`ast.parse` and `compile` support a `feature_version` parameter that
tells the parser to parse the input string, as if it were written in
an older Python version.
The `feature_version` is propagated to the tokenizer, which uses it
to handle the three different stages of support for `async` and
`await`. Additionally, it disallows the following at parser level:
- The '@' operator in < 3.5
- Async functions in < 3.5
- Async comprehensions in < 3.6
- Underscores in numeric literals in < 3.6
- Await expression in < 3.5
- Variable annotations in < 3.6
- Async for-loops in < 3.5
- Async with-statements in < 3.5
- F-strings in < 3.6
Closeswe-like-parsers/cpython#124.
This implements full support for # type: <type> comments, # type: ignore <stuff> comments, and the func_type parsing mode for ast.parse() and compile().
Closes https://github.com/we-like-parsers/cpython/issues/95.
(For now, you need to use the master branch of mypy, since another issue unique to 3.9 had to be fixed there, and there's no mypy release yet.)
The only thing missing is `feature_version=N`, which is being tracked in https://github.com/we-like-parsers/cpython/issues/124.
After parsing is done in single statement mode, the tokenizer buffer has to be checked for additional lines and a `SyntaxError` must be raised, in case there are any.
Co-authored-by: Pablo Galindo <Pablogsal@gmail.com>
An E_EOF error was only being caught after the parser exited before this commit. There are some cases though, where the tokenizer returns ERRORTOKEN *and* has set an E_EOF error (like when EOF directly follows a line continuation character) which weren't correctly handled before.
This commit also allows to pass flags to the new parser in all interfaces and fixes a bug in the parser generator that was causing to inline rules with actions, making them disappear.
When there is a SyntaxError after reading the last input character from
the tokenizer and if no newline follows it, the error message used to be
`unexpected EOF while parsing`, which is wrong.
Rename _PyInterpreterState_GET_UNSAFE() to _PyInterpreterState_GET()
for consistency with _PyThreadState_GET() and to have a shorter name
(help to fit into 80 columns).
Add also "assert(tstate != NULL);" to the function.
Fix a leak and subsequent crash in parsetok.c caused by realloc misuse on a rare codepath.
Realloc returns a null pointer on failure, and then growable_comment_array_deallocate crashes later when it dereferences it.
* Re-add removed classes Suite, slice, Param, AugLoad and AugStore.
* Add docstrings for dummy classes.
* Add docstrings for attribute aliases.
* Set __module__ to "ast" instead of "_ast".
* Remove the slice type.
* Make Slice a kind of the expr type instead of the slice type.
* Replace ExtSlice(slices) with Tuple(slices, Load()).
* Replace Index(value) with a value itself.
All non-terminal nodes in AST for expressions are now of the expr type.
The Py_FatalError() function is replaced with a macro which logs
automatically the name of the current function, unless the
Py_LIMITED_API macro is defined.
Changes:
* Add _Py_FatalErrorFunc() function.
* Remove the function name from the message of Py_FatalError() calls
which included the function name.
* Update tests.
The AST "Suite" node is no longer used and it can be removed from the ASDL definition and related structures (compiler, visitors, ...).
Co-Authored-By: Victor Stinner <vstinner@python.org>
Co-authored-by: Brett Cannon <54418+brettcannon@users.noreply.github.com>
Co-authored-by: Pablo Galindo <Pablogsal@gmail.com>
The function PyTokenizer_FromUTF8 from Parser/tokenizer.c had a comment:
/* XXX: constify members. */
This patch addresses that.
In the tok_state struct:
* end and start were non-const but could be made const
* str and input were const but should have been non-const
Changes to support this include:
* decode_str() now returns a char * since it is allocated.
* PyTokenizer_FromString() and PyTokenizer_FromUTF8() each creates a
new char * for an allocate string instead of reusing the input
const char *.
* PyTokenizer_Get() and tok_get() now take const char ** arguments.
* Various local vars are const or non-const accordingly.
I was able to remove five casts that cast away constness.
Summary: This mostly migrates Python-ast.c to PEP384 and removes all statics from the whole file. This modifies the generator itself that generates the Python-ast.c. It leaves in the usage of _PyObject_LookupAttr even though it's not fully PEP384 compatible (this could always be shimmed in by anyone who needs it).
This is the converse of GH-15353 -- in addition to plenty of
scripts in the tree that are marked with the executable bit
(and so can be directly executed), there are a few that have
a leading `#!` which could let them be executed, but it doesn't
do anything because they don't have the executable bit set.
Here's a command which finds such files and marks them. The
first line finds files in the tree with a `#!` line *anywhere*;
the next-to-last step checks that the *first* line is actually of
that form. In between we filter out files that already have the
bit set, and some files that are meant as fragments to be
consumed by one or another kind of preprocessor.
$ git grep -l '^#!' \
| grep -vxFf <( \
git ls-files --stage \
| perl -lane 'print $F[3] if (!/^100644/)' \
) \
| grep -ve '\.in$' -e '^Doc/includes/' \
| while read f; do
head -c2 "$f" | grep -qxF '#!' \
&& chmod a+x "$f"; \
done
* Refactor Parser/pgen and add documentation and explanations
To improve the readability and maintainability of the parser
generator perform the following transformations:
* Separate the metagrammar parser in its own class to simplify
the parser generator logic.
* Create separate classes for DFAs and NFAs and move methods that
act exclusively on them from the parser generator to these
classes.
* Add docstrings and comment documenting the process to go from
the grammar file into NFAs and then DFAs. Detail some of the
algorithms and give some background explanations of some concepts
that will helps readers not familiar with the parser generation
process.
* Select more descriptive names for some variables and variables.
* PEP8 formatting and quote-style homogenization.
The output of the parser generator remains the same (Include/graminit.h
and Python/graminit.c remain untouched by running the new parser generator).
When using the "=" debug functionality of f-strings, use another Constant node (or a merged constant node) instead of adding expr_text to the FormattedValue node.
This disallows things like `# type: ignoreé`, which seems wrong.
Also switch to using Py_ISALNUM for the alnum check, for consistency
with other code (and maybe correctness re: locale issues?).
https://bugs.python.org/issue36878
GH-13238 made extra text after a # type: ignore accepted by the parser.
This finishes the job and actually plumbs the extra text through the
parser and makes it available in the AST.
This makes the parser consistent with the tokenize module (already the case
in `pypy`).
sample
------
```python
x = 5\
```
before
------
```console
$ python3 t.py
$ python3 -mtokenize t.py
t.py:2:0: error: EOF in multi-line statement
```
after
-----
```console
$ ./python t.py
File "t.py", line 3
x = 5\
^
SyntaxError: unexpected EOF while parsing
$ ./python -m tokenize t.py
t.py:2:0: error: EOF in multi-line statement
```
https://bugs.python.org/issue2180
In the parser, when using the type_comments=True option, recognize
a TYPE_IGNORE as anything containing `# type: ignore` followed by
a non-alphanumeric character. This is to allow ignores such as
`# type: ignore[E1000]`.
If a "=" is specified a the end of an f-string expression, the f-string will evaluate to the text of the expression, followed by '=', followed by the repr of the value of the expression.
This commit contains the implementation of PEP570: Python positional-only parameters.
* Update Grammar/Grammar with new typedarglist and varargslist
* Regenerate grammar files
* Update and regenerate AST related files
* Update code object
* Update marshal.c
* Update compiler and symtable
* Regenerate importlib files
* Update callable objects
* Implement positional-only args logic in ceval.c
* Regenerate frozen data
* Update standard library to account for positional-only args
* Add test file for positional-only args
* Update other test files to account for positional-only args
* Add News entry
* Update inspect module and related tests
Now that the parser generator is written in Python (Parser/pgen) we can make use of it to regenerate the Lib/keyword file that contains the language keywords instead of parsing the autogenerated grammar files. This also allows checking in the CI that the autogenerated files are up to date.
Currently, when arguments on Parser/asdl_c.py are parsed
``ìf`` sentence is used. This PR Propose to use ``elif``
to avoid multiple evaluting of the ifs.
https://bugs.python.org/issue36385
The value is a string for string and byte literals, None otherwise.
It is 'u' for u"..." literals, 'b' for b"..." literals, '' for "..." literals.
The 'r' (raw) prefix is ignored.
Does not apply to f-strings.
This appears sufficient to make mypy capable of using the stdlib ast module instead of typed_ast (assuming a mypy patch I'm working on).
WIP: I need to make the tests pass. @ilevkivskyi @serhiy-storchaka
https://bugs.python.org/issue36280
d_initial, the first state of a particular DFA in the parser has always been initialized to 0 in the old pgen as well as the new pgen. As this value is not used and the first state of each DFA is assumed to be the first element in the array representing it, remove d_initial from the parser to reduce complexity.
This adds a `feature_version` flag to `ast.parse()` (documented) and `compile()` (hidden) that allow tweaking the parser to support older versions of the grammar. In particular if `feature_version` is 5 or 6, the hacks for the `async` and `await` keyword from PEP 492 are reinstated. (For 7 or higher, these are unconditionally treated as keywords, but they are still special tokens rather than `NAME` tokens that the parser driver recognizes.)
https://bugs.python.org/issue35975
Pgen is the oldest piece of technology in the CPython repository, building it requires various #if[n]def PGEN hacks in other parts of the code and it also depends more and more on CPython internals. This commit removes the old pgen C code and replaces it for a new version implemented in pure Python. This is a modified and adapted version of lib2to3/pgen2 that can generate grammar files compatibles with the current parser.
This commit also eliminates all the #ifdef and code branches related to pgen, simplifying the code and making it more maintainable. The regen-grammar step now uses $(PYTHON_FOR_REGEN) that can be any version of the interpreter, so the new pgen code maintains compatibility with older versions of the interpreter (this also allows regenerating the grammar with the current CI solution that uses Python3.5). The new pgen Python module also makes use of the Grammar/Tokens file that holds the token specification, so is always kept in sync and avoids having to maintain duplicate token definitions.
* Add tokenization of :=
- Add token to Include/token.h. Add token to documentation in Doc/library/token.rst.
- Run `./python Lib/token.py` to regenerate Lib/token.py.
- Update Parser/tokenizer.c: add case to handle `:=`.
* Add initial usage of := in grammar.
* Update Python.asdl to match the grammar updates. Regenerated Include/Python-ast.h and Python/Python-ast.c
* Update AST and compiler files in Python/ast.c and Python/compile.c. Basic functionality, this isn't scoped properly
* Regenerate Lib/symbol.py using `./python Lib/symbol.py`
* Tests - Fix failing tests in test_parser.py due to changes in token numbers for internal representation
* Tests - Add simple test for := token
* Tests - Add simple tests for named expressions using expr and suite
* Tests - Update number of levels for nested expressions to prevent stack overflow
* Update symbol table to handle NamedExpr
* Update Grammar to allow assignment expressions in if statements.
Regenerate Python/graminit.c accordingly using `make regen-grammar`
* Tests - Add additional tests for named expressions in RoundtripLegalSyntaxTestCase, based on examples and information directly from PEP 572
Note: failing tests are currently commented out (4 out of 24 tests currently fail)
* Tests - Add temporary syntax test failure tests in test_parser.py
Note: There is an outstanding TODO for this -- syntax tests need to be
moved to a different file (presumably test_syntax.py), but this is
covering what needs to be tested at the moment, and it's more convenient
to run a single test for the time being
* Add support for allowing assignment expressions as function argument annotations. Uncomment tests for these cases because they all pass now!
* Tests - Move existing syntax tests out of test_parser.py and into test_named_expressions.py. Refactor syntax tests to use unittest
* Add TargetScopeError exception to extend SyntaxError
Note: This simply creates the TargetScopeError exception, it is not yet
used anywhere
* Tests - Update tests per PEP 572
Continue refactoring test suite:
The named expression test suite now checks for any invalid cases that
throw exceptions (no longer limited to SyntaxErrors), assignment tests
to ensure that variables are properly assigned, and scope tests to
ensure that variable availability and values are correct
Note:
- There are still tests that are marked to skip, as they are not yet
implemented
- There are approximately 300 lines of the PEP that have not yet been
addressed, though these may be deferred
* Documentation - Small updates to XXX/todo comments
- Remove XXX from child description in ast.c
- Add comment with number of previously supported nested expressions for
3.7.X in test_parser.py
* Fix assert in seq_for_testlist()
* Cleanup - Denote "Not implemented -- No keyword args" on failing test case. Fix PEP8 error for blank lines at beginning of test classes in test_parser.py
* Tests - Wrap all file opens in `with...as` to ensure files are closed
* WIP: handle f(a := 1)
* Tests and Cleanup - No longer skips keyword arg test. Keyword arg test now uses a simpler test case and does not rely on an external file. Remove print statements from ast.c
* Tests - Refactor last remaining test case that relied on on external file to use a simpler test case without the dependency
* Tests - Add better description of remaning skipped tests. Add test checking scope when using assignment expression in a function argument
* Tests - Add test for nested comprehension, testing value and scope. Fix variable name in skipped comprehension scope test
* Handle restriction of LHS for named expressions - can only assign to LHS of type NAME. Specifically, restrict assignment to tuples
This adds an alternative set_context specifically for named expressions,
set_namedexpr_context. Thus, context is now set differently for standard
assignment versus assignment for named expressions in order to handle
restrictions.
* Tests - Update negative test case for assigning to lambda to match new error message. Add negative test case for assigning to tuple
* Tests - Reorder test cases to group invalid syntax cases and named assignment target errors
* Tests - Update test case for named expression in function argument - check that result and variable are set correctly
* Todo - Add todo for TargetScopeError based on Guido's comment (2b3acd37bd (r30472562))
* Tests - Add named expression tests for assignment operator in function arguments
Note: One of two tests are skipped, as function arguments are currently treating
an assignment expression inside of parenthesis as one child, which does
not properly catch the named expression, nor does it count arguments
properly
* Add NamedStore to expr_context. Regenerate related code with `make regen-ast`
* Add usage of NamedStore to ast_for_named_expr in ast.c. Update occurances of checking for Store to also handle NamedStore where appropriate
* Add ste_comprehension to _symtable_entry to track if the namespace is a comprehension. Initialize ste_comprehension to 0. Set set_comprehension to 1 in symtable_handle_comprehension
* s/symtable_add_def/symtable_add_def_helper. Add symtable_add_def to handle grabbing st->st_cur and passing it to symtable_add_def_helper. This now allows us to call the original code from symtable_add_def by instead calling symtable_add_def_helper with a different ste.
* Refactor symtable_record_directive to take lineno and col_offset as arguments instead of stmt_ty. This allows symtable_record_directive to be used for stmt_ty and expr_ty
* Handle elevating scope for named expressions in comprehensions.
* Handle error for usage of named expression inside a class block
* Tests - No longer skip scope tests. Add additional scope tests
* Cleanup - Update error message for named expression within a comprehension within a class. Update comments. Add assert for symtable_extend_namedexpr_scope to validate that we always find at least a ModuleScope if we don't find a Class or FunctionScope
* Cleanup - Add missing case for NamedStore in expr_context_name. Remove unused var in set_namedexpr_content
* Refactor - Consolidate set_context and set_namedexpr_context to reduce duplicated code. Special cases for named expressions are handled by checking if ctx is NamedStore
* Cleanup - Add additional use cases for ast_for_namedexpr in usage comment. Fix multiple blank lines in test_named_expressions
* Tests - Remove unnecessary test case. Renumber test case function names
* Remove TargetScopeError for now. Will add back if needed
* Cleanup - Small comment nit for consistency
* Handle positional argument check with named expression
* Add TargetScopeError exception definition. Add documentation for TargetScopeError in c-api docs. Throw TargetScopeError instead of SyntaxError when using a named expression in a comprehension within a class scope
* Increase stack size for parser by 200. This is a minimal change (approx. 5kb) and should not have an impact on any systems. Update parser test to allow 99 nested levels again
* Add TargetScopeError to exception_hierarchy.txt for test_baseexception.py_
* Tests - Major update for named expression tests, both in test_named_expressions and test_parser
- Add test for TargetScopeError
- Add tests for named expressions in comprehension scope and edge cases
- Add tests for named expressions in function arguments (declarations
and call sites)
- Reorganize tests to group them more logically
* Cleanup - Remove unnecessary comment
* Cleanup - Comment nitpicks
* Explicitly disallow assignment expressions to a name inside parentheses, e.g.: ((x) := 0)
- Add check for LHS types to detect a parenthesis then a name (see note)
- Add test for this scenario
- Update tests for changed error message for named assignment to a tuple
(also, see note)
Note: This caused issues with the previous error handling for named assignment
to a LHS that contained an expression, such as a tuple. Thus, the check
for the LHS of a named expression must be changed to be more specific if
we wish to maintain the previous error messages
* Cleanup - Wrap lines more strictly in test file
* Revert "Explicitly disallow assignment expressions to a name inside parentheses, e.g.: ((x) := 0)"
This reverts commit f1531400ca7d7a2d148830c8ac703f041740896d.
* Add NEWS.d entry
* Tests - Fix error in test_pickle.test_exceptions by adding TargetScopeError to list of exceptions
* Tests - Update error message tests to reflect improved messaging convention (s/can't/cannot)
* Remove cases that cannot be reached in compile.c. Small linting update.
* Update Grammar/Tokens to add COLONEQUAL. Regenerate all files
* Update TargetScopeError PRE_INIT and POST_INIT, as this was purposefully left out when fixing rebase conflicts
* Add NamedStore back and regenerate files
* Pass along line number and end col info for named expression
* Simplify News entry
* Fix compiler warning and explicity mark fallthrough
The majority of this PR is tediously passing `end_lineno` and `end_col_offset` everywhere. Here are non-trivial points:
* It is not possible to reconstruct end positions in AST "on the fly", some information is lost after an AST node is constructed, so we need two more attributes for every AST node `end_lineno` and `end_col_offset`.
* I add end position information to both CST and AST. Although it may be technically possible to avoid adding end positions to CST, the code becomes more cumbersome and less efficient.
* Since the end position is not known for non-leaf CST nodes while the next token is added, this requires a bit of extra care (see `_PyNode_FinalizeEndPos`). Unless I made some mistake, the algorithm should be linear.
* For statements, I "trim" the end position of suites to not include the terminal newlines and dedent (this seems to be what people would expect), for example in
```python
class C:
pass
pass
```
the end line and end column for the class definition is (2, 8).
* For `end_col_offset` I use the common Python convention for indexing, for example for `pass` the `end_col_offset` is 4 (not 3), so that `[0:4]` gives one the source code that corresponds to the node.
* I added a helper function `ast.get_source_segment()`, to get source text segment corresponding to a given AST node. It is also useful for testing.
An (inevitable) downside of this PR is that AST now takes almost 25% more memory. I think however it is probably justified by the benefits.
