as_string.py

# -*- coding: utf-8 -*-
# Copyright (c) 2009-2011, 2013-2014 LOGILAB S.A. (Paris, FRANCE) <contact@logilab.fr>
# Copyright (c) 2010 Daniel Harding <dharding@gmail.com>
# Copyright (c) 2013-2016, 2018 Claudiu Popa <pcmanticore@gmail.com>
# Copyright (c) 2013-2014 Google, Inc.
# Copyright (c) 2015-2016 Ceridwen <ceridwenv@gmail.com>
# Copyright (c) 2016 Jared Garst <jgarst@users.noreply.github.com>
# Copyright (c) 2016 Jakub Wilk <jwilk@jwilk.net>
# Copyright (c) 2017 Łukasz Rogalski <rogalski.91@gmail.com>
# Copyright (c) 2017 rr- <rr-@sakuya.pl>
# Copyright (c) 2018 brendanator <brendan.maginnis@gmail.com>
# Copyright (c) 2018 Nick Drozd <nicholasdrozd@gmail.com>

# Licensed under the LGPL: https://www.gnu.org/licenses/old-licenses/lgpl-2.1.en.html
# For details: https://github.com/PyCQA/astroid/blob/master/COPYING.LESSER

"""This module renders Astroid nodes as string:

* :func:`to_code` function return equivalent (hopefully valid) python string

* :func:`dump` function return an internal representation of nodes found
  in the tree, useful for debugging or understanding the tree structure
"""

# pylint: disable=unused-argument

DOC_NEWLINE = "\0"


class AsStringVisitor:
    """Visitor to render an Astroid node as a valid python code string"""

    def __init__(self, indent):
        self.indent = indent

    def __call__(self, node):
        """Makes this visitor behave as a simple function"""
        return node.accept(self).replace(DOC_NEWLINE, "\n")

    def _docs_dedent(self, doc):
        """Stop newlines in docs being indented by self._stmt_list"""
        return '\n%s"""%s"""' % (self.indent, doc.replace("\n", DOC_NEWLINE))

    def _stmt_list(self, stmts, indent=True):
        """return a list of nodes to string"""
        stmts = "\n".join(nstr for nstr in [n.accept(self) for n in stmts] if nstr)
        if indent:
            return self.indent + stmts.replace("\n", "\n" + self.indent)

        return stmts

    def _precedence_parens(self, node, child, is_left=True):
        """Wrap child in parens only if required to keep same semantics"""
        if self._should_wrap(node, child, is_left):
            return "(%s)" % child.accept(self)

        return child.accept(self)

    def _should_wrap(self, node, child, is_left):
        """Wrap child if:
            - it has lower precedence
            - same precedence with position opposite to associativity direction
        """
        node_precedence = node.op_precedence()
        child_precedence = child.op_precedence()

        if node_precedence > child_precedence:
            # 3 * (4 + 5)
            return True

        if (
            node_precedence == child_precedence
            and is_left != node.op_left_associative()
        ):
            # 3 - (4 - 5)
            # (2**3)**4
            return True

        return False

    ## visit_<node> methods ###########################################

    def visit_arguments(self, node):
        """return an astroid.Function node as string"""
        return node.format_args()

    def visit_assignattr(self, node):
        """return an astroid.AssAttr node as string"""
        return self.visit_attribute(node)

    def visit_assert(self, node):
        """return an astroid.Assert node as string"""
        if node.fail:
            return "assert %s, %s" % (node.test.accept(self), node.fail.accept(self))
        return "assert %s" % node.test.accept(self)

    def visit_assignname(self, node):
        """return an astroid.AssName node as string"""
        return node.name

    def visit_assign(self, node):
        """return an astroid.Assign node as string"""
        lhs = " = ".join(n.accept(self) for n in node.targets)
        return "%s = %s" % (lhs, node.value.accept(self))

    def visit_augassign(self, node):
        """return an astroid.AugAssign node as string"""
        return "%s %s %s" % (node.target.accept(self), node.op, node.value.accept(self))

    def visit_annassign(self, node):
        """Return an astroid.AugAssign node as string"""

        target = node.target.accept(self)
        annotation = node.annotation.accept(self)
        if node.value is None:
            return "%s: %s" % (target, annotation)
        return "%s: %s = %s" % (target, annotation, node.value.accept(self))

    def visit_repr(self, node):
        """return an astroid.Repr node as string"""
        return "`%s`" % node.value.accept(self)

    def visit_binop(self, node):
        """return an astroid.BinOp node as string"""
        left = self._precedence_parens(node, node.left)
        right = self._precedence_parens(node, node.right, is_left=False)
        if node.op == "**":
            return "%s%s%s" % (left, node.op, right)

        return "%s %s %s" % (left, node.op, right)

    def visit_boolop(self, node):
        """return an astroid.BoolOp node as string"""
        values = ["%s" % self._precedence_parens(node, n) for n in node.values]
        return (" %s " % node.op).join(values)

    def visit_break(self, node):
        """return an astroid.Break node as string"""
        return "break"

    def visit_call(self, node):
        """return an astroid.Call node as string"""
        expr_str = self._precedence_parens(node, node.func)
        args = [arg.accept(self) for arg in node.args]
        if node.keywords:
            keywords = [kwarg.accept(self) for kwarg in node.keywords]
        else:
            keywords = []

        args.extend(keywords)
        return "%s(%s)" % (expr_str, ", ".join(args))

    def visit_classdef(self, node):
        """return an astroid.ClassDef node as string"""
        decorate = node.decorators.accept(self) if node.decorators else ""
        bases = ", ".join(n.accept(self) for n in node.bases)
        metaclass = node.metaclass()
        if metaclass and not node.has_metaclass_hack():
            if bases:
                bases = "(%s, metaclass=%s)" % (bases, metaclass.name)
            else:
                bases = "(metaclass=%s)" % metaclass.name
        else:
            bases = "(%s)" % bases if bases else ""
        docs = self._docs_dedent(node.doc) if node.doc else ""
        return "\n\n%sclass %s%s:%s\n%s\n" % (
            decorate,
            node.name,
            bases,
            docs,
            self._stmt_list(node.body),
        )

    def visit_compare(self, node):
        """return an astroid.Compare node as string"""
        rhs_str = " ".join(
            [
                "%s %s" % (op, self._precedence_parens(node, expr, is_left=False))
                for op, expr in node.ops
            ]
        )
        return "%s %s" % (self._precedence_parens(node, node.left), rhs_str)

    def visit_comprehension(self, node):
        """return an astroid.Comprehension node as string"""
        ifs = "".join(" if %s" % n.accept(self) for n in node.ifs)
        return "for %s in %s%s" % (
            node.target.accept(self),
            node.iter.accept(self),
            ifs,
        )

    def visit_const(self, node):
        """return an astroid.Const node as string"""
        if node.value is Ellipsis:
            return "..."
        return repr(node.value)

    def visit_continue(self, node):
        """return an astroid.Continue node as string"""
        return "continue"

    def visit_delete(self, node):  # XXX check if correct
        """return an astroid.Delete node as string"""
        return "del %s" % ", ".join(child.accept(self) for child in node.targets)

    def visit_delattr(self, node):
        """return an astroid.DelAttr node as string"""
        return self.visit_attribute(node)

    def visit_delname(self, node):
        """return an astroid.DelName node as string"""
        return node.name

    def visit_decorators(self, node):
        """return an astroid.Decorators node as string"""
        return "@%s\n" % "\n@".join(item.accept(self) for item in node.nodes)

    def visit_dict(self, node):
        """return an astroid.Dict node as string"""
        return "{%s}" % ", ".join(self._visit_dict(node))

    def _visit_dict(self, node):
        for key, value in node.items:
            key = key.accept(self)
            value = value.accept(self)
            if key == "**":
                # It can only be a DictUnpack node.
                yield key + value
            else:
                yield "%s: %s" % (key, value)

    def visit_dictunpack(self, node):
        return "**"

    def visit_dictcomp(self, node):
        """return an astroid.DictComp node as string"""
        return "{%s: %s %s}" % (
            node.key.accept(self),
            node.value.accept(self),
            " ".join(n.accept(self) for n in node.generators),
        )

    def visit_expr(self, node):
        """return an astroid.Discard node as string"""
        return node.value.accept(self)

    def visit_emptynode(self, node):
        """dummy method for visiting an Empty node"""
        return ""

    def visit_excepthandler(self, node):
        if node.type:
            if node.name:
                excs = "except %s, %s" % (
                    node.type.accept(self),
                    node.name.accept(self),
                )
            else:
                excs = "except %s" % node.type.accept(self)
        else:
            excs = "except"
        return "%s:\n%s" % (excs, self._stmt_list(node.body))

    def visit_ellipsis(self, node):
        """return an astroid.Ellipsis node as string"""
        return "..."

    def visit_empty(self, node):
        """return an Empty node as string"""
        return ""

    def visit_exec(self, node):
        """return an astroid.Exec node as string"""
        if node.locals:
            return "exec %s in %s, %s" % (
                node.expr.accept(self),
                node.locals.accept(self),
                node.globals.accept(self),
            )
        if node.globals:
            return "exec %s in %s" % (node.expr.accept(self), node.globals.accept(self))
        return "exec %s" % node.expr.accept(self)

    def visit_extslice(self, node):
        """return an astroid.ExtSlice node as string"""
        return ", ".join(dim.accept(self) for dim in node.dims)

    def visit_for(self, node):
        """return an astroid.For node as string"""
        fors = "for %s in %s:\n%s" % (
            node.target.accept(self),
            node.iter.accept(self),
            self._stmt_list(node.body),
        )
        if node.orelse:
            fors = "%s\nelse:\n%s" % (fors, self._stmt_list(node.orelse))
        return fors

    def visit_importfrom(self, node):
        """return an astroid.ImportFrom node as string"""
        return "from %s import %s" % (
            "." * (node.level or 0) + node.modname,
            _import_string(node.names),
        )

    def visit_functiondef(self, node):
        """return an astroid.Function node as string"""
        decorate = node.decorators.accept(self) if node.decorators else ""
        docs = self._docs_dedent(node.doc) if node.doc else ""
        trailer = ":"
        if node.returns:
            return_annotation = " -> " + node.returns.as_string()
            trailer = return_annotation + ":"
        def_format = "\n%sdef %s(%s)%s%s\n%s"
        return def_format % (
            decorate,
            node.name,
            node.args.accept(self),
            trailer,
            docs,
            self._stmt_list(node.body),
        )

    def visit_generatorexp(self, node):
        """return an astroid.GeneratorExp node as string"""
        return "(%s %s)" % (
            node.elt.accept(self),
            " ".join(n.accept(self) for n in node.generators),
        )

    def visit_attribute(self, node):
        """return an astroid.Getattr node as string"""
        return "%s.%s" % (self._precedence_parens(node, node.expr), node.attrname)

    def visit_global(self, node):
        """return an astroid.Global node as string"""
        return "global %s" % ", ".join(node.names)

    def visit_if(self, node):
        """return an astroid.If node as string"""
        ifs = ["if %s:\n%s" % (node.test.accept(self), self._stmt_list(node.body))]
        if node.has_elif_block():
            ifs.append("el%s" % self._stmt_list(node.orelse, indent=False))
        elif node.orelse:
            ifs.append("else:\n%s" % self._stmt_list(node.orelse))
        return "\n".join(ifs)

    def visit_ifexp(self, node):
        """return an astroid.IfExp node as string"""
        return "%s if %s else %s" % (
            self._precedence_parens(node, node.body, is_left=True),
            self._precedence_parens(node, node.test, is_left=True),
            self._precedence_parens(node, node.orelse, is_left=False),
        )

    def visit_import(self, node):
        """return an astroid.Import node as string"""
        return "import %s" % _import_string(node.names)

    def visit_keyword(self, node):
        """return an astroid.Keyword node as string"""
        if node.arg is None:
            return "**%s" % node.value.accept(self)
        return "%s=%s" % (node.arg, node.value.accept(self))

    def visit_lambda(self, node):
        """return an astroid.Lambda node as string"""
        args = node.args.accept(self)
        body = node.body.accept(self)
        if args:
            return "lambda %s: %s" % (args, body)

        return "lambda: %s" % body

    def visit_list(self, node):
        """return an astroid.List node as string"""
        return "[%s]" % ", ".join(child.accept(self) for child in node.elts)

    def visit_listcomp(self, node):
        """return an astroid.ListComp node as string"""
        return "[%s %s]" % (
            node.elt.accept(self),
            " ".join(n.accept(self) for n in node.generators),
        )

    def visit_module(self, node):
        """return an astroid.Module node as string"""
        docs = '"""%s"""\n\n' % node.doc if node.doc else ""
        return docs + "\n".join(n.accept(self) for n in node.body) + "\n\n"

    def visit_name(self, node):
        """return an astroid.Name node as string"""
        return node.name

    def visit_pass(self, node):
        """return an astroid.Pass node as string"""
        return "pass"

    def visit_print(self, node):
        """return an astroid.Print node as string"""
        nodes = ", ".join(n.accept(self) for n in node.values)
        if not node.nl:
            nodes = "%s," % nodes
        if node.dest:
            return "print >> %s, %s" % (node.dest.accept(self), nodes)
        return "print %s" % nodes

    def visit_raise(self, node):
        """return an astroid.Raise node as string"""
        if node.exc:
            if node.inst:
                if node.tback:
                    return "raise %s, %s, %s" % (
                        node.exc.accept(self),
                        node.inst.accept(self),
                        node.tback.accept(self),
                    )
                return "raise %s, %s" % (node.exc.accept(self), node.inst.accept(self))
            return "raise %s" % node.exc.accept(self)
        return "raise"

    def visit_return(self, node):
        """return an astroid.Return node as string"""
        if node.is_tuple_return() and len(node.value.elts) > 1:
            elts = [child.accept(self) for child in node.value.elts]
            return "return %s" % ", ".join(elts)

        if node.value:
            return "return %s" % node.value.accept(self)

        return "return"

    def visit_index(self, node):
        """return an astroid.Index node as string"""
        return node.value.accept(self)

    def visit_set(self, node):
        """return an astroid.Set node as string"""
        return "{%s}" % ", ".join(child.accept(self) for child in node.elts)

    def visit_setcomp(self, node):
        """return an astroid.SetComp node as string"""
        return "{%s %s}" % (
            node.elt.accept(self),
            " ".join(n.accept(self) for n in node.generators),
        )

    def visit_slice(self, node):
        """return an astroid.Slice node as string"""
        lower = node.lower.accept(self) if node.lower else ""
        upper = node.upper.accept(self) if node.upper else ""
        step = node.step.accept(self) if node.step else ""
        if step:
            return "%s:%s:%s" % (lower, upper, step)
        return "%s:%s" % (lower, upper)

    def visit_subscript(self, node):
        """return an astroid.Subscript node as string"""
        idx = node.slice
        if idx.__class__.__name__.lower() == "index":
            idx = idx.value
        idxstr = idx.accept(self)
        if idx.__class__.__name__.lower() == "tuple" and idx.elts:
            # Remove parenthesis in tuple and extended slice.
            # a[(::1, 1:)] is not valid syntax.
            idxstr = idxstr[1:-1]
        return "%s[%s]" % (self._precedence_parens(node, node.value), idxstr)

    def visit_tryexcept(self, node):
        """return an astroid.TryExcept node as string"""
        trys = ["try:\n%s" % self._stmt_list(node.body)]
        for handler in node.handlers:
            trys.append(handler.accept(self))
        if node.orelse:
            trys.append("else:\n%s" % self._stmt_list(node.orelse))
        return "\n".join(trys)

    def visit_tryfinally(self, node):
        """return an astroid.TryFinally node as string"""
        return "try:\n%s\nfinally:\n%s" % (
            self._stmt_list(node.body),
            self._stmt_list(node.finalbody),
        )

    def visit_tuple(self, node):
        """return an astroid.Tuple node as string"""
        if len(node.elts) == 1:
            return "(%s, )" % node.elts[0].accept(self)
        return "(%s)" % ", ".join(child.accept(self) for child in node.elts)

    def visit_unaryop(self, node):
        """return an astroid.UnaryOp node as string"""
        if node.op == "not":
            operator = "not "
        else:
            operator = node.op
        return "%s%s" % (operator, self._precedence_parens(node, node.operand))

    def visit_while(self, node):
        """return an astroid.While node as string"""
        whiles = "while %s:\n%s" % (node.test.accept(self), self._stmt_list(node.body))
        if node.orelse:
            whiles = "%s\nelse:\n%s" % (whiles, self._stmt_list(node.orelse))
        return whiles

    def visit_with(self, node):  # 'with' without 'as' is possible
        """return an astroid.With node as string"""
        items = ", ".join(
            ("%s" % expr.accept(self)) + (vars and " as %s" % (vars.accept(self)) or "")
            for expr, vars in node.items
        )
        return "with %s:\n%s" % (items, self._stmt_list(node.body))

    def visit_yield(self, node):
        """yield an ast.Yield node as string"""
        yi_val = (" " + node.value.accept(self)) if node.value else ""
        expr = "yield" + yi_val
        if node.parent.is_statement:
            return expr

        return "(%s)" % (expr,)

    def visit_starred(self, node):
        """return Starred node as string"""
        return "*" + node.value.accept(self)

    # These aren't for real AST nodes, but for inference objects.

    def visit_frozenset(self, node):
        return node.parent.accept(self)

    def visit_super(self, node):
        return node.parent.accept(self)

    def visit_uninferable(self, node):
        return str(node)


class AsStringVisitor3(AsStringVisitor):
    """AsStringVisitor3 overwrites some AsStringVisitor methods"""

    def visit_excepthandler(self, node):
        if node.type:
            if node.name:
                excs = "except %s as %s" % (
                    node.type.accept(self),
                    node.name.accept(self),
                )
            else:
                excs = "except %s" % node.type.accept(self)
        else:
            excs = "except"
        return "%s:\n%s" % (excs, self._stmt_list(node.body))

    def visit_nonlocal(self, node):
        """return an astroid.Nonlocal node as string"""
        return "nonlocal %s" % ", ".join(node.names)

    def visit_raise(self, node):
        """return an astroid.Raise node as string"""
        if node.exc:
            if node.cause:
                return "raise %s from %s" % (
                    node.exc.accept(self),
                    node.cause.accept(self),
                )
            return "raise %s" % node.exc.accept(self)
        return "raise"

    def visit_yieldfrom(self, node):
        """ Return an astroid.YieldFrom node as string. """
        yi_val = (" " + node.value.accept(self)) if node.value else ""
        expr = "yield from" + yi_val
        if node.parent.is_statement:
            return expr

        return "(%s)" % (expr,)

    def visit_asyncfunctiondef(self, node):
        function = super(AsStringVisitor3, self).visit_functiondef(node)
        return "async " + function.strip()

    def visit_await(self, node):
        return "await %s" % node.value.accept(self)

    def visit_asyncwith(self, node):
        return "async %s" % self.visit_with(node)

    def visit_asyncfor(self, node):
        return "async %s" % self.visit_for(node)

    def visit_joinedstr(self, node):
        # Special treatment for constants,
        # as we want to join literals not reprs
        string = "".join(
            value.value if type(value).__name__ == "Const" else value.accept(self)
            for value in node.values
        )
        return "f'%s'" % string

    def visit_formattedvalue(self, node):
        return "{%s}" % node.value.accept(self)

    def visit_comprehension(self, node):
        """return an astroid.Comprehension node as string"""
        return "%s%s" % (
            "async " if node.is_async else "",
            super(AsStringVisitor3, self).visit_comprehension(node),
        )

    def visit_namedexpr(self, node):
        """Return an assignment expression node as string"""
        target = node.target.accept(self)
        value = node.value.accept(self)
        return "%s := %s" % (target, value)


def _import_string(names):
    """return a list of (name, asname) formatted as a string"""
    _names = []
    for name, asname in names:
        if asname is not None:
            _names.append("%s as %s" % (name, asname))
        else:
            _names.append(name)
    return ", ".join(_names)


AsStringVisitor = AsStringVisitor3

# This sets the default indent to 4 spaces.
to_code = AsStringVisitor("    ")