mercurial/node.py

import-checker: make imported_modules yield absolute dotted_name_of_path

This patch makes `imported_modules()` always yield absolute
`dotted_name_of_path()`-ed name by strict detection with
`fromlocal()`.

This change improves circular detection in some points:

  - locally defined modules, of which name collides against one of
    standard library, can be examined correctly

    For example, circular import related to `commands` is overlooked
    before this patch.

  - names not useful for circular detection are ignored

    Names below are also yielded before this patch:

      - module names of standard library (= not locally defined one)
      - non-module names (e.g. `node.nullid` of `from node import nullid`)

    These redundant names decrease performance of circular detection.

    For example, with files at 1ef96a3b8b89, average loops per file in
    `checkmod()` is reduced from 165 to 109.

  - `__init__` can be handled correctly in `checkmod()`

    For example, current implementation has problems below:

      - `from xxx import yyy` doesn't recognize `xxx.__init__` as imported

      - `xxx.__init__` imported via `import xxx` is treated as `xxx`,
        and circular detection is aborted, because `key` of such
        module name is not `xxx` but `xxx.__init__`

  - it is easy to enhance for `from . import xxx` style or so (in the
    future)

    Module name detection in `imported_modules()` can use information
    in `ast.ImportFrom` fully.

It is assumed that all locally defined modules are correctly specified
to `import-checker.py` at once.

Strictly speaking, when `from foo.bar.baz import module1` imports
`foo.bar.baz.module1` module, current `imported_modules()` yields only
`foo.bar.baz.__init__`, even though also `foo.__init__` and
`foo.bar.__init__` should be yielded to detect circular import
exactly.

But this limitation is reasonable one for improvement in this patch,
because current `__init__` files in Mercurial seems to be implemented
carefully.

# node.py - basic nodeid manipulation for mercurial
#
# Copyright 2005, 2006 Matt Mackall <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

import binascii

nullrev = -1
nullid = "\0" * 20

# This ugly style has a noticeable effect in manifest parsing
hex = binascii.hexlify
bin = binascii.unhexlify

def short(node):
    return hex(node[:6])