1 files changed, 290 insertions, 0 deletions
diff --git a/third_party/python/Jinja2/jinja2/idtracking.py b/third_party/python/Jinja2/jinja2/idtracking.py
new file mode 100644
index 0000000000..9a0d838017
--- /dev/null
+++ b/third_party/python/Jinja2/jinja2/idtracking.py
@@ -0,0 +1,290 @@
+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."""