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64 lines
2.3 KiB
Scala
64 lines
2.3 KiB
Scala
package com.twitter.product_mixer.component_library.filter
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import com.twitter.product_mixer.core.functional_component.filter.Filter
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import com.twitter.product_mixer.core.functional_component.filter.FilterResult
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import com.twitter.product_mixer.core.model.common.CandidateWithFeatures
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import com.twitter.product_mixer.core.model.common.UniversalNoun
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import com.twitter.product_mixer.core.model.common.identifier.FilterIdentifier
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import com.twitter.product_mixer.core.pipeline.PipelineQuery
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import com.twitter.stitch.Stitch
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/**
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* Predicate which will be applied to each candidate. True indicates that the candidate will be
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* @tparam Candidate - the type of the candidate
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*/
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trait ShouldKeepCandidate[Candidate] {
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def apply(candidate: Candidate): Boolean
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}
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object PredicateFilter {
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/**
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* Builds a simple Filter out of a predicate function from the candidate to a boolean. For clarity,
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* we recommend including the name of the shouldKeepCandidate parameter.
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*
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* {{{
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* Filter.fromPredicate(
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* FilterIdentifier("SomeFilter"),
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* shouldKeepCandidate = { candidate: UserCandidate => candidate.id % 2 == 0L }
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* )
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* }}}
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*
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* @param identifier A FilterIdentifier for the new filter
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* @param shouldKeepCandidate A predicate function from the candidate. Candidates will be kept
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* when this function returns True.
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*/
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def fromPredicate[Candidate <: UniversalNoun[Any]](
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identifier: FilterIdentifier,
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shouldKeepCandidate: ShouldKeepCandidate[Candidate]
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): Filter[PipelineQuery, Candidate] = {
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val i = identifier
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new Filter[PipelineQuery, Candidate] {
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override val identifier: FilterIdentifier = i
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/**
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* Filter the list of candidates
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*
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* @return a FilterResult including both the list of kept candidate and the list of removed candidates
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*/
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override def apply(
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query: PipelineQuery,
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candidates: Seq[CandidateWithFeatures[Candidate]]
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): Stitch[FilterResult[Candidate]] = {
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val (keptCandidates, removedCandidates) = candidates.map(_.candidate).partition {
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filterCandidate =>
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shouldKeepCandidate(filterCandidate)
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}
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Stitch.value(FilterResult(kept = keptCandidates, removed = removedCandidates))
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}
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}
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}
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}
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