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# Studies for using difflib on structures
from difflib import SequenceMatcher
from hashable import HashableNodeImpl
from pprint import pprint
import sys
__docformat__ = 'reStructuredText'
aI = ( 1, 2, 3, 5, 6, 7, )
bI = ( 2, 3, 4, 8, 6 )
sm = SequenceMatcher(None, aI, bI)
# print(sm.find_longest_match(0, len(aI), 0, len(bI)))
# print(sm.get_matching_blocks())
# print(list(sm.get_grouped_opcodes(0))) # Useful for context diffs
# print(sm.get_opcodes()) # The way to go
class TreeNode(object):
tag = None
children = ( )
def __init__(self, tag, children=( )):
self.tag = tag
self.children = children
class HashableTreeNodeImpl(HashableNodeImpl):
def __init__(self):
super(self.__class__, self).__init__(TreeNode)
def rootHash(self, node):
return hash(node.tag)
def childHash(self, node):
"""Return a hash for the children only. Subclasses should override
this."""
return hash(node)
def rootEq(self, node, other):
return type(node) == type(other) and node.tag == other.tag
def childEq(self, node, other):
return node == other
def getChildren(self, node):
return node.children
# To generate a diff tree:
#
# * ``equal`` opcodes need a copy
#
# * ``insert`` and ``delete`` opcodes must be processed as such
#
# * ``replace`` opcodes need to be analyzed recursively to find a
# minimal set of changes
def resolveDeepReplace(hashableNodeImpl, opcodes, a, b):
"""Resolves ``replace`` elements in `opcodes` pertaining to `a` and
`b`. Returns opcodes including nested elements for these cases.
`hashableNodeImpl` is the `HashableNodeImpl` used to control the hashable
feature."""
result = [ ]
for i in xrange(len(opcodes)):
( opcode, aBeg, aEnd, bBeg, bEnd ) = opcodes[i]
if opcode != 'replace':
result.append(opcodes[i])
continue
try:
hashableNodeImpl.pushRootOnly(True)
sm = SequenceMatcher(None, a[aBeg:aEnd], b[bBeg:bEnd])
rootOpcodes = sm.get_opcodes()
for j in xrange(len(rootOpcodes)):
( subOpcode, aSubBeg, aSubEnd, bSubBeg, bSubEnd ) = rootOpcodes[j]
if subOpcode != 'equal':
result.append(( subOpcode, aBeg + aSubBeg, aBeg + aSubEnd,
bBeg + bSubBeg, bBeg + bSubEnd, ))
else:
for k in xrange(aSubEnd - aSubBeg):
aIdx = aBeg + aSubBeg + k
bIdx = bBeg + bSubBeg + k
result.append(('descend',
aIdx, aIdx + 1, bIdx, bIdx + 1,
resolveRootEqual(hashableNodeImpl,
a[aIdx], b[bIdx]), ))
finally:
hashableNodeImpl.popRootOnly()
return result
def resolveRootEqual(hashableNodeImpl, aElem, bElem):
"""Considers children of `aElem` and `bElem` which have equal roots.
Returns opcodes for the children. `hashableNodeImpl` is the
`HashableNodeImpl` used to control the hashable feature."""
a = hashableNodeImpl.getChildren(aElem)
b = hashableNodeImpl.getChildren(bElem)
try:
hashableNodeImpl.pushRootOnly(False)
sm = SequenceMatcher(None, a, b)
nestedOpcodes = sm.get_opcodes()
return resolveDeepReplace(hashableNodeImpl, nestedOpcodes, a, b)
finally:
hashableNodeImpl.popRootOnly()
hashableNodeImpl = HashableTreeNodeImpl()
aT = ( TreeNode('first'),
TreeNode('second', (
TreeNode('second.first'),
TreeNode('second.second'),
)),
TreeNode('third', (
TreeNode(2),
)),
TreeNode('fourth'),
)
bT = ( TreeNode('first'),
TreeNode('second', (
TreeNode('second.first', (
TreeNode('second.first.first'),
)),
TreeNode('second.second1'),
TreeNode('second.second'),
)),
TreeNode('second1', (
TreeNode(2),
)),
TreeNode('third', (
TreeNode(2),
)),
TreeNode('fourth1'),
)
sm = SequenceMatcher(None, aT, bT)
top = sm.get_opcodes()
pprint(top)
print('---')
# Use a pseudo root
pprint(resolveRootEqual(hashableNodeImpl,
TreeNode(None, aT), TreeNode(None, bT)),
sys.stdout, 2, 40, None)
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