Only include syntax layers specified by build tags; lazy-load syntax layers

syntax/1entry.go

@@ -0,0 +1,25 @@
+package syntax
+
+import "sync"
+
+var syntaxMap = make(map[string]*lazySyntax)
+
+type lazySyntax struct {
+	once        sync.Once
+	syntaxLayer []byte
+	init        func() []byte
+}
+
+func (ls *lazySyntax) get() []byte {
+	ls.once.Do(func() {
+		ls.syntaxLayer = ls.init()
+	})
+	return ls.syntaxLayer
+}
+
+func Get(id string) []byte {
+	if syntax, exists := syntaxMap[id]; exists {
+		return syntax.get()
+	}
+	return nil
+}

syntax/stxGo.go

@@ -1,7 +1,10 @@
+//go:build stxGo
+
 package syntax
 
-func GetGo() []byte {
-	return []byte(`filetype: go
+func init() {
+	syntaxMap["go"] = &lazySyntax{init: func() []byte {
+		return []byte(`filetype: go
 
 detect:
     filename: "\\.go$"
@@ -67,4 +70,5 @@ rules:
         rules:
             - todo: "(TODO|XXX|FIXME):?"
 `)
+	}}
 }