copy<K, V> static method

Map<K, V?> copy<K, V>(
  1. Map<K, V?> source,
  2. Map<K, V?> dest, [
  3. bool filter(
    1. K key,
    2. V? value
    )?
])

Copies entries from source to dest and returns dest.

If filter is null (default), all entries are copied. Otherwise only entries for which filter(key, value) returns true are copied.

Implementation

static Map<K, V?> copy<K, V>(Map<K, V?> source, Map<K, V?> dest,
    [bool filter(K key, V? value)?]) {
  for (final key in source.keys) {
    final value = source[key];
    if (filter == null || filter(key, value))
      dest[key] = value;
  }
  return dest;
}