Allow macros with no arguments (#23)

Author: andresmgot

macros.go

@@ -9,9 +9,6 @@ import (
 )
 
 var (
-	// ErrorNoArguments is returned when a macro is used but there were no arguments
-	// TODO: Note that it's possible that not every macro has an argument, and we should maybe adjust for this case
-	ErrorNoArguments = errors.New("there were no arguments provided to the macro")
 	// ErrorBadArgumentCount is returned from macros when the wrong number of arguments were provided
 	ErrorBadArgumentCount = errors.New("unexpected number of arguments")
 )
@@ -34,7 +31,7 @@ func trimAll(s []string) []string {
 }
 
 func getMacroRegex(name string) string {
-	return fmt.Sprintf("\\$__%s\\((.*?)\\)", name)
+	return fmt.Sprintf("\\$__%s(?:\\((.*?)\\))?", name)
 }
 
 func interpolate(driver Driver, query *Query) (string, error) {
@@ -52,12 +49,12 @@ func interpolate(driver Driver, query *Query) (string, error) {
 				continue
 			}
 
-			if len(match) == 1 {
-				// This macro has no arguments
-				return "", ErrorNoArguments
+			args := []string{}
+			if len(match) > 1 {
+				// This macro has arguments
+				args = trimAll(strings.Split(match[1], ","))
 			}
 
-			args := trimAll(strings.Split(match[1], ","))
 			res, err := macro(query.WithSQL(rawSQL), args)
 			if err != nil {
 				return "", err

macros_test.go

@@ -48,7 +48,7 @@ func TestInterpolate(t *testing.T) {
 		{input: "select * from $__foo()", output: "select * from bar", name: "correct macro"},
 		{input: "select '$__foo()' from $__foo()", output: "select 'bar' from bar", name: "multiple instances of same macro"},
 		{input: "select * from $__foo()$__foo()", output: "select * from barbar", name: "multiple instances of same macro without space"},
-		{input: "select * from $__foo", output: "select * from $__foo", name: "macro without paranthesis"},
+		{input: "select * from $__foo", output: "select * from bar", name: "macro without paranthesis"},
 		{input: "select * from $__params()", output: "select * from bar", name: "macro without params"},
 		{input: "select * from $__params(hello)", output: "select * from bar_hello", name: "with param"},
 		{input: "select * from $__params(hello) AND $__params(hello)", output: "select * from bar_hello AND bar_hello", name: "same macro multiple times with same param"},