | benjamin.peterson | 2009-05-08 19:35:38 -0500 (Fri, 08 May 2009) | 1 line
remove compat code
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r72493 | benjamin.peterson | 2009-05-08 19:54:15 -0500 (Fri, 08 May 2009) | 1 line
add a test for \r\n newlines
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Tim Hatch
Zsolt Dollenstein
Min ho Kim
Anthony Sottile
Monson Shao
Serhiy Storchaka
Jelle Zijlstra
Łukasz Langa
Benjamin Peterson
Eric Appelt
Jakub Stasiak
Gregory P. Smith ext:(%20%5BGoogle%20Inc.%5D)
Yury Selivanov
Yury Selivanov
Berker Peksag
Ezio Melotti
Antoine Pitrou
Barry Warsaw
Martin v. Löwis