"""Interface to xsdbXML functionality.
This module is somewhat experimental.
To use this module you need the
xsdbXML package available from http://xsdb.sourceforge.net
installed.
As illustrated in the test function below you can "mount" an
xsdb context into a gadfly database, for example, as follows
connection = database.gadfly()
connection.startup("dummy", "dummy", 1) # scratch database
# map in S (suppliers table) from athos.rutgers.edu.
viewXSDB(connection, "S", ["snum", "sname", "status", "city"],
'<consult href="http://athos.rutgers.edu/~aaron/supplier.xsdb"/>')
cursor = connection.cursor()
cursor.execute("select * from s")
print cursor.pp()
cursor.execute("select * from s where city='London'")
print cursor.pp()
Using this facility a gadfly database may query remote relations in xml
format, among other possibilities.
"""
#import store, string
from gadfly import store,database,semantics
from gadfly.semantics import kjbuckets
import string, types
def viewXSDB(connection, name, namelist, assertionText, semijoin=True):
theview = XSDBView(name, namelist, assertionText)
connection.add_remote_view(name, theview)
class XSDBView(store.View):
def __init__(this, name, namelist, text, semijoin=True):
this.semijoin = semijoin
this.name = name
this.namelist = namelist
this.XSDBtext = text
capsToNames = {}
uppers = [ (string.upper(n), n) for n in namelist ]
this.mapUpper = kjbuckets.kjDict(uppers)
this.mapUpper.Wash()
def __repr__(this):
return "xsdb view %s on %s as %s" % (this.name, this.namelist, this.XSDBtext)
irepr = __repr__
def attributes(this):
return map(string.upper, this.namelist)
def relbind(self, db, atts):
return self
def rows(this, andseqs=0, assignment=None, transform=None, subseq=None):
from xsdbXMLpy import interp
#print "assignment", assignment
#print "transform", transform
#print "subseq", subseq
result = []
# compute the rows by evaluating the text...
# simple case: just make a query and map the results
mapUpper = this.mapUpper
invUpper = ~mapUpper
namelist = this.namelist
uppernamelist = invUpper.dump(namelist)
nnames = len(namelist)
namestring = string.join(namelist)
if not this.semijoin or subseq is None:
# simple case: just make a query and map the results
theQuery = """
<query names="%s">
<select names="%s">
%s
</select>
</query>
""" % ( namestring, namestring, this.XSDBtext )
else:
# complicated case: make a query with a semijoin
invTransform = ~transform
#print "invTransform is", invTransform
fullTransform = invUpper * invTransform
#print "fullTranform is", fullTransform
transformedSubseq = []
transformedAssignment = invUpper * assignment
for s in subseq:
t = s.remap(fullTransform)
#print "t is", t
if t is not None:
t = t+transformedAssignment
if t.Clean():
#print "transformed t", t
transformedSubseq.append(t)
disj = disjunction(transformedSubseq)
theQuery = """
<query names="%s">
<select names="%s">
<and>
%s
%s
</and>
</select>
</query>
""" % ( namestring, namestring, disj, this.XSDBtext )
#print "thequery", theQuery
q = interp.Query(theQuery)
#print "result", q.stringResult()
for t in q.tuples():
if nnames<1:
d = kjbuckets.kjDict()
elif nnames==1:
d = kjbuckets.kjDict()
d[ string.upper(namelist[0]) ] = t[0]
else:
d = kjbuckets.kjUndump(uppernamelist, t)
#print "appending", d
result.append(d)
if andseqs:
return (result, range(len(result)))
else:
return result
def atom(name, value):
tv = type(value)
if tv is types.StringType:
return '<s at="%s">%s</s>' % (name, value)
elif tv is types.IntType:
return '<i at="%s">%s</i>' % (name, value)
elif tv is types.FloatType:
return '<f at="%s">%s</f>' % (name, value)
else:
raise ValueError, "don't know what to do with "+repr((name, tv, value))
def conjunction(D):
if not D:
return "<anything/>"
keys = D.keys()
if len(keys)==1:
k = keys[0]
return atom(k, D[k])
keys.sort()
L = []
for k in keys:
L.append(atom(k, D[k]))
return "<and> %s </and>" % string.join(L)
def disjunction(L):
L2 = map(conjunction, L)
if not L2:
return "<nothing/>"
if len(L2)==1:
return L2[0]
L2.insert(0, "<or>")
L2.append("</or>")
return string.join(L2, "\n")
def test0():
#import database
connection = database.gadfly()
connection.startup("dummy", "dummy", 1) # scratch database
#print connection.database
viewXSDB(connection, "X", ["a", "b"], """
<or>
<and> <i at="a">1</i> <i at="b">1</i> </and>
<and> <i at="a">2</i> <i at="b">1</i> </and>
<and> <i at="a">1</i> <i at="b">2</i> </and>
<and> <i at="a">2</i> <i at="b">2</i> </and>
</or>
""")
viewXSDB(connection, "S", ["snum", "sname", "status", "city"],
'<consult href="http://athos.rutgers.edu/~aaron/supplier.xsdb"/>')
cursor = connection.cursor()
cursor.execute("select a,b from x where b=1")
print cursor.pp()
cursor.execute("select * from s")
print cursor.pp()
cursor.execute("select * from s where city='London'")
print cursor.pp()
if __name__=="__main__":
test0()
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