move crawl-delay into a feature as it won't be user by many

Cargo.toml

@@ -10,6 +10,9 @@ license = "MIT"
 keywords = ["robots", "txt", "parse", "compile"]
 repository = "https://github.com/crestonbunch/cylon"
 
+[features]
+crawl-delay = []
+
 [dependencies]
 futures-util = "0.3"
 serde = "1.0"

src/dfa.rs

@@ -1,3 +1,4 @@
+#[cfg(feature = "crawl-delay")]
 use std::cmp::Ordering;
 
 use serde_derive::{Deserialize, Serialize};
@@ -45,10 +46,12 @@ enum State {
 pub struct Cylon {
     states: Vec<State>,
     transitions: Vec<Vec<Transition>>,
+    #[cfg(feature = "crawl-delay")]
     delay: Option<u64>,
 }
 
 impl Cylon {
+    #[cfg(feature = "crawl-delay")]
     pub fn delay(&self) -> Option<u64> {
         self.delay
     }
@@ -204,6 +207,8 @@ impl Cylon {
             transitions.push(t);
         }
 
+        #[cfg(feature = "crawl-delay")]
+        {
             let mut delays: Vec<Option<u64>> = rules.iter().filter(|rule| { 
                 match rule {
                     Rule::Delay(_) => true,
@@ -221,15 +226,19 @@ impl Cylon {
 
                 }
             });
-        
-            
-
             Self {
                 delay: *delays.get(0).unwrap_or(&None),
                 states,
                 transitions,
             }
         }
+
+        #[cfg(not(feature = "crawl-delay"))]
+        Self {
+            states,
+            transitions,
+        }
+    }
 }
 
 #[cfg(test)]

src/parse.rs

@@ -312,6 +312,7 @@ mod tests {
     }
 
     #[test]
+    #[cfg(feature = "crawl-delay")]
     fn test_crawl_delay() {
         tokio_test::block_on(async {
             let example_robots = r#"