LESS-reg-js

//  -------------------------------------------------------
//  LESS-reg-js 1.0
//  (c) Nodebite 2014, Thomas Frank
//  MIT license, free to use everywhere.
//  
//  Register a JavaScript as a LESS function.
//  (Yes! This is valid LESS!)
//
//  -------------------------------------------------------
//
//  Usage:

//  -------------------------------------------------------
//  
//  Register a function
//
//  .reg-js(`reg('functionName',function([arg1..arg5]){
//
//    A normal JavaScript function
//    that MUST return an JSON-eqsque object such as
//    {
//        h1:{"padding":0,"margin":"3px"},
//        h2:{"padding-top":"5px","overflow":"hidden"}
//    } etc.
//
//  })`);
//
//  Note: To return several rules for the same selector
//  use "h2", "h2_", "h2__" etc as keys/names...
// 
//  ------------------------------------------------------- 
//
//  Call a function:
//
//  .run-js("functionName",[arg1..arg5]);
//
//  Note: To call a JS-function within another JS-function:
//  this.functionName([arg1..arg5]);
//
//  ------------------------------------------------------- 
//

// register a javascript function
.reg-js(@def){}
.reg-js(`(function(){
  this.reg = function(methodname,method){
    this.api = this.api || {};
    this.api[methodname] = method;
    return " ";
  };
  return " ";
})()`);

// run a javascript function
.run-js(@methodname,@a1:"",@a2:"",@a3:"",@a4:"",@a5:""){
  @temp: ~`(function(){
    var css = this.api.jsonToCss(
      this.api[@{methodname}](@{a1},@{a2},@{a3},@{a4},@{a5})
    );
    var i = css.indexOf("{");
    var j = css.indexOf(":");
    this.tres1 = css.substring(0,i);
    this.tres2 = css.substring(i+4,j);
    this.tres3 = css.substring(j+2,css.lastIndexOf(";"));
    return ' ';
  })()`;
  // break up the funciton result in 3 vars
  // to get around LESS limitiation on variable output
  @r1: ~`(function(){ return this.tres1 || ' '; })()`;
  @r2: ~`(function(){ return this.tres2 || ' '; })()`;
  @r3: ~`(function(){ return this.tres3 || ' '; })()`;
  @{r1} {@{r2}:@r3}
}

// helper function to convert 
// a json-esque structure to css
.reg-js(`reg('jsonToCss',function(json){
  var css = "";
  for(var i in json){
    css += i.split("_").join("")  + ' {\n';
    for(var j in json[i]){
      css += "  " + j + ": " + json[i][j] + ";\n";
    }
    css += "}\n\n";
  }
  css = css || " ";
  return css;
})`);