How to rewrite SASS map-merge, map-get in LESS - sass

Question

Can you help me to write some code for create sprite template in Less via gulp spritesmith?
I have sprite.template.mustache with Sass functions and mixins:
$icons: (0:0)
{{#items}}
$icons: map-merge($icons,({{name}}: (X: {{px.offset_x}}, Y:{{px.offset_y}}, W: {{px.width}}, H: {{px.height}}, TW: {{px.total_width}}, TH: {{px.total_height}}, IMG: '{{{escaped_image}}}')))
{{/items}}
{{#options.functions}}
// Gets an attribute from the sass map
#function icon-attr($icon, $attr)
$icon: map-get($icons, $icon)
#return map-get($icon, $attr)
#mixin sprite($iconName)
background-image: url(icon-attr($iconName, IMG))
width: icon-attr($iconName, W)
height: icon-attr($iconName, H)
background-position: icon-attr($iconName, X) icon-attr($iconName, Y)
#mixin sprite-position($iconName)
background-position: icon-attr($iconName, X) icon-attr($iconName, Y)
#mixin sprite-retina($iconName)
background-image: url(icon-attr($iconName, IMG))
$width: icon-attr($iconName, W)
$height: icon-attr($iconName, H)
width: $width/2
height: $height/2
$x: icon-attr($iconName, X)
$y: icon-attr($iconName, Y)
background-position: $x/2 $y/2
$tw: icon-attr($iconName, TW)
$th: icon-attr($iconName, TH)
background-size: $tw/2 $th/2
{{/options.functions}}
I have some trouble with rewriting functions: "map-merge" and "map-get" to Less.
I know that there are no such functions in LESS, but I also know that there are own arrays that can be configured.

Answer 1

Here is the result that I got:
{{#items}}
#{{name}}: {{px.offset_x}}, {{px.offset_y}}, {{px.width}}, {{px.height}}, {{px.total_width}}, {{px.total_height}}, '{{{escaped_image}}}';
{{/items}}
// #{{name}} - name of the img.
{{#options.functions}}
.icon-attr(#icon){
#url: extract(#icon, 7);
#width: extract(#icon, 3);
#height: extract(#icon, 4);
#positionX: extract(#icon, 1);
#positionY: extract(#icon, 2);
#total_width: extract(#icon, 5);
#total_height: extract(#icon, 6);
}
{{/options.functions}}
.sprite(#icon){
.icon-attr(#icon);
display: inline-block;
background-image: url(#url);
width: #width;
height: #height;
background-position: #positionX #positionY;
}
.sprite-position(#icon){
.icon-attr(#icon);
background-position: #positionX #positionY;
}
.sprite-retina(#icon){
.icon-attr(#icon);
background-image: url(#url);
#width_retina: #width;
#height_retina: #height;
width: #width_retina/2;
height: #height_retina/2;
#x: #positionX;
#y: #positionY;
background-position: #x/2 #y/2;
#tw: #total_width;
#th: #total_height;
background-size: #tw/2 #th/2;
}
Example of use:
.icon-search {
.sprite(#search);
}

Answer 2

For a complex map-like data structures manipulation see Lists Less plugin.
But for this particular snippet you don't in fact need any complex structures and thus extra plugins/functions. Plain mixins can serve as a map and its functions in this case just perfect.
Minimal illustrative example:
// declare icon map, each item is injected via {{#items}} template:
.icon(foo) {
#x: 11;
#y: 22;
// etc.
}
.icon(bar) {
#x: 33;
#y: 44;
// etc.
}
// using the map:
.sprite-retina(#icon-name) {
// expand icon properties into this scope:
.icon(#icon-name);
// use the propertes:
x: #x;
y: #y;
// etc.
}