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  1. importPackage(java.io)
  2. importPackage(java.lang)
  3.  
  4. // Reverse a calculation procedure involving different kinds of price increase
  5.  
  6. // Increase by percent
  7. function proz(p) { 
  8.   return function(x) {
  9.     return x*(1+p/100)
  10.     }
  11.   }  
  12.  
  13. // Increase by absolute value  
  14. function abs(q) { 
  15.   var f = function(x) {
  16.     return x+q
  17.     }
  18.   f.isAbsolute = true
  19.   return f
  20.   }
  21.  
  22. // Increase by percent of the calculation base  
  23. function proz_base(p) {
  24.   return function(x,base) {
  25.     return x+base*p/100
  26.     }
  27.   }  
  28.  
  29. function schema( ) {
  30.   var conditions = convertToArray( arguments );
  31.   return {
  32. // "compute" applies the schema to a base price
  33.       compute:compute,
  34. // "resolve" finds the base price yielding the specified result        
  35.       resolve:function(result) {
  36.         return ( result - compute(0) ) / reducedSchema().compute(1) 
  37.         }
  38.       }
  39.  
  40.   function compute(base) {
  41.     return conditions.reduce( function(result,cond) {
  42.       return cond(result,base)
  43.       }, 
  44.       base )
  45.     }
  46.  
  47.   function reducedSchema() {
  48.   	return schema.apply( null, conditions.filter( isRelative ) )
  49.     }  
  50.  
  51.   function isRelative( cond ) {
  52.   	return ! cond.isAbsolute
  53.   	}
  54.  
  55.   }
  56.  
  57. function convertToArray( arraylikeThing ) {
  58.   return Array.prototype.slice.apply( arraylikeThing )
  59.   }
  60.  
  61.  
  62. // Test 
  63. var s = schema( 
  64. 	proz( 7 ), 
  65. 	abs(5), 
  66. 	proz_base(10), 
  67. 	abs(3), 
  68. 	proz(13) 
  69. 	)
  70.  
  71. System.out.println( s.compute( s.resolve( 20 ) ) )
Success #stdin #stdout 0.44s 381888KB
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20.0
https://ideone.com/GGZIbM
Reverse a pricing procedure
language:
JavaScript (rhino 1.7.9)
created:
10 years ago
visibility:
public

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