query.py
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"""
@todo: revise (actually make) documentation
"""
from snakes.plugins import plugin
from snakes.pnml import Tree, loads, dumps
import imp, sys, socket, traceback, operator
class QueryError (Exception) :
pass
class Query (object) :
def __init__ (self, name, *larg, **karg) :
self._name = name
self._larg = tuple(larg)
self._karg = dict(karg)
__pnmltag__ = "query"
def __pnmldump__ (self) :
"""
>>> Query('set', 'x', 42).__pnmldump__()
<?xml version="1.0" encoding="utf-8"?>
<pnml>
<query name="set">
<argument>
<object type="str">
x
</object>
</argument>
<argument>
<object type="int">
42
</object>
</argument>
</query>
</pnml>
>>> Query('test', x=1).__pnmldump__()
<?xml version="1.0" encoding="utf-8"?>
<pnml>
<query name="test">
<keyword name="x">
<object type="int">
1
</object>
</keyword>
</query>
</pnml>
>>> Query('test', 'x', 42, y=1).__pnmldump__()
<?xml version="1.0" encoding="utf-8"?>
<pnml>
<query name="test">
<argument>
<object type="str">
x
</object>
</argument>
<argument>
<object type="int">
42
</object>
</argument>
<keyword name="y">
<object type="int">
1
</object>
</keyword>
</query>
</pnml>
>>> Query('set', 'x', Query('call', 'x.upper')).__pnmldump__()
<?xml version="1.0" encoding="utf-8"?>
<pnml>
<query name="set">
<argument>
<object type="str">
x
</object>
</argument>
<argument>
<query name="call">
<argument>
<object type="str">
x.upper
</object>
</argument>
</query>
</argument>
</query>
</pnml>
"""
children = []
for arg in self._larg :
children.append(Tree("argument", None,
Tree.from_obj(arg)))
for name, value in self._karg.items() :
children.append(Tree("keyword", None,
Tree.from_obj(value),
name=name))
return Tree(self.__pnmltag__, None, *children, **{"name": self._name})
@classmethod
def __pnmlload__ (cls, tree) :
"""
>>> Tree._tag2obj = {'query': Query}
>>> t = Query('test', 'x', 42, y=1).__pnmldump__()
>>> q = Query.__pnmlload__(t)
>>> q._name
'test'
>>> q._larg
('x', 42)
>>> q._karg
{'y': 1}
"""
larg = (child.child().to_obj()
for child in tree.get_children("argument"))
karg = dict((child["name"], child.child().to_obj())
for child in tree.get_children("keyword"))
return cls(tree["name"], *larg, **karg)
def run (self, envt) :
"""
>>> import imp
>>> env = imp.new_module('environment')
>>> Query('set', 'x', 'hello').run(env)
>>> env.x
'hello'
>>> Query('set', 'x', Query('call', 'x.upper')).run(env)
>>> env.x
'HELLO'
>>> Query('test', 1, 2, 3).run(env)
Traceback (most recent call last):
...
QueryError: unknown query 'test'
"""
try :
handler = getattr(self, "_run_%s" % self._name)
except AttributeError :
raise QueryError("unknown query %r" % self._name)
self._envt = envt
larg = tuple(a.run(envt) if isinstance(a, self.__class__) else a
for a in self._larg)
karg = dict((n, v.run(envt) if isinstance(v, self.__class__) else v)
for n, v in self._karg.items())
try :
return handler(*larg, **karg)
except TypeError :
cls, val, tb = sys.exc_info()
try :
fun, msg = str(val).strip().split("()", 1)
except :
raise val
if fun.startswith("_run_") and hasattr(self, fun) :
raise TypeError(fun[5:] + "()" + msg)
raise val
def _get_object (self, path) :
obj = self._envt
for n in path :
obj = getattr(obj, n)
return obj
def _run_set (self, name, value) :
"""
>>> import imp
>>> env = imp.new_module('environment')
>>> Query('set', 'x', 1).run(env)
>>> env.x
1
"""
path = name.split(".")
setattr(self._get_object(path[:-1]), path[-1], value)
def _run_get (self, name) :
"""
>>> import imp
>>> env = imp.new_module('environment')
>>> env.x = 2
>>> Query('get', 'x').run(env)
2
"""
path = name.split(".")
return self._get_object(path)
def _run_del (self, name) :
"""
>>> import imp
>>> env = imp.new_module('environment')
>>> env.x = 2
>>> Query('del', 'x').run(env)
>>> env.x
Traceback (most recent call last):
...
AttributeError: 'module' object has no attribute 'x'
"""
path = name.split(".")
delattr(self._get_object(path[:-1]), path[-1])
def _run_call (self, fun, *larg, **karg) :
"""
>>> import imp
>>> env = imp.new_module('environment')
>>> env.x = 'hello'
>>> Query('call', 'x.center', 7).run(env)
' hello '
>>> env.__dict__.update(__builtins__)
>>> Query('call', Query('call', 'getattr',
... Query('call', 'x.center', 7),
... 'upper')).run(env)
' HELLO '
"""
if isinstance(fun, str) :
fun = self._get_object(fun.split("."))
return fun(*larg, **karg)
@plugin("snakes.nets")
def extend (module) :
class UDPServer (object) :
def __init__ (self, port, size=2**20, verbose=0) :
self._size = size
self._verbose = verbose
self._sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
self._sock.bind(("", port))
self._env = imp.new_module("snk")
self._env.__dict__.update(__builtins__)
self._env.__dict__.update(operator.__dict__)
self._env.__dict__.update(module.__dict__)
def recvfrom (self) :
return self._sock.recvfrom(self._size)
def sendto (self, data, address) :
self._sock.sendto(data.strip() + "\n", address)
def run (self) :
while True :
data, address = self.recvfrom()
data = data.strip()
if self._verbose :
print("# query from %s:%u" % address)
try :
if self._verbose > 1 :
print(data)
res = loads(data).run(self._env)
if res is None :
res = Tree("answer", None, status="ok")
else :
res = Tree("answer", None, Tree.from_obj(res),
status="ok")
except :
cls, val, tb = sys.exc_info()
res = Tree("answer", str(val).strip(),
error=cls.__name__, status="error")
if self._verbose > 1 :
print("# error")
for entry in traceback.format_exception(cls, val, tb) :
for line in entry.splitlines() :
print("## %s" % line)
if self._verbose :
if self._verbose > 1 :
print("# answer")
print(res.to_pnml())
elif res["status"] == "error" :
print("# answer: %s: %s" % (res["error"], res.data))
else :
print("# answer: %s" % res["status"])
self.sendto(res.to_pnml(), address)
class TCPServer (UDPServer) :
def __init__ (self, port, size=2**20, verbose=0) :
self._size = size
self._verbose = verbose
self._sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
self._sock.bind(("", port))
self._sock.listen(1)
self._env = imp.new_module("snk")
self._env.__dict__.update(__builtins__)
self._env.__dict__.update(operator.__dict__)
self._env.__dict__.update(module.__dict__)
self._connection = {}
def recvfrom (self) :
connection, address = self._sock.accept()
self._connection[address] = connection
parts = []
while True :
parts.append(connection.recv(self._size))
if len(parts[-1]) < self._size :
break
return "".join(parts), address
def sendto (self, data, address) :
self._connection[address].send(data.rstrip() + "\n")
self._connection[address].close()
del self._connection[address]
return Query, UDPServer, TCPServer