I have a function to go through all sessionScopes:
function clearMap( map:Map ){ // Get iterator for the keys
var iterator = map.keySet().iterator(); // Remove all items
while( iterator.hasNext() ){
//would like to read here the keyValue
}
}
clearMap(sessionScope);
I would like to read the key value for each item in the map. (keys ending with _languagecode I would like to remove) but how can I do this?
With iterator.next()you have access to the key itself so you should be able to do something like this in SSJS:
function clearMap( map:Map ){ // Get iterator for the keys
var iterator = map.keySet().iterator(); // Remove all items
while( iterator.hasNext() ){
var key = iterator.next();
if (key == 'something you want to test for') {
map.remove(key);
}
}
}
Related
Beginner here,
I'm a bit lost with es6 set, map and generators.
How can I select an item in a map, then iterate backwards from that point on effectively? Preferably without going through the whole set/map.
let v = myMap.get('key')
so, from 'v' to the beginning of the map (backwards)?
thank you!
You can create a set of iteration helpers and then compound to create the effect you want:
/* iterTo iterates the iterable from the start and up to (inclusive) key is found.
The function "understands" the Map type when comparing keys as well as
any other iterables where the value itself is the key to match. */
function* iterTo(iterable, key) {
for(let i of iterable) {
yield i;
if((iterable instanceof Map && i[0] === key) || i === key)
return;
}
}
// Same as iterTo, but starts at the key and goes all the way to the end
function* iterFrom(iterable, key) {
let found = false;
for(let i of iterable) {
if(found = (found || (iterable instanceof Map && i[0] === key) || i === key))
yield i;
}
}
// reverseIter creates a reverse facade for iterable
function* reverseIter(iterable) {
let all = [...iterable];
for(let i = all.length; i--; )
yield all[i];
}
You can then use and compound like this:
let m = new Map();
m.set(1, 'a');
m.set(2, 'b');
m.set(3, 'c');
m.set(4, 'd');
m.set(5, 'e');
let s = new Set();
s.add(100);
s.add(200);
s.add(300);
s.add(400);
console.log(...iterTo(m, 3), ...iterFrom(m, 3));
console.log(...reverseIter(iterTo(m, 3)), ...reverseIter(iterFrom(m, 3)));
console.log(...reverseIter(iterTo(s, 200)));
What you probably want is a slice of the keys from the first element to the index of the key, reverse that, iterate over that and get the values from the map.
I am assuming your map is an object:
let keys = Object.keys(map);
return keys.slice(0, keys.indexOf('key')).map((k) => map[k]);
You don't really need a generator.
I'm trying to run a check on a webdb running on a cordova/jQuery-mobile application:
This function will check whether the table exists in the DB and subsequently return a true or false. I have tried to change the return type from boolean to integer (0 and 1) but with no success.
function checkConfigTable(tablename) {
db.transaction
(
function (tx)
{
tx.executeSql
(
'SELECT name FROM sqlite_master WHERE type="table" AND name=?',
[tablename],
function(tx,results)
{
var len = results.rows.length;
if(len>0)
{
return true;
}
else {
return false;
}
}, errorCB
);
},errorCB,successCB
);
}
I want to then call checkConfigTable from this other one just to alert the return value (only for test purposes at the moment) but I am always getting "undefined" as return value.
// Function to retrieve current login config
function getSavedLogin(configid) {
var x = checkConfigTable("config");
alert('table: ' + x);
}
If I substitute the return with an alert directly in checkConfigTable() the correct values are shown in the alert box.
In order to send a POST request I need to enumerate all properties of a given object. This object may or may not be dynamic. I'm looking for the most elegant solution. This is what I've got so far:
function createURLVariables(params:Object):URLVariables
{
// Workaround: Flash Player performs a GET if no params are passed
params ||= {forcePost: true};
var vars:URLVariables = new URLVariables();
var propertyName:String;
var propertyList:XMLList = describeType(params)..variable;
var propertyListLength:int = propertyList.length();
// A dynamic object won't return properties in this fashion
if (propertyListLength > 0)
{
for (var i:int; i < propertyListLength; i++)
{
propertyName = propertyList[i].#name;
vars[propertyName] = params[propertyName];
}
}
else
{
for (propertyName in params)
vars[propertyName] = params[propertyName];
}
return vars;
}
One potential problem is that this won't return properties for getters (accessors).
I took the following approach in the as3corelib JSON Encoder. You'll have to modify this to suit your needs, but it should give you an idea to work from. Note that there is some recursion in here (the convertToString call, which you might not need:
/**
* Converts an object to it's JSON string equivalent
*
* #param o The object to convert
* #return The JSON string representation of <code>o</code>
*/
private function objectToString( o:Object ):String
{
// create a string to store the object's jsonstring value
var s:String = "";
// determine if o is a class instance or a plain object
var classInfo:XML = describeType( o );
if ( classInfo.#name.toString() == "Object" )
{
// the value of o[key] in the loop below - store this
// as a variable so we don't have to keep looking up o[key]
// when testing for valid values to convert
var value:Object;
// loop over the keys in the object and add their converted
// values to the string
for ( var key:String in o )
{
// assign value to a variable for quick lookup
value = o[key];
// don't add function's to the JSON string
if ( value is Function )
{
// skip this key and try another
continue;
}
// when the length is 0 we're adding the first item so
// no comma is necessary
if ( s.length > 0 ) {
// we've already added an item, so add the comma separator
s += ","
}
s += escapeString( key ) + ":" + convertToString( value );
}
}
else // o is a class instance
{
// Loop over all of the variables and accessors in the class and
// serialize them along with their values.
for each ( var v:XML in classInfo..*.(
name() == "variable"
||
(
name() == "accessor"
// Issue #116 - Make sure accessors are readable
&& attribute( "access" ).charAt( 0 ) == "r" )
) )
{
// Issue #110 - If [Transient] metadata exists, then we should skip
if ( v.metadata && v.metadata.( #name == "Transient" ).length() > 0 )
{
continue;
}
// When the length is 0 we're adding the first item so
// no comma is necessary
if ( s.length > 0 ) {
// We've already added an item, so add the comma separator
s += ","
}
s += escapeString( v.#name.toString() ) + ":"
+ convertToString( o[ v.#name ] );
}
}
return "{" + s + "}";
}
I have an array of objects. Each object has a property called name. I want to efficiently remove an object with a particular name from the array. Is this the BEST way?
private function RemoveSpoke(Name:String):void {
var Temp:Array=new Array;
for each (var S:Object in Spokes) {
if (S.Name!=Name) {
Temp.push(S);
}
}
Spokes=Temp;
}
If you are willing to spend some memory on a lookup table this will be pretty fast:
private function remove( data:Array, objectTable:Object, name:String):void {
var index:int = data.indexOf( objectTable[name] );
objectTable[name] = null;
data.splice( index, 1 );
}
The test for this looks like this:
private function test():void{
var lookup:Object = {};
var Spokes:Array = [];
for ( var i:int = 0; i < 1000; i++ )
{
var obj:Object = { name: (Math.random()*0xffffff).toString(16), someOtherProperty:"blah" };
if ( lookup[ obj.name ] == null )
{
lookup[ obj.name ] = obj;
Spokes.push( obj );
}
}
var t:int = getTimer();
for ( var i:int = 0; i < 500; i++ )
{
var test:Object = Spokes[int(Math.random()*Spokes.length)];
remove(Spokes,lookup,test.name)
}
trace( getTimer() - t );
}
myArray.splice(myArray.indexOf(myInstance), 1);
The fastest way will be this:
function remove(array: Array, name: String): void {
var n: int = array.length
while(--n > -1) {
if(name == array[n].name) {
array.splice(n, 1)
return
}
}
}
remove([{name: "hi"}], "hi")
You can also remove the return statement if you want to get rid of all alements that match the given predicate.
I don't have data to back it up but my guess is that array.filter might be the fastest.
In general you should prefer the old for-loop over "for each" and "for each in" and use Vector if your elements are of the same type. If performance is really important you should consider using a linked list.
Check out Grant Skinners slides http://gskinner.com/talks/quick/ and Jackson Dunstan's Blog for more infos about optimization.
If you don't mind using the ArrayCollection, which is a wrapper for the Array class, you could do something like this:
private function RemoveSpoke(Name:String, Spokes:Array):Array{
var ac:ArrayCollection = new ArrayCollection(Spokes);
for (var i:int=0, imax:int=ac.length; i<imax; i++) {
if (Spokes[i].hasOwnProperty("Name") && Spokes[i].Name === Name) {
ac.removeItemAt(i);
return ac.source;
}
}
return ac.source;
}
You could also use ArrayCollection with a filterFunction to get a view into the same Array object
Perhaps this technique (optimized splice method by CJ's) will further improve the one proposed by Quasimondo:
http://cjcat.blogspot.com/2010/05/stardust-v11-with-fast-array-splicing_21.html
Here's an efficient function in terms of reusability, allowing you to do more than remove the element. It returns the index, or -1 if not found.
function searchByProp(arr:Array, prop:String, value:Object): int
{
var item:Object;
var n: int = arr.length;
for(var i:int=n;i>0;i--)
{
item = arr[i-1];
if(item.hasOwnProperty(prop))
if( value == item[prop] )
return i-1;
}
return -1;
}
OK, I am sorting an XMLListCollection in alphabetical order. I have one issue though. If the value is "ALL" I want it to be first in the list. In most cases this happens already but values that are numbers are being sorted before "ALL". I want "ALL" to always be the first selection in my dataProvider and then the rest alphabetical.
So I am trying to write my own sort function. Is there a way I can check if one of the values is all, and if not tell it to do the regular compare on the values?
Here is what I have:
function myCompare(a:Object, b:Object, fields:Array = null):int
{
if(String(a).toLowerCase() == 'all')
{
return -1;
}
else
if(String(b).toLowerCase() == 'all')
{
return 1;
}
// NEED to return default comparison results here?
}
//------------------------------
var sort:Sort = new Sort();
sort.compareFunction = myCompare;
Is there a solution for what I am trying to do?
The solution from John Isaacks is awesome, but he forgot about "fields" variable and his example doesn't work for more complicated objects (other than Strings)
Example:
// collection with custom objects. We want to sort them on "value" property
// var item:CustomObject = new CustomObject();
// item.name = 'Test';
// item.value = 'Simple Value';
var collection:ArrayCollection = new ArrayCollection();
var s:Sort = new Sort();
s.fields = [new SortField("value")];
s.compareFunction = myCompare;
collection.sort = s;
collection.refresh();
private function myCompare(a:Object, b:Object, fields:Array = null):int
{
if(String((a as CustomObject).value).toLowerCase() == 'all')
{
return -1;
}
else if(String((b as CustomObject).value).toLowerCase() == 'all')
{
return 1;
}
// NEED to return default comparison results here?
var s:Sort = new Sort();
s.fields = fields;
var f:Function = s.compareFunction;
return f.call(null,a,b,fields);
}
Well I tried something out, and I am really surprised it actually worked, but here is what I did.
The Sort class has a private function called internalCompare. Since it is private you cannot call it. BUT there is a getter function called compareFunction, and if no compare function is defined it returns a reference to the internalCompare function. So what I did was get this reference and then call it.
private function myCompare(a:Object, b:Object, fields:Array = null):int
{
if(String(a).toLowerCase() == 'all')
{
return -1;
}
else if(String(b).toLowerCase() == 'all')
{
return 1;
}
// NEED to return default comparison results here?
var s:Sort = new Sort();
var f:Function = s.compareFunction;
return f.call(null,a,b,fields);
}
Thanks guys, this helped a lot. In our case, we needed all empty rows (in a DataGrid) on the bottom. All non-empty rows should be sorted normally. Our row data is all dynamic Objects (converted from JSON) -- the call to ValidationHelper.hasData() simply checks if the row is empty. For some reason the fields sometimes contain the dataField String value instead of SortFields, hence the check before setting the 'fields' property:
private function compareEmptyAlwaysLast(a:Object, b:Object, fields:Array = null):int {
var result:int;
if (!ValidationHelper.hasData(a)) {
result = 1;
} else if (!ValidationHelper.hasData(b)) {
result = -1;
} else {
if (fields && fields.length > 0 && fields[0] is SortField) {
STATIC_SORT.fields = fields;
}
var f:Function = STATIC_SORT.compareFunction;
result = f.call(null,a,b,fields);
}
return result;
}
I didn't find these approaches to work for my situation, which was to alphabetize a list of Strings and then append a 'Create new...' item at the end of the list.
The way I handled things is a little inelegant, but reliable.
I sorted my ArrayCollection of Strings, called orgNameList, with an alpha sort, like so:
var alphaSort:Sort = new Sort();
alphaSort.fields = [new SortField(null, true)];
orgNameList.sort = alphaSort;
orgNameList.refresh();
Then I copied the elements of the sorted list into a new ArrayCollection, called customerDataList. The result being that the new ArrayCollection of elements are in alphabetical order, but are not under the influence of a Sort object. So, adding a new element will add it to the end of the ArrayCollection. Likewise, adding an item to a particular index in the ArrayCollection will also work as expected.
for each(var org:String in orgNameList)
{
customerDataList.addItem(org);
}
Then I just tacked on the 'Create new...' item, like this:
if(userIsAllowedToCreateNewCustomer)
{
customerDataList.addItem(CREATE_NEW);
customerDataList.refresh();
}