"""

This is the syntax tree for Python syntaxes (2 & 3). The classes represent

syntax elements like functions and imports.

All of the nodes can be traced back to the `Python grammar file

<https://docs.python.org/3/reference/grammar.html>`_. If you want to know how

a tree is structured, just analyse that file (for each Python version it's a

bit different).

There's a lot of logic here that makes it easier for Jedi (and other libraries)

to deal with a Python syntax tree.

By using :py:meth:`parso.tree.NodeOrLeaf.get_code` on a module, you can get

back the 1-to-1 representation of the input given to the parser. This is

important if you want to refactor a parser tree.

>>> from parso import parse

>>> parser = parse('import os')

>>> module = parser.get_root_node()

>>> module

<Module: @1-1>

Any subclasses of :class:`Scope`, including :class:`Module` has an attribute

:attr:`iter_imports <Scope.iter_imports>`:

>>> list(module.iter_imports())

[<ImportName: import os@1,0>]

Changes to the Python Grammar

-----------------------------

A few things have changed when looking at Python grammar files:

- :class:`Param` does not exist in Python grammar files. It is essentially a

part of a ``parameters`` node. |parso| splits it up to make it easier to

analyse parameters. However this just makes it easier to deal with the syntax

tree, it doesn't actually change the valid syntax.

- A few nodes like `lambdef` and `lambdef_nocond` have been merged in the

syntax tree to make it easier to do deal with them.

Parser Tree Classes

-------------------

"""

import re

from parso._compatibility import utf8_repr, unicode

from parso.tree import Node, BaseNode, Leaf, ErrorNode, ErrorLeaf, \

search_ancestor

from parso.python.prefix import split_prefix

_FLOW_CONTAINERS = set(['if_stmt', 'while_stmt', 'for_stmt', 'try_stmt',

'with_stmt', 'async_stmt', 'suite'])

_RETURN_STMT_CONTAINERS = set(['suite', 'simple_stmt']) | _FLOW_CONTAINERS

_FUNC_CONTAINERS = set(['suite', 'simple_stmt', 'decorated']) | _FLOW_CONTAINERS

_GET_DEFINITION_TYPES = set([

'expr_stmt', 'comp_for', 'with_stmt', 'for_stmt', 'import_name',

'import_from', 'param'

])

_IMPORTS = set(['import_name', 'import_from'])

class DocstringMixin(object):

__slots__ = ()

def get_doc_node(self):

"""

Returns the string leaf of a docstring. e.g. ``r'''foo'''``.

"""

if self.type == 'file_input':

node = self.children[0]

elif self.type in ('funcdef', 'classdef'):

node = self.children[self.children.index(':') + 1]

if node.type == 'suite': # Normally a suite

node = node.children[1] # -> NEWLINE stmt

else: # ExprStmt

simple_stmt = self.parent

c = simple_stmt.parent.children

index = c.index(simple_stmt)

if not index:

return None

node = c[index - 1]

if node.type == 'simple_stmt':

node = node.children[0]

if node.type == 'string':

return node

return None

class PythonMixin(object):

"""

Some Python specific utitilies.

"""

__slots__ = ()

def get_name_of_position(self, position):

"""

Given a (line, column) tuple, returns a :py:class:`Name` or ``None`` if

there is no name at that position.

"""

for c in self.children:

if isinstance(c, Leaf):

if c.type == 'name' and c.start_pos <= position <= c.end_pos:

return c

else:

result = c.get_name_of_position(position)

if result is not None:

return result

return None

class PythonLeaf(PythonMixin, Leaf):

__slots__ = ()

def _split_prefix(self):

return split_prefix(self, self.get_start_pos_of_prefix())

def get_start_pos_of_prefix(self):

"""

Basically calls :py:meth:`parso.tree.NodeOrLeaf.get_start_pos_of_prefix`.

"""

# TODO it is really ugly that we have to override it. Maybe change

# indent error leafs somehow? No idea how, though.

previous_leaf = self.get_previous_leaf()

if previous_leaf is not None and previous_leaf.type == 'error_leaf' \

and previous_leaf.token_type in ('INDENT', 'ERROR_DEDENT'):

previous_leaf = previous_leaf.get_previous_leaf()

if previous_leaf is None:

return self.line - self.prefix.count('\n'), 0 # It's the first leaf.

return previous_leaf.end_pos

class _LeafWithoutNewlines(PythonLeaf):

"""

Simply here to optimize performance.

"""

__slots__ = ()

@property

def end_pos(self):

return self.line, self.column + len(self.value)

# Python base classes

class PythonBaseNode(PythonMixin, BaseNode):

__slots__ = ()

class PythonNode(PythonMixin, Node):

__slots__ = ()

class PythonErrorNode(PythonMixin, ErrorNode):

__slots__ = ()

class PythonErrorLeaf(ErrorLeaf, PythonLeaf):

__slots__ = ()

class EndMarker(_LeafWithoutNewlines):

__slots__ = ()

type = 'endmarker'

@utf8_repr

def __repr__(self):

return "<%s: prefix=%s>" % (type(self).__name__, repr(self.prefix))

class Newline(PythonLeaf):

"""Contains NEWLINE and ENDMARKER tokens."""

__slots__ = ()

type = 'newline'

@utf8_repr

def __repr__(self):

return "<%s: %s>" % (type(self).__name__, repr(self.value))

class Name(_LeafWithoutNewlines):

"""

A string. Sometimes it is important to know if the string belongs to a name

or not.

"""

type = 'name'

__slots__ = ()

def __repr__(self):

return "<%s: %s@%s,%s>" % (type(self).__name__, self.value,

self.line, self.column)

def is_definition(self):

"""

Returns True if the name is being defined.

"""

return self.get_definition() is not None

def get_definition(self, import_name_always=False):

"""

Returns None if there's on definition for a name.

:param import_name_alway: Specifies if an import name is always a

definition. Normally foo in `from foo import bar` is not a

definition.

"""

node = self.parent

type_ = node.type

if type_ in ('power', 'atom_expr'):

# In `self.x = 3` self is not a definition, but x is.

return None

if type_ in ('funcdef', 'classdef'):

if self == node.name:

return node

return None

if type_ == 'except_clause':

# TODO in Python 2 this doesn't work correctly. See grammar file.

# I think we'll just let it be. Python 2 will be gone in a few

# years.

if self.get_previous_sibling() == 'as':

return node.parent # The try_stmt.

return None

while node is not None:

if node.type == 'suite':

return None

if node.type in _GET_DEFINITION_TYPES:

if self in node.get_defined_names():

return node

if import_name_always and node.type in _IMPORTS:

return node

return None

node = node.parent

return None

class Literal(PythonLeaf):

__slots__ = ()

class Number(Literal):

type = 'number'

__slots__ = ()

class String(Literal):

type = 'string'

__slots__ = ()

@property

def string_prefix(self):

return re.match('\w*(?=[\'"])', self.value).group(0)

def _get_payload(self):

match = re.search(

r'''('{3}|"{3}|'|")(.*)$''',

self.value,

flags=re.DOTALL

)

return match.group(2)[:-len(match.group(1))]

class FStringString(Leaf):

"""

f-strings contain f-string expressions and normal python strings. These are

the string parts of f-strings.

"""

type = 'fstring_string'

__slots__ = ()

class FStringStart(Leaf):

"""

f-strings contain f-string expressions and normal python strings. These are

the string parts of f-strings.

"""

type = 'fstring_start'

__slots__ = ()

class FStringEnd(Leaf):

"""

f-strings contain f-string expressions and normal python strings. These are

the string parts of f-strings.

"""

type = 'fstring_end'

__slots__ = ()

class _StringComparisonMixin(object):

def __eq__(self, other):

"""

Make comparisons with strings easy.

Improves the readability of the parser.

"""

if isinstance(other, (str, unicode)):

return self.value == other

return self is other

def __ne__(self, other):

"""Python 2 compatibility."""

return not self.__eq__(other)

def __hash__(self):

return hash(self.value)

class Operator(_LeafWithoutNewlines, _StringComparisonMixin):

type = 'operator'

__slots__ = ()

class Keyword(_LeafWithoutNewlines, _StringComparisonMixin):

type = 'keyword'

__slots__ = ()

class Scope(PythonBaseNode, DocstringMixin):

"""

Super class for the parser tree, which represents the state of a python

text file.

A Scope is either a function, class or lambda.

"""

__slots__ = ()

def __init__(self, children):

super(Scope, self).__init__(children)

def iter_funcdefs(self):

"""

Returns a generator of `funcdef` nodes.

"""

return self._search_in_scope('funcdef')

def iter_classdefs(self):

"""

Returns a generator of `classdef` nodes.

"""

return self._search_in_scope('classdef')

def iter_imports(self):

"""

Returns a generator of `import_name` and `import_from` nodes.

"""

return self._search_in_scope('import_name', 'import_from')

def _search_in_scope(self, *names):

def scan(children):

for element in children:

if element.type in names:

yield element

if element.type in _FUNC_CONTAINERS:

for e in scan(element.children):

yield e

return scan(self.children)

def get_suite(self):

"""

Returns the part that is executed by the function.

"""

return self.children[-1]

def __repr__(self):

try:

name = self.name.value

except AttributeError:

name = ''

return "<%s: %s@%s-%s>" % (type(self).__name__, name,

self.start_pos[0], self.end_pos[0])

class Module(Scope):

"""

The top scope, which is always a module.

Depending on the underlying parser this may be a full module or just a part

of a module.

"""

__slots__ = ('_used_names',)

type = 'file_input'

def __init__(self, children):

super(Module, self).__init__(children)

self._used_names = None

def _iter_future_import_names(self):

"""

:return: A list of future import names.

:rtype: list of str

"""

# In Python it's not allowed to use future imports after the first

# actual (non-future) statement. However this is not a linter here,

# just return all future imports. If people want to scan for issues

# they should use the API.

for imp in self.iter_imports():

if imp.type == 'import_from' and imp.level == 0:

for path in imp.get_paths():

names = [name.value for name in path]

if len(names) == 2 and names[0] == '__future__':

yield names[1]

def _has_explicit_absolute_import(self):

"""

Checks if imports in this module are explicitly absolute, i.e. there

is a ``__future__`` import.

Currently not public, might be in the future.

:return bool:

"""

for name in self._iter_future_import_names():

if name == 'absolute_import':

return True

return False

def get_used_names(self):

"""

Returns all the :class:`Name` leafs that exist in this module. This

includes both definitions and references of names.

"""

if self._used_names is None:

# Don't directly use self._used_names to eliminate a lookup.

dct = {}

def recurse(node):

try:

children = node.children

except AttributeError:

if node.type == 'name':

arr = dct.setdefault(node.value, [])

arr.append(node)

else:

for child in children:

recurse(child)

recurse(self)

self._used_names = dct

return self._used_names

class Decorator(PythonBaseNode):

type = 'decorator'

__slots__ = ()

class ClassOrFunc(Scope):

__slots__ = ()

@property

def name(self):

"""

Returns the `Name` leaf that defines the function or class name.

"""

return self.children[1]

def get_decorators(self):

"""

:rtype: list of :class:`Decorator`

"""

decorated = self.parent

if decorated.type == 'decorated':

if decorated.children[0].type == 'decorators':

return decorated.children[0].children

else:

return decorated.children[:1]

else:

return []

class Class(ClassOrFunc):

"""

Used to store the parsed contents of a python class.

"""

type = 'classdef'

__slots__ = ()

def __init__(self, children):

super(Class, self).__init__(children)

def get_super_arglist(self):

"""

Returns the `arglist` node that defines the super classes. It returns

None if there are no arguments.

"""

if self.children[2] != '(': # Has no parentheses

return None

else:

if self.children[3] == ')': # Empty parentheses

return None

else:

return self.children[3]

def _create_params(parent, argslist_list):

"""

`argslist_list` is a list that can contain an argslist as a first item, but

most not. It's basically the items between the parameter brackets (which is

at most one item).

This function modifies the parser structure. It generates `Param` objects

from the normal ast. Those param objects do not exist in a normal ast, but

make the evaluation of the ast tree so much easier.

You could also say that this function replaces the argslist node with a

list of Param objects.

"""

def check_python2_nested_param(node):

"""

Python 2 allows params to look like ``def x(a, (b, c))``, which is

basically a way of unpacking tuples in params. Python 3 has ditched

this behavior. Jedi currently just ignores those constructs.

"""

return node.type == 'fpdef' and node.children[0] == '('

try:

first = argslist_list[0]

except IndexError:

return []

if first.type in ('name', 'fpdef'):

if check_python2_nested_param(first):

return [first]

else:

return [Param([first], parent)]

elif first == '*':

return [first]

else: # argslist is a `typedargslist` or a `varargslist`.

if first.type == 'tfpdef':

children = [first]

else:

children = first.children

new_children = []

start = 0

# Start with offset 1, because the end is higher.

for end, child in enumerate(children + [None], 1):

if child is None or child == ',':

param_children = children[start:end]

if param_children: # Could as well be comma and then end.

if param_children[0] == '*' \

and (len(param_children) == 1

or param_children[1] == ',') \

or check_python2_nested_param(param_children[0]):

for p in param_children:

p.parent = parent

new_children += param_children

else:

new_children.append(Param(param_children, parent))

start = end

return new_children

class Function(ClassOrFunc):

"""

Used to store the parsed contents of a python function.

Children::

0. <Keyword: def>

1. <Name>

2. parameter list (including open-paren and close-paren <Operator>s)

3. or 5. <Operator: :>

4. or 6. Node() representing function body

3. -> (if annotation is also present)

4. annotation (if present)

"""

type = 'funcdef'

def __init__(self, children):

super(Function, self).__init__(children)

parameters = self.children[2] # After `def foo`

parameters.children[1:-1] = _create_params(parameters, parameters.children[1:-1])

def _get_param_nodes(self):

return self.children[2].children

def get_params(self):

"""

Returns a list of `Param()`.

"""

return [p for p in self._get_param_nodes() if p.type == 'param']

@property

def name(self):

return self.children[1] # First token after `def`

def iter_yield_exprs(self):

"""

Returns a generator of `yield_expr`.

"""

def scan(children):

for element in children:

if element.type in ('classdef', 'funcdef', 'lambdef'):

continue

try:

nested_children = element.children

except AttributeError:

if element.value == 'yield':

if element.parent.type == 'yield_expr':

yield element.parent

else:

yield element

else:

for result in scan(nested_children):

yield result

return scan(self.children)

def iter_return_stmts(self):

"""

Returns a generator of `return_stmt`.

"""

def scan(children):

for element in children:

if element.type == 'return_stmt' \

or element.type == 'keyword' and element.value == 'return':

yield element

if element.type in _RETURN_STMT_CONTAINERS:

for e in scan(element.children):

yield e

return scan(self.children)

def iter_raise_stmts(self):

"""

Returns a generator of `raise_stmt`. Includes raise statements inside try-except blocks

"""

def scan(children):

for element in children:

if element.type == 'raise_stmt' \

or element.type == 'keyword' and element.value == 'raise':

yield element

if element.type in _RETURN_STMT_CONTAINERS:

for e in scan(element.children):

yield e

return scan(self.children)

def is_generator(self):

"""

:return bool: Checks if a function is a generator or not.

"""

return next(self.iter_yield_exprs(), None) is not None

@property

def annotation(self):

"""

Returns the test node after `->` or `None` if there is no annotation.

"""

try:

if self.children[3] == "->":

return self.children[4]

assert self.children[3] == ":"

return None

except IndexError:

return None

class Lambda(Function):

"""

Lambdas are basically trimmed functions, so give it the same interface.

Children::

0. <Keyword: lambda>

*. <Param x> for each argument x

-2. <Operator: :>

-1. Node() representing body

"""

type = 'lambdef'

__slots__ = ()

def __init__(self, children):

# We don't want to call the Function constructor, call its parent.

super(Function, self).__init__(children)

# Everything between `lambda` and the `:` operator is a parameter.

self.children[1:-2] = _create_params(self, self.children[1:-2])

@property

def name(self):

"""

Raises an AttributeError. Lambdas don't have a defined name.

"""

raise AttributeError("lambda is not named.")

def _get_param_nodes(self):

return self.children[1:-2]

@property

def annotation(self):

"""

Returns `None`, lambdas don't have annotations.

"""

return None

def __repr__(self):

return "<%s@%s>" % (self.__class__.__name__, self.start_pos)

class Flow(PythonBaseNode):

__slots__ = ()

class IfStmt(Flow):

type = 'if_stmt'

__slots__ = ()

def get_test_nodes(self):

"""

E.g. returns all the `test` nodes that are named as x, below:

if x:

pass

elif x:

pass

"""

for i, c in enumerate(self.children):

if c in ('elif', 'if'):

yield self.children[i + 1]

def get_corresponding_test_node(self, node):

"""

Searches for the branch in which the node is and returns the

corresponding test node (see function above). However if the node is in

the test node itself and not in the suite return None.

"""

start_pos = node.start_pos

for check_node in reversed(list(self.get_test_nodes())):

if check_node.start_pos < start_pos:

if start_pos < check_node.end_pos:

return None

# In this case the node is within the check_node itself,

# not in the suite

else:

return check_node

def is_node_after_else(self, node):

"""

Checks if a node is defined after `else`.

"""

for c in self.children:

if c == 'else':

if node.start_pos > c.start_pos:

return True

else:

return False

class WhileStmt(Flow):

type = 'while_stmt'

__slots__ = ()

class ForStmt(Flow):

type = 'for_stmt'

__slots__ = ()

def get_testlist(self):

"""

Returns the input node ``y`` from: ``for x in y:``.

"""

return self.children[3]

def get_defined_names(self):

return _defined_names(self.children[1])

class TryStmt(Flow):

type = 'try_stmt'

__slots__ = ()

def get_except_clause_tests(self):

"""

Returns the ``test`` nodes found in ``except_clause`` nodes.

Returns ``[None]`` for except clauses without an exception given.

"""

for node in self.children:

if node.type == 'except_clause':

yield node.children[1]

elif node == 'except':

yield None

class WithStmt(Flow):

type = 'with_stmt'

__slots__ = ()

def get_defined_names(self):

"""

Returns the a list of `Name` that the with statement defines. The

defined names are set after `as`.

"""

names = []

for with_item in self.children[1:-2:2]:

# Check with items for 'as' names.

if with_item.type == 'with_item':

names += _defined_names(with_item.children[2])

return names

def get_test_node_from_name(self, name):

node = name.parent

if node.type != 'with_item':

raise ValueError('The name is not actually part of a with statement.')

return node.children[0]

class Import(PythonBaseNode):

__slots__ = ()

def get_path_for_name(self, name):

"""

The path is the list of names that leads to the searched name.

:return list of Name:

"""

try:

# The name may be an alias. If it is, just map it back to the name.

name = self._aliases()[name]

except KeyError:

pass

for path in self.get_paths():

if name in path:

return path[:path.index(name) + 1]

raise ValueError('Name should be defined in the import itself')

def is_nested(self):

return False # By default, sub classes may overwrite this behavior

def is_star_import(self):

return self.children[-1] == '*'

class ImportFrom(Import):

type = 'import_from'

__slots__ = ()

def get_defined_names(self):

"""

Returns the a list of `Name` that the import defines. The

defined names are set after `import` or in case an alias - `as` - is

present that name is returned.

"""

return [alias or name for name, alias in self._as_name_tuples()]

def _aliases(self):

"""Mapping from alias to its corresponding name."""

return dict((alias, name) for name, alias in self._as_name_tuples()

if alias is not None)

def get_from_names(self):

for n in self.children[1:]:

if n not in ('.', '...'):

break

if n.type == 'dotted_name': # from x.y import

return n.children[::2]

elif n == 'import': # from . import

return []

else: # from x import

return [n]

@property

def level(self):

"""The level parameter of ``__import__``."""

level = 0

for n in self.children[1:]:

if n in ('.', '...'):

level += len(n.value)

else:

break

return level

def _as_name_tuples(self):

last = self.children[-1]

if last == ')':

last = self.children[-2]

elif last == '*':

return # No names defined directly.

if last.type == 'import_as_names':

as_names = last.children[::2]

else:

as_names = [last]

for as_name in as_names:

if as_name.type == 'name':

yield as_name, None

else:

yield as_name.children[::2] # yields x, y -> ``x as y``

def get_paths(self):

"""

The import paths defined in an import statement. Typically an array

like this: ``[<Name: datetime>, <Name: date>]``.

:return list of list of Name:

"""

dotted = self.get_from_names()

if self.children[-1] == '*':

return [dotted]

return [dotted + [name] for name, alias in self._as_name_tuples()]

class ImportName(Import):

"""For ``import_name`` nodes. Covers normal imports without ``from``."""

type = 'import_name'

__slots__ = ()

def get_defined_names(self):

"""

Returns the a list of `Name` that the import defines. The defined names

is always the first name after `import` or in case an alias - `as` - is

present that name is returned.

"""

return [alias or path[0] for path, alias in self._dotted_as_names()]

@property

def level(self):

"""The level parameter of ``__import__``."""

return 0 # Obviously 0 for imports without from.

def get_paths(self):

return [path for path, alias in self._dotted_as_names()]

def _dotted_as_names(self):

"""Generator of (list(path), alias) where alias may be None."""

dotted_as_names = self.children[1]

if dotted_as_names.type == 'dotted_as_names':

as_names = dotted_as_names.children[::2]

else:

as_names = [dotted_as_names]

for as_name in as_names:

if as_name.type == 'dotted_as_name':

alias = as_name.children[2]

as_name = as_name.children[0]

else:

alias = None

if as_name.type == 'name':

yield [as_name], alias

else:

# dotted_names

yield as_name.children[::2], alias

def is_nested(self):

"""

This checks for the special case of nested imports, without aliases and

from statement::

import foo.bar

"""

return bool([1 for path, alias in self._dotted_as_names()

if alias is None and len(path) > 1])

def _aliases(self):

"""

:return list of Name: Returns all the alias

"""

return dict((alias, path[-1]) for path, alias in self._dotted_as_names()

if alias is not None)

class KeywordStatement(PythonBaseNode):

"""

For the following statements: `assert`, `del`, `global`, `nonlocal`,

`raise`, `return`, `yield`, `return`, `yield`.

`pass`, `continue` and `break` are not in there, because they are just

simple keywords and the parser reduces it to a keyword.

"""

__slots__ = ()

@property

def type(self):

"""

Keyword statements start with the keyword and end with `_stmt`. You can

crosscheck this with the Python grammar.

"""

return '%s_stmt' % self.keyword

@property

def keyword(self):

return self.children[0].value

class AssertStmt(KeywordStatement):

__slots__ = ()

@property

def assertion(self):

return self.children[1]

class GlobalStmt(KeywordStatement):

__slots__ = ()

def get_global_names(self):

return self.children[1::2]