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added 1st optimization

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git-svn-id: http://galileo.dmi.unict.it/svn/relational/trunk@135 014f5005-505e-4b48-8d0a-63407b615a7c
This commit is contained in:
LtWorf 2009-04-28 21:11:18 +00:00
parent 923ac12588
commit e898eed426
2 changed files with 19 additions and 4 deletions
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18
relational/optimizations.py
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@ -21,8 +21,22 @@
The list general_optimizations contains pointers to general functions, so they can be called The list general_optimizations contains pointers to general functions, so they can be called
within a cycle.''' within a cycle.'''
def duplicated_select(n): import optimizer
pass
def duplicated_select(n):
'''This function locates and deletes things like
σ a ( σ a(C)) and the ones like σ a ( σ b(C))'''
if n.name=='σ' and n.child.name=='σ':
if n.prop != n.child.prop: #Nested but different, joining them
n.prop = n.prop + " and " + n.child.prop
n.child=n.child.child
#recoursive scan
if n.kind==optimizer.UNARY:
duplicated_select(n.child)
elif n.kind==optimizer.BINARY:
duplicated_select(n.right)
duplicated_select(n.left)
return n
general_optimizations=[duplicated_select] general_optimizations=[duplicated_select]

5
relational/optimizer.py
View File

@ -174,6 +174,7 @@ def general_optimize(expression):
'''This function performs general optimizations. Means that it will not need to '''This function performs general optimizations. Means that it will not need to
know the fields used by the relations''' know the fields used by the relations'''
n=tree(expression) #Gets the tree n=tree(expression) #Gets the tree
print n
for i in optimizations.general_optimizations: for i in optimizations.general_optimizations:
n=i(n) #Performs the optimization n=i(n) #Performs the optimization
return n.__str__() return n.__str__()
@ -187,7 +188,7 @@ if __name__=="__main__":
#a= tokenize("(a - (a ᑌ b) * π a,b (a-b)) - ρ 123 (a)") #a= tokenize("(a - (a ᑌ b) * π a,b (a-b)) - ρ 123 (a)")
#a= tokenize(u"π a,b (a*b)") #a= tokenize(u"π a,b (a*b)")
#a=tokenize("(a-b*c)*(b-c)") #a=tokenize("(a-b*c)*(b-c)")
a=tokenize("((((((((a)))))))) * b -c ") a=general_optimize("σ b>5 ( σ a>2 (C)) * σ a>2 ( σ a>2 (C))")
print a print a
print node(a) #print node(a)
#print tokenize("(a)") #print tokenize("(a)")