35 lines
1.1 KiB
Dart
35 lines
1.1 KiB
Dart
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/// Exposes the [mergeMap] function, which... merges Maps.
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library merge_map;
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_copyValues<K, V>(
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Map<K, V> from, Map<K, V?>? to, bool recursive, bool acceptNull) {
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for (var key in from.keys) {
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if (from[key] is Map<K, V> && recursive) {
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if (!(to![key] is Map<K, V>)) {
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to[key] = <K, V>{} as V;
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}
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_copyValues(from[key] as Map, to[key] as Map?, recursive, acceptNull);
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} else {
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if (from[key] != null || acceptNull) to![key] = from[key];
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}
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}
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}
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/// Merges the values of the given maps together.
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///
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/// `recursive` is set to `true` by default. If set to `true`,
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/// then nested maps will also be merged. Otherwise, nested maps
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/// will overwrite others.
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///
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/// `acceptNull` is set to `false` by default. If set to `false`,
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/// then if the value on a map is `null`, it will be ignored, and
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/// that `null` will not be copied.
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Map<K, V> mergeMap<K, V>(Iterable<Map<K, V>> maps,
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{bool recursive: true, bool acceptNull: false}) {
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Map<K, V> result = <K, V>{};
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maps.forEach((Map<K, V> map) {
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if (map != null) _copyValues(map, result, recursive, acceptNull);
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});
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return result;
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}
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