Enum hdk::prelude::ChainQueryFilterRange

pub enum ChainQueryFilterRange {
    Unbounded,
    HeaderSeqRange(u32, u32),
    HeaderHashRange(HoloHash<Header>, HoloHash<Header>),
    HeaderHashTerminated(HoloHash<Header>, u32),
}

Defines several ways that queries can be restricted to a range. Notably hash bounded ranges disambiguate forks whereas sequence indexes do not as the same position can be found in many forks. The reason that this does NOT use native rust range traits is that the hash bounded queries MUST be inclusive otherwise the integrity and fork disambiguation logic is impossible. An exclusive range bound that does not include the final header tells us nothing about which fork to select between N forks of equal length that proceed it. With an inclusive hash bounded range the final header always points unambiguously at the “correct” fork that the range is over. Start hashes are not needed to provide this property so ranges can be hash terminated with a length of preceeding elements to return only. Technically the seq bounded ranges do not imply any fork disambiguation and so could be a range but for simplicity we left the API symmetrical in boundedness across all enum variants. @TODO It may be possible to provide/implement RangeBounds in the case that a full sequence of elements/headers is provided but it would need to be handled as inclusive first, to enforce the integrity of the query, then the exclusiveness achieved by simply removing the final element after the fact.

Variants

Unbounded

Do NOT apply any range filtering for this query.

HeaderSeqRange(u32, u32)

A range over source chain sequence numbers. This is ambiguous over forking histories and so should NOT be used in validation logic. Inclusive start, inclusive end.

HeaderHashRange(HoloHash<Header>, HoloHash<Header>)

A range over source chain header hashes. This CAN be used in validation logic as forks are disambiguated. Inclusive start and end (unlike std::ops::Range).

HeaderHashTerminated(HoloHash<Header>, u32)

The terminating header hash and N preceeding elements. N = 0 returns only the element with this HeaderHash. This CAN be used in validation logic as forks are not possible when “looking up” towards genesis from some HeaderHash.

Trait Implementations

impl Clone for ChainQueryFilterRange

pub fn clone(&self) -> ChainQueryFilterRange

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ChainQueryFilterRange

pub fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Default for ChainQueryFilterRange

pub fn default() -> ChainQueryFilterRange

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for ChainQueryFilterRange

pub fn deserialize<__D>(
    __deserializer: __D
) -> Result<ChainQueryFilterRange, <__D as Deserializer<'de>>::Error> where
    __D: Deserializer<'de>, 

Deserialize this value from the given Serde deserializer.

impl PartialEq<ChainQueryFilterRange> for ChainQueryFilterRange

pub fn eq(&self, other: &ChainQueryFilterRange) -> bool

This method tests for self and other values to be equal, and is used by ==.

pub fn ne(&self, other: &ChainQueryFilterRange) -> bool

This method tests for !=.

impl Serialize for ChainQueryFilterRange

pub fn serialize<__S>(
    &self,
    __serializer: __S
) -> Result<<__S as Serializer>::Ok, <__S as Serializer>::Error> where
    __S: Serializer, 

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for ChainQueryFilterRange