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refactored the LCS + made it more sutible for diffing...

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Signed-off-by: Alex A. Naanou <alex.nanou@gmail.com>
This commit is contained in:
Alex A. Naanou 2018-07-10 13:10:08 +03:00
parent 9c89adeea7
commit e7f8029948
1 changed files with 69 additions and 61 deletions
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130
diff.js
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@ -100,74 +100,81 @@ var _diff_item_order = function(diff, A, B, options, filter){
}
// get common chuncs...
// XXX add chunk offsets to results...
var getCommonSections =
function(A, B, a, b, min_chunk, cmp, index){
a = a || 0
b = b || 0
min_chunk = min_chunk || 2
// get common chuncs (LCS)...
var getCommonSections = function(A, B, cmp, min_chunk){
cmp = cmp || function(a, b){
return a === b || a == b }
index = index || []
return a === b || a == b ? a : false }
var index = index || []
// XXX do we actually need this???
min_chunk = min_chunk || 1
var _getCommonSections = function(a, b){
// index...
var res = (index[a] || [])[b]
if(res != null){
return res
}
// collect common chunk...
var l = 0
var chunk = {
A: a,
B: b,
chunk: [],
}
while(a+l < A.length && b+l < B.length){
var e = cmp(A[a+l], B[b+l])
if(!e){
break
}
chunk.chunk.push(e)
l++
}
// discard small chunks...
l = l < min_chunk ? 0 : l
// get next chunks...
var L = A.length > a+l + min_chunk ?
_getCommonSections(l+a+1, l+b)
: [0]
var R = B.length > b+l + min_chunk ?
_getCommonSections(l+a, l+b+1)
: [0]
// select the best chunk-set...
// NOTE: we maximize the number of elements in a chunk set then
// minimize the number of chunks per set...
var next = L[0] == R[0] ?
(L.length < R.length ? L : R)
: L[0] > R[0] ?
L
: R
var res =
// non-empty chunk and next...
next[0] > 0 && l > 0 ?
[l + next[0], chunk].concat(next.slice(1))
// non-empty chunk and empty next...
: l > 0 ?
[l, chunk]
// empty chunk...
: next
// index...
index[a] = index[a] || []
index[a][b] = res
// index...
var res = (index[a] || [])[b]
if(res != null){
return res
}
}
// get common chunk...
var l = 0
var chunk = []
while(a+l < A.length
&& b+l < B.length
&& cmp(A[a+l], B[b+l])){
chunk.push(A[a+l])
l++
}
// discard small chunks...
if(l < min_chunk){
chunk = []
l = 0
}
// get next chunks...
var L = A.length > a+l + min_chunk ?
getCommonSections(
A, B,
l+a+1, l+b,
min_chunk, cmp, index)
: [0]
var R = B.length > b+l + min_chunk ?
getCommonSections(
A, B,
l+a, l+b+1,
min_chunk, cmp, index)
: [0]
// select the best chunk-set...
// NOTE: we maximize the number of elements in a chunk set then
// minimize the number of chunks per set...
var next = L[0] == R[0] ?
(L.length < R.length ? L : R)
: L[0] > R[0] ?
L
: R
var res = next[0] > 0 && l > 0 ?
[l + next[0], chunk].concat(next.slice(1))
: l > 0 ?
[l, chunk]
: next
// index...
index[a] = index[a] || []
index[a][b] = res
return res
return _getCommonSections(0, 0)
}
// XXX
var getCommonSections2 = function(A, B, a, b, min_chunk, cmp){
a = a || 0
b = b || 0
@ -200,6 +207,7 @@ var makeIndex = function(L){
}, new Map()) }
// XXX
var getCommonSections3 = function(A, B){
var A_index = makeIndex(A)
var B_index = makeIndex(B)