cm

Former-commit-id: 8f99121b81dc76c04d5910117885d9286873f26c

mvc2/binder/func_result.go

@@ -0,0 +1,53 @@
+package binder
+
+import (
+	"errors"
+	"reflect"
+)
+
+var (
+	errBad = errors.New("bad")
+)
+
+func makeReturnValue(fn reflect.Value) (func([]reflect.Value) reflect.Value, reflect.Type, error) {
+	typ := indirectTyp(fn.Type())
+
+	// invalid if not a func.
+	if typ.Kind() != reflect.Func {
+		return nil, typ, errBad
+	}
+
+	// invalid if not returns one single value.
+	if typ.NumOut() != 1 {
+		return nil, typ, errBad
+	}
+
+	// invalid if input args length is not one.
+	if typ.NumIn() != 1 {
+		return nil, typ, errBad
+	}
+
+	// invalid if that single input arg is not a typeof context.Context.
+	if !isContext(typ.In(0)) {
+		return nil, typ, errBad
+	}
+
+	outTyp := typ.Out(0)
+	zeroOutVal := reflect.New(outTyp).Elem()
+
+	bf := func(ctxValue []reflect.Value) reflect.Value {
+		// []reflect.Value{reflect.ValueOf(ctx)}
+		results := fn.Call(ctxValue) // ctxValue is like that because of; read makeHandler.
+		if len(results) == 0 {
+			return zeroOutVal
+		}
+
+		v := results[0]
+		if !v.IsValid() {
+			return zeroOutVal
+		}
+		return v
+	}
+
+	return bf, outTyp, nil
+}