add ymake export to ydb

1 files changed, 840 insertions, 0 deletions

diff --git a/contrib/tools/cython/Cython/Compiler/Visitor.py b/contrib/tools/cython/Cython/Compiler/Visitor.py
new file mode 100644
index 0000000000..a35d13e1d0
--- /dev/null
+++ b/contrib/tools/cython/Cython/Compiler/Visitor.py
@@ -0,0 +1,840 @@
+# cython: infer_types=True
+# cython: language_level=3
+# cython: auto_pickle=False
+
+#
+#   Tree visitor and transform framework
+#
+
+from __future__ import absolute_import, print_function
+
+import sys
+import inspect
+
+from . import TypeSlots
+from . import Builtin
+from . import Nodes
+from . import ExprNodes
+from . import Errors
+from . import DebugFlags
+from . import Future
+
+import cython
+
+
+cython.declare(_PRINTABLE=tuple)
+
+if sys.version_info[0] >= 3:
+    _PRINTABLE = (bytes, str, int, float)
+else:
+    _PRINTABLE = (str, unicode, long, int, float)
+
+
+class TreeVisitor(object):
+    """
+    Base class for writing visitors for a Cython tree, contains utilities for
+    recursing such trees using visitors. Each node is
+    expected to have a child_attrs iterable containing the names of attributes
+    containing child nodes or lists of child nodes. Lists are not considered
+    part of the tree structure (i.e. contained nodes are considered direct
+    children of the parent node).
+
+    visit_children visits each of the children of a given node (see the visit_children
+    documentation). When recursing the tree using visit_children, an attribute
+    access_path is maintained which gives information about the current location
+    in the tree as a stack of tuples: (parent_node, attrname, index), representing
+    the node, attribute and optional list index that was taken in each step in the path to
+    the current node.
+
+    Example:
+
+    >>> class SampleNode(object):
+    ...     child_attrs = ["head", "body"]
+    ...     def __init__(self, value, head=None, body=None):
+    ...         self.value = value
+    ...         self.head = head
+    ...         self.body = body
+    ...     def __repr__(self): return "SampleNode(%s)" % self.value
+    ...
+    >>> tree = SampleNode(0, SampleNode(1), [SampleNode(2), SampleNode(3)])
+    >>> class MyVisitor(TreeVisitor):
+    ...     def visit_SampleNode(self, node):
+    ...         print("in %s %s" % (node.value, self.access_path))
+    ...         self.visitchildren(node)
+    ...         print("out %s" % node.value)
+    ...
+    >>> MyVisitor().visit(tree)
+    in 0 []
+    in 1 [(SampleNode(0), 'head', None)]
+    out 1
+    in 2 [(SampleNode(0), 'body', 0)]
+    out 2
+    in 3 [(SampleNode(0), 'body', 1)]
+    out 3
+    out 0
+    """
+    def __init__(self):
+        super(TreeVisitor, self).__init__()
+        self.dispatch_table = {}
+        self.access_path = []
+
+    def dump_node(self, node):
+        ignored = list(node.child_attrs or []) + [
+            u'child_attrs', u'pos', u'gil_message', u'cpp_message', u'subexprs']
+        values = []
+        pos = getattr(node, 'pos', None)
+        if pos:
+            source = pos[0]
+            if source:
+                import os.path
+                source = os.path.basename(source.get_description())
+            values.append(u'%s:%s:%s' % (source, pos[1], pos[2]))
+        attribute_names = dir(node)
+        for attr in attribute_names:
+            if attr in ignored:
+                continue
+            if attr.startswith('_') or attr.endswith('_'):
+                continue
+            try:
+                value = getattr(node, attr)
+            except AttributeError:
+                continue
+            if value is None or value == 0:
+                continue
+            elif isinstance(value, list):
+                value = u'[...]/%d' % len(value)
+            elif not isinstance(value, _PRINTABLE):
+                continue
+            else:
+                value = repr(value)
+            values.append(u'%s = %s' % (attr, value))
+        return u'%s(%s)' % (node.__class__.__name__, u',\n    '.join(values))
+
+    def _find_node_path(self, stacktrace):
+        import os.path
+        last_traceback = stacktrace
+        nodes = []
+        while hasattr(stacktrace, 'tb_frame'):
+            frame = stacktrace.tb_frame
+            node = frame.f_locals.get(u'self')
+            if isinstance(node, Nodes.Node):
+                code = frame.f_code
+                method_name = code.co_name
+                pos = (os.path.basename(code.co_filename),
+                       frame.f_lineno)
+                nodes.append((node, method_name, pos))
+                last_traceback = stacktrace
+            stacktrace = stacktrace.tb_next
+        return (last_traceback, nodes)
+
+    def _raise_compiler_error(self, child, e):
+        trace = ['']
+        for parent, attribute, index in self.access_path:
+            node = getattr(parent, attribute)
+            if index is None:
+                index = ''
+            else:
+                node = node[index]
+                index = u'[%d]' % index
+            trace.append(u'%s.%s%s = %s' % (
+                parent.__class__.__name__, attribute, index,
+                self.dump_node(node)))
+        stacktrace, called_nodes = self._find_node_path(sys.exc_info()[2])
+        last_node = child
+        for node, method_name, pos in called_nodes:
+            last_node = node
+            trace.append(u"File '%s', line %d, in %s: %s" % (
+                pos[0], pos[1], method_name, self.dump_node(node)))
+        raise Errors.CompilerCrash(
+            getattr(last_node, 'pos', None), self.__class__.__name__,
+            u'\n'.join(trace), e, stacktrace)
+
+    @cython.final
+    def find_handler(self, obj):
+        # to resolve, try entire hierarchy
+        cls = type(obj)
+        pattern = "visit_%s"
+        mro = inspect.getmro(cls)
+        for mro_cls in mro:
+            handler_method = getattr(self, pattern % mro_cls.__name__, None)
+            if handler_method is not None:
+                return handler_method
+        print(type(self), cls)
+        if self.access_path:
+            print(self.access_path)
+            print(self.access_path[-1][0].pos)
+            print(self.access_path[-1][0].__dict__)
+        raise RuntimeError("Visitor %r does not accept object: %s" % (self, obj))
+
+    def visit(self, obj):
+        return self._visit(obj)
+
+    @cython.final
+    def _visit(self, obj):
+        try:
+            try:
+                handler_method = self.dispatch_table[type(obj)]
+            except KeyError:
+                handler_method = self.find_handler(obj)
+                self.dispatch_table[type(obj)] = handler_method
+            return handler_method(obj)
+        except Errors.CompileError:
+            raise
+        except Errors.AbortError:
+            raise
+        except Exception as e:
+            if DebugFlags.debug_no_exception_intercept:
+                raise
+            self._raise_compiler_error(obj, e)
+
+    @cython.final
+    def _visitchild(self, child, parent, attrname, idx):
+        self.access_path.append((parent, attrname, idx))
+        result = self._visit(child)
+        self.access_path.pop()
+        return result
+
+    def visitchildren(self, parent, attrs=None):
+        return self._visitchildren(parent, attrs)
+
+    @cython.final
+    @cython.locals(idx=cython.Py_ssize_t)
+    def _visitchildren(self, parent, attrs):
+        """
+        Visits the children of the given parent. If parent is None, returns
+        immediately (returning None).
+
+        The return value is a dictionary giving the results for each
+        child (mapping the attribute name to either the return value
+        or a list of return values (in the case of multiple children
+        in an attribute)).
+        """
+        if parent is None: return None
+        result = {}
+        for attr in parent.child_attrs:
+            if attrs is not None and attr not in attrs: continue
+            child = getattr(parent, attr)
+            if child is not None:
+                if type(child) is list:
+                    childretval = [self._visitchild(x, parent, attr, idx) for idx, x in enumerate(child)]
+                else:
+                    childretval = self._visitchild(child, parent, attr, None)
+                    assert not isinstance(childretval, list), 'Cannot insert list here: %s in %r' % (attr, parent)
+                result[attr] = childretval
+        return result
+
+
+class VisitorTransform(TreeVisitor):
+    """
+    A tree transform is a base class for visitors that wants to do stream
+    processing of the structure (rather than attributes etc.) of a tree.
+
+    It implements __call__ to simply visit the argument node.
+
+    It requires the visitor methods to return the nodes which should take
+    the place of the visited node in the result tree (which can be the same
+    or one or more replacement). Specifically, if the return value from
+    a visitor method is:
+
+    - [] or None; the visited node will be removed (set to None if an attribute and
+    removed if in a list)
+    - A single node; the visited node will be replaced by the returned node.
+    - A list of nodes; the visited nodes will be replaced by all the nodes in the
+    list. This will only work if the node was already a member of a list; if it
+    was not, an exception will be raised. (Typically you want to ensure that you
+    are within a StatListNode or similar before doing this.)
+    """
+    def visitchildren(self, parent, attrs=None, exclude=None):
+        # generic def entry point for calls from Python subclasses
+        if exclude is not None:
+            attrs = self._select_attrs(parent.child_attrs if attrs is None else attrs, exclude)
+        return self._process_children(parent, attrs)
+
+    @cython.final
+    def _select_attrs(self, attrs, exclude):
+        return [name for name in attrs if name not in exclude]
+
+    @cython.final
+    def _process_children(self, parent, attrs=None):
+        # fast cdef entry point for calls from Cython subclasses
+        result = self._visitchildren(parent, attrs)
+        for attr, newnode in result.items():
+            if type(newnode) is list:
+                newnode = self._flatten_list(newnode)
+            setattr(parent, attr, newnode)
+        return result
+
+    @cython.final
+    def _flatten_list(self, orig_list):
+        # Flatten the list one level and remove any None
+        newlist = []
+        for x in orig_list:
+            if x is not None:
+                if type(x) is list:
+                    newlist.extend(x)
+                else:
+                    newlist.append(x)
+        return newlist
+
+    def recurse_to_children(self, node):
+        self._process_children(node)
+        return node
+
+    def __call__(self, root):
+        return self._visit(root)
+
+
+class CythonTransform(VisitorTransform):
+    """
+    Certain common conventions and utilities for Cython transforms.
+
+     - Sets up the context of the pipeline in self.context
+     - Tracks directives in effect in self.current_directives
+    """
+    def __init__(self, context):
+        super(CythonTransform, self).__init__()
+        self.context = context
+
+    def __call__(self, node):
+        from . import ModuleNode
+        if isinstance(node, ModuleNode.ModuleNode):
+            self.current_directives = node.directives
+        return super(CythonTransform, self).__call__(node)
+
+    def visit_CompilerDirectivesNode(self, node):
+        old = self.current_directives
+        self.current_directives = node.directives
+        self._process_children(node)
+        self.current_directives = old
+        return node
+
+    def visit_Node(self, node):
+        self._process_children(node)
+        return node
+
+
+class ScopeTrackingTransform(CythonTransform):
+    # Keeps track of type of scopes
+    #scope_type: can be either of 'module', 'function', 'cclass', 'pyclass', 'struct'
+    #scope_node: the node that owns the current scope
+
+    def visit_ModuleNode(self, node):
+        self.scope_type = 'module'
+        self.scope_node = node
+        self._process_children(node)
+        return node
+
+    def visit_scope(self, node, scope_type):
+        prev = self.scope_type, self.scope_node
+        self.scope_type = scope_type
+        self.scope_node = node
+        self._process_children(node)
+        self.scope_type, self.scope_node = prev
+        return node
+
+    def visit_CClassDefNode(self, node):
+        return self.visit_scope(node, 'cclass')
+
+    def visit_PyClassDefNode(self, node):
+        return self.visit_scope(node, 'pyclass')
+
+    def visit_FuncDefNode(self, node):
+        return self.visit_scope(node, 'function')
+
+    def visit_CStructOrUnionDefNode(self, node):
+        return self.visit_scope(node, 'struct')
+
+
+class EnvTransform(CythonTransform):
+    """
+    This transformation keeps a stack of the environments.
+    """
+    def __call__(self, root):
+        self.env_stack = []
+        self.enter_scope(root, root.scope)
+        return super(EnvTransform, self).__call__(root)
+
+    def current_env(self):
+        return self.env_stack[-1][1]
+
+    def current_scope_node(self):
+        return self.env_stack[-1][0]
+
+    def global_scope(self):
+        return self.current_env().global_scope()
+
+    def enter_scope(self, node, scope):
+        self.env_stack.append((node, scope))
+
+    def exit_scope(self):
+        self.env_stack.pop()
+
+    def visit_FuncDefNode(self, node):
+        self.enter_scope(node, node.local_scope)
+        self._process_children(node)
+        self.exit_scope()
+        return node
+
+    def visit_GeneratorBodyDefNode(self, node):
+        self._process_children(node)
+        return node
+
+    def visit_ClassDefNode(self, node):
+        self.enter_scope(node, node.scope)
+        self._process_children(node)
+        self.exit_scope()
+        return node
+
+    def visit_CStructOrUnionDefNode(self, node):
+        self.enter_scope(node, node.scope)
+        self._process_children(node)
+        self.exit_scope()
+        return node
+
+    def visit_ScopedExprNode(self, node):
+        if node.expr_scope:
+            self.enter_scope(node, node.expr_scope)
+            self._process_children(node)
+            self.exit_scope()
+        else:
+            self._process_children(node)
+        return node
+
+    def visit_CArgDeclNode(self, node):
+        # default arguments are evaluated in the outer scope
+        if node.default:
+            attrs = [attr for attr in node.child_attrs if attr != 'default']
+            self._process_children(node, attrs)
+            self.enter_scope(node, self.current_env().outer_scope)
+            self.visitchildren(node, ('default',))
+            self.exit_scope()
+        else:
+            self._process_children(node)
+        return node
+
+
+class NodeRefCleanupMixin(object):
+    """
+    Clean up references to nodes that were replaced.
+
+    NOTE: this implementation assumes that the replacement is
+    done first, before hitting any further references during
+    normal tree traversal.  This needs to be arranged by calling
+    "self.visitchildren()" at a proper place in the transform
+    and by ordering the "child_attrs" of nodes appropriately.
+    """
+    def __init__(self, *args):
+        super(NodeRefCleanupMixin, self).__init__(*args)
+        self._replacements = {}
+
+    def visit_CloneNode(self, node):
+        arg = node.arg
+        if arg not in self._replacements:
+            self.visitchildren(arg)
+        node.arg = self._replacements.get(arg, arg)
+        return node
+
+    def visit_ResultRefNode(self, node):
+        expr = node.expression
+        if expr is None or expr not in self._replacements:
+            self.visitchildren(node)
+            expr = node.expression
+        if expr is not None:
+            node.expression = self._replacements.get(expr, expr)
+        return node
+
+    def replace(self, node, replacement):
+        self._replacements[node] = replacement
+        return replacement
+
+
+find_special_method_for_binary_operator = {
+    '<':  '__lt__',
+    '<=': '__le__',
+    '==': '__eq__',
+    '!=': '__ne__',
+    '>=': '__ge__',
+    '>':  '__gt__',
+    '+':  '__add__',
+    '&':  '__and__',
+    '/':  '__div__',
+    '//': '__floordiv__',
+    '<<': '__lshift__',
+    '%':  '__mod__',
+    '*':  '__mul__',
+    '|':  '__or__',
+    '**': '__pow__',
+    '>>': '__rshift__',
+    '-':  '__sub__',
+    '^':  '__xor__',
+    'in': '__contains__',
+}.get
+
+
+find_special_method_for_unary_operator = {
+    'not': '__not__',
+    '~':   '__inv__',
+    '-':   '__neg__',
+    '+':   '__pos__',
+}.get
+
+
+class MethodDispatcherTransform(EnvTransform):
+    """
+    Base class for transformations that want to intercept on specific
+    builtin functions or methods of builtin types, including special
+    methods triggered by Python operators.  Must run after declaration
+    analysis when entries were assigned.
+
+    Naming pattern for handler methods is as follows:
+
+    * builtin functions: _handle_(general|simple|any)_function_NAME
+
+    * builtin methods: _handle_(general|simple|any)_method_TYPENAME_METHODNAME
+    """
+    # only visit call nodes and Python operations
+    def visit_GeneralCallNode(self, node):
+        self._process_children(node)
+        function = node.function
+        if not function.type.is_pyobject:
+            return node
+        arg_tuple = node.positional_args
+        if not isinstance(arg_tuple, ExprNodes.TupleNode):
+            return node
+        keyword_args = node.keyword_args
+        if keyword_args and not isinstance(keyword_args, ExprNodes.DictNode):
+            # can't handle **kwargs
+            return node
+        args = arg_tuple.args
+        return self._dispatch_to_handler(node, function, args, keyword_args)
+
+    def visit_SimpleCallNode(self, node):
+        self._process_children(node)
+        function = node.function
+        if function.type.is_pyobject:
+            arg_tuple = node.arg_tuple
+            if not isinstance(arg_tuple, ExprNodes.TupleNode):
+                return node
+            args = arg_tuple.args
+        else:
+            args = node.args
+        return self._dispatch_to_handler(node, function, args, None)
+
+    def visit_PrimaryCmpNode(self, node):
+        if node.cascade:
+            # not currently handled below
+            self._process_children(node)
+            return node
+        return self._visit_binop_node(node)
+
+    def visit_BinopNode(self, node):
+        return self._visit_binop_node(node)
+
+    def _visit_binop_node(self, node):
+        self._process_children(node)
+        # FIXME: could special case 'not_in'
+        special_method_name = find_special_method_for_binary_operator(node.operator)
+        if special_method_name:
+            operand1, operand2 = node.operand1, node.operand2
+            if special_method_name == '__contains__':
+                operand1, operand2 = operand2, operand1
+            elif special_method_name == '__div__':
+                if Future.division in self.current_env().global_scope().context.future_directives:
+                    special_method_name = '__truediv__'
+            obj_type = operand1.type
+            if obj_type.is_builtin_type:
+                type_name = obj_type.name
+            else:
+                type_name = "object"  # safety measure
+            node = self._dispatch_to_method_handler(
+                special_method_name, None, False, type_name,
+                node, None, [operand1, operand2], None)
+        return node
+
+    def visit_UnopNode(self, node):
+        self._process_children(node)
+        special_method_name = find_special_method_for_unary_operator(node.operator)
+        if special_method_name:
+            operand = node.operand
+            obj_type = operand.type
+            if obj_type.is_builtin_type:
+                type_name = obj_type.name
+            else:
+                type_name = "object"  # safety measure
+            node = self._dispatch_to_method_handler(
+                special_method_name, None, False, type_name,
+                node, None, [operand], None)
+        return node
+
+    ### dispatch to specific handlers
+
+    def _find_handler(self, match_name, has_kwargs):
+        call_type = has_kwargs and 'general' or 'simple'
+        handler = getattr(self, '_handle_%s_%s' % (call_type, match_name), None)
+        if handler is None:
+            handler = getattr(self, '_handle_any_%s' % match_name, None)
+        return handler
+
+    def _delegate_to_assigned_value(self, node, function, arg_list, kwargs):
+        assignment = function.cf_state[0]
+        value = assignment.rhs
+        if value.is_name:
+            if not value.entry or len(value.entry.cf_assignments) > 1:
+                # the variable might have been reassigned => play safe
+                return node
+        elif value.is_attribute and value.obj.is_name:
+            if not value.obj.entry or len(value.obj.entry.cf_assignments) > 1:
+                # the underlying variable might have been reassigned => play safe
+                return node
+        else:
+            return node
+        return self._dispatch_to_handler(
+            node, value, arg_list, kwargs)
+
+    def _dispatch_to_handler(self, node, function, arg_list, kwargs):
+        if function.is_name:
+            # we only consider functions that are either builtin
+            # Python functions or builtins that were already replaced
+            # into a C function call (defined in the builtin scope)
+            if not function.entry:
+                return node
+            entry = function.entry
+            is_builtin = (
+                entry.is_builtin or
+                entry is self.current_env().builtin_scope().lookup_here(function.name))
+            if not is_builtin:
+                if function.cf_state and function.cf_state.is_single:
+                    # we know the value of the variable
+                    # => see if it's usable instead
+                    return self._delegate_to_assigned_value(
+                        node, function, arg_list, kwargs)
+                if arg_list and entry.is_cmethod and entry.scope and entry.scope.parent_type.is_builtin_type:
+                    if entry.scope.parent_type is arg_list[0].type:
+                        # Optimised (unbound) method of a builtin type => try to "de-optimise".
+                        return self._dispatch_to_method_handler(
+                            entry.name, self_arg=None, is_unbound_method=True,
+                            type_name=entry.scope.parent_type.name,
+                            node=node, function=function, arg_list=arg_list, kwargs=kwargs)
+                return node
+            function_handler = self._find_handler(
+                "function_%s" % function.name, kwargs)
+            if function_handler is None:
+                return self._handle_function(node, function.name, function, arg_list, kwargs)
+            if kwargs:
+                return function_handler(node, function, arg_list, kwargs)
+            else:
+                return function_handler(node, function, arg_list)
+        elif function.is_attribute:
+            attr_name = function.attribute
+            if function.type.is_pyobject:
+                self_arg = function.obj
+            elif node.self and function.entry:
+                entry = function.entry.as_variable
+                if not entry or not entry.is_builtin:
+                    return node
+                # C implementation of a Python builtin method - see if we find further matches
+                self_arg = node.self
+                arg_list = arg_list[1:]  # drop CloneNode of self argument
+            else:
+                return node
+            obj_type = self_arg.type
+            is_unbound_method = False
+            if obj_type.is_builtin_type:
+                if obj_type is Builtin.type_type and self_arg.is_name and arg_list and arg_list[0].type.is_pyobject:
+                    # calling an unbound method like 'list.append(L,x)'
+                    # (ignoring 'type.mro()' here ...)
+                    type_name = self_arg.name
+                    self_arg = None
+                    is_unbound_method = True
+                else:
+                    type_name = obj_type.name
+            else:
+                type_name = "object"  # safety measure
+            return self._dispatch_to_method_handler(
+                attr_name, self_arg, is_unbound_method, type_name,
+                node, function, arg_list, kwargs)
+        else:
+            return node
+
+    def _dispatch_to_method_handler(self, attr_name, self_arg,
+                                    is_unbound_method, type_name,
+                                    node, function, arg_list, kwargs):
+        method_handler = self._find_handler(
+            "method_%s_%s" % (type_name, attr_name), kwargs)
+        if method_handler is None:
+            if (attr_name in TypeSlots.method_name_to_slot
+                    or attr_name == '__new__'):
+                method_handler = self._find_handler(
+                    "slot%s" % attr_name, kwargs)
+            if method_handler is None:
+                return self._handle_method(
+                    node, type_name, attr_name, function,
+                    arg_list, is_unbound_method, kwargs)
+        if self_arg is not None:
+            arg_list = [self_arg] + list(arg_list)
+        if kwargs:
+            result = method_handler(
+                node, function, arg_list, is_unbound_method, kwargs)
+        else:
+            result = method_handler(
+                node, function, arg_list, is_unbound_method)
+        return result
+
+    def _handle_function(self, node, function_name, function, arg_list, kwargs):
+        """Fallback handler"""
+        return node
+
+    def _handle_method(self, node, type_name, attr_name, function,
+                       arg_list, is_unbound_method, kwargs):
+        """Fallback handler"""
+        return node
+
+
+class RecursiveNodeReplacer(VisitorTransform):
+    """
+    Recursively replace all occurrences of a node in a subtree by
+    another node.
+    """
+    def __init__(self, orig_node, new_node):
+        super(RecursiveNodeReplacer, self).__init__()
+        self.orig_node, self.new_node = orig_node, new_node
+
+    def visit_CloneNode(self, node):
+        if node is self.orig_node:
+            return self.new_node
+        if node.arg is self.orig_node:
+            node.arg = self.new_node
+        return node
+
+    def visit_Node(self, node):
+        self._process_children(node)
+        if node is self.orig_node:
+            return self.new_node
+        else:
+            return node
+
+def recursively_replace_node(tree, old_node, new_node):
+    replace_in = RecursiveNodeReplacer(old_node, new_node)
+    replace_in(tree)
+
+
+class NodeFinder(TreeVisitor):
+    """
+    Find out if a node appears in a subtree.
+    """
+    def __init__(self, node):
+        super(NodeFinder, self).__init__()
+        self.node = node
+        self.found = False
+
+    def visit_Node(self, node):
+        if self.found:
+            pass  # short-circuit
+        elif node is self.node:
+            self.found = True
+        else:
+            self._visitchildren(node, None)
+
+def tree_contains(tree, node):
+    finder = NodeFinder(node)
+    finder.visit(tree)
+    return finder.found
+
+
+# Utils
+def replace_node(ptr, value):
+    """Replaces a node. ptr is of the form used on the access path stack
+    (parent, attrname, listidx|None)
+    """
+    parent, attrname, listidx = ptr
+    if listidx is None:
+        setattr(parent, attrname, value)
+    else:
+        getattr(parent, attrname)[listidx] = value
+
+
+class PrintTree(TreeVisitor):
+    """Prints a representation of the tree to standard output.
+    Subclass and override repr_of to provide more information
+    about nodes. """
+    def __init__(self, start=None, end=None):
+        TreeVisitor.__init__(self)
+        self._indent = ""
+        if start is not None or end is not None:
+            self._line_range = (start or 0, end or 2**30)
+        else:
+            self._line_range = None
+
+    def indent(self):
+        self._indent += "  "
+
+    def unindent(self):
+        self._indent = self._indent[:-2]
+
+    def __call__(self, tree, phase=None):
+        print("Parse tree dump at phase '%s'" % phase)
+        self.visit(tree)
+        return tree
+
+    # Don't do anything about process_list, the defaults gives
+    # nice-looking name[idx] nodes which will visually appear
+    # under the parent-node, not displaying the list itself in
+    # the hierarchy.
+    def visit_Node(self, node):
+        self._print_node(node)
+        self.indent()
+        self.visitchildren(node)
+        self.unindent()
+        return node
+
+    def visit_CloneNode(self, node):
+        self._print_node(node)
+        self.indent()
+        line = node.pos[1]
+        if self._line_range is None or self._line_range[0] <= line <= self._line_range[1]:
+            print("%s- %s: %s" % (self._indent, 'arg', self.repr_of(node.arg)))
+        self.indent()
+        self.visitchildren(node.arg)
+        self.unindent()
+        self.unindent()
+        return node
+
+    def _print_node(self, node):
+        line = node.pos[1]
+        if self._line_range is None or self._line_range[0] <= line <= self._line_range[1]:
+            if len(self.access_path) == 0:
+                name = "(root)"
+            else:
+                parent, attr, idx = self.access_path[-1]
+                if idx is not None:
+                    name = "%s[%d]" % (attr, idx)
+                else:
+                    name = attr
+            print("%s- %s: %s" % (self._indent, name, self.repr_of(node)))
+
+    def repr_of(self, node):
+        if node is None:
+            return "(none)"
+        else:
+            result = node.__class__.__name__
+            if isinstance(node, ExprNodes.NameNode):
+                result += "(type=%s, name=\"%s\")" % (repr(node.type), node.name)
+            elif isinstance(node, Nodes.DefNode):
+                result += "(name=\"%s\")" % node.name
+            elif isinstance(node, ExprNodes.ExprNode):
+                t = node.type
+                result += "(type=%s)" % repr(t)
+            elif node.pos:
+                pos = node.pos
+                path = pos[0].get_description()
+                if '/' in path:
+                    path = path.split('/')[-1]
+                if '\\' in path:
+                    path = path.split('\\')[-1]
+                result += "(pos=(%s:%s:%s))" % (path, pos[1], pos[2])
+
+            return result
+
+if __name__ == "__main__":
+    import doctest
+    doctest.testmod()