@fractorysolutions/safe-units/src/measure/genericMeasureClass.ts

Type-safe TypeScript units of measure

import { getExponentValue } from "../exponent/exponentValueArithmetic";
import { defaultFormatUnit } from "./format";
import {
  GenericMeasure,
  MeasureFormatter,
  NumericOperations,
} from "./genericMeasure";
import {
  AllowedExponents,
  DivideUnits,
  DivisorUnit,
  ExponentiateUnit,
  MultiplicandUnit,
  MultiplyUnits,
  Unit,
  UnitWithSymbols,
} from "./unitTypeArithmetic";
import {
  divideUnits,
  exponentiateUnit,
  multiplyUnits,
} from "./unitValueArithmetic";

type GenericMeasureConstructor<N> = new <U extends Unit>(
  value: N,
  unit: UnitWithSymbols<U>,
  symbol?: string,
) => GenericMeasure<N, U>;

export function createMeasureClass<N>(
  num: NumericOperations<N>,
): GenericMeasureConstructor<N> {
  function getFormatter(
    formatter: MeasureFormatter<N> | undefined,
  ): Required<MeasureFormatter<N>> {
    if (formatter === undefined) {
      return {
        formatValue: num.format,
        formatUnit: defaultFormatUnit,
      };
    } else {
      return {
        formatValue: formatter.formatValue || num.format,
        formatUnit: formatter.formatUnit || defaultFormatUnit,
      };
    }
  }

  class Measure<U extends Unit> implements GenericMeasure<N, U> {
    public readonly symbol: string | undefined;
    public squared!: "2" extends AllowedExponents<U>
      ? () => GenericMeasure<N, ExponentiateUnit<U, "2">>
      : never;
    public cubed!: "3" extends AllowedExponents<U>
      ? () => GenericMeasure<N, ExponentiateUnit<U, "3">>
      : never;

    constructor(
      public readonly value: N,
      public readonly unit: UnitWithSymbols<U>,
      symbol?: string,
    ) {
      this.symbol = symbol;
    }

    // Arithmetic

    public plus(other: GenericMeasure<N, U>): Measure<U> {
      return new Measure(num.add(this.value, other.value), this.unit);
    }

    public minus(other: GenericMeasure<N, U>): Measure<U> {
      return new Measure(num.sub(this.value, other.value), this.unit);
    }

    public negate(): Measure<U> {
      return new Measure(num.neg(this.value), this.unit);
    }

    public scale(value: N): Measure<U> {
      return new Measure(num.mult(this.value, value), this.unit);
    }

    public times<V extends MultiplicandUnit<U>>(
      other: GenericMeasure<N, V>,
    ): Measure<MultiplyUnits<U, V>> {
      return new Measure(
        num.mult(this.value, other.value),
        multiplyUnits(this.unit, other.unit),
      ) as any;
    }

    public over<V extends DivisorUnit<U>>(
      other: GenericMeasure<N, V>,
    ): Measure<DivideUnits<U, V>> {
      return new Measure(
        num.div(this.value, other.value),
        divideUnits(this.unit, other.unit),
      ) as any;
    }

    public per<V extends DivisorUnit<U>>(
      other: GenericMeasure<N, V>,
    ): Measure<DivideUnits<U, V>> {
      return this.over(other);
    }

    public div<V extends DivisorUnit<U>>(
      other: GenericMeasure<N, V>,
    ): Measure<DivideUnits<U, V>> {
      return this.over(other);
    }

    public toThe<E extends AllowedExponents<U>>(
      power: E,
    ): Measure<ExponentiateUnit<U, E>> {
      return new Measure(
        num.pow(this.value, getExponentValue(power)),
        exponentiateUnit(this.unit, power),
      );
    }

    public inverse(): GenericMeasure<N, ExponentiateUnit<U, "-1">> {
      return this.toThe("-1");
    }

    public reciprocal(): GenericMeasure<N, ExponentiateUnit<U, "-1">> {
      return this.toThe("-1");
    }

    public unsafeMap<V extends Unit>(
      valueMap: (value: N) => N,
      unitMap?: (unit: UnitWithSymbols<U>) => UnitWithSymbols<V>,
    ): GenericMeasure<N, V> {
      const newUnit = unitMap === undefined ? this.unit : unitMap(this.unit);
      return new Measure<V>(
        valueMap(this.value),
        newUnit as unknown as UnitWithSymbols<V>,
      );
    }

    // Comparisons

    public compare(other: GenericMeasure<N, U>): number {
      return num.compare(this.value, other.value);
    }

    public lt(other: GenericMeasure<N, U>): boolean {
      return this.compare(other) < 0;
    }

    public lte(other: GenericMeasure<N, U>): boolean {
      return this.compare(other) <= 0;
    }

    public eq(other: GenericMeasure<N, U>): boolean {
      return this.compare(other) === 0;
    }

    public neq(other: GenericMeasure<N, U>): boolean {
      return this.compare(other) !== 0;
    }

    public gte(other: GenericMeasure<N, U>): boolean {
      return this.compare(other) >= 0;
    }

    public gt(other: GenericMeasure<N, U>): boolean {
      return this.compare(other) > 0;
    }

    // Formatting

    public toString(formatter?: MeasureFormatter<N>): string {
      const { formatValue, formatUnit } = getFormatter(formatter);
      return `${formatValue(this.value)} ${formatUnit(this.unit)}`.trimRight();
    }

    public in(
      unit: GenericMeasure<N, U>,
      formatter?: MeasureFormatter<N>,
    ): string {
      if (unit.symbol === undefined) {
        return this.toString(formatter);
      }
      const { formatValue } = getFormatter(formatter);
      const value = formatValue(num.div(this.value, unit.value));
      return `${value} ${unit.symbol}`;
    }

    public valueIn(unit: GenericMeasure<N, U>): N {
      return this.over(unit).value;
    }

    public withSymbol(symbol: string | undefined): GenericMeasure<N, U> {
      return new Measure(this.value, this.unit, symbol);
    }

    public clone(): GenericMeasure<N, U> {
      return new Measure(this.value, this.unit);
    }
  }

  Measure.prototype.squared = function (): any {
    return this.toThe("2");
  };

  Measure.prototype.cubed = function (): any {
    return this.toThe("3");
  };

  return Measure;
}