Comparing definitions

Use sameDefinition to compare rule or cascade documents after normalising their structure. Use fingerprint to obtain the normalised document as a stable JSON string.

These operations compare document structure. They do not evaluate definitions over time.

Canonical form

canonical removes structural differences introduced by grouping, input order, and shorthand:

import { all, canonical, timeOfDayRange, weekdays } from "@kensio/quando";

const openingHours = all(all(weekdays()), timeOfDayRange("09:00", "17:00"));

console.log(canonical(openingHours));

For rules, canonicalisation:

• Flattens nested all and any groups.
• Unwraps a group that contains one rule.
• Simplifies identity rules, constants, and double negation.
• Sorts and removes duplicate group members, weekdays, and dates.
• Normalises date and time strings.

For cascades, it canonicalises every layer scope and nested replacement. Layer order stays unchanged because it controls priority and merge order. An explicit "override" strategy is removed because override is the default.

Equality

import { all, sameDefinition, timeOfDayRange, weekdays } from "@kensio/quando";

const built = all(all(weekdays()), timeOfDayRange("09:00", "17:00"));
const written = all(timeOfDayRange("09:00:00", "17:00:00"), weekdays());

console.log(sameDefinition(built, written));

true

sameDefinition canonicalises both values and compares their fingerprints.

Fingerprints

import { fingerprint, weekdays } from "@kensio/quando";

const key = fingerprint(weekdays());

The result is the canonical JSON string. Equal canonical values have equal fingerprints. Cascade values must also have stable JSON representations if you store the fingerprint as a persistent key.

Canonical sorting uses UTF-16 code units. It is independent of the machine’s language settings, giving the same rule the same fingerprint across machines.

Structural limits

Canonicalisation does not prove semantic equality. Different rule types remain different even when they happen to cover the same time:

import { always, daysOfWeek, sameDefinition } from "@kensio/quando";

const everyNamedDay = daysOfWeek(
  "monday",
  "tuesday",
  "wednesday",
  "thursday",
  "friday",
  "saturday",
  "sunday",
);

console.log(sameDefinition(always(), everyNamedDay));

false

canonical, sameDefinition, and fingerprint expect valid Quando data. Parse stored data before comparing it.

Use coverageChanges to compare the time covered by two definitions within a window. It evaluates both definitions and reports added and removed intervals. See the queries guide.