feat: till_needle function

zung_mini/src/lib.rs

@@ -27,11 +27,34 @@ enum MiniCommands {
         command: ProgBarCommands,
     },
 
-    /// Split the provided string on the provided needle.
+    /// Perform splitting functions over a string.
     Strsplit {
+        #[command(subcommand)]
+        command: StrsplitCommands,
+    },
+}
+
+#[derive(Clone, Subcommand, Debug)]
+#[command(arg_required_else_help = true)]
+enum StrsplitCommands {
+    /// Split the provided string on the provided needle.
+    Split {
+        /// The needle to be fond in the haystack.
+        #[arg(short, long)]
+        needle: String,
+
+        /// The haystack to find the needle in.
+        #[arg(short, long)]
+        string: String,
+    },
+
+    /// Split the provided string until the needle occurs in the String.
+    Until {
+        /// The needle to be fond in the haystack.
         #[arg(short, long)]
         needle: String,
 
+        /// The haystack to find the needle in.
         #[arg(short, long)]
         string: String,
     },
@@ -99,10 +122,16 @@ impl MiniArgs {
                 }
             }
 
-            MiniCommands::Strsplit { needle, string } => {
-                let result = string.strsplit(&needle).into_vec();
-                println!("{:?}", result);
-            }
+            MiniCommands::Strsplit { command } => match command {
+                StrsplitCommands::Split { needle, string } => {
+                    let result = string.strsplit(&needle).into_vec();
+                    println!("{:?}", result);
+                }
+                StrsplitCommands::Until { needle, string } => {
+                    let result = string.till_needle(needle);
+                    println!("{:?}", result);
+                }
+            },
         }
     }
 }

zung_mini/src/strsplit/mod.rs

@@ -66,6 +66,32 @@ where
     fn strsplit<P>(&'a self, needle: P) -> Strsplit<'a, P>
     where
         P: 'b + AsRef<str>;
+
+    /// Returns the substring before the first occurrence of the given `needle`
+    /// without scanning the entire string.
+    ///
+    /// This function splits the string using the provided `needle` and immediately
+    /// returns the portion of the string before the first occurrence of the `needle`.
+    /// It stops searching once the `needle` is found, making it efficient as it
+    /// avoids iterating over the entire string unnecessarily. If the `needle` is not found,
+    /// the function returns the entire string.
+    ///
+    /// # Example
+    ///
+    /// ```rust
+    /// use zung_mini::strsplit::StrsplitExt;
+    /// let text = "hello world";
+    ///
+    /// let result = text.till_needle(" ");
+    /// assert_eq!(result, "hello");
+    /// ```
+    fn till_needle<P>(&'a self, needle: P) -> &str
+    where
+        P: 'b + AsRef<str> + Clone,
+    {
+        let mut splitter = self.strsplit(needle.clone());
+        splitter.next().unwrap()
+    }
 }
 
 impl<'a, 'b> StrsplitExt<'a, 'b> for String
@@ -218,4 +244,53 @@ mod tests {
         let a = "a b c, d e f";
         assert_eq!(a.strsplit(",").into_vec(), vec!["a b c", " d e f"]);
     }
+
+    #[test]
+    fn till_needle_finds_substring() {
+        let text = "hello world";
+        let result = text.till_needle(" ");
+        assert_eq!(result, "hello");
+    }
+
+    #[test]
+    fn till_needle_returns_entire_string_if_needle_not_found() {
+        let text = "hello";
+        let result = text.till_needle(",");
+        assert_eq!(result, "hello");
+    }
+
+    #[test]
+    fn till_needle_with_multiple_occurrences() {
+        let text = "apple,banana,orange";
+        let result = text.till_needle(",");
+        assert_eq!(result, "apple"); // Stops at first occurrence
+    }
+
+    #[test]
+    fn till_needle_returns_none_for_empty_string() {
+        let text = "";
+        let result = text.till_needle(",");
+        assert_eq!(result, "");
+    }
+
+    #[test]
+    #[should_panic(expected = "Empty needle is not allowed")]
+    fn till_needle_empty_needle_panics() {
+        let text = "example";
+        let _ = text.till_needle(""); // Should panic due to empty needle
+    }
+
+    #[test]
+    fn till_needle_handles_special_characters() {
+        let text = "[email protected]";
+        let result = text.till_needle("@");
+        assert_eq!(result, "foo");
+    }
+
+    #[test]
+    fn till_needle_works_with_longer_needle() {
+        let text = "this is a test string";
+        let result = text.till_needle("is");
+        assert_eq!(result, "th");
+    }
 }