swap_rename_select working

git-svn-id: http://galileo.dmi.unict.it/svn/relational/trunk@161 014f5005-505e-4b48-8d0a-63407b615a7c

relational/optimizations.py

@@ -168,6 +168,46 @@ def subsequent_renames(n):
         changes+=subsequent_renames(n.left)
     return changes
 
+def tokenize_select(expression):
+    '''This function returns the list of tokens present in a
+    selection. The expression can't contain parenthesis.'''
+    op=('//=','**=','and','not','//','**','<<','>>','==','!=','>=','<=','+=','-=','*=','/=','%=','or','+','-','*','/','&','|','^','~','<','>','%','=')
+    tokens=[]
+    temp=""
+    
+    while len(expression)!=0:
+        expression=expression.strip()
+        if expression[0:3] in op:#3char op
+            tokens.append(temp)
+            temp=""
+            tokens.append(expression[0:3])
+            expression=expression[3:]
+        elif expression[0:2] in op:#2char op
+            tokens.append(temp)
+            temp=""
+            tokens.append(expression[0:2])
+            expression=expression[2:]
+        elif expression[0:1] in op:#1char op
+            tokens.append(temp)
+            temp=""
+            tokens.append(expression[0:1])
+            expression=expression[1:]
+        elif expression[0:1]=="'":#Quote
+            end=expression.index("'",1)
+            while expression[end-1]=="\\":
+                end=expression.index("'",end+1)
+            
+            #Add string to list
+            tokens.append(expression[0:end+1])
+            expression=expression[end+1:]
+        else:
+            temp+=expression[0:1]
+            expression=expression[1:]
+            pass
+    if len(temp)!=0:
+        tokens.append(temp)
+    return tokens
+
 def swap_rename_select(n):
     '''This function locates things like σ k(ρ j(R)) and replaces
     them with ρ j(σ k(R)). Renaming the attributes used in the
@@ -175,6 +215,35 @@ def swap_rename_select(n):
     #TODO document into the wiki
     changes=0
     
+    if n.name=='σ' and n.child.name=='ρ':
+        
+        #Dictionary containing attributes of rename
+        _vars={}
+        for i in n.child.prop.split(','):
+            q=i.split('➡')
+            _vars[q[1].strip()]=q[0].strip()
+        
+        #tokenizes expression in select
+        _tokens=tokenize_select(n.prop)
+        print _tokens, _vars
+        
+        #Renaming stuff
+        for i in range(len(_tokens)):
+            if _tokens[i] in _vars:
+                _tokens[i]=_vars[_tokens[i]]
+        print _tokens, _vars
+        
+        n.name='ρ'
+        n.child.name='σ'
+        
+        n.prop=n.child.prop
+        n.child.prop=""
+        for i in _tokens:
+            n.child.prop+=i+ " "
+        
+        
+        pass
+    
     #recoursive scan
     if n.kind==optimizer.UNARY:        
         changes+=swap_rename_select(n.child)

relational/optimizer.py

@@ -194,7 +194,7 @@ if __name__=="__main__":
     #a=tokenize("(a-b*c)*(b-c)")
     #print tree("σ i==2 (c ᑌ d - (aᑎb))") == tree("σ i==3 (c ᑌ d - (aᑎb))")
         
-    a=general_optimize("σ age==3(ρ ciccio➡age,nome➡nom(R))")
+    a=general_optimize("σ age==3 and qq<=2 or nome!='ciccio d\\'urso'(ρ ciccio➡age,nome➡nom(R))")
     #a=general_optimize("σ i==2 (σ b>5 (d))")
     print a
     #print node(a)