DatabaseCollation no longer uses a deprecated String initializer

Author: groue

GRDB/Core/Database.swift

@@ -806,7 +806,7 @@ public final class Database: CustomStringConvertible, CustomDebugStringConvertib
             collationPointer,
             { (collationPointer, length1, buffer1, length2, buffer2) in
                 let collation = Unmanaged<DatabaseCollation>.fromOpaque(collationPointer!).takeUnretainedValue()
-                return CInt(collation.function(length1, buffer1, length2, buffer2).rawValue)
+                return collation.xCompare(length1, buffer1.unsafelyUnwrapped, length2, buffer2.unsafelyUnwrapped)
             }, nil)
         guard code == SQLITE_OK else {
             // Assume a GRDB bug: there is no point throwing any error.

GRDB/Core/DatabaseCollation.swift

@@ -53,12 +53,21 @@ public final class DatabaseCollation: Identifiable, Sendable {
         }
     }
 
+    /// Feeds the `xCompare` parameter of sqlite3_create_collation_v2
+    /// <https://www.sqlite.org/c3ref/create_collation.html>
+    typealias XCompare = @Sendable (
+        _ length1: CInt,
+        _ buffer1: UnsafeRawPointer,
+        _ length2: CInt,
+        _ buffer2: UnsafeRawPointer
+    ) -> CInt
+    
     /// The identifier of the collation.
     public var id: ID { ID(name: name) }
 
     /// The name of the collation.
     public let name: String
-    let function: @Sendable (CInt, UnsafeRawPointer?, CInt, UnsafeRawPointer?) -> ComparisonResult
+    let xCompare: XCompare
 
     /// Creates a collation.
     ///
@@ -75,21 +84,16 @@ public final class DatabaseCollation: Identifiable, Sendable {
     /// - parameters:
     ///     - name: The collation name.
     ///     - function: A function that compares two strings.
-    public init(_ name: String, function: @escaping @Sendable (String, String) -> ComparisonResult) {
+    public convenience init(_ name: String, function: @escaping @Sendable (String, String) -> ComparisonResult) {
+        self.init(name, xCompare: { (length1, buffer1, length2, buffer2) in
+            let string1 = String(decoding: UnsafeRawBufferPointer(start: buffer1, count: Int(length1)), as: UTF8.self)
+            let string2 = String(decoding: UnsafeRawBufferPointer(start: buffer2, count: Int(length2)), as: UTF8.self)
+            return CInt(function(string1, string2).rawValue)
+        })
+    }
+    
+    init(_ name: String, xCompare: @escaping XCompare) {
         self.name = name
-        self.function = { (length1, buffer1, length2, buffer2) in
-            // Buffers are not C strings: they do not end with \0.
-            let string1 = String(
-                bytesNoCopy: UnsafeMutableRawPointer(mutating: buffer1.unsafelyUnwrapped),
-                length: Int(length1),
-                encoding: .utf8,
-                freeWhenDone: false)!
-            let string2 = String(
-                bytesNoCopy: UnsafeMutableRawPointer(mutating: buffer2.unsafelyUnwrapped),
-                length: Int(length2),
-                encoding: .utf8,
-                freeWhenDone: false)!
-            return function(string1, string2)
-        }
+        self.xCompare = xCompare
     }
 }

Tests/GRDBTests/DatabaseCollationTests.swift

@@ -6,38 +6,38 @@ class DatabaseCollationTests: GRDBTestCase {
     func testDefaultCollations() throws {
         let dbQueue = try makeDatabaseQueue()
         try dbQueue.inDatabase { db in
-            try db.execute(sql: "CREATE TABLE strings (id INTEGER PRIMARY KEY, name TEXT)")
-            try db.execute(sql: "INSERT INTO strings VALUES (1, '1')")
-            try db.execute(sql: "INSERT INTO strings VALUES (2, '2')")
-            try db.execute(sql: "INSERT INTO strings VALUES (3, '10')")
-            try db.execute(sql: "INSERT INTO strings VALUES (4, 'a')")
-            try db.execute(sql: "INSERT INTO strings VALUES (5, 'à')")
-            try db.execute(sql: "INSERT INTO strings VALUES (6, 'A')")
-            try db.execute(sql: "INSERT INTO strings VALUES (7, 'Z')")
-            try db.execute(sql: "INSERT INTO strings VALUES (8, 'z')")
+            try db.execute(sql: """
+                CREATE TABLE strings (id INTEGER PRIMARY KEY, name TEXT);
+                INSERT INTO strings VALUES (1, '1');
+                INSERT INTO strings VALUES (2, '2');
+                INSERT INTO strings VALUES (3, '10');
+                INSERT INTO strings VALUES (4, 'a');
+                INSERT INTO strings VALUES (5, 'à');
+                INSERT INTO strings VALUES (6, 'A');
+                INSERT INTO strings VALUES (7, 'Z');
+                INSERT INTO strings VALUES (8, 'z');
+                INSERT INTO strings VALUES (9, '');
+                INSERT INTO strings VALUES (10, NULL);
+                INSERT INTO strings VALUES (11, x'42FF'); -- Invalid UTF8 "B�"
+                """)
 
-            // Swift 4.2 and Swift 4.1 don't sort strings in the same way
-            if "z" < "à" {
-                XCTAssertEqual(
-                    try Int.fetchAll(db, sql: "SELECT id FROM strings ORDER BY name COLLATE \(DatabaseCollation.unicodeCompare.name), id"),
-                    [1,3,2,6,7,4,8,5])
-            } else {
-                XCTAssertEqual(
-                    try Int.fetchAll(db, sql: "SELECT id FROM strings ORDER BY name COLLATE \(DatabaseCollation.unicodeCompare.name), id"),
-                    [1,3,2,6,7,4,5,8])
-            }
+            // Note that "B�" is always last. We can observe that SQLite
+            // does not invoke the collation for invalid UTF8 strings.
+            XCTAssertEqual(
+                try Int.fetchAll(db, sql: "SELECT id FROM strings ORDER BY name COLLATE \(DatabaseCollation.unicodeCompare.name), id"),
+                [10,9,1,3,2,6,7,4,8,5,11])
             XCTAssertEqual(
                 try Int.fetchAll(db, sql: "SELECT id FROM strings ORDER BY name COLLATE \(DatabaseCollation.caseInsensitiveCompare.name), id"),
-                [1,3,2,4,6,5,7,8])
+                [10,9,1,3,2,4,6,5,7,8,11])
             XCTAssertEqual(
                 try Int.fetchAll(db, sql: "SELECT id FROM strings ORDER BY name COLLATE \(DatabaseCollation.localizedCaseInsensitiveCompare.name), id"),
-                [1,3,2,4,6,5,7,8])
+                [10,9,1,3,2,4,6,5,7,8,11])
             XCTAssertEqual(
                 try Int.fetchAll(db, sql: "SELECT id FROM strings ORDER BY name COLLATE \(DatabaseCollation.localizedCompare.name), id"),
-                [1,3,2,4,6,5,8,7])
+                [10,9,1,3,2,4,6,5,8,7,11])
             XCTAssertEqual(
                 try Int.fetchAll(db, sql: "SELECT id FROM strings ORDER BY name COLLATE \(DatabaseCollation.localizedStandardCompare.name), id"),
-                [1,2,3,4,6,5,8,7])
+                [10,9,1,2,3,4,6,5,8,7,11])
         }
     }