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relational
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Styled code

master
Salvo 'LtWorf' Tomaselli 2016-01-03 16:55:10 +07:00
parent d384a902cf
commit 17410a0b19
1 changed files with 19 additions and 28 deletions
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47
relational/optimizations.py
Unescape Escape View File

@ -156,7 +156,9 @@ def futile_union_intersection_subtraction(n):
replace_node(n, n.right)
# Subtraction and selection of the same thing
elif (n.name == DIFFERENCE and (n.right.name == SELECTION and n.right.child == n.left)): # Subtraction of two equal things, but one has a selection
elif n.name == DIFFERENCE and \
n.right.name == SELECTION and \
n.right.child == n.left:
n.name = n.right.name
n.kind = n.right.kind
n.child = n.right.child
@ -164,7 +166,7 @@ def futile_union_intersection_subtraction(n):
n.left = n.right = None
# Subtraction of the same thing or with selection on the left child
elif (n.name == DIFFERENCE and ((n.left == n.right) or (n.left.name == SELECTION and n.left.child == n.right))): # Empty relation
elif n.name == DIFFERENCE and (n.left == n.right or (n.left.name == SELECTION and n.left.child == n.right)):
changes = 1
n.kind = parser.UNARY
n.name = SELECTION
@ -291,16 +293,11 @@ def futile_renames(n):
value = _vars.get(key)
if key == value:
_vars.pop(value) # Removes the unused one
# Reset prop var
n.prop = ""
# Generates new prop var
for i in _vars.items():
n.prop += u"%s%s%s," % (i[0], ARROW, i[1])
n.prop = n.prop[:-1] # Removing ending comma
if len(n.prop) == 0: # Nothing to rename, removing the rename op
if len(_vars) == 0: # Nothing to rename, removing the rename op
replace_node(n, n.child)
else:
n.prop = ','.join('%s%s%s' % (i[0], ARROW, i[1]) for i in _vars.items())
return changes + recoursive_scan(futile_renames, n)
@ -313,7 +310,7 @@ def subsequent_renames(n):
futile_renames(n)
changes = 0
if n.name == RENAME and n.child.name == n.name:
if n.name == RENAME and n.child.name == RENAME:
# Located two nested renames.
changes = 1
# Joining the attribute into one
@ -338,16 +335,10 @@ def subsequent_renames(n):
_vars.pop(value) # Removes the unused one
_vars.pop(key) # Removes the unused one
# Reset prop var
n.prop = ""
# Generates new prop var
for i in _vars.items():
n.prop += u"%s%s%s," % (i[0], ARROW, i[1])
n.prop = n.prop[:-1] # Removing ending comma
if len(n.prop) == 0: # Nothing to rename, removing the rename op
if len(_vars) == 0: # Nothing to rename, removing the rename op
replace_node(n, n.child)
else:
n.prop = ','.join('%s%s%s' % (i[0], ARROW, i[1]) for i in _vars.items())
return changes + recoursive_scan(subsequent_renames, n)
@ -419,10 +410,8 @@ def swap_rename_projection(n):
if i not in _pr_reborn:
_vars.pop(i)
n.name = n.child.name
n.prop = ''
for i in _vars.keys():
n.prop += u'%s%s%s,' % (_vars[i], ARROW, i)
n.prop = n.prop[:-1]
n.prop = ','.join('%s%s%s' % (i[1], ARROW, i[0]) for i in _vars.items())
n.child.name = PROJECTION
n.child.prop = ''
@ -465,9 +454,7 @@ def swap_rename_select(n):
n.child.name = SELECTION
n.prop = n.child.prop
n.child.prop = ''
for i in _tokens:
n.child.prop += i + ' '
n.child.prop = ' '.join(_tokens)
return changes + recoursive_scan(swap_rename_select, n)
@ -477,7 +464,10 @@ def select_union_intersect_subtract(n):
and replaces them with σ (i OR q) (a)
Removing a O(n²) operation like the union'''
changes = 0
if n.name in (UNION, INTERSECTION, DIFFERENCE) and n.left.name == SELECTION and n.right.name == SELECTION and n.left.child == n.right.child:
if n.name in {UNION, INTERSECTION, DIFFERENCE} and \
n.left.name == SELECTION and \
n.right.name == SELECTION and \
n.left.child == n.right.child:
changes = 1
d = {UNION: 'or', INTERSECTION: 'and', DIFFERENCE: 'and not'}
@ -544,6 +534,7 @@ def union_and_product(n):
changes = 1
return changes + recoursive_scan(union_and_product, n)
def projection_and_union(n, rels):
'''
Turns