TR-942: Avoid all remaining try! calls in SQLite.swift by making Statement a sequence of success-or-error cases instead of try!-evaluated success cases.

Author: MrMage

Sources/SQLite/Core/Statement.swift

@@ -200,10 +200,33 @@ extension Statement : Sequence {
 
 }
 
+public enum ResultOrError<ResultType> {
+	case success(ResultType)
+	case error(Error)
+	
+	public func map<T>(_ transform: (ResultType) throws -> T) rethrows -> ResultOrError<T> {
+		switch self {
+		case let .success(result): return try .success(transform(result))
+		case let .error(error): return .error(error)
+		}
+	}
+	
+	public func unwrapOrThrow() throws -> ResultType {
+		switch self {
+		case let .success(result): return result
+		case let .error(error): throw error
+		}
+	}
+}
+
 extension Statement : IteratorProtocol {
 
-    public func next() -> [Binding?]? {
-        return try! step() ? Array(row) : nil
+    public func next() -> ResultOrError<[Binding?]>? {
+		do {
+			return try step() ? .success(Array(row)) : nil
+		} catch {
+			return .error(error)
+		}
     }
 
 }

Sources/SQLite/Typed/Query.swift

@@ -892,7 +892,7 @@ public struct Delete : ExpressionType {
 
 extension Connection {
 
-    public func prepare(_ query: QueryType) throws -> AnySequence<Row> {
+    public func prepare(_ query: QueryType) throws -> AnySequence<ResultOrError<Row>> {
         let expression = query.expression
         let statement = try prepare(expression.template, expression.bindings)
 
@@ -940,7 +940,7 @@ extension Connection {
         }()
 
         return AnySequence {
-            AnyIterator { statement.next().map { Row(columnNames, $0) } }
+			AnyIterator { statement.next().map { $0.map { Row(columnNames, $0) } } }
         }
     }
 
@@ -967,7 +967,7 @@ extension Connection {
     }
 
     public func pluck(_ query: QueryType) throws -> Row? {
-        return try prepare(query.limit(1, query.clauses.limit?.offset)).makeIterator().next()
+        return try prepare(query.limit(1, query.clauses.limit?.offset)).makeIterator().next()?.unwrapOrThrow()
     }
 
     /// Runs an `Insert` query.