Represent set as map[string]bool instead of map[string]struct{}.

main.go

@@ -115,10 +115,10 @@ func generate(name string, args []string) {
 }
 
 // Converts a slice string into a simple lookup map.
-func lookupMap(s []string) map[string]struct{} {
-	lookup := make(map[string]struct{}, len(s))
+func lookupMap(s []string) map[string]bool {
+	lookup := make(map[string]bool, len(s))
 	for _, str := range s {
-		lookup[str] = struct{}{}
+		lookup[str] = true
 	}
 	return lookup
 }

package.go

@@ -112,7 +112,7 @@ func (pkg *Package) HasRequiredFunctions() bool {
 // Filter removes any enums, or functions found in this package that are not
 // listed in the given lookup maps. If either of the maps has a length of zero,
 // filtering does not occur for that type (e.g. all functions are left intact).
-func (pkg *Package) Filter(enums, functions map[string]struct{}) {
+func (pkg *Package) Filter(enums, functions map[string]bool) {
 	if len(enums) > 0 {
 		// Remove any enum not listed in the enums lookup map.
 		for name := range pkg.Enums {