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extract.py
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extract.py
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import re
from contextlib import contextmanager
from itertools import chain
from rope.base import ast, codeanalyze
from rope.base.change import ChangeSet, ChangeContents
from rope.base.exceptions import RefactoringError
from rope.base.utils.datastructures import OrderedSet
from rope.refactor import sourceutils, similarfinder, patchedast, suites, usefunction
# Extract refactoring has lots of special cases. I tried to split it
# to smaller parts to make it more manageable:
#
# _ExtractInfo: holds information about the refactoring; it is passed
# to the parts that need to have information about the refactoring
#
# _ExtractCollector: merely saves all of the information necessary for
# performing the refactoring.
#
# _DefinitionLocationFinder: finds where to insert the definition.
#
# _ExceptionalConditionChecker: checks for exceptional conditions in
# which the refactoring cannot be applied.
#
# _ExtractMethodParts: generates the pieces of code (like definition)
# needed for performing extract method.
#
# _ExtractVariableParts: like _ExtractMethodParts for variables.
#
# _ExtractPerformer: Uses above classes to collect refactoring
# changes.
#
# There are a few more helper functions and classes used by above
# classes.
class _ExtractRefactoring:
kind_prefixes = {}
def __init__(self, project, resource, start_offset, end_offset, variable=False):
self.project = project
self.resource = resource
self.start_offset = self._fix_start(resource.read(), start_offset)
self.end_offset = self._fix_end(resource.read(), end_offset)
def _fix_start(self, source, offset):
while offset < len(source) and source[offset].isspace():
offset += 1
return offset
def _fix_end(self, source, offset):
while offset > 0 and source[offset - 1].isspace():
offset -= 1
return offset
def get_changes(self, extracted_name, similar=False, global_=False, kind=None):
"""Get the changes this refactoring makes
:parameters:
- `extracted_name`: target name, when starts with @ - set kind to
classmethod, $ - staticmethod
- `similar`: if `True`, similar expressions/statements are also
replaced.
- `global_`: if `True`, the extracted method/variable will
be global.
- `kind`: kind of target refactoring to (staticmethod, classmethod)
"""
extracted_name, kind = self._get_kind_from_name(extracted_name, kind)
info = _ExtractInfo(
self.project,
self.resource,
self.start_offset,
self.end_offset,
extracted_name,
variable=self._get_kind(kind) == "variable",
similar=similar,
make_global=global_,
)
info.kind = self._get_kind(kind)
new_contents = _ExtractPerformer(info).extract()
changes = ChangeSet(f"Extract {info.kind} <{extracted_name}>")
changes.add_change(ChangeContents(self.resource, new_contents))
return changes
def _get_kind_from_name(self, extracted_name, kind):
for sign, selected_kind in self.kind_prefixes.items():
if extracted_name.startswith(sign):
self._validate_kind_prefix(kind, selected_kind)
return extracted_name[1:], selected_kind
return extracted_name, kind
@staticmethod
def _validate_kind_prefix(kind, selected_kind):
if kind and kind != selected_kind:
raise RefactoringError("Kind and shortcut in name mismatch")
@classmethod
def _get_kind(cls, kind):
raise NotImplementedError(f"You have to sublass {cls}")
class ExtractMethod(_ExtractRefactoring):
kind = "method"
allowed_kinds = ("function", "method", "staticmethod", "classmethod")
kind_prefixes = {"@": "classmethod", "$": "staticmethod"}
@classmethod
def _get_kind(cls, kind):
return kind if kind in cls.allowed_kinds else cls.kind
class ExtractVariable(_ExtractRefactoring):
def __init__(self, *args, **kwds):
kwds = dict(kwds)
kwds["variable"] = True
super().__init__(*args, **kwds)
kind = "variable"
def _get_kind(cls, kind):
return cls.kind
class _ExtractInfo:
"""Holds information about the extract to be performed"""
def __init__(
self, project, resource, start, end, new_name, variable, similar, make_global
):
self.project = project
self.resource = resource
self.pymodule = project.get_pymodule(resource)
self.global_scope = self.pymodule.get_scope()
self.source = self.pymodule.source_code
self.lines = self.pymodule.lines
self.new_name = new_name
self.variable = variable
self.similar = similar
self._init_parts(start, end)
self.kind = None
self._init_scope()
self.make_global = make_global
def _init_parts(self, start, end):
self.region = (
self._choose_closest_line_end(start),
self._choose_closest_line_end(end, end=True),
)
start = self.logical_lines.logical_line_in(
self.lines.get_line_number(self.region[0])
)[0]
end = self.logical_lines.logical_line_in(
self.lines.get_line_number(self.region[1])
)[1]
self.region_lines = (start, end)
self.lines_region = (
self.lines.get_line_start(self.region_lines[0]),
self.lines.get_line_end(self.region_lines[1]),
)
@property
def logical_lines(self):
return self.pymodule.logical_lines
def _init_scope(self):
start_line = self.region_lines[0]
scope = self.global_scope.get_inner_scope_for_line(start_line)
if scope.get_kind() != "Module" and scope.get_start() == start_line:
scope = scope.parent
self.scope = scope
self.scope_region = self._get_scope_region(self.scope)
def _get_scope_region(self, scope):
return (
self.lines.get_line_start(scope.get_start()),
self.lines.get_line_end(scope.get_end()) + 1,
)
def _choose_closest_line_end(self, offset, end=False):
lineno = self.lines.get_line_number(offset)
line_start = self.lines.get_line_start(lineno)
line_end = self.lines.get_line_end(lineno)
if self.source[line_start:offset].strip() == "":
if end:
return line_start - 1
else:
return line_start
elif self.source[offset:line_end].strip() == "":
return min(line_end, len(self.source))
return offset
@property
def one_line(self):
return self.region != self.lines_region and (
self.logical_lines.logical_line_in(self.region_lines[0])
== self.logical_lines.logical_line_in(self.region_lines[1])
)
@property
def global_(self):
return self.scope.parent is None
@property
def method(self):
return self.scope.parent is not None and self.scope.parent.get_kind() == "Class"
@property
def indents(self):
return sourceutils.get_indents(self.pymodule.lines, self.region_lines[0])
@property
def scope_indents(self):
if self.global_:
return 0
return sourceutils.get_indents(self.pymodule.lines, self.scope.get_start())
@property
def extracted(self):
return self.source[self.region[0] : self.region[1]]
_cached_parsed_extraced = None
@property
def _parsed_extracted(self):
if self._cached_parsed_extraced is None:
self._cached_parsed_extraced = _parse_text(self.extracted)
return self._cached_parsed_extraced
_returned = None
@property
def returned(self):
"""Does the extracted piece contain return statement"""
if self._returned is None:
self._returned = usefunction._returns_last(self._parsed_extracted)
return self._returned
_returning_named_expr = None
@property
def returning_named_expr(self):
"""Does the extracted piece contains named expression/:= operator)"""
if self._returning_named_expr is None:
self._returning_named_expr = usefunction._namedexpr_last(
self._parsed_extracted
)
return self._returning_named_expr
_returning_generator = None
@property
def returning_generator_exp(self):
"""Does the extracted piece contains a generator expression"""
if self._returning_generator is None:
self._returning_generator = (
isinstance(self._parsed_extracted, ast.Module)
and isinstance(self._parsed_extracted.body[0], ast.Expr)
and isinstance(self._parsed_extracted.body[0].value, ast.GeneratorExp)
)
return self._returning_generator
class _ExtractCollector:
"""Collects information needed for performing the extract"""
def __init__(self, info):
self.definition = None
self.body_pattern = None
self.checks = {}
self.replacement_pattern = None
self.matches = None
self.replacements = None
self.definition_location = None
class _ExtractPerformer:
def __init__(self, info):
self.info = info
_ExceptionalConditionChecker()(self.info)
def extract(self):
extract_info = self._collect_info()
content = codeanalyze.ChangeCollector(self.info.source)
definition = extract_info.definition
lineno, indents = extract_info.definition_location
offset = self.info.lines.get_line_start(lineno)
indented = sourceutils.fix_indentation(definition, indents)
content.add_change(offset, offset, indented)
self._replace_occurrences(content, extract_info)
return content.get_changed()
def _replace_occurrences(self, content, extract_info):
for match in extract_info.matches:
replacement = similarfinder.CodeTemplate(extract_info.replacement_pattern)
mapping = {}
for name in replacement.get_names():
node = match.get_ast(name)
if node:
start, end = patchedast.node_region(match.get_ast(name))
mapping[name] = self.info.source[start:end]
else:
mapping[name] = name
region = match.get_region()
content.add_change(region[0], region[1], replacement.substitute(mapping))
def _collect_info(self):
extract_collector = _ExtractCollector(self.info)
self._find_definition(extract_collector)
self._find_matches(extract_collector)
self._find_definition_location(extract_collector)
return extract_collector
def _find_matches(self, collector):
regions = self._where_to_search()
finder = similarfinder.SimilarFinder(self.info.pymodule)
matches = []
for start, end in regions:
region_matches = finder.get_matches(
collector.body_pattern, collector.checks, start, end
)
# Don't extract overlapping regions
last_match_end = -1
for region_match in region_matches:
if self.info.one_line and self._is_assignment(region_match):
continue
start, end = region_match.get_region()
if last_match_end < start:
matches.append(region_match)
last_match_end = end
collector.matches = matches
@staticmethod
def _is_assignment(region_match):
return isinstance(
region_match.ast, (ast.Attribute, ast.Subscript)
) and isinstance(region_match.ast.ctx, ast.Store)
def _where_to_search(self):
if self.info.similar:
if self.info.make_global or self.info.global_:
return [(0, len(self.info.pymodule.source_code))]
if self.info.method and not self.info.variable:
class_scope = self.info.scope.parent
regions = []
method_kind = _get_function_kind(self.info.scope)
for scope in class_scope.get_scopes():
if (
method_kind == "method"
and _get_function_kind(scope) != "method"
):
continue
start = self.info.lines.get_line_start(scope.get_start())
end = self.info.lines.get_line_end(scope.get_end())
regions.append((start, end))
return regions
else:
if self.info.variable:
return [self.info.scope_region]
else:
return [self.info._get_scope_region(self.info.scope.parent)]
else:
return [self.info.region]
def _find_definition_location(self, collector):
matched_lines = []
for match in collector.matches:
start = self.info.lines.get_line_number(match.get_region()[0])
start_line = self.info.logical_lines.logical_line_in(start)[0]
matched_lines.append(start_line)
location_finder = _DefinitionLocationFinder(self.info, matched_lines)
collector.definition_location = (
location_finder.find_lineno(),
location_finder.find_indents(),
)
def _find_definition(self, collector):
if self.info.variable:
parts = _ExtractVariableParts(self.info)
else:
parts = _ExtractMethodParts(self.info)
collector.definition = parts.get_definition()
collector.body_pattern = parts.get_body_pattern()
collector.replacement_pattern = parts.get_replacement_pattern()
collector.checks = parts.get_checks()
class _DefinitionLocationFinder:
def __init__(self, info, matched_lines):
self.info = info
self.matched_lines = matched_lines
# This only happens when subexpressions cannot be matched
if not matched_lines:
self.matched_lines.append(self.info.region_lines[0])
def find_lineno(self):
if self.info.variable and not self.info.make_global:
return self._get_before_line()
if self.info.global_:
toplevel = self._find_toplevel(self.info.scope)
ast = self.info.pymodule.get_ast()
newlines = sorted(self.matched_lines + [toplevel.get_end() + 1])
return suites.find_visible(ast, newlines)
if self.info.make_global:
toplevel = self._find_toplevel(self.info.scope)
return toplevel.get_end() + 1
return self._get_after_scope()
def _find_toplevel(self, scope):
toplevel = scope
if toplevel.parent is not None:
while toplevel.parent.parent is not None:
toplevel = toplevel.parent
return toplevel
def find_indents(self):
if self.info.variable and not self.info.make_global:
return sourceutils.get_indents(self.info.lines, self._get_before_line())
else:
if self.info.global_ or self.info.make_global:
return 0
return self.info.scope_indents
def _get_before_line(self):
ast = self.info.scope.pyobject.get_ast()
return suites.find_visible(ast, self.matched_lines)
def _get_after_scope(self):
return self.info.scope.get_end() + 1
class _ExceptionalConditionChecker:
def __call__(self, info):
self.base_conditions(info)
if info.one_line:
self.one_line_conditions(info)
else:
self.multi_line_conditions(info)
def base_conditions(self, info):
if info.region[1] > info.scope_region[1]:
raise RefactoringError("Bad region selected for extract method")
end_line = info.region_lines[1]
end_scope = info.global_scope.get_inner_scope_for_line(end_line)
if end_scope != info.scope and end_scope.get_end() != end_line:
raise RefactoringError("Bad region selected for extract method")
try:
extracted = info.extracted
if info.one_line:
extracted = "(%s)" % extracted
if _UnmatchedBreakOrContinueFinder.has_errors(extracted):
raise RefactoringError(
"A break/continue without having a matching for/while loop."
)
except SyntaxError:
raise RefactoringError(
"Extracted piece should contain complete statements."
)
def one_line_conditions(self, info):
if self._is_region_on_a_word(info):
raise RefactoringError("Should extract complete statements.")
if info.variable and not info.one_line:
raise RefactoringError("Extract variable should not span multiple lines.")
if usefunction._named_expr_count(
info._parsed_extracted
) - usefunction._namedexpr_last(info._parsed_extracted):
raise RefactoringError(
"Extracted piece cannot contain named expression (:= operator)."
)
def multi_line_conditions(self, info):
node = _parse_text(info.source[info.region[0] : info.region[1]])
count = usefunction._return_count(node)
extracted = info.extracted
if count > 1:
raise RefactoringError(
"Extracted piece can have only one return statement."
)
if usefunction._yield_count(node):
raise RefactoringError("Extracted piece cannot have yield statements.")
if not hasattr(
ast, "PyCF_ALLOW_TOP_LEVEL_AWAIT"
) and _AsyncStatementFinder.has_errors(extracted):
raise RefactoringError(
"Extracted piece can only have async/await "
"statements if Rope is running on Python "
"3.8 or higher"
)
if count == 1 and not usefunction._returns_last(node):
raise RefactoringError("Return should be the last statement.")
if info.region != info.lines_region:
raise RefactoringError(
"Extracted piece should contain complete statements."
)
def _is_region_on_a_word(self, info):
if (
info.region[0] > 0
and self._is_on_a_word(info, info.region[0] - 1)
or self._is_on_a_word(info, info.region[1] - 1)
):
return True
def _is_on_a_word(self, info, offset):
prev = info.source[offset]
if not (prev.isalnum() or prev == "_") or offset + 1 == len(info.source):
return False
next = info.source[offset + 1]
return next.isalnum() or next == "_"
class _ExtractMethodParts:
def __init__(self, info):
self.info = info
self.info_collector = self._create_info_collector()
self.info.kind = self._get_kind_by_scope()
self._check_constraints()
def _get_kind_by_scope(self):
if self._extacting_from_staticmethod():
return "staticmethod"
elif self._extracting_from_classmethod():
return "classmethod"
return self.info.kind
def _check_constraints(self):
if self._extracting_staticmethod() or self._extracting_classmethod():
if not self.info.method:
raise RefactoringError(
"Cannot extract to staticmethod/classmethod outside class"
)
def _extacting_from_staticmethod(self):
return (
self.info.method and _get_function_kind(self.info.scope) == "staticmethod"
)
def _extracting_from_classmethod(self):
return self.info.method and _get_function_kind(self.info.scope) == "classmethod"
def get_definition(self):
if self.info.global_:
return "\n%s\n" % self._get_function_definition()
else:
return "\n%s" % self._get_function_definition()
def get_replacement_pattern(self):
variables = []
variables.extend(self._find_function_arguments())
variables.extend(self._find_function_returns())
return similarfinder.make_pattern(self._get_call(), variables)
def get_body_pattern(self):
variables = []
variables.extend(self._find_function_arguments())
variables.extend(self._find_function_returns())
variables.extend(self._find_temps())
return similarfinder.make_pattern(self._get_body(), variables)
def _get_body(self):
result = sourceutils.fix_indentation(self.info.extracted, 0)
if self.info.one_line:
result = "(%s)" % result
return result
def _find_temps(self):
return usefunction.find_temps(self.info.project, self._get_body())
def get_checks(self):
if self.info.method and not self.info.make_global:
if _get_function_kind(self.info.scope) == "method":
class_name = similarfinder._pydefined_to_str(
self.info.scope.parent.pyobject
)
return {self._get_self_name(): "type=" + class_name}
return {}
def _create_info_collector(self):
zero = self.info.scope.get_start() - 1
start_line = self.info.region_lines[0] - zero
end_line = self.info.region_lines[1] - zero
info_collector = _FunctionInformationCollector(
start_line, end_line, self.info.global_
)
body = self.info.source[self.info.scope_region[0] : self.info.scope_region[1]]
node = _parse_text(body)
ast.walk(node, info_collector)
return info_collector
def _get_function_definition(self):
args = self._find_function_arguments()
returns = self._find_function_returns()
result = []
self._append_decorators(result)
result.append("def %s:\n" % self._get_function_signature(args))
unindented_body = self._get_unindented_function_body(returns)
indents = sourceutils.get_indent(self.info.project)
function_body = sourceutils.indent_lines(unindented_body, indents)
result.append(function_body)
definition = "".join(result)
return definition + "\n"
def _append_decorators(self, result):
if self._extracting_staticmethod():
result.append("@staticmethod\n")
elif self._extracting_classmethod():
result.append("@classmethod\n")
def _extracting_classmethod(self):
return self.info.kind == "classmethod"
def _extracting_staticmethod(self):
return self.info.kind == "staticmethod"
def _get_function_signature(self, args):
args = list(args)
prefix = ""
if self._extracting_method() or self._extracting_classmethod():
self_name = self._get_self_name()
if self_name is None:
raise RefactoringError(
"Extracting a method from a function with no self argument."
)
if self_name in args:
args.remove(self_name)
args.insert(0, self_name)
return prefix + self.info.new_name + "(%s)" % self._get_comma_form(args)
def _extracting_method(self):
return not self._extracting_staticmethod() and (
self.info.method
and not self.info.make_global
and _get_function_kind(self.info.scope) == "method"
)
def _get_self_name(self):
if self._extracting_classmethod():
return "cls"
return self._get_scope_self_name()
def _get_scope_self_name(self):
if self.info.scope.pyobject.get_kind() == "staticmethod":
return
param_names = self.info.scope.pyobject.get_param_names()
if param_names:
return param_names[0]
def _get_function_call(self, args):
return "{prefix}{name}({args})".format(
prefix=self._get_function_call_prefix(args),
name=self.info.new_name,
args=self._get_comma_form(args),
)
def _get_function_call_prefix(self, args):
prefix = ""
if self.info.method and not self.info.make_global:
if self._extracting_staticmethod() or self._extracting_classmethod():
prefix = self.info.scope.parent.pyobject.get_name() + "."
else:
self_name = self._get_self_name()
if self_name in args:
args.remove(self_name)
prefix = self_name + "."
return prefix
def _get_comma_form(self, names):
return ", ".join(names)
def _get_call(self):
args = self._find_function_arguments()
returns = self._find_function_returns()
call_prefix = ""
if returns and (not self.info.one_line or self.info.returning_named_expr):
assignment_operator = " := " if self.info.one_line else " = "
call_prefix = self._get_comma_form(returns) + assignment_operator
if self.info.returned:
call_prefix = "return "
return call_prefix + self._get_function_call(args)
def _find_function_arguments(self):
# if not make_global, do not pass any global names; they are
# all visible.
if self.info.global_ and not self.info.make_global:
return list(
self.info_collector.read
& self.info_collector.postread
& self.info_collector.written
)
if not self.info.one_line:
result = self.info_collector.prewritten & self.info_collector.read
result |= (
self.info_collector.prewritten
& self.info_collector.postread
& (self.info_collector.maybe_written - self.info_collector.written)
)
return list(result)
start = self.info.region[0]
if start == self.info.lines_region[0]:
start = start + re.search("\\S", self.info.extracted).start()
function_definition = self.info.source[start : self.info.region[1]]
read = _VariableReadsAndWritesFinder.find_reads_for_one_liners(
function_definition
)
return list(self.info_collector.prewritten.intersection(read))
def _find_function_returns(self):
if self.info.one_line:
written = self.info_collector.written | self.info_collector.maybe_written
return list(written & self.info_collector.postread)
if self.info.returned:
return []
written = self.info_collector.written | self.info_collector.maybe_written
return list(written & self.info_collector.postread)
def _get_unindented_function_body(self, returns):
if self.info.one_line:
return self._get_single_expression_function_body()
return self._get_multiline_function_body(returns)
def _get_multiline_function_body(self, returns):
unindented_body = sourceutils.fix_indentation(self.info.extracted, 0)
unindented_body = self._insert_globals(unindented_body)
if returns:
unindented_body += "\nreturn %s" % self._get_comma_form(returns)
return unindented_body
def _get_single_expression_function_body(self):
extracted = _get_single_expression_body(self.info.extracted, info=self.info)
body = "return " + extracted
return self._insert_globals(body)
def _insert_globals(self, unindented_body):
globals_in_body = self._get_globals_in_body(unindented_body)
globals_ = self.info_collector.globals_ & (
self.info_collector.written | self.info_collector.maybe_written
)
globals_ = globals_ - globals_in_body
if globals_:
unindented_body = "global {}\n{}".format(
", ".join(globals_), unindented_body
)
return unindented_body
@staticmethod
def _get_globals_in_body(unindented_body):
node = _parse_text(unindented_body)
visitor = _GlobalFinder()
ast.walk(node, visitor)
return visitor.globals_
class _ExtractVariableParts:
def __init__(self, info):
self.info = info
def get_definition(self):
extracted = _get_single_expression_body(self.info.extracted, info=self.info)
return self.info.new_name + " = " + extracted + "\n"
def get_body_pattern(self):
return "(%s)" % self.info.extracted.strip()
def get_replacement_pattern(self):
return self.info.new_name
def get_checks(self):
return {}
class _FunctionInformationCollector:
def __init__(self, start, end, is_global):
self.start = start
self.end = end
self.is_global = is_global
self.prewritten = OrderedSet()
self.maybe_written = OrderedSet()
self.written = OrderedSet()
self.read = OrderedSet()
self.postread = OrderedSet()
self.postwritten = OrderedSet()
self.host_function = True
self.conditional = False
self.globals_ = OrderedSet()
self.surrounded_by_loop = 0
self.loop_depth = 0
def _read_variable(self, name, lineno):
if self.start <= lineno <= self.end:
if name not in self.written:
if not self.conditional or name not in self.maybe_written:
self.read.add(name)
if self.end < lineno:
if name not in self.postwritten:
self.postread.add(name)
def _written_variable(self, name, lineno):
if self.start <= lineno <= self.end:
if self.conditional:
self.maybe_written.add(name)
else:
self.written.add(name)
if self.loop_depth > 0 and name in self.read:
self.postread.add(name)
if self.start > lineno:
self.prewritten.add(name)
if self.end < lineno:
self.postwritten.add(name)
def _FunctionDef(self, node):
if not self.is_global and self.host_function:
self.host_function = False
for name in _get_argnames(node.args):
self._written_variable(name, node.lineno)
for child in node.body:
ast.walk(child, self)
else:
self._written_variable(node.name, node.lineno)
visitor = _VariableReadsAndWritesFinder()
for child in node.body:
ast.walk(child, visitor)
for name in visitor.read - visitor.written:
self._read_variable(name, node.lineno)
def _Global(self, node):
self.globals_.add(*node.names)
def _AsyncFunctionDef(self, node):
self._FunctionDef(node)
def _Name(self, node):
if isinstance(node.ctx, (ast.Store, ast.AugStore)):
self._written_variable(node.id, node.lineno)
if not isinstance(node.ctx, ast.Store):
self._read_variable(node.id, node.lineno)
def _MatchAs(self, node):
self._written_variable(node.name, node.lineno)
if node.pattern:
ast.walk(node.pattern, self)
def _Assign(self, node):
ast.walk(node.value, self)
for child in node.targets:
ast.walk(child, self)
def _AugAssign(self, node):
ast.walk(node.value, self)
if isinstance(node.target, ast.Name):
target_id = node.target.id
self._read_variable(target_id, node.target.lineno)
self._written_variable(target_id, node.target.lineno)
else:
ast.walk(node.target, self)
def _ClassDef(self, node):
self._written_variable(node.name, node.lineno)
def _ListComp(self, node):
self._comp_exp(node)
def _GeneratorExp(self, node):
self._comp_exp(node)
def _SetComp(self, node):
self._comp_exp(node)
def _DictComp(self, node):
self._comp_exp(node)
def _comp_exp(self, node):
read = OrderedSet(self.read)
written = OrderedSet(self.written)
maybe_written = OrderedSet(self.maybe_written)
for child in ast.get_child_nodes(node):
ast.walk(child, self)
comp_names = list(
chain.from_iterable(
self._flatten_nested_tuple_of_names(generator.target)
for generator in node.generators
)
)
self.read = self.read - comp_names | read
self.written = self.written - comp_names | written
self.maybe_written = self.maybe_written - comp_names | maybe_written
def _flatten_nested_tuple_of_names(self, node):
if isinstance(node, ast.Tuple):
for elt in node.elts:
yield self._flatten_nested_tuple_of_names(elt)
elif isinstance(node, ast.Name):
yield node.id
else:
assert False, "Unexpected node type in list comprehension target: %s" % node
def _If(self, node):
self._handle_conditional_node(node)
def _While(self, node):
with self._handle_loop_context(node):
self._handle_conditional_node(node)
def _For(self, node):
with self._handle_loop_context(node), self._handle_conditional_context(node):
# iter has to be checked before the target variables
ast.walk(node.iter, self)
ast.walk(node.target, self)
for child in node.body:
ast.walk(child, self)
for child in node.orelse:
ast.walk(child, self)
def _handle_conditional_node(self, node):
with self._handle_conditional_context(node):
for child in ast.get_child_nodes(node):
ast.walk(child, self)
@contextmanager
def _handle_conditional_context(self, node):
if self.start <= node.lineno <= self.end:
self.conditional = True
try:
yield
finally:
self.conditional = False
@contextmanager
def _handle_loop_context(self, node):
if node.lineno < self.start:
self.loop_depth += 1
try:
yield
finally:
self.loop_depth -= 1
def _get_argnames(arguments):
result = [node.arg for node in arguments.args if isinstance(node, ast.arg)]
if arguments.vararg:
result.append(arguments.vararg.arg)
if arguments.kwarg:
result.append(arguments.kwarg.arg)
return result
class _VariableReadsAndWritesFinder:
def __init__(self):
self.written = set()
self.read = set()
def _Name(self, node):
if isinstance(node.ctx, (ast.Store, ast.AugStore)):
self.written.add(node.id)
if not isinstance(node, ast.Store):
self.read.add(node.id)
def _FunctionDef(self, node):
self.written.add(node.name)
visitor = _VariableReadsAndWritesFinder()
for child in ast.get_child_nodes(node):
ast.walk(child, visitor)
self.read.update(visitor.read - visitor.written)
def _Class(self, node):
self.written.add(node.name)
@staticmethod
def find_reads_and_writes(code):
if code.strip() == "":
return set(), set()
node = _parse_text(code)
visitor = _VariableReadsAndWritesFinder()
ast.walk(node, visitor)
return visitor.read, visitor.written
@staticmethod
def find_reads_for_one_liners(code):
if code.strip() == "":
return set(), set()
node = _parse_text(code)
visitor = _VariableReadsAndWritesFinder()
ast.walk(node, visitor)
return visitor.read
class _BaseErrorFinder:
@classmethod
def has_errors(cls, code):