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modified tree. Now it is able to return the fields that an operation will return 

git-svn-id: http://galileo.dmi.unict.it/svn/relational/trunk@163 014f5005-505e-4b48-8d0a-63407b615a7c
master
LtWorf 2009-05-12 12:36:01 +07:00
parent e35b85e534
commit ccc8a5ee0d
2 changed files with 79 additions and 13 deletions
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17
relational/optimizations.py
Unescape Escape View File

@ -173,28 +173,28 @@ def tokenize_select(expression):
selection. The expression can't contain parenthesis.'''
op=('//=','**=','and','not','//','**','<<','>>','==','!=','>=','<=','+=','-=','*=','/=','%=','or','+','-','*','/','&','|','^','~','<','>','%','=')
tokens=[]
temp=""
temp=''
while len(expression)!=0:
expression=expression.strip()
if expression[0:3] in op:#3char op
tokens.append(temp)
temp=""
temp=''
tokens.append(expression[0:3])
expression=expression[3:]
elif expression[0:2] in op:#2char op
tokens.append(temp)
temp=""
temp=''
tokens.append(expression[0:2])
expression=expression[2:]
elif expression[0:1] in op:#1char op
tokens.append(temp)
temp=""
temp=''
tokens.append(expression[0:1])
expression=expression[1:]
elif expression[0:1]=="'":#Quote
elif expression[0:1]=="'":#String
end=expression.index("'",1)
while expression[end-1]=="\\":
while expression[end-1]=='\\':
end=expression.index("'",end+1)
#Add string to list
@ -231,13 +231,14 @@ def swap_rename_select(n):
if _tokens[i] in _vars:
_tokens[i]=_vars[_tokens[i]]
#Swapping operators
n.name='ρ'
n.child.name='σ'
n.prop=n.child.prop
n.child.prop=""
n.child.prop=''
for i in _tokens:
n.child.prop+=i+ " "
n.child.prop+=i+ ' '
#recoursive scan
if n.kind==optimizer.UNARY:

75
relational/optimizer.py
Unescape Escape View File

@ -31,12 +31,26 @@ u_operators=('π','σ','ρ')
class node (object):
'''This class is a node of a relational expression. Leaves are relations and internal nodes are operations.'''
'''This class is a node of a relational expression. Leaves are relations and internal nodes are operations.
The kind property says if the node is a binary operator, unary operator or relation.
Since relations are leaves, a relation node will have no attribute for children.
If the node is a binary operator, it will have left and right properties.
If the node is a unary operator, it will have a child, pointing to the child node and a prop containing
the string with the props of the operation.
It can be helpful to know the fields returned by an operation. Providing a dictionary with names and instances
of relations in the constructor, the node is able to return the list of fields that the result will have.
'''
kind=None
def __init__(self,expression=None):
if expression==None or len(expression)==0:
return
'''Generates the tree from the tokenized expression'''
while len(expression)==1 and isinstance(expression[0],list): #We have a list, removing
expression=expression[0]
@ -61,6 +75,46 @@ class node (object):
return
pass
def result_format(self,rels):
'''This function returns a list containing the fields that the resulting relation will have.
Since it needs to know real instances of relations, it requires a dictionary where keys are
the names of the relations and the values are the relation objects.'''
print "Rels========",rels
if rels==None:
return
if self.kind==RELATION:
return rels[self.name].header.attributes
elif self.kind==BINARY and self.name in ('-','ᑌ','ᑎ'):
print "OK"
return self.left.result_format(rels)
elif self.name=='π':
l=[]
for i in self.prop.split(','):
l.append(i.strip())
return l
elif self.name=='*':
return self.left.result_format(rels)+self.right.result_format(rels)
elif self.name=='σ' :
return self.child.result_format(rels)
elif self.name=='ρ':
_vars={}
for i in n.prop.split(','):
q=i.split('➡')
_vars[q[0].strip()]=q[1].strip()
_fields=self.child.result_format(rels)
for i in range(len(_fields)):
if _fields[i] in _vars:
_fields[i]=_vars[_fields[i]]
return _fields
elif self.name in ('ᐅᐊ','ᐅLEFTᐊ','ᐅRIGHTᐊ','ᐅFULLᐊ'):
return list(set(self.left.result_format(rels)).union(set(self.right.result_format(rels))))
pass
def __eq__(self,other):
if not (isinstance(other,node) and self.name==other.name and self.kind==other.kind):
return False
@ -185,17 +239,28 @@ def general_optimize(expression):
if __name__=="__main__":
#n=node(u"((a ᑌ b) - c ᑌ d) - b")
#n=node(u"((((((((((((2)))))))))))) - (3 * 5) - 2")
#n=node(u"π a,b (d-a*b)")
#print n.__str__()
#a= tokenize("(a - (a ᑌ b) * π a,b (a-b)) - ρ 123 (a)")
#a= tokenize(u"π a,b (a*b)")
#a=tokenize("(a-b*c)*(b-c)")
#print tree("σ i==2 (c ᑌ d - (aᑎb))") == tree("σ i==3 (c ᑌ d - (aᑎb))")
import relation
rels={}
rels["P1"]= relation.relation("/home/salvo/dev/relational/trunk/samples/people.csv")
rels["P2"]= relation.relation("/home/salvo/dev/relational/trunk/samples/people.csv")
rels["R1"]= relation.relation("/home/salvo/dev/relational/trunk/samples/person_room.csv")
rels["R2"]= relation.relation("/home/salvo/dev/relational/trunk/samples/person_room.csv")
print rels
#n=tree("π indice,qq,name (ρ age➡qq,id➡indice (P1-P2))")
n=tree("P1 ᐅᐊ R2")
print n
print n.result_format(rels)
a=general_optimize("σ age==3 and qq<=2 or nome!='ciccio d\\'urso'(ρ ciccio➡age,nome➡nom(R-Q))")
#a=general_optimize("σ age==3 and qq<=2 or nome!='ciccio d\\'urso'(ρ ciccio➡age,nome➡nom(R-Q))")
#a=general_optimize("σ i==2 (σ b>5 (d))")
print a
#print a
#print node(a)
#print tokenize("(a)")