Add compact map for shared sequences, single and maybe

RxCocoa/Traits/SharedSequence/SharedSequence+Operators.swift

@@ -25,6 +25,30 @@ extension SharedSequenceConvertibleType {
  }
 }
 
+// MARK: compactMap
+extension SharedSequenceConvertibleType {
+
+ /**
+ Projects each element of an observable sequence into an optional form and filters all optional results.
+ 
+ Equivalent to:
+ 
+ func compactMap<Result>(_ transform: @escaping (Self.E) -> Result?) -> SharedSequence<SharingStrategy, Result> {
+ return self.map(transform).filter { $0 != nil }.map { $0! }
+ }
+ 
+ - parameter transform: A transform function to apply to each source element and which returns an element or nil.
+ - returns: An observable sequence whose elements are the result of filtering the transform function for each element of the source.
+ 
+ */
+ public func compactMap<Result>(_ selector: @escaping (Element) -> Result?) -> SharedSequence<SharingStrategy, Result> {
+ let source = self
+ .asObservable()
+ .compactMap(selector)
+ return SharedSequence<SharingStrategy, Result>(source)
+ }
+}
+
 // MARK: filter
 extension SharedSequenceConvertibleType {
  /**

RxSwift/Traits/Maybe.swift

@@ -238,6 +238,18 @@ extension PrimitiveSequenceType where Trait == MaybeTrait {
  return Maybe(raw: self.primitiveSequence.source.map(transform))
  }
 
+ /**
+ Projects each element of an observable sequence into an optional form and filters all optional results.
+ 
+ - parameter transform: A transform function to apply to each source element.
+ - returns: An observable sequence whose elements are the result of filtering the transform function for each element of the source.
+ 
+ */
+ public func compactMap<Result>(_ transform: @escaping (Element) throws -> Result?)
+ -> Maybe<Result> {
+ return Maybe(raw: self.primitiveSequence.source.compactMap(transform))
+ }
+
  /**
  Projects each element of an observable sequence to an observable sequence and merges the resulting observable sequences into one observable sequence.
 

RxSwift/Traits/Single.swift

@@ -213,6 +213,18 @@ extension PrimitiveSequenceType where Trait == SingleTrait {
  return Single(raw: self.primitiveSequence.source.map(transform))
  }
 
+ /**
+ Projects each element of an observable sequence into an optional form and filters all optional results.
+
+ - parameter transform: A transform function to apply to each source element.
+ - returns: An observable sequence whose elements are the result of filtering the transform function for each element of the source.
+
+ */
+ public func compactMap<Result>(_ transform: @escaping (Element) throws -> Result?)
+ -> Maybe<Result> {
+ return Maybe(raw: self.primitiveSequence.source.compactMap(transform))
+ }
+
  /**
  Projects each element of an observable sequence to an observable sequence and merges the resulting observable sequences into one observable sequence.