"""Fixer for import statements.

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If spam is being imported from the local directory, this import:

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from spam import eggs

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Becomes:

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from .spam import eggs

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And this import:

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import spam

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Becomes:

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from . import spam

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"""

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# Local imports

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from .. import fixer_base

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from os.path import dirname, join, exists, sep

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from ..fixer_util import FromImport, syms, token

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def traverse_imports(names):

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"""

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Walks over all the names imported in a dotted_as_names node.

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"""

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pending = [names]

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while pending:

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node = pending.pop()

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if node.type == token.NAME:

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yield node.value

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elif node.type == syms.dotted_name:

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yield "".join([ch.value for ch in node.children])

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elif node.type == syms.dotted_as_name:

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pending.append(node.children[0])

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elif node.type == syms.dotted_as_names:

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pending.extend(node.children[::-2])

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else:

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raise AssertionError("unknown node type")

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class FixImport(fixer_base.BaseFix):

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BM_compatible = True

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PATTERN = """

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import_from< 'from' imp=any 'import' ['('] any [')'] >

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|

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import_name< 'import' imp=any >

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"""

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def start_tree(self, tree, name):

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super(FixImport, self).start_tree(tree, name)

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self.skip = "absolute_import" in tree.future_features

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def transform(self, node, results):

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if self.skip:

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return

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imp = results['imp']

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if node.type == syms.import_from:

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# Some imps are top-level (eg: 'import ham')

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# some are first level (eg: 'import ham.eggs')

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# some are third level (eg: 'import ham.eggs as spam')

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# Hence, the loop

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while not hasattr(imp, 'value'):

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imp = imp.children[0]

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if self.probably_a_local_import(imp.value):

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imp.value = "." + imp.value

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imp.changed()

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else:

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have_local = False

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have_absolute = False

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for mod_name in traverse_imports(imp):

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if self.probably_a_local_import(mod_name):

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have_local = True

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else:

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have_absolute = True

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if have_absolute:

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if have_local:

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# We won't handle both sibling and absolute imports in the

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# same statement at the moment.

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self.warning(node, "absolute and local imports together")

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return

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new = FromImport(".", [imp])

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new.prefix = node.prefix

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return new

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def probably_a_local_import(self, imp_name):

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if imp_name.startswith("."):

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# Relative imports are certainly not local imports.

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return False

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imp_name = imp_name.split(".", 1)[0]

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base_path = dirname(self.filename)

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base_path = join(base_path, imp_name)

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# If there is no __init__.py next to the file its not in a package

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# so can't be a relative import.

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if not exists(join(dirname(base_path), "__init__.py")):

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return False

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for ext in [".py", sep, ".pyc", ".so", ".sl", ".pyd"]:

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if exists(base_path + ext):

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return True

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return False

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