Merge pull request #1 from ypopovych/master

Strings to enum constants

Author: ottosuess

Sources/SQLite/Typed/AggregateFunctions.swift

@@ -22,6 +22,19 @@
 // THE SOFTWARE.
 //
 
+private enum Functions: String {
+    case count
+    case max
+    case min
+    case avg
+    case sum
+    case total
+    
+    func wrap<T>(_ expression: Expressible) -> Expression<T> {
+        return self.rawValue.wrap(expression)
+    }
+}
+
 extension ExpressionType where UnderlyingType : Value {
 
     /// Builds a copy of the expression prefixed with the `DISTINCT` keyword.
@@ -48,7 +61,7 @@ extension ExpressionType where UnderlyingType : Value {
     /// - Returns: A copy of the expression wrapped with the `count` aggregate
     ///   function.
     public var count: Expression<Int> {
-        return "count".wrap(self)
+        return Functions.count.wrap(self)
     }
 
 }
@@ -79,7 +92,7 @@ extension ExpressionType where UnderlyingType : _OptionalType, UnderlyingType.Wr
     /// - Returns: A copy of the expression wrapped with the `count` aggregate
     ///   function.
     public var count: Expression<Int> {
-        return "count".wrap(self)
+        return Functions.count.wrap(self)
     }
 
 }
@@ -96,7 +109,7 @@ extension ExpressionType where UnderlyingType : Value, UnderlyingType.Datatype :
     /// - Returns: A copy of the expression wrapped with the `max` aggregate
     ///   function.
     public var max: Expression<UnderlyingType?> {
-        return "max".wrap(self)
+        return Functions.max.wrap(self)
     }
 
     /// Builds a copy of the expression wrapped with the `min` aggregate
@@ -109,7 +122,7 @@ extension ExpressionType where UnderlyingType : Value, UnderlyingType.Datatype :
     /// - Returns: A copy of the expression wrapped with the `min` aggregate
     ///   function.
     public var min: Expression<UnderlyingType?> {
-        return "min".wrap(self)
+        return Functions.min.wrap(self)
     }
 
 }
@@ -126,7 +139,7 @@ extension ExpressionType where UnderlyingType : _OptionalType, UnderlyingType.Wr
     /// - Returns: A copy of the expression wrapped with the `max` aggregate
     ///   function.
     public var max: Expression<UnderlyingType> {
-        return "max".wrap(self)
+        return Functions.max.wrap(self)
     }
 
     /// Builds a copy of the expression wrapped with the `min` aggregate
@@ -139,7 +152,7 @@ extension ExpressionType where UnderlyingType : _OptionalType, UnderlyingType.Wr
     /// - Returns: A copy of the expression wrapped with the `min` aggregate
     ///   function.
     public var min: Expression<UnderlyingType> {
-        return "min".wrap(self)
+        return Functions.min.wrap(self)
     }
 
 }
@@ -156,7 +169,7 @@ extension ExpressionType where UnderlyingType : Value, UnderlyingType.Datatype :
     /// - Returns: A copy of the expression wrapped with the `min` aggregate
     ///   function.
     public var average: Expression<Double?> {
-        return "avg".wrap(self)
+        return Functions.avg.wrap(self)
     }
 
     /// Builds a copy of the expression wrapped with the `sum` aggregate
@@ -169,7 +182,7 @@ extension ExpressionType where UnderlyingType : Value, UnderlyingType.Datatype :
     /// - Returns: A copy of the expression wrapped with the `min` aggregate
     ///   function.
     public var sum: Expression<UnderlyingType?> {
-        return "sum".wrap(self)
+        return Functions.sum.wrap(self)
     }
 
     /// Builds a copy of the expression wrapped with the `total` aggregate
@@ -182,7 +195,7 @@ extension ExpressionType where UnderlyingType : Value, UnderlyingType.Datatype :
     /// - Returns: A copy of the expression wrapped with the `min` aggregate
     ///   function.
     public var total: Expression<Double> {
-        return "total".wrap(self)
+        return Functions.total.wrap(self)
     }
 
 }
@@ -199,7 +212,7 @@ extension ExpressionType where UnderlyingType : _OptionalType, UnderlyingType.Wr
     /// - Returns: A copy of the expression wrapped with the `min` aggregate
     ///   function.
     public var average: Expression<Double?> {
-        return "avg".wrap(self)
+        return Functions.avg.wrap(self)
     }
 
     /// Builds a copy of the expression wrapped with the `sum` aggregate
@@ -212,7 +225,7 @@ extension ExpressionType where UnderlyingType : _OptionalType, UnderlyingType.Wr
     /// - Returns: A copy of the expression wrapped with the `min` aggregate
     ///   function.
     public var sum: Expression<UnderlyingType> {
-        return "sum".wrap(self)
+        return Functions.sum.wrap(self)
     }
 
     /// Builds a copy of the expression wrapped with the `total` aggregate
@@ -225,15 +238,15 @@ extension ExpressionType where UnderlyingType : _OptionalType, UnderlyingType.Wr
     /// - Returns: A copy of the expression wrapped with the `min` aggregate
     ///   function.
     public var total: Expression<Double> {
-        return "total".wrap(self)
+        return Functions.total.wrap(self)
     }
 
 }
 
 extension ExpressionType where UnderlyingType == Int {
 
     static func count(_ star: Star) -> Expression<UnderlyingType> {
-        return "count".wrap(star(nil, nil))
+        return Functions.count.wrap(star(nil, nil))
     }
 
 }