Simplify chooseUniform to work with any collection

This allows us to also use it e.g. for Dictionary keys without having to
convert them to an Array first.

Change-Id: I72d8e224abc943556e14290eb566bc43f65f596d
Reviewed-on: https://chrome-internal-review.googlesource.com/c/v8/fuzzilli/+/8587038
Auto-Submit: Matthias Liedtke <mliedtke@google.com>
Commit-Queue: Matthias Liedtke <mliedtke@google.com>
Reviewed-by: Manish Goregaokar <manishearth@google.com>
Commit-Queue: Manish Goregaokar <manishearth@google.com>

Author: Liedtke

Sources/Fuzzilli/Base/ProgramBuilder.swift

@@ -4437,16 +4437,14 @@ public class ProgramBuilder {
         return createObject(with: properties)
     }
 
-    fileprivate static let allTimeZoneAbbreviations: [String] = Array(TimeZone.abbreviationDictionary.keys)
-
     // Generate a random time zone identifier
     @discardableResult
     func randomTimeZone() -> Variable {
         // Bias towards knownTimeZoneIdentifiers since it's a larger array
         if probability(0.7) {
             return loadString(chooseUniform(from: TimeZone.knownTimeZoneIdentifiers))
         } else {
-            return loadString(chooseUniform(from: ProgramBuilder.allTimeZoneAbbreviations))
+            return loadString(chooseUniform(from: TimeZone.abbreviationDictionary.keys))
         }
     }
 

Sources/Fuzzilli/Util/Random.swift

@@ -55,22 +55,9 @@ extension String {
 }
 
 /// Returns a uniformly choosen, random element from the given collection.
-public func chooseUniform<E>(from collection: [E]) -> E {
+public func chooseUniform<C: Collection>(from collection: C) -> C.Element {
     assert(collection.count != 0, "cannot choose from an empty sequence")
-    return collection[Int.random(in: 0..<collection.count)]
-}
-
-/// Returns a uniformly choosen, random element from the given collection.
-public func chooseUniform<E>(from collection: ArraySlice<E>) -> E {
-    assert(collection.count != 0, "cannot choose from an empty sequence")
-    return collection[Int.random(in: 0..<collection.count)]
-}
-
-/// Returns a uniformly choosen, random element from the given collection.
-public func chooseUniform<E>(from collection: Set<E>) -> E {
-    assert(collection.count != 0, "cannot choose from an empty set")
-    let i = collection.index(collection.startIndex, offsetBy: Int.random(in: 0..<collection.count))
-    return collection[i]
+    return collection.randomElement()!
 }
 
 /// Returns a random element from the given collection favouring later elements by the given factor.