diff options
Diffstat (limited to 'python/jinja2/idtracking.py')
| -rw-r--r-- | python/jinja2/idtracking.py | 286 |
1 files changed, 286 insertions, 0 deletions
diff --git a/python/jinja2/idtracking.py b/python/jinja2/idtracking.py new file mode 100644 index 0000000..491bfe0 --- /dev/null +++ b/python/jinja2/idtracking.py @@ -0,0 +1,286 @@ +from jinja2.visitor import NodeVisitor +from jinja2._compat import iteritems + + +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.""" |