docs: adds ExitStack alternative to future_style.md (#3247)

[etc/vim.git] / src / black / parsing.py

diff --git a/src/black/parsing.py b/src/black/parsing.py
index 8e9feea9120db796afdf980b10ddc5e7864cebd0..64c0b1e30183fda1e711c27bda48264cba4e000d 100644 (file)
--- a/src/black/parsing.py
+++ b/src/black/parsing.py
@@ -2,23 +2,33 @@
 Parse Python code and perform AST validation.
 """
 import ast
 Parse Python code and perform AST validation.
 """
 import ast

+import platform

 import sys
 import sys

-from typing import Iterable, Iterator, List, Set, Union
+from typing import Any, Iterable, Iterator, List, Set, Tuple, Type, Union

 
 

-# lib2to3 fork
-from blib2to3.pytree import Node, Leaf
-from blib2to3 import pygram, pytree
+if sys.version_info < (3, 8):
+    from typing_extensions import Final
+else:
+    from typing import Final
+
+from black.mode import Feature, TargetVersion, supports_feature
+from black.nodes import syms
+from blib2to3 import pygram

 from blib2to3.pgen2 import driver
 from blib2to3.pgen2.grammar import Grammar
 from blib2to3.pgen2.parse import ParseError
 from blib2to3.pgen2 import driver
 from blib2to3.pgen2.grammar import Grammar
 from blib2to3.pgen2.parse import ParseError

+from blib2to3.pgen2.tokenize import TokenError
+from blib2to3.pytree import Leaf, Node

 
 

-from black.mode import TargetVersion, Feature, supports_feature
-from black.nodes import syms
+ast3: Any
+
+_IS_PYPY = platform.python_implementation() == "PyPy"

 
 try:
 
 try:

-    from typed_ast import ast3, ast27
+    from typed_ast import ast3

 except ImportError:
 except ImportError:

-    if sys.version_info < (3, 8):
+    # Either our python version is too low, or we're on pypy
+    if sys.version_info < (3, 7) or (sys.version_info < (3, 8) and not _IS_PYPY):

         print(
             "The typed_ast package is required but not installed.\n"
             "You can upgrade to Python 3.8+ or install typed_ast with\n"
         print(
             "The typed_ast package is required but not installed.\n"
             "You can upgrade to Python 3.8+ or install typed_ast with\n"


@@ -27,7 +37,10 @@ except ImportError:
         )
         sys.exit(1)
     else:
         )
         sys.exit(1)
     else:

-        ast3 = ast27 = ast
+        ast3 = ast
+
+
+PY2_HINT: Final = "Python 2 support was removed in version 22.0."

 
 
 class InvalidInput(ValueError):
 
 
 class InvalidInput(ValueError):


@@ -42,32 +55,26 @@ def get_grammars(target_versions: Set[TargetVersion]) -> List[Grammar]:
             pygram.python_grammar_no_print_statement_no_exec_statement_async_keywords,
             # Python 3.0-3.6
             pygram.python_grammar_no_print_statement_no_exec_statement,
             pygram.python_grammar_no_print_statement_no_exec_statement_async_keywords,
             # Python 3.0-3.6
             pygram.python_grammar_no_print_statement_no_exec_statement,

-            # Python 2.7 with future print_function import
-            pygram.python_grammar_no_print_statement,
-            # Python 2.7
-            pygram.python_grammar,
-        ]
-
-    if all(version.is_python2() for version in target_versions):
-        # Python 2-only code, so try Python 2 grammars.
-        return [
-            # Python 2.7 with future print_function import
-            pygram.python_grammar_no_print_statement,
-            # Python 2.7
-            pygram.python_grammar,
+            # Python 3.10+
+            pygram.python_grammar_soft_keywords,

         ]
 
         ]
 

-    # Python 3-compatible code, so only try Python 3 grammar.

     grammars = []
     # If we have to parse both, try to parse async as a keyword first
     grammars = []
     # If we have to parse both, try to parse async as a keyword first

-    if not supports_feature(target_versions, Feature.ASYNC_IDENTIFIERS):
-        # Python 3.7+
+    if not supports_feature(
+        target_versions, Feature.ASYNC_IDENTIFIERS
+    ) and not supports_feature(target_versions, Feature.PATTERN_MATCHING):
+        # Python 3.7-3.9

         grammars.append(
             pygram.python_grammar_no_print_statement_no_exec_statement_async_keywords
         )
     if not supports_feature(target_versions, Feature.ASYNC_KEYWORDS):
         # Python 3.0-3.6
         grammars.append(pygram.python_grammar_no_print_statement_no_exec_statement)
         grammars.append(
             pygram.python_grammar_no_print_statement_no_exec_statement_async_keywords
         )
     if not supports_feature(target_versions, Feature.ASYNC_KEYWORDS):
         # Python 3.0-3.6
         grammars.append(pygram.python_grammar_no_print_statement_no_exec_statement)

+    if supports_feature(target_versions, Feature.PATTERN_MATCHING):
+        # Python 3.10+
+        grammars.append(pygram.python_grammar_soft_keywords)
+

     # At least one of the above branches must have been taken, because every Python
     # version has exactly one of the two 'ASYNC_*' flags
     return grammars
     # At least one of the above branches must have been taken, because every Python
     # version has exactly one of the two 'ASYNC_*' flags
     return grammars


@@ -78,8 +85,10 @@ def lib2to3_parse(src_txt: str, target_versions: Iterable[TargetVersion] = ()) -
     if not src_txt.endswith("\n"):
         src_txt += "\n"
 
     if not src_txt.endswith("\n"):
         src_txt += "\n"
 

-    for grammar in get_grammars(set(target_versions)):
-        drv = driver.Driver(grammar, pytree.convert)
+    grammars = get_grammars(set(target_versions))
+    errors = {}
+    for grammar in grammars:
+        drv = driver.Driver(grammar)

         try:
             result = drv.parse_string(src_txt, True)
             break
         try:
             result = drv.parse_string(src_txt, True)
             break


@@ -91,8 +100,29 @@ def lib2to3_parse(src_txt: str, target_versions: Iterable[TargetVersion] = ()) -
                 faulty_line = lines[lineno - 1]
             except IndexError:
                 faulty_line = "<line number missing in source>"
                 faulty_line = lines[lineno - 1]
             except IndexError:
                 faulty_line = "<line number missing in source>"

-            exc = InvalidInput(f"Cannot parse: {lineno}:{column}: {faulty_line}")
+            errors[grammar.version] = InvalidInput(
+                f"Cannot parse: {lineno}:{column}: {faulty_line}"
+            )
+
+        except TokenError as te:
+            # In edge cases these are raised; and typically don't have a "faulty_line".
+            lineno, column = te.args[1]
+            errors[grammar.version] = InvalidInput(
+                f"Cannot parse: {lineno}:{column}: {te.args[0]}"
+            )
+

     else:
     else:

+        # Choose the latest version when raising the actual parsing error.
+        assert len(errors) >= 1
+        exc = errors[max(errors)]
+
+        if matches_grammar(src_txt, pygram.python_grammar) or matches_grammar(
+            src_txt, pygram.python_grammar_no_print_statement
+        ):
+            original_msg = exc.args[0]
+            msg = f"{original_msg}\n{PY2_HINT}"
+            raise InvalidInput(msg) from None
+

         raise exc from None
 
     if isinstance(result, Leaf):
         raise exc from None
 
     if isinstance(result, Leaf):


@@ -100,55 +130,93 @@ def lib2to3_parse(src_txt: str, target_versions: Iterable[TargetVersion] = ()) -
     return result
 
 
     return result
 
 

+def matches_grammar(src_txt: str, grammar: Grammar) -> bool:
+    drv = driver.Driver(grammar)
+    try:
+        drv.parse_string(src_txt, True)
+    except (ParseError, TokenError, IndentationError):
+        return False
+    else:
+        return True
+
+

 def lib2to3_unparse(node: Node) -> str:
     """Given a lib2to3 node, return its string representation."""
     code = str(node)
     return code
 
 
 def lib2to3_unparse(node: Node) -> str:
     """Given a lib2to3 node, return its string representation."""
     code = str(node)
     return code
 
 

-def parse_ast(src: str) -> Union[ast.AST, ast3.AST, ast27.AST]:
+def parse_single_version(
+    src: str, version: Tuple[int, int]
+) -> Union[ast.AST, ast3.AST]:

     filename = "<unknown>"
     filename = "<unknown>"

-    if sys.version_info >= (3, 8):
-        # TODO: support Python 4+ ;)
-        for minor_version in range(sys.version_info[1], 4, -1):
-            try:
-                return ast.parse(src, filename, feature_version=(3, minor_version))
-            except SyntaxError:
-                continue
+    # typed-ast is needed because of feature version limitations in the builtin ast 3.8>
+    if sys.version_info >= (3, 8) and version >= (3,):
+        return ast.parse(src, filename, feature_version=version, type_comments=True)
+
+    if _IS_PYPY:
+        # PyPy 3.7 doesn't support type comment tracking which is not ideal, but there's
+        # not much we can do as typed-ast won't work either.
+        if sys.version_info >= (3, 8):
+            return ast3.parse(src, filename, type_comments=True)
+        else:
+            return ast3.parse(src, filename)

     else:
     else:

-        for feature_version in (7, 6):
-            try:
-                return ast3.parse(src, filename, feature_version=feature_version)
-            except SyntaxError:
-                continue
-    if ast27.__name__ == "ast":
-        raise SyntaxError(
-            "The requested source code has invalid Python 3 syntax.\n"
-            "If you are trying to format Python 2 files please reinstall Black"
-            " with the 'python2' extra: `python3 -m pip install black[python2]`."
-        )
-    return ast27.parse(src)
+        # Typed-ast is guaranteed to be used here and automatically tracks type
+        # comments separately.
+        return ast3.parse(src, filename, feature_version=version[1])

 
 

+    raise AssertionError("INTERNAL ERROR: Tried parsing unsupported Python version!")
+
+
+def parse_ast(src: str) -> Union[ast.AST, ast3.AST]:
+    # TODO: support Python 4+ ;)
+    versions = [(3, minor) for minor in range(3, sys.version_info[1] + 1)]
+
+    first_error = ""
+    for version in sorted(versions, reverse=True):
+        try:
+            return parse_single_version(src, version)
+        except SyntaxError as e:
+            if not first_error:
+                first_error = str(e)

 
 

-def stringify_ast(
-    node: Union[ast.AST, ast3.AST, ast27.AST], depth: int = 0
-) -> Iterator[str]:
+    raise SyntaxError(first_error)
+
+
+ast3_AST: Final[Type[ast3.AST]] = ast3.AST
+
+
+def _normalize(lineend: str, value: str) -> str:
+    # To normalize, we strip any leading and trailing space from
+    # each line...
+    stripped: List[str] = [i.strip() for i in value.splitlines()]
+    normalized = lineend.join(stripped)
+    # ...and remove any blank lines at the beginning and end of
+    # the whole string
+    return normalized.strip()
+
+
+def stringify_ast(node: Union[ast.AST, ast3.AST], depth: int = 0) -> Iterator[str]:

     """Simple visitor generating strings to compare ASTs by content."""
 
     node = fixup_ast_constants(node)
 
     yield f"{'  ' * depth}{node.__class__.__name__}("
 
     """Simple visitor generating strings to compare ASTs by content."""
 
     node = fixup_ast_constants(node)
 
     yield f"{'  ' * depth}{node.__class__.__name__}("
 

+    type_ignore_classes: Tuple[Type[Any], ...]

     for field in sorted(node._fields):  # noqa: F402
     for field in sorted(node._fields):  # noqa: F402

-        # TypeIgnore has only one field 'lineno' which breaks this comparison
-        type_ignore_classes = (ast3.TypeIgnore, ast27.TypeIgnore)
-        if sys.version_info >= (3, 8):
-            type_ignore_classes += (ast.TypeIgnore,)
-        if isinstance(node, type_ignore_classes):
-            break
+        # TypeIgnore will not be present using pypy < 3.8, so need for this
+        if not (_IS_PYPY and sys.version_info < (3, 8)):
+            # TypeIgnore has only one field 'lineno' which breaks this comparison
+            type_ignore_classes = (ast3.TypeIgnore,)
+            if sys.version_info >= (3, 8):
+                type_ignore_classes += (ast.TypeIgnore,)
+            if isinstance(node, type_ignore_classes):
+                break

 
         try:
 
         try:

-            value = getattr(node, field)
+            value: object = getattr(node, field)

         except AttributeError:
             continue
 
         except AttributeError:
             continue
 


@@ -160,38 +228,35 @@ def stringify_ast(
                 # parentheses and they change the AST.
                 if (
                     field == "targets"
                 # parentheses and they change the AST.
                 if (
                     field == "targets"

-                    and isinstance(node, (ast.Delete, ast3.Delete, ast27.Delete))
-                    and isinstance(item, (ast.Tuple, ast3.Tuple, ast27.Tuple))
+                    and isinstance(node, (ast.Delete, ast3.Delete))
+                    and isinstance(item, (ast.Tuple, ast3.Tuple))

                 ):
                 ):

-                    for item in item.elts:
-                        yield from stringify_ast(item, depth + 2)
+                    for elt in item.elts:
+                        yield from stringify_ast(elt, depth + 2)

 
 

-                elif isinstance(item, (ast.AST, ast3.AST, ast27.AST)):
+                elif isinstance(item, (ast.AST, ast3.AST)):

                     yield from stringify_ast(item, depth + 2)
 
                     yield from stringify_ast(item, depth + 2)
 

-        elif isinstance(value, (ast.AST, ast3.AST, ast27.AST)):
+        # Note that we are referencing the typed-ast ASTs via global variables and not
+        # direct module attribute accesses because that breaks mypyc. It's probably
+        # something to do with the ast3 variables being marked as Any leading
+        # mypy to think this branch is always taken, leaving the rest of the code
+        # unanalyzed. Tighting up the types for the typed-ast AST types avoids the
+        # mypyc crash.
+        elif isinstance(value, (ast.AST, ast3_AST)):

             yield from stringify_ast(value, depth + 2)
 
         else:
             yield from stringify_ast(value, depth + 2)
 
         else:

+            normalized: object

             # Constant strings may be indented across newlines, if they are
             # docstrings; fold spaces after newlines when comparing. Similarly,
             # trailing and leading space may be removed.
             # Constant strings may be indented across newlines, if they are
             # docstrings; fold spaces after newlines when comparing. Similarly,
             # trailing and leading space may be removed.

-            # Note that when formatting Python 2 code, at least with Windows
-            # line-endings, docstrings can end up here as bytes instead of
-            # str so make sure that we handle both cases.

             if (
                 isinstance(node, ast.Constant)
                 and field == "value"
             if (
                 isinstance(node, ast.Constant)
                 and field == "value"

-                and isinstance(value, (str, bytes))
+                and isinstance(value, str)

             ):
             ):

-                lineend = "\n" if isinstance(value, str) else b"\n"
-                # To normalize, we strip any leading and trailing space from
-                # each line...
-                stripped = [line.strip() for line in value.splitlines()]
-                normalized = lineend.join(stripped)  # type: ignore[attr-defined]
-                # ...and remove any blank lines at the beginning and end of
-                # the whole string
-                normalized = normalized.strip()
+                normalized = _normalize("\n", value)

             else:
                 normalized = value
             yield f"{'  ' * (depth+2)}{normalized!r},  # {value.__class__.__name__}"
             else:
                 normalized = value
             yield f"{'  ' * (depth+2)}{normalized!r},  # {value.__class__.__name__}"


@@ -199,14 +264,12 @@ def stringify_ast(
     yield f"{'  ' * depth})  # /{node.__class__.__name__}"
 
 
     yield f"{'  ' * depth})  # /{node.__class__.__name__}"
 
 

-def fixup_ast_constants(
-    node: Union[ast.AST, ast3.AST, ast27.AST]
-) -> Union[ast.AST, ast3.AST, ast27.AST]:
+def fixup_ast_constants(node: Union[ast.AST, ast3.AST]) -> Union[ast.AST, ast3.AST]:

     """Map ast nodes deprecated in 3.8 to Constant."""
     """Map ast nodes deprecated in 3.8 to Constant."""

-    if isinstance(node, (ast.Str, ast3.Str, ast27.Str, ast.Bytes, ast3.Bytes)):
+    if isinstance(node, (ast.Str, ast3.Str, ast.Bytes, ast3.Bytes)):

         return ast.Constant(value=node.s)
 
         return ast.Constant(value=node.s)
 

-    if isinstance(node, (ast.Num, ast3.Num, ast27.Num)):
+    if isinstance(node, (ast.Num, ast3.Num)):

         return ast.Constant(value=node.n)
 
     if isinstance(node, (ast.NameConstant, ast3.NameConstant)):
         return ast.Constant(value=node.n)
 
     if isinstance(node, (ast.NameConstant, ast3.NameConstant)):