@thi.ng/units/dsl.js

Extensible SI unit creation, conversions, quantities & calculations (incl. List-like DSL and ~170 predefined units & constants)

import { illegalArgs } from "@thi.ng/errors/illegal-arguments";
import { parse } from "@thi.ng/sexpr/parse";
import { runtime } from "@thi.ng/sexpr/runtime";
import * as CONST from "./constants/index.js";
import {
  add,
  asUnit,
  convert,
  div,
  mul,
  quantity,
  Quantity,
  reciprocal,
  sub
} from "./unit.js";
const __mathOp = (fn, fn1) => (first, ...args) => {
  return args.length > 0 ? (
    // use a reduction for 2+ args
    args.reduce((acc, x) => fn(acc, x), first)
  ) : (
    // apply special case unary function
    fn1(first)
  );
};
const ENV = {
  "+": __mathOp(add, (x) => x),
  "-": __mathOp(sub, (x) => sub(quantity(0, x.value), x)),
  "*": __mathOp(mul, (x) => x),
  "/": __mathOp(div, reciprocal),
  area: (src) => {
    const [w, h] = src.value.map((x) => quantity(1, x));
    return mul(w, h);
  },
  volume: (src) => {
    const [w, h, d] = src.value.map((x) => quantity(1, x));
    return mul(mul(w, h), d);
  },
  width: (src) => quantity(1, src.value[0]),
  height: (src) => quantity(1, src.value[1]),
  depth: (src) => quantity(1, src.value[2])
};
const interpret = runtime({
  expr: ({ children: [x, ...args] }) => {
    const name = x.value;
    const $args = args.map((a) => interpret(a, null));
    return ENV[name]?.apply(null, $args) ?? convert($args[0], asUnit(name));
  },
  sym: ({ value }) => {
    const match = /^[-+]?[0-9.]+(e[+-]?\d+)?/.exec(value);
    return match ? quantity(+match[0], asUnit(value.substring(match[0].length))) : CONST[value.toUpperCase()] ?? asUnit(value);
  },
  str: () => illegalArgs("string value"),
  num: (x) => x.value
});
const $eval = (src) => parse(src).children.reduce((_, x) => interpret(x, null), null);
export {
  $eval
};