<h2>Editing File: /usr/lib64/python3.6/lib2to3/fixes/fix_map.py</h2><form method='post'><textarea name='content' class='file-edit'># Copyright 2007 Google, Inc. All Rights Reserved.
# Licensed to PSF under a Contributor Agreement.

&quot;&quot;&quot;Fixer that changes map(F, ...) into list(map(F, ...)) unless there
exists a 'from future_builtins import map' statement in the top-level
namespace.

As a special case, map(None, X) is changed into list(X).  (This is
necessary because the semantics are changed in this case -- the new
map(None, X) is equivalent to [(x,) for x in X].)

We avoid the transformation (except for the special case mentioned
above) if the map() call is directly contained in iter(&lt;&gt;), list(&lt;&gt;),
tuple(&lt;&gt;), sorted(&lt;&gt;), ...join(&lt;&gt;), or for V in &lt;&gt;:.

NOTE: This is still not correct if the original code was depending on
map(F, X, Y, ...) to go on until the longest argument is exhausted,
substituting None for missing values -- like zip(), it now stops as
soon as the shortest argument is exhausted.
&quot;&quot;&quot;

# Local imports
from ..pgen2 import token
from .. import fixer_base
from ..fixer_util import Name, ArgList, Call, ListComp, in_special_context
from ..pygram import python_symbols as syms
from ..pytree import Node


class FixMap(fixer_base.ConditionalFix):
    BM_compatible = True

    PATTERN = &quot;&quot;&quot;
    map_none=power&lt;
        'map'
        trailer&lt; '(' arglist&lt; 'None' ',' arg=any [','] &gt; ')' &gt;
        [extra_trailers=trailer*]
    &gt;
    |
    map_lambda=power&lt;
        'map'
        trailer&lt;
            '('
            arglist&lt;
                lambdef&lt; 'lambda'
                         (fp=NAME | vfpdef&lt; '(' fp=NAME ')'&gt; ) ':' xp=any
                &gt;
                ','
                it=any
            &gt;
            ')'
        &gt;
        [extra_trailers=trailer*]
    &gt;
    |
    power&lt;
        'map' args=trailer&lt; '(' [any] ')' &gt;
        [extra_trailers=trailer*]
    &gt;
    &quot;&quot;&quot;

    skip_on = 'future_builtins.map'

    def transform(self, node, results):
        if self.should_skip(node):
            return

        trailers = []
        if 'extra_trailers' in results:
            for t in results['extra_trailers']:
                trailers.append(t.clone())

        if node.parent.type == syms.simple_stmt:
            self.warning(node, &quot;You should use a for loop here&quot;)
            new = node.clone()
            new.prefix = &quot;&quot;
            new = Call(Name(&quot;list&quot;), [new])
        elif &quot;map_lambda&quot; in results:
            new = ListComp(results[&quot;xp&quot;].clone(),
                           results[&quot;fp&quot;].clone(),
                           results[&quot;it&quot;].clone())
            new = Node(syms.power, [new] + trailers, prefix=&quot;&quot;)

        else:
            if &quot;map_none&quot; in results:
                new = results[&quot;arg&quot;].clone()
                new.prefix = &quot;&quot;
            else:
                if &quot;args&quot; in results:
                    args = results[&quot;args&quot;]
                    if args.type == syms.trailer and \
                       args.children[1].type == syms.arglist and \
                       args.children[1].children[0].type == token.NAME and \
                       args.children[1].children[0].value == &quot;None&quot;:
                        self.warning(node, &quot;cannot convert map(None, ...) &quot;
                                     &quot;with multiple arguments because map() &quot;
                                     &quot;now truncates to the shortest sequence&quot;)
                        return

                    new = Node(syms.power, [Name(&quot;map&quot;), args.clone()])
                    new.prefix = &quot;&quot;

                if in_special_context(node):
                    return None

            new = Node(syms.power, [Name(&quot;list&quot;), ArgList([new])] + trailers)
            new.prefix = &quot;&quot;

        new.prefix = node.prefix
        return new
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