Feat: adds clear function to HitsSource

Sources/InstantSearchCore/Hits/HitsInteractor.swift

@@ -154,7 +154,10 @@ public class HitsInteractor<Record: Codable>: AnyHitsInteractor {
 
     infiniteScrollingController.calculatePagesAndLoad(currentRow: rowIndex, offset: pageLoadOffset, pageMap: hitsPageMap)
   }
-
+
+  public func clear() {
+    paginator.clear()
+  }
 }
 
 extension HitsInteractor {

Sources/InstantSearchCore/Hits/HitsSource.swift

@@ -14,7 +14,7 @@ public protocol HitsSource: AnyObject {
 
   func numberOfHits() -> Int
   func hit(atIndex index: Int) -> Record?
-
+  func clear()
 }
 
 extension HitsInteractor: HitsSource {}

Sources/InstantSearchCore/Pagination/Paginator.swift

@@ -39,4 +39,7 @@ class Paginator<Item> {
     isInvalidated = true
   }
 
+  public func clear() {
+    pageMap = nil
+  }
 }

Sources/InstantSearchSwiftUI/DataModel/HitsObservableController.swift

@@ -16,9 +16,15 @@ import SwiftUI
 /// HitsController implementation adapted for usage with SwiftUI views
 @available(iOS 13.0, OSX 10.15, tvOS 13.0, watchOS 6.0, *)
 public class HitsObservableController<Hit: Codable>: ObservableObject, HitsController {
-
+  
   /// List of hits itemsto present
-  @Published public var hits: [Hit?]
+  @Published public var hits: [Hit?] {
+    didSet {
+      if hits.isEmpty {
+        hitsSource?.clear()
+      }
+    }
+  }
 
   /// The state ID to assign to the scrollview presenting the hits
   @Published public var scrollID: UUID

Tests/InstantSearchCoreTests/Unit/Hits/HitsInteractorTests.swift

@@ -235,5 +235,31 @@ class HitsInteractorTests: XCTestCase {
     waitForExpectations(timeout: 5)
 
   }
+
+  func testClearTriggering() throws {
+    let paginationController = Paginator<TestRecord<Int>>()
+    let infiniteScrollingController = TestInfiniteScrollingController()
+
+    let hits = (0..<20).map(TestRecord.withValue)
+    let results = SearchResponse(hits: hits)
+
+    let vm = HitsInteractor(
+      settings: .init(showItemsOnEmptyQuery: true),
+      paginationController: paginationController,
+      infiniteScrollingController: infiniteScrollingController
+    )
+
+    let exp = expectation(description: "on results updated")
+
+    vm.onResultsUpdated.subscribe(with: self) { (_, _) in
+      XCTAssertEqual(vm.numberOfHits(), hits.count)
+      exp.fulfill()
+    }
+    vm.update(results)
+    waitForExpectations(timeout: 3, handler: .none)
+
+    vm.clear()
+    XCTAssertEqual(vm.numberOfHits(), 0)
+  }
 
 }

Tests/InstantSearchCoreTests/Unit/PaginatorTests.swift

@@ -93,5 +93,15 @@ class PaginatorTests: XCTestCase {
     XCTAssertEqual(paginator.pageMap?.count, 3)
 
   }
+
+  func testClear() {
+    let paginator = Paginator<String>()
+    let page = TestPageable(index: 0, items: ["i1", "i2", "i3"])
+    paginator.process(page)
+    XCTAssertEqual(paginator.pageMap?.count, 3)
+
+    paginator.clear()
+    XCTAssertNil(paginator.pageMap)
+  }
 
 }

Tests/InstantSearchTests/TestHitsSource.swift

@@ -13,7 +13,7 @@ class TestHitsSource: HitsSource {
 
   typealias Hit = String
 
-  let hits: [String]
+  var hits: [String]
 
   init(hits: [String]) {
     self.hits = hits
@@ -28,4 +28,7 @@ class TestHitsSource: HitsSource {
     return hits[index]
   }
 
+  func clear() {
+    hits = []
+  }
 }