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https://github.com/flynx/ImageGrid.git
synced 2025-10-31 03:10:07 +00:00
rewritten binSearch(...) impementation, still needs testing...
Signed-off-by: Alex A. Naanou <alex.nanou@gmail.com>
This commit is contained in:
parent
e7196b76e9
commit
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118
ui/data.js
118
ui/data.js
@ -86,8 +86,8 @@ function imageNameCmp(a, b, data){
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//
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// This will return:
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// - 0 if a is equal to position i
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// - -1 if a is less position i
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// - +1 if a is greater position i
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// - -1 if a is less than position i
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// - +1 if a is greater than position i
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//
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// NOTE: the signature is different from the traditional cmp(a, b) so as
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// to enable more complex comparisons involving adjacent elements
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@ -113,9 +113,15 @@ function cmp(a, i, lst){
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//
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// NOTE: this is here mostly to make debuging easy...
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function isBetween(a, i, lst){
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//console.log('>>>', a, i, lst)
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var b = lst[i]
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// special case: tail...
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if(i == lst.length-1 && a >= b){
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return 0
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}
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var c = lst[i+1]
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// hit...
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if(a == b || (a > b && a < c)){
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return 0
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@ -130,18 +136,8 @@ function isBetween(a, i, lst){
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// Basic liner search...
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function linSearch(target, lst, check, return_position, disable_direct_indexing){
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// XXX is this the correct default?
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check = check == null ? isBetween : check
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// special case: target in the list directly...
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if(disable_direct_indexing
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&& check(target, lst.indexOf(target), lst) == 0){
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return target
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}
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// special case: tail...
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if(check(target, lst.length-1, lst) >= 0){
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return lst[lst.length-1]
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}
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function linSearch(target, lst, check, return_position){
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check = check == null ? cmp : check
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for(var i=0; i < lst.length; i++){
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if(check(target, i, lst) == 0){
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@ -152,78 +148,88 @@ function linSearch(target, lst, check, return_position, disable_direct_indexing)
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// no hit...
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return return_position ? -1 : null
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}
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Array.prototype.linSearch = function(target, cmp){
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return linSearch(target, this, cmp, true)
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}
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// Basic binary search implementation...
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//
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// NOTE: this will return the object by default, to return position set
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// return_position to true.
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// NOTE: by default this will use isBetween as a predicate.
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// NOTE: this still depends on .indexOf(...), to disable set
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// disable_direct_indexing to true
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// XXX BUGGY
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// XXX this is a mess, needs revision...
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function binSearch(target, lst, check, return_position, disable_direct_indexing){
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// XXX is this the correct default?
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check = check == null ? isBetween : check
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// special case: target in the list directly...
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if(disable_direct_indexing
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&& check(target, lst.indexOf(target), lst) == 0){
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return target
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}
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// special case: tail...
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if(check(target, lst.length-1, lst) >= 0){
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return lst[lst.length-1]
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}
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// special case: head...
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var res = check(target, 0, lst)
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if(res == 0){
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return lst[0]
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} else if(res < 0){
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// no hit...
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return return_position ? -1 : null
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}
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// NOTE: by default this will use cmp as a predicate.
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function binSearch(target, lst, check, return_position){
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check = check == null ? cmp : check
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var h = 0
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var t = lst.length - 1
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var m, res
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var l = Math.ceil(lst.length/2)
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var i = l
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while(h <= t){
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m = Math.floor((h + t)/2)
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res = check(target, m, lst)
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while(l > 0){
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// XXX this is a hack -- should we reach 0 using floor(..) instead?
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l = l <= 1 ? 0 : Math.ceil(l/2)
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res = check(target, i, lst)
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// right branch...
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if(res > 0){
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i += l
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// left branch...
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// match...
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if(res == 0){
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return return_position ? m : lst[m]
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// below...
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} else if(res < 0){
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i -= l
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// hit...
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t = m - 1
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// above...
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} else {
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return return_position ? i : lst[i]
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h = m + 1
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}
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}
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// no hit...
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// no result...
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return return_position ? -1 : null
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}
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Array.prototype.binSearch = function(target, cmp){
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return binSearch(target, this, cmp, true)
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}
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function match(f0, f1){
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return function(){
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var a = f0.apply(f0, arguments)
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var b = f1.apply(f1, arguments)
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if(a != b){
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console.warn('Result mismatch: f0:'+a+' f1:'+b)
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}
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return a
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}
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}
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// Same as getImageBefore, but uses gids and searches in DATA...
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//
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// NOTE: this uses it's own predicate...
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function getGIDBefore(gid, ribbon, search){
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search = search == null ? linSearch : search
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search = search == null ? binSearch : search
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//search = search == null ? match(linSearch, binSearch) : search
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ribbon = DATA.ribbons[ribbon]
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var order = DATA.order
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var target = order.indexOf(gid)
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return search(target, ribbon, function (a, i, lst){
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return search(target, ribbon, function(a, i, lst){
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var b = order.indexOf(lst[i])
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// special case: tail...
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if(i == lst.length-1 && a >= b){
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return 0
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}
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var c = order.indexOf(lst[i+1])
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// hit...
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if(a == b || (a > b && a < c)){
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return 0
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// before...
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} else if(a < b){
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return -1
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// later...
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} else {
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return 1
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