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import os
from alembic import util
import shutil
import re
import inspect
import datetime
_rev_file = re.compile(r'([a-z0-9]+)\.py$')
_mod_def_re = re.compile(r'(upgrade|downgrade)_([a-z0-9]+)')
class ScriptDirectory(object):
def __init__(self, dir):
self.dir = dir
self.versions = os.path.join(self.dir, 'versions')
if not os.access(dir, os.F_OK):
raise util.CommandError("Path doesn't exist: %r. Please use "
"the 'init' command to create a new "
"scripts folder." % dir)
@classmethod
def from_config(cls, config):
return ScriptDirectory(
config.get_main_option('script_location'))
def walk_revisions(self):
"""Iterate through all revisions.
This is actually a breadth-first tree traversal,
with leaf nodes being heads.
"""
heads = set(self._get_heads())
base = self._get_rev("base")
while heads:
todo = set(heads)
heads = set()
for head in todo:
if head in heads:
break
for sc in self._revs(head, base):
if sc.is_branch_point and sc.revision not in todo:
heads.add(sc.revision)
break
else:
yield sc
def _get_rev(self, id_):
if id_ == 'head':
id_ = self._current_head()
elif id_ == 'base':
id_ = None
try:
return self._revision_map[id_]
except KeyError:
raise util.CommandError("No such revision %s" % id_)
def _revs(self, upper, lower):
lower = self._get_rev(lower)
upper = self._get_rev(upper)
script = upper
while script != lower:
yield script
script = self._revision_map[script.down_revision]
def upgrade_from(self, destination, current_rev):
return [
(script.module.upgrade, script.revision) for script in
reversed(list(self._revs(destination, current_rev)))
]
def downgrade_to(self, destination, current_rev):
return [
(script.module.downgrade, script.down_revision) for script in
self._revs(current_rev, destination)
]
def run_env(self):
util.load_python_file(self.dir, 'env.py')
@util.memoized_property
def _revision_map(self):
map_ = {}
for file_ in os.listdir(self.versions):
script = Script.from_path(self.versions, file_)
if script is None:
continue
if script.revision in map_:
util.warn("Revision %s is present more than once" % script.revision)
map_[script.revision] = script
for rev in map_.values():
if rev.down_revision is None:
continue
if rev.down_revision not in map_:
util.warn("Revision %s referenced from %s is not present"
% (rev.down_revision, rev))
rev.down_revision = None
else:
map_[rev.down_revision].add_nextrev(rev.revision)
map_[None] = None
return map_
def _current_head(self):
current_heads = self._get_heads()
if len(current_heads) > 1:
raise Exception("Only a single head supported so far...")
if current_heads:
return current_heads[0]
else:
return None
def _get_heads(self):
heads = []
for script in self._revision_map.values():
if script and script.is_head:
heads.append(script.revision)
return heads
def _get_origin(self):
for script in self._revision_map.values():
if script.down_revision is None \
and script.revision in self._revision_map:
return script
else:
return None
def generate_template(self, src, dest, **kw):
util.status("Generating %s" % os.path.abspath(dest),
util.template_to_file,
src,
dest,
**kw
)
def copy_file(self, src, dest):
util.status("Generating %s" % os.path.abspath(dest),
shutil.copy,
src, dest)
def generate_rev(self, revid, message):
current_head = self._current_head()
filename = "%s.py" % revid
self.generate_template(
os.path.join(self.dir, "script.py.mako"),
os.path.join(self.versions, filename),
up_revision=str(revid),
down_revision=current_head,
create_date=datetime.datetime.now(),
message=message if message is not None else ("empty message")
)
script = Script.from_path(self.versions, filename)
self._revision_map[script.revision] = script
if script.down_revision:
self._revision_map[script.down_revision].add_nextrev(script.revision)
return script
class Script(object):
nextrev = frozenset()
def __init__(self, module, rev_id):
self.module = module
self.revision = rev_id
self.down_revision = getattr(module, 'down_revision', None)
@property
def doc(self):
return re.split(r"\n\n", self.module.__doc__)[0]
def add_nextrev(self, rev):
self.nextrev = self.nextrev.union([rev])
@property
def is_head(self):
return not bool(self.nextrev)
@property
def is_branch_point(self):
return len(self.nextrev) > 1
def __str__(self):
return "%s -> %s%s%s, %s" % (
self.down_revision,
self.revision,
" (head)" if self.is_head else "",
" (branchpoint)" if self.is_branch_point else "",
self.doc)
@classmethod
def from_path(cls, dir_, filename):
m = _rev_file.match(filename)
if not m:
return None
module = util.load_python_file(dir_, filename)
return Script(module, m.group(1))
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