69 lines
2.2 KiB
Dart
69 lines
2.2 KiB
Dart
|
import 'dart:collection';
|
||
|
|
import 'exception.dart';
|
||
|
|
import 'parser.dart';
|
||
|
|
import 'range_header_item.dart';
|
||
|
|
import 'range_header_impl.dart';
|
||
|
|
|
||
|
|
/// Represents the contents of a parsed `Range` header.
|
||
|
|
abstract class RangeHeader {
|
||
|
|
/// Returns an immutable list of the ranges that were parsed.
|
||
|
|
UnmodifiableListView<RangeHeaderItem> get items;
|
||
|
|
|
||
|
|
const factory RangeHeader(Iterable<RangeHeaderItem> items,
|
||
|
|
{String? rangeUnit}) = _ConstantRangeHeader;
|
||
|
|
|
||
|
|
/// Eliminates any overlapping [items], sorts them, and folds them all into the most efficient representation possible.
|
||
|
|
static UnmodifiableListView<RangeHeaderItem> foldItems(
|
||
|
|
Iterable<RangeHeaderItem> items) {
|
||
|
|
var out = <RangeHeaderItem>{};
|
||
|
|
|
||
|
|
for (var item in items) {
|
||
|
|
// Remove any overlapping items, consolidate them.
|
||
|
|
while (out.any((x) => x.overlaps(item))) {
|
||
|
|
var f = out.firstWhere((x) => x.overlaps(item));
|
||
|
|
out.remove(f);
|
||
|
|
item = item.consolidate(f);
|
||
|
|
}
|
||
|
|
|
||
|
|
out.add(item);
|
||
|
|
}
|
||
|
|
|
||
|
|
return UnmodifiableListView(out.toList()..sort());
|
||
|
|
}
|
||
|
|
|
||
|
|
/// Attempts to parse a [RangeHeader] from its [text] representation.
|
||
|
|
///
|
||
|
|
/// You can optionally pass a custom list of [allowedRangeUnits].
|
||
|
|
/// The default is `['bytes']`.
|
||
|
|
///
|
||
|
|
/// If [fold] is `true`, the items will be folded into the most compact
|
||
|
|
/// possible representation.
|
||
|
|
///
|
||
|
|
factory RangeHeader.parse(String text,
|
||
|
|
{Iterable<String>? allowedRangeUnits, bool fold = true}) {
|
||
|
|
var tokens = scan(text, allowedRangeUnits?.toList() ?? ['bytes']);
|
||
|
|
var parser = Parser(tokens);
|
||
|
|
var header = parser.parseRangeHeader();
|
||
|
|
if (header == null) {
|
||
|
|
throw InvalidRangeHeaderException('Header is null');
|
||
|
|
}
|
||
|
|
var items = foldItems(header.items);
|
||
|
|
return RangeHeaderImpl(header.rangeUnit, items);
|
||
|
|
}
|
||
|
|
|
||
|
|
/// Returns this header's range unit. Most commonly, this is `bytes`.
|
||
|
|
String? get rangeUnit;
|
||
|
|
}
|
||
|
|
|
||
|
|
class _ConstantRangeHeader implements RangeHeader {
|
||
|
|
final Iterable<RangeHeaderItem> items_;
|
||
|
|
@override
|
||
|
|
final String? rangeUnit;
|
||
|
|
|
||
|
|
const _ConstantRangeHeader(this.items_, {this.rangeUnit = 'bytes'});
|
||
|
|
|
||
|
|
@override
|
||
|
|
UnmodifiableListView<RangeHeaderItem> get items =>
|
||
|
|
UnmodifiableListView(items_);
|
||
|
|
}
|