Add Row object

Behaves like a dictionary, mostly, but provides typed access to a row's
values. Query objects yield them on iteration/access:

    let email = Expression<String>("email")
    let users = db["users"]

    for user in users.select(email) {
        if let email = user[email] {
            // email is String
        }
    }

Signed-off-by: Stephen Celis <stephen@stephencelis.com>

Author: stephencelis

SQLite Common Tests/QueryTests.swift

@@ -258,7 +258,7 @@ class QueryTests: XCTestCase {
     func test_first_returnsTheFirstRow() {
         InsertUsers(db, "alice", "betsy")
         ExpectExecutions(db, ["SELECT * FROM users LIMIT 1": 1]) { _ in
-            XCTAssertEqual(1, self.users.first!["id"] as Int)
+            XCTAssertEqual(1, self.users.first![self.id]!)
         }
     }
 
@@ -354,4 +354,9 @@ class QueryTests: XCTestCase {
         XCTAssertEqual(50.0, users.total(age))
     }
 
+    func test_row_withBoundColumn_returnsValue() {
+        InsertUser(db, "alice", age: 20)
+        XCTAssertEqual(21, users.select(age + 1).first![age + 1]!)
+    }
+
 }

SQLite Common/Query.swift

@@ -362,7 +362,7 @@ public struct Query {
     // MARK: - Array
 
     /// The first result (or nil if the query has no results).
-    public var first: Values? { return limit(1).generate().next() }
+    public var first: Row? { return limit(1).generate().next() }
 
     /// Returns true if the query has no results.
     public var isEmpty: Bool { return first == nil }
@@ -508,6 +508,63 @@ public struct Query {
 
 }
 
+/// A row object. Returned by iterating over a Query. Provides typed subscript
+/// access to a row’s values.
+public struct Row {
+
+    private var values: Values
+
+    private init(_ values: Values) {
+        self.values = values
+    }
+
+    /// Returns a row’s value for the given column.
+    ///
+    /// :param: column An expression representing a column selected in a Query.
+    ///
+    /// returns The value for the given column.
+    public func get<T: Value>(column: Expression<T>) -> T? {
+        return values[column.SQL] as? T
+    }
+
+    /// Returns a row’s value for the given column.
+    ///
+    /// :param: column An expression representing a column selected in a Query.
+    ///
+    /// returns The value for the given column.
+    public subscript(column: Expression<Bool>) -> Bool? {
+        return get(column)
+    }
+
+    /// Returns a row’s value for the given column.
+    ///
+    /// :param: column An expression representing a column selected in a Query.
+    ///
+    /// returns The value for the given column.
+    public subscript(column: Expression<Double>) -> Double? {
+        return get(column)
+    }
+
+    /// Returns a row’s value for the given column.
+    ///
+    /// :param: column An expression representing a column selected in a Query.
+    ///
+    /// returns The value for the given column.
+    public subscript(column: Expression<Int>) -> Int? {
+        return get(column)
+    }
+
+    /// Returns a row’s value for the given column.
+    ///
+    /// :param: column An expression representing a column selected in a Query.
+    ///
+    /// returns The value for the given column.
+    public subscript(column: Expression<String>) -> String? {
+        return get(column)
+    }
+
+}
+
 // MARK: - SequenceType
 extension Query: SequenceType {
 
@@ -524,9 +581,9 @@ public struct QueryGenerator: GeneratorType {
 
     private init(_ statement: Statement) { self.statement = statement }
 
-    public func next() -> Values? {
+    public func next() -> Row? {
         statement.next()
-        return statement.values
+        return statement.values.map { Row($0) }
     }
 
 }

SQLite.playground/Documentation/fragment-14.html

@@ -4,7 +4,7 @@
 <meta id='xcode-display' name='xcode-display' content='render'>
 <section>
     <p>
-        You may notice that iteration works a little differently here. Rather than arrays of rows, we are given dictionaries of column names to row values. This gives us a little more powerful of a mapping to work with and pass around.
+        You may notice that iteration works a little differently here. Rather than arrays of raw values, we are given <code>Row</code> objects, which can be subscripted with the same expressions we prepared above. This gives us a little more powerful of a mapping to work with and pass around.
     </p>
     <p>
         Queries can be used and reused, and can quickly return rows, counts and other aggregate values.

SQLite.playground/section-28.swift

@@ -1,4 +1,4 @@
 // SELECT * FROM users
 for user in users {
-    println(user["email"])
+    println(user[email])
 }