FromStr for BytesPattern

lib/src/lib.rs

@@ -2,6 +2,7 @@ extern crate data_encoding;
 
 use data_encoding::HEXUPPER;
 use std::ops::Deref;
+use std::str::FromStr;
 
 pub struct BytesPattern {
     bytes: Vec<u8>,
@@ -46,8 +47,13 @@ impl BytesPattern {
     }
 }
 
-impl From<&str> for BytesPattern {
-    fn from(str_val: &str) -> Self {
+impl FromStr for BytesPattern {
+    type Err = &'static str;
+    fn from_str(str_val: &str) -> Result<Self, Self::Err> {
+        if str_val.is_empty() {    
+            return Err("string is empty");
+        }
+
         let mut elements: Vec<&str> = str_val.split(' ').collect();
         let mask: Vec<bool> = elements.iter().map(|item| *item == "??").collect();
 
@@ -61,7 +67,7 @@ impl From<&str> for BytesPattern {
             .decode(elements.join("").as_bytes())
             .expect("decode pattern");
 
-        Self::from((bytes, mask))
+        Ok(Self::from((bytes, mask)))
     }
 }