restructure code from lib to mod

src/rsnmplib/helper.rs

@@ -0,0 +1,21 @@
+use log::{debug, error, info};
+use regex::Regex;
+
+pub(crate) fn compile_re(regex: Option<String>, name: &str) -> Option<Regex> {
+    if let Some(r) = regex {
+        let re = Regex::new(&r);
+        match re {
+            Ok(r) => {
+                debug!("Sucessfull compiled {} filter regex: {:?}", name, r);
+                Some(r)
+            }
+            Err(e) => {
+                error!("Error compiling {} filter regex: {:?}", name, e);
+                None
+            }
+        }
+    } else {
+        info!("No filter regex for {} supplied", name);
+        None
+    }
+}