simple-squiggle

A restricted subset of Squiggle
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function_transform.js (1275B)

      1 /**
      2  * Function transforms
      3  *
      4  * When using functions via the expression parser, it is possible to preprocess
      5  * function arguments and post process a functions return value by writing a
      6  * *transform* for the function. A transform is a function wrapping around a
      7  * function to be transformed or completely replaces a function.
      8  */
      9 const { create, all } = require('../..')
     10 const math = create(all)
     11 
     12 // create a function
     13 function addIt (a, b) {
     14   return a + b
     15 }
     16 
     17 // attach a transform function to the function addIt
     18 addIt.transform = function (a, b) {
     19   console.log('input: a=' + a + ', b=' + b)
     20   // we can manipulate the input arguments here before executing addIt
     21 
     22   const res = addIt(a, b)
     23 
     24   console.log('result: ' + res)
     25   // we can manipulate the result here before returning
     26 
     27   return res
     28 }
     29 
     30 // import the function into math.js
     31 math.import({
     32   addIt: addIt
     33 })
     34 
     35 // use the function via the expression parser
     36 console.log('Using expression parser:')
     37 console.log('2+4=' + math.evaluate('addIt(2, 4)'))
     38 // This will output:
     39 //
     40 //     input: a=2, b=4
     41 //     result: 6
     42 //     2+4=6
     43 
     44 // when used via plain JavaScript, the transform is not invoked
     45 console.log('')
     46 console.log('Using plain JavaScript:')
     47 console.log('2+4=' + math.addIt(2, 4))
     48 // This will output:
     49 //
     50 //     6