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from ._compat import iteritems
from .visitor import NodeVisitor
VAR_LOAD_PARAMETER = "param"
VAR_LOAD_RESOLVE = "resolve"
VAR_LOAD_ALIAS = "alias"
VAR_LOAD_UNDEFINED = "undefined"
def find_symbols(nodes, parent_symbols=None):
sym = Symbols(parent=parent_symbols)
visitor = FrameSymbolVisitor(sym)
for node in nodes:
visitor.visit(node)
return sym
def symbols_for_node(node, parent_symbols=None):
sym = Symbols(parent=parent_symbols)
sym.analyze_node(node)
return sym
class Symbols(object):
def __init__(self, parent=None, level=None):
if level is None:
if parent is None:
level = 0
else:
level = parent.level + 1
self.level = level
self.parent = parent
self.refs = {}
self.loads = {}
self.stores = set()
def analyze_node(self, node, **kwargs):
visitor = RootVisitor(self)
visitor.visit(node, **kwargs)
def _define_ref(self, name, load=None):
ident = "l_%d_%s" % (self.level, name)
self.refs[name] = ident
if load is not None:
self.loads[ident] = load
return ident
def find_load(self, target):
if target in self.loads:
return self.loads[target]
if self.parent is not None:
return self.parent.find_load(target)
def find_ref(self, name):
if name in self.refs:
return self.refs[name]
if self.parent is not None:
return self.parent.find_ref(name)
def ref(self, name):
rv = self.find_ref(name)
if rv is None:
raise AssertionError(
"Tried to resolve a name to a reference that "
"was unknown to the frame (%r)" % name
)
return rv
def copy(self):
rv = object.__new__(self.__class__)
rv.__dict__.update(self.__dict__)
rv.refs = self.refs.copy()
rv.loads = self.loads.copy()
rv.stores = self.stores.copy()
return rv
def store(self, name):
self.stores.add(name)
# If we have not see the name referenced yet, we need to figure
# out what to set it to.
if name not in self.refs:
# If there is a parent scope we check if the name has a
# reference there. If it does it means we might have to alias
# to a variable there.
if self.parent is not None:
outer_ref = self.parent.find_ref(name)
if outer_ref is not None:
self._define_ref(name, load=(VAR_LOAD_ALIAS, outer_ref))
return
# Otherwise we can just set it to undefined.
self._define_ref(name, load=(VAR_LOAD_UNDEFINED, None))
def declare_parameter(self, name):
self.stores.add(name)
return self._define_ref(name, load=(VAR_LOAD_PARAMETER, None))
def load(self, name):
target = self.find_ref(name)
if target is None:
self._define_ref(name, load=(VAR_LOAD_RESOLVE, name))
def branch_update(self, branch_symbols):
stores = {}
for branch in branch_symbols:
for target in branch.stores:
if target in self.stores:
continue
stores[target] = stores.get(target, 0) + 1
for sym in branch_symbols:
self.refs.update(sym.refs)
self.loads.update(sym.loads)
self.stores.update(sym.stores)
for name, branch_count in iteritems(stores):
if branch_count == len(branch_symbols):
continue
target = self.find_ref(name)
assert target is not None, "should not happen"
if self.parent is not None:
outer_target = self.parent.find_ref(name)
if outer_target is not None:
self.loads[target] = (VAR_LOAD_ALIAS, outer_target)
continue
self.loads[target] = (VAR_LOAD_RESOLVE, name)
def dump_stores(self):
rv = {}
node = self
while node is not None:
for name in node.stores:
if name not in rv:
rv[name] = self.find_ref(name)
node = node.parent
return rv
def dump_param_targets(self):
rv = set()
node = self
while node is not None:
for target, (instr, _) in iteritems(self.loads):
if instr == VAR_LOAD_PARAMETER:
rv.add(target)
node = node.parent
return rv
class RootVisitor(NodeVisitor):
def __init__(self, symbols):
self.sym_visitor = FrameSymbolVisitor(symbols)
def _simple_visit(self, node, **kwargs):
for child in node.iter_child_nodes():
self.sym_visitor.visit(child)
visit_Template = (
visit_Block
) = (
visit_Macro
) = (
visit_FilterBlock
) = visit_Scope = visit_If = visit_ScopedEvalContextModifier = _simple_visit
def visit_AssignBlock(self, node, **kwargs):
for child in node.body:
self.sym_visitor.visit(child)
def visit_CallBlock(self, node, **kwargs):
for child in node.iter_child_nodes(exclude=("call",)):
self.sym_visitor.visit(child)
def visit_OverlayScope(self, node, **kwargs):
for child in node.body:
self.sym_visitor.visit(child)
def visit_For(self, node, for_branch="body", **kwargs):
if for_branch == "body":
self.sym_visitor.visit(node.target, store_as_param=True)
branch = node.body
elif for_branch == "else":
branch = node.else_
elif for_branch == "test":
self.sym_visitor.visit(node.target, store_as_param=True)
if node.test is not None:
self.sym_visitor.visit(node.test)
return
else:
raise RuntimeError("Unknown for branch")
for item in branch or ():
self.sym_visitor.visit(item)
def visit_With(self, node, **kwargs):
for target in node.targets:
self.sym_visitor.visit(target)
for child in node.body:
self.sym_visitor.visit(child)
def generic_visit(self, node, *args, **kwargs):
raise NotImplementedError(
"Cannot find symbols for %r" % node.__class__.__name__
)
class FrameSymbolVisitor(NodeVisitor):
"""A visitor for `Frame.inspect`."""
def __init__(self, symbols):
self.symbols = symbols
def visit_Name(self, node, store_as_param=False, **kwargs):
"""All assignments to names go through this function."""
if store_as_param or node.ctx == "param":
self.symbols.declare_parameter(node.name)
elif node.ctx == "store":
self.symbols.store(node.name)
elif node.ctx == "load":
self.symbols.load(node.name)
def visit_NSRef(self, node, **kwargs):
self.symbols.load(node.name)
def visit_If(self, node, **kwargs):
self.visit(node.test, **kwargs)
original_symbols = self.symbols
def inner_visit(nodes):
self.symbols = rv = original_symbols.copy()
for subnode in nodes:
self.visit(subnode, **kwargs)
self.symbols = original_symbols
return rv
body_symbols = inner_visit(node.body)
elif_symbols = inner_visit(node.elif_)
else_symbols = inner_visit(node.else_ or ())
self.symbols.branch_update([body_symbols, elif_symbols, else_symbols])
def visit_Macro(self, node, **kwargs):
self.symbols.store(node.name)
def visit_Import(self, node, **kwargs):
self.generic_visit(node, **kwargs)
self.symbols.store(node.target)
def visit_FromImport(self, node, **kwargs):
self.generic_visit(node, **kwargs)
for name in node.names:
if isinstance(name, tuple):
self.symbols.store(name[1])
else:
self.symbols.store(name)
def visit_Assign(self, node, **kwargs):
"""Visit assignments in the correct order."""
self.visit(node.node, **kwargs)
self.visit(node.target, **kwargs)
def visit_For(self, node, **kwargs):
"""Visiting stops at for blocks. However the block sequence
is visited as part of the outer scope.
"""
self.visit(node.iter, **kwargs)
def visit_CallBlock(self, node, **kwargs):
self.visit(node.call, **kwargs)
def visit_FilterBlock(self, node, **kwargs):
self.visit(node.filter, **kwargs)
def visit_With(self, node, **kwargs):
for target in node.values:
self.visit(target)
def visit_AssignBlock(self, node, **kwargs):
"""Stop visiting at block assigns."""
self.visit(node.target, **kwargs)
def visit_Scope(self, node, **kwargs):
"""Stop visiting at scopes."""
def visit_Block(self, node, **kwargs):
"""Stop visiting at blocks."""
def visit_OverlayScope(self, node, **kwargs):
"""Do not visit into overlay scopes."""
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