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import ast |
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from contextlib import contextmanager |
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def add_scope_context(node): |
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"""Provide to scope context to all nodes""" |
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return ScopeTransformer().visit(node) |
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class ScopeMixin(object): |
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""" |
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Adds a scope property with the current scope (function, module) |
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a node is part of. |
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""" |
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scopes = [] |
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@contextmanager |
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def enter_scope(self, node): |
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if self._is_scopable_node(node): |
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self.scopes.append(node) |
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yield |
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self.scopes.pop() |
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else: |
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yield |
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@property |
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def scope(self): |
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try: |
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return self.scopes[-1] |
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except IndexError: |
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return None |
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def _is_scopable_node(self, node): |
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scopes = [ast.Module, ast.FunctionDef, ast.For, ast.If, ast.With] |
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return len([s for s in scopes if isinstance(node, s)]) > 0 |
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class ScopeList(list): |
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""" |
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Wraps around list of scopes and provides find method for finding |
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the definition of a variable |
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""" |
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def find(self, lookup): |
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"""Find definition of variable lookup.""" |
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def is_match(var): |
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return ((isinstance(var, ast.alias) and var.name == lookup) or |
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(isinstance(var, ast.Name) and var.id == lookup)) |
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def find_definition(scope, var_attr="vars"): |
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for var in getattr(scope, var_attr): |
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if is_match(var): |
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return var |
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for scope in self: |
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defn = find_definition(scope) |
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if not defn and hasattr(scope, "body_vars"): |
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defn = find_definition(scope, "body_vars") |
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if not defn and hasattr(scope, "orelse_vars"): |
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defn = find_definition(scope, "orelse_vars") |
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if defn: |
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return defn |
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def find_import(self, lookup): |
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for scope in reversed(self): |
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if hasattr(scope, "imports"): |
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for imp in scope.imports: |
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if imp.name == lookup: |
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return imp |
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class ScopeTransformer(ast.NodeTransformer, ScopeMixin): |
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""" |
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Adds a scope attribute to each node. |
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The scope contains the current scope (function, module, for loop) |
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a node is part of. |
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""" |
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def visit(self, node): |
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with self.enter_scope(node): |
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node.scopes = ScopeList(self.scopes) |
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return super(ScopeTransformer, self).visit(node) |
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