@dwidge/function-ops

This package provides a utility to instrument a function with a logger function.

The instrument function returns a new function that behaves the same as the original function, but calls the logger function whenever an expression is evaluated.

Installation

npm i @dwidge/function-ops

Usage

instrument(
  () => {},
  (type, [start, end], [exp, val], ...args) => {}
);

const instrument = require("@dwidge/function-ops");

const f = function (a, b, c) {
  a = b + c * 2;
  return a - Math.min(1, 2, 3, c);
};

const logger = (type, [start, end], [exp, val], ...args) => {
  console.log(`${type}@${start}-${end}`);
  console.log(`  ${exp} = ${val}`);
  console.log(
    `  where ${args.map(([exp, val]) => `${exp} = ${val}`).join(" and ")}`
  );
};

const flog = instrument(f, logger);
console.log(flog(3, 4, 5));

BinaryExpression@28-37
  b + c * 2 = 14
  where b = 4 and c * 2 = 10
BinaryExpression@32-37
  c * 2 = 10
  where c = 5 and 2 = 2
BinaryExpression@49-73
  a - Math.min(1, 2, 3, c) = 13
  where a = 14 and Math.min(1, 2, 3, c) = 1
CallExpression@53-73
  Math.min(1, 2, 3, c) = 1
  where 1 = 1 and 2 = 2 and 3 = 3 and c = 5
13

Logger

(type, [start, end], [exp, val], ...args) => {};

Argument	Type	Description
type	string	The type of the expression being logged
[start, end]	array	An array representing the start and end positions of the expression in the original function
[exp, val]	array	An array representing the expression and its value
args	array	An array of arrays representing the arguments of the expression, each array containing two elements [exp, val] representing the expression and its value

Testing

npm test

Credits

transform-ast
ChatGPT

License

This package is licensed under the Boost Software License. See the LICENSE file for more information.