Compute statement hashability from underlying query fragment (#245)

* Compute statement hashability from underlying query fragment

We currently depend directly on the hashability of `Statement` in the
various fetch property wrappers, but this conformance has been found to
be problematic and so we should remove it. We can make this change
today, though, before removing it, by computing the hashability of a
statement from its query fragment data.

* wip

* wip

Author: stephencelis

Examples/CaseStudies/ObservableModelDemo.swift

@@ -3,7 +3,7 @@ import SwiftUI
 
 struct ObservableModelDemo: SwiftUICaseStudy {
   let readMe = """
-    This demonstrates how to use the `@FetchAll` and `@FetchOne` tools in an @Observable model. \
+    This demonstrates how to use the `@FetchAll` and `@FetchOne` tools in an `@Observable` model. \
     In SwiftUI, the `@Query` macro only works when installed directly in a SwiftUI view, and \
     cannot be used outside of views.
 

Examples/Examples.xcodeproj/project.xcworkspace/xcshareddata/swiftpm/Package.resolved

@@ -66,7 +66,11 @@ class SearchRemindersModel {
     withErrorReporting {
       try database.write { db in
         try Reminder
-          .where { $0.isCompleted && $0.id.in(baseQuery.select { $1.id }) }
+          .where {
+            $0.isCompleted && $0.id.in(
+              baseQuery(searchText: searchText, searchTokens: searchTokens).select { $1.id }
+            )
+          }
           .where {
             if let monthsAgo {
               #sql("\($0.dueDate) < date('now', '-\(raw: monthsAgo) months')")
@@ -78,29 +82,6 @@ class SearchRemindersModel {
     }
   }
 
-  private var baseQuery: SelectOf<ReminderText, Reminder> {
-    let searchText = searchText.quoted()
-
-    return
-      ReminderText
-      .where {
-        if !searchText.isEmpty {
-          $0.match(searchText)
-        }
-      }
-      .where {
-        for token in searchTokens {
-          switch token.kind {
-          case .near:
-            $0.match("NEAR(\(token.rawValue.quoted()))")
-          case .tag:
-            $0.tags.match(token.rawValue)
-          }
-        }
-      }
-      .join(Reminder.all) { $0.rowid.eq($1.rowid) }
-  }
-
   private func updateQuery(debounce: Bool = true) async throws {
     if debounce {
       try await clock.sleep(for: .seconds(0.3))
@@ -120,7 +101,8 @@ class SearchRemindersModel {
       } else {
         try await $searchResults.load(
           SearchRequest(
-            baseQuery: baseQuery,
+            searchText: searchText,
+            searchTokens: searchTokens,
             showCompletedInSearchResults: showCompletedInSearchResults
           ),
           animation: .default
@@ -145,10 +127,12 @@ class SearchRemindersModel {
       var completedCount = 0
       var rows: [Row] = []
     }
-    let baseQuery: SelectOf<ReminderText, Reminder>
+    let searchText: String
+    let searchTokens: [Token]
     let showCompletedInSearchResults: Bool
     func fetch(_ db: Database) throws -> Value {
-      try Value(
+      let baseQuery = baseQuery(searchText: searchText, searchTokens: searchTokens)
+      return try Value(
         completedCount:
           baseQuery
           .where { $1.isCompleted }
@@ -280,6 +264,32 @@ struct SearchRemindersView: View {
   }
 }
 
+fileprivate func baseQuery(
+  searchText: String,
+  searchTokens: [SearchRemindersModel.Token]
+) -> SelectOf<ReminderText, Reminder> {
+  let searchText = searchText.quoted()
+
+  return
+    ReminderText
+    .where {
+      if !searchText.isEmpty {
+        $0.match(searchText)
+      }
+    }
+    .where {
+      for token in searchTokens {
+        switch token.kind {
+        case .near:
+          $0.match("NEAR(\(token.rawValue.quoted()))")
+        case .tag:
+          $0.tags.match(token.rawValue)
+        }
+      }
+    }
+    .join(Reminder.all) { $0.rowid.eq($1.rowid) }
+}
+
 extension String {
   fileprivate func quoted() -> String {
     split(separator: " ")

Examples/Reminders/SearchReminders.swift

@@ -5,19 +5,10 @@ protocol StatementKeyRequest<QueryValue>: FetchKeyRequest {
 
 extension StatementKeyRequest {
   static func == (lhs: Self, rhs: Self) -> Bool {
-    // NB: A Swift 6.1 regression prevents this from compiling:
-    //     https://github.com/swiftlang/swift/issues/79623
-    // return AnyHashable(lhs.statement) == AnyHashable(rhs.statement)
-    let lhs = lhs.statement
-    let rhs = rhs.statement
-    return AnyHashable(lhs) == AnyHashable(rhs)
+    lhs.statement.query == rhs.statement.query
   }
 
   func hash(into hasher: inout Hasher) {
-    // NB: A Swift 6.1 regression prevents this from compiling:
-    //     https://github.com/swiftlang/swift/issues/79623
-    // hasher.combine(statement)
-    let statement = statement
-    hasher.combine(statement)
+    hasher.combine(statement.query)
   }
 }