Full Consistency With HashMap

[bluss]

Missing methods (stable):

• with_hasher Add with_hasher, hasher methods #35
• hasher Add with_hasher, hasher methods #35
• shrink_to_fit
• is_empty Implement method .is_empty() #22
• drain Adds a OrderMap::drain() method #27
• values, values_mut Consistency with HashMap: missing values iterator. #17

New methods:

As a rule, we don't implement unstable methods; they are implemented when they are stable in Rust beta

• get_key_value Tracking issue for {HashMap, BTreeMap}::get_key_value stabilization rust-lang/rust#49347
• Entry::and_modify (unstable)
• Entry::or_default (unstable)
• try_reserve Tracking issue for try_reserve: RFC 2116 fallible collection allocation rust-lang/rust#48043
• remove_entry Tracking issue for HashMap::remove_entry rust-lang/rust#46344

Trait impls

• PartialEq + Eq Implement PartialEq and Eq #23
• Extend<(&K, &V)> Implement Extend<(&K, &V)> for Copy types #34
• Ser/De Implement optional Serde 1.0 support #28
• ESI for iterators Added ExactSizeIterator support. #26
• Debug for Entry
• Clone for some iterators (Keys, Values, Iter, probably all of them)

Type Conflicts:

• Entry<K, V> vs Entry<K, V, S> (not important) Factor out "OrderMapCore" and other generics bloat saving measures #59
• retain's &K vs &mut K Add trait MutableKeys #39
• drain's signature (not important)
• OccupiedEntry::insert's signature Signature of OccupiedEntry::insert #68

[LunaBorowska]

#28 implements Ser/De

[bluss]

I can't find any discrepancies between HashSet and OrderSet. A second close look is of course welcome, but I think @cuviper already did this carefully when implementing OrderSet, so it should already be fine.

[CAD97]

indexmap::map::Keys is not Clone where std::collections::hash_map::Keys is. (Just noticed this moving some code that needed stable ordering over.) Is this an innate limitation or just an oversight?

[bluss]

Just an oversight, please check all iterators you can and PRs welcome.

[cuviper]

I think we are as close as we can get at this point. New additions to std can continue being considered individually.