Selection can now accept expressions with parenthesis

git-svn-id: http://galileo.dmi.unict.it/svn/relational/trunk@196 014f5005-505e-4b48-8d0a-63407b615a7c

CHANGELOG

@@ -87,3 +87,4 @@
 - Implemented swap_rename_projection general optimization
 - Replaced old relational algebra to python compiler with new one based on the new tokenizer/parser (Rev 188)
 - Code refactory to move the new parser into parser.py out of optimizer.py, that will still be compatible (Rev 190)
+- Selection can now accept expressions with parenthesis

relational/optimizations.py

@@ -31,6 +31,8 @@ A function will have to return the number of changes performed on the tree.
 '''
 
 import optimizer
+import parser
+sel_op=('//=','**=','and','not','in','//','**','<<','>>','==','!=','>=','<=','+=','-=','*=','/=','%=','or','+','-','*','/','&','|','^','~','<','>','%','=','(',')',',','[',']')
 
 def replace_node(replace,replacement):
     '''This function replaces "replace" node with the node "with",
@@ -287,44 +289,82 @@ def subsequent_renames(n):
 
     return changes+recoursive_scan(subsequent_renames,n)
 
+class level_string(str):
+    level=0
+
 def tokenize_select(expression):
     '''This function returns the list of tokens present in a
-    selection. The expression can't contain parenthesis.'''
+    selection. The expression can contain parenthesis.
-    op=('//=','**=','and','not','//','**','<<','>>','==','!=','>=','<=','+=','-=','*=','/=','%=','or','+','-','*','/','&','|','^','~','<','>','%','=')
+    It will use a subclass of str with the attribute level, which
+    will specify the nesting level of the token into parenthesis.'''
+    
+    l=0
+    while l!=len(expression):
+        l=len(expression)
+        if expression.startswith('(') and parser.find_matching_parenthesis(expression)+1==len(expression):
+            expression= expression[1:-1]
+    
     tokens=[]
     temp=''
+    level=0
     
     while len(expression)!=0:
         expression=expression.strip()
-        if expression[0:3] in op:#3char op
+        
-            tokens.append(temp)
+        if expression[0:1]=='(': #Expression into parenthesis
+            level+=1
+        elif expression[0:1]==')':
+            level-=1
+        
+        if expression[0:3] in sel_op:#3char op
+            t=level_string(temp)
+            t.level=level
+            tokens.append(t)
             temp=''
-            tokens.append(expression[0:3])
+            t=level_string(expression[0:3])
+            t.level=level            
+            tokens.append(t)
             expression=expression[3:]
-        elif expression[0:2] in op:#2char op
+        elif expression[0:2] in sel_op:#2char op
-            tokens.append(temp)
+            t=level_string(temp)
+            t.level=level
+            tokens.append(t)
             temp=''
-            tokens.append(expression[0:2])
+            t=level_string(expression[0:2])
+            t.level=level
+            tokens.append(t)
             expression=expression[2:]
-        elif expression[0:1] in op:#1char op
+        elif expression[0:1] in sel_op:#1char op
-            tokens.append(temp)
+            t=level_string(temp)
+            t.level=level
+            tokens.append(t)
             temp=''
-            tokens.append(expression[0:1])
+            t=level_string(expression[0:1])
+            t.level=level
+            tokens.append(t)
             expression=expression[1:]
         elif expression[0:1]=="'":#String
             end=expression.index("'",1)
             while expression[end-1]=='\\':
                 end=expression.index("'",end+1)
-            
             #Add string to list
-            tokens.append(expression[0:end+1])
+            t=level_string(expression[0:end+1])
+            t.level=level
+            tokens.append(t)
             expression=expression[end+1:]
         else:
             temp+=expression[0:1]
             expression=expression[1:]
             pass
     if len(temp)!=0:
-        tokens.append(temp)
+        t=level_string(temp)
+        t.level=level
+        tokens.append(t)
+    while True:
+        try:
+            tokens.remove('')
+        except:
+            break
     return tokens
 
 def swap_rename_projection(n):
@@ -425,7 +465,7 @@ def selection_and_product(n,rels):
         temp=[]
         
         for i in tokens:
-            if i=='and':
+            if i=='and' and i.level==0:
                 groups.append(temp)
                 temp=[]
             else:
@@ -442,7 +482,7 @@ def selection_and_product(n,rels):
             l_fields=False #has fields in left?
             r_fields=False #has fields in left?
             
-            for j in i:
+            for j in set(i).difference(sel_op):
                 j=j.split('.')[0]
                 if j in l_attr:#Field in left
                     l_fields=True
@@ -473,6 +513,8 @@ def selection_and_product(n,rels):
                     l_node.prop+=i+ ' '
                 if len(left)>0:
                     l_node.prop+=' and '
+            if '(' in l_node.prop:
+                l_node.prop='(%s)' % l_node.prop
         
         #Preparing right selection
         if len(right)>0:
@@ -489,7 +531,8 @@ def selection_and_product(n,rels):
                     r_node.prop+=i+ ' '
                 if len(right)>0:
                     r_node.prop+=' and '
-                    
+            if '(' in r_node.prop:
+                r_node.prop='(%s)' % r_node.prop
         #Changing main selection
         n.prop=''
         if len(both)!=0:
@@ -499,6 +542,8 @@ def selection_and_product(n,rels):
                     n.prop+=i+ ' '
                 if len(both)>0:
                     n.prop+=' and '
+            if '(' in n.prop:
+                n.prop='(%s)' % n.prop
         else:#No need for general select
             replace_node(n,n.child)
             
@@ -506,3 +551,4 @@ def selection_and_product(n,rels):
         
 general_optimizations=[duplicated_select,down_to_unions_subtractions_intersections,duplicated_projection,selection_inside_projection,subsequent_renames,swap_rename_select,futile_union_intersection_subtraction,swap_union_renames,swap_rename_projection]
 specific_optimizations=[selection_and_product]
+        

relational/parser.py

@@ -36,16 +36,17 @@ class node (object):
     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.'''
+    the string with the props of the operation.
+    
+    This class is used to convert an expression into python code.'''
     kind=None
     
     def __init__(self,expression=None):
-        
+        '''Generates the tree from the tokenized expression
+        If no expression is specified then it will create an empty node'''
         if expression==None or len(expression)==0:
             return
         
-        '''Generates the tree from the tokenized expression'''
-        
         #If the list contains only a list, it will consider the lower level list.
         #This will allow things like ((((((a))))) to work
         while len(expression)==1 and isinstance(expression[0],list): 
@@ -85,7 +86,8 @@ class node (object):
                 return       
         pass
     def toPython(self):
-        '''This method converts the expression into python code'''
+        '''This method converts the expression into python code, which will require the
+        relation module to be executed.'''
         if self.name in b_operators:
             return '%s.%s(%s)' % (self.left.toPython(),op_functions[self.name],self.right.toPython())
         elif self.name in u_operators:
@@ -136,10 +138,6 @@ class node (object):
             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
@@ -168,6 +166,19 @@ class node (object):
                 
             return (le+ self.name +re)
 
+def find_matching_parenthesis(expression,start=0):
+    '''This function returns the position of the matching
+    close parenthesis to the 1st open parenthesis found
+    starting from start (0 by default)'''
+    par_count=0 #Count of parenthesis
+    for i in range(start,len(expression)):
+        if expression[i]=='(':
+            par_count+=1
+        elif expression[i]==')':
+            par_count-=1
+            if par_count==0:
+                return i #Closing parenthesis of the parameter
+
 def tokenize(expression):
     '''This function converts an expression into a list where
     every token of the expression is an item of a list. Expressions into
@@ -198,17 +209,7 @@ def tokenize(expression):
     while len(expression)>0:
         if expression.startswith('('): #Parenthesis state
             state=2
-            par_count=0 #Count of parenthesis
+            end=find_matching_parenthesis(expression)
-            end=0
-            
-            for i in range(len(expression)):
-                if expression[i]=='(':
-                    par_count+=1
-                elif expression[i]==')':
-                    par_count-=1
-                    if par_count==0:
-                        end=i
-                        break
             #Appends the tokenization of the content of the parenthesis
             items.append(tokenize(expression[1:end]))
             #Removes the entire parentesis and content from the expression
@@ -217,9 +218,13 @@ def tokenize(expression):
         elif expression.startswith("σ") or expression.startswith("π") or expression.startswith("ρ"): #Unary 2 bytes
             items.append(expression[0:2]) #Adding operator in the top of the list
             expression=expression[2:].strip() #Removing operator from the expression
-            par=expression.find('(')
             
-            items.append(expression[:par]) #Inserting parameter of the operator
+            if expression.startswith('('): #Expression with parenthesis, so adding what's between open and close without tokenization
+                par=expression.find('(',find_matching_parenthesis(expression)) 
+            else: #Expression without parenthesis, so adding what's between start and parenthesis as whole  
+                par=expression.find('(')
+            
+            items.append(expression[:par].strip()) #Inserting parameter of the operator
             expression=expression[par:].strip() #Removing parameter from the expression
         elif expression.startswith("*") or expression.startswith("-"): # Binary 1 byte
             items.append(expression[0])
@@ -291,4 +296,3 @@ if __name__=="__main__":
     while True:
         e=raw_input("Expression: ")
         print parse(e)
-        

relational/rtypes.py

@@ -1,3 +1,4 @@
+# -*- coding: utf-8 -*-
 # Relational
 # Copyright (C) 2008  Salvo "LtWorf" Tomaselli
 # 
@@ -16,7 +17,9 @@
 # 
 # author Salvo "LtWorf" Tomaselli <tiposchi@tiscali.it>
 
-'''Custom types for relational algebra'''
+'''Custom types for relational algebra.
+Purpose of this module is having the isFloat function and
+implementing dates to use in selection.'''
 
 import datetime