refactor: replace ignored numeric literals with constants

src/common/decimal.ts

@@ -1,3 +1,19 @@
+export const DECIMAL_RADIX = 10n;
+
+const SIGN_LENGTH = 1;
+const NEGATIVE_SIGN = -1n;
+const POSITIVE_SIGN = 1n;
+const ZERO_UNITS = 0n;
+const EQUAL = 0;
+const GREATER_THAN = 1;
+const LESS_THAN = -1;
+const INTEGER_SCALE = 0;
+const MIN_WHOLE_DIGITS = 1;
+const DIGITS_START = 0;
+const PREVIOUS_DIGIT_OFFSET = 1;
+const DIGIT_STEP = 1;
+const ROUNDING_DIVISOR = 2n;
+
 export type Decimal = { scale: number; value: bigint };
 
 export function decimalFromString(value: string): Decimal {
@@ -6,9 +22,9 @@ export function decimalFromString(value: string): Decimal {
     throw new Error('Invalid decimal string');
   }
   const negative = value.startsWith('-');
-  const [whole, fraction = ''] = (negative ? value.slice(1) : value).split('.');
+  const [whole, fraction = ''] = (negative ? value.slice(SIGN_LENGTH) : value).split('.');
   return {
-    value: (negative ? -1n : 1n) * BigInt(`${whole}${fraction}`),
+    value: (negative ? NEGATIVE_SIGN : POSITIVE_SIGN) * BigInt(`${whole}${fraction}`),
     scale: fraction.length,
   };
 }
@@ -17,8 +33,8 @@ export function add(left: Decimal, right: Decimal): Decimal {
   const scale = Math.max(left.scale, right.scale);
   return {
     value:
-      left.value * 10n ** BigInt(scale - left.scale) +
-      right.value * 10n ** BigInt(scale - right.scale),
+      left.value * DECIMAL_RADIX ** BigInt(scale - left.scale) +
+      right.value * DECIMAL_RADIX ** BigInt(scale - right.scale),
     scale,
   };
 }
@@ -32,37 +48,37 @@ export function multiply(left: Decimal, right: Decimal): Decimal {
 }
 
 export function isZero(value: Decimal): boolean {
-  return value.value === 0n;
+  return value.value === ZERO_UNITS;
 }
 
 export function compare(left: Decimal, right: Decimal): number {
   const difference = subtract(left, right).value;
-  return difference === 0n ? 0 : difference > 0n ? 1 : -1;
+  return difference === ZERO_UNITS ? EQUAL : difference > ZERO_UNITS ? GREATER_THAN : LESS_THAN;
 }
 
 export function formatDecimal({ value, scale }: Decimal): string {
-  if (value === 0n) return '0';
-  const sign = value < 0n ? '-' : '';
-  if (scale === 0) return `${sign}${value < 0n ? -value : value}`;
-  const digits = (value < 0n ? -value : value)
+  if (value === ZERO_UNITS) return '0';
+  const sign = value < ZERO_UNITS ? '-' : '';
+  if (scale === INTEGER_SCALE) return `${sign}${value < ZERO_UNITS ? -value : value}`;
+  const digits = (value < ZERO_UNITS ? -value : value)
     .toString()
-    .padStart(scale + 1, '0');
-  const whole = digits.slice(0, -scale) || '0';
+    .padStart(scale + MIN_WHOLE_DIGITS, '0');
+  const whole = digits.slice(DIGITS_START, -scale) || '0';
   const rawFraction = digits.slice(-scale);
   let fractionEnd = rawFraction.length;
-  while (rawFraction.charAt(fractionEnd - 1) === '0') fractionEnd -= 1;
-  const fraction = rawFraction.slice(0, fractionEnd);
+  while (rawFraction.charAt(fractionEnd - PREVIOUS_DIGIT_OFFSET) === '0') fractionEnd -= DIGIT_STEP;
+  const fraction = rawFraction.slice(DIGITS_START, fractionEnd);
   const fractionalPart = fraction ? '.' + fraction : '';
   return `${sign}${whole}${fractionalPart}`;
 }
 
 // Round half away from zero; callers choose presentation precision explicitly.
 export function divide(left: Decimal, right: Decimal, scale: number): Decimal {
-  if (right.value === 0n) throw new Error('Division by zero');
-  const numerator = left.value * 10n ** BigInt(right.scale + scale);
-  const denominator = right.value * 10n ** BigInt(left.scale);
-  const sign = (numerator < 0n) !== (denominator < 0n) ? -1n : 1n;
-  const n = numerator < 0n ? -numerator : numerator;
-  const d = denominator < 0n ? -denominator : denominator;
-  return { value: sign * ((n + d / 2n) / d), scale };
+  if (right.value === ZERO_UNITS) throw new Error('Division by zero');
+  const numerator = left.value * DECIMAL_RADIX ** BigInt(right.scale + scale);
+  const denominator = right.value * DECIMAL_RADIX ** BigInt(left.scale);
+  const sign = (numerator < ZERO_UNITS) !== (denominator < ZERO_UNITS) ? NEGATIVE_SIGN : POSITIVE_SIGN;
+  const n = numerator < ZERO_UNITS ? -numerator : numerator;
+  const d = denominator < ZERO_UNITS ? -denominator : denominator;
+  return { value: sign * ((n + d / ROUNDING_DIVISOR) / d), scale };
 }

src/common/time.ts

@@ -1,2 +1,4 @@
+export const ISO_DATE_LENGTH = 10;
+export const ISO_DATE_START = 0;
 export const MILLISECONDS_PER_SECOND = 1_000;
 export const MILLISECONDS_PER_DAY = 86_400_000;