213 lines
6.6 KiB
Python
213 lines
6.6 KiB
Python
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# Copyright © 2018–2019 Io Mintz <io@mintz.cc>
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# Permission is hereby granted, free of charge, to any person obtaining a copy
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# of this software and associated documentation files (the “Software”),
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# to deal in the Software without restriction, including without limitation the
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# rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
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# sell copies of the Software, and to permit persons to whom the Software is
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# furnished to do so, subject to the following conditions:
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# The above copyright notice and this permission notice shall be included in
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# all copies or substantial portions of the Software.
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# THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS
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# OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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# THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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# THE SOFTWARE.
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import ast
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import contextlib
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from collections import namedtuple
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from .constants import *
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def parse_ast(root_node, **kwargs): return ast.fix_missing_locations(Transformer(**kwargs).visit(root_node))
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def remove_string_right(haystack, needle):
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left, needle, right = haystack.rpartition(needle)
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if not right:
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return left
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# needle not found
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return haystack
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def remove_import_op(name): return remove_string_right(name, MARKER)
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def has_any_import_op(name): return MARKER in name
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def has_invalid_import_op(name):
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removed = remove_import_op(name)
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return MARKER in removed or not removed
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def has_valid_import_op(name): return name.endswith(MARKER) and remove_import_op(name)
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SyntaxErrorContext = namedtuple('SyntaxErrorContext', 'filename lineno column line')
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class Transformer(ast.NodeTransformer):
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def __init__(self, *, filename=None, source=None):
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self.filename = filename
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self.source_lines = source.splitlines() if source is not None else None
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def visit_Attribute(self, node):
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"""
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convert Attribute nodes containing import expressions into Attribute nodes containing import calls
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"""
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self._ensure_only_valid_import_ops(node)
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maybe_transformed = self._transform_attribute_attr(node)
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if maybe_transformed:
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return maybe_transformed
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else:
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transformed_lhs = self.visit(node.value)
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return ast.copy_location(
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ast.Attribute(
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value=transformed_lhs,
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ctx=node.ctx,
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attr=node.attr),
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node)
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def visit_Name(self, node):
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"""convert solitary Names that have import expressions, such as "a!", into import calls"""
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self._ensure_only_valid_import_ops(node)
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is_import = id = has_valid_import_op(node.id)
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if is_import:
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return ast.copy_location(self._import_call(id, node.ctx), node)
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return node
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@staticmethod
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def _import_call(attribute_source, ctx):
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return ast.Call(
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func=ast.Name(id=IMPORTER, ctx=ctx),
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args=[ast.Str(attribute_source)],
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keywords=[])
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def _transform_attribute_attr(self, node):
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"""convert an Attribute node's left hand side into an import call"""
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attr = is_import = has_valid_import_op(node.attr)
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if not is_import:
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return None
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node.attr = attr
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as_source = self.attribute_source(node)
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return ast.copy_location(
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self._import_call(as_source, node.ctx),
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node)
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def attribute_source(self, node: ast.Attribute, _seen_import_op=False):
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"""return a source-code representation of an Attribute node"""
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if self._has_valid_import_op(node):
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_seen_import_op = True
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stripped = self._remove_import_op(node)
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if type(node) is ast.Name:
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if _seen_import_op:
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raise self._syntax_error('multiple import expressions not allowed', node) from None
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return stripped
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lhs = self.attribute_source(node.value, _seen_import_op)
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rhs = stripped
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return lhs + '.' + rhs
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def visit_def_(self, node):
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if not has_any_import_op(node.name):
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# it's valid so far, just ensure that arguments and body are also visited
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return self.generic_visit(node)
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if isinstance(node, ast.ClassDef):
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type_name = 'class'
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else:
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type_name = 'function'
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raise self._syntax_error(
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f'"{IMPORT_OP}" not allowed in the name of a {type_name}',
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node
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) from None
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visit_FunctionDef = visit_def_
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visit_ClassDef = visit_def_
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def visit_arg(self, node):
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"""ensure foo(x! = 1) or def foo(x!) does not occur"""
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if node.arg is not None and has_any_import_op(node.arg):
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raise self._syntax_error(
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f'"{IMPORT_OP}" not allowed in function arguments',
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node
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) from None
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# regular arguments may have import expr annotations as children
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return super().generic_visit(node)
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def visit_keyword(self, node):
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self.visit_arg(node)
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# keyword arguments may have import expressions as children
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return super().generic_visit(node)
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def visit_alias(self, node):
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# from x import y **as z**
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self._ensure_no_import_ops(node)
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return node
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def visit_ImportFrom(self, node):
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self._ensure_no_import_ops(node)
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# ImportFrom nodes can have alias children that we also need to check
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return super().generic_visit(node)
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def _ensure_only_valid_import_ops(self, node):
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if self._for_any_child_node_string(has_invalid_import_op, node):
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raise self._syntax_error(
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f'"{IMPORT_OP}" only allowed at end of attribute name',
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node
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) from None
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def _ensure_no_import_ops(self, node):
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if self._for_any_child_node_string(has_any_import_op, node):
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raise self._syntax_error(
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'import expressions are only allowed in variables and attributes',
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node
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) from None
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@classmethod
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def _for_any_child_node_string(cls, predicate, node):
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for child_node in ast.walk(node):
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if cls._for_any_node_string(predicate, node):
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return True
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return False
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@staticmethod
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def _for_any_node_string(predicate, node):
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for field, value in ast.iter_fields(node):
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if isinstance(value, str) and predicate(value):
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return True
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return False
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def _call_on_name_or_attribute(func):
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def checker(node):
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if type(node) is ast.Attribute:
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to_check = node.attr
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elif type(node) is ast.Name:
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to_check = node.id
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return func(to_check)
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return staticmethod(checker)
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_has_valid_import_op = _call_on_name_or_attribute(has_valid_import_op)
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_remove_import_op = _call_on_name_or_attribute(remove_import_op)
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del _call_on_name_or_attribute
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def _syntax_error(self, message, node):
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lineno = getattr(node, 'lineno', None)
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column = getattr(node, 'col_offset', None)
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line = None
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if self.source_lines is not None and lineno:
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with contextlib.suppress(IndexError):
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line = self.source_lines[lineno-1]
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ctx = SyntaxErrorContext(filename=self.filename, lineno=lineno, column=column, line=line)
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return SyntaxError(message, ctx)
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