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CalendarMatcher

A CalendarMatcher selects which native dates match a modifier or disabled rule. Three shapes are supported uniformly:

type CalendarMatcher =
  | readonly DisabledDateInput[] // individual days
  | readonly DisabledDateRangeInput[] // inclusive ranges
  | ((nativeDate: Date) => boolean); // predicate

DisabledDateInput is unknown — the active system's from() normalises each value.

Date List​

modifiers={{
  booked: [
    new Date(2024, 4, 7),
    '2024-05-15', // if your system's from() accepts strings
  ],
}}

Range List​

Discriminated by a start + end field on the first entry:

modifiers={{
  holiday: [
    { start: new Date(2024, 11, 24), end: new Date(2024, 11, 26) },
  ],
}}

Ranges are inclusive on both ends.

Predicate​

modifiers={{
  weekend: (d) => d.getDay() === 0 || d.getDay() === 6,
}}

Predicates receive a native Date. If the function throws, the library treats the day as not matched (never crashes the grid).

Empty Arrays​

An empty array matches nothing.

Grid Utilities​

The same matching logic powers matchDate in react-native-headless-calendar for advanced use outside the store:

import {
  matchDate,
  createGregorianSystem,
} from 'react-native-headless-calendar';

const sys = createGregorianSystem();
matchDate(sys, date, (d) => d.getMonth() === 5);