remove one string clone

Author: Dima

datafusion/functions/src/regex/regexpcount.rs

@@ -310,7 +310,7 @@ where
             };
 
             let pattern = get_pattern(regex, flags_scalar)?;
-            let re = compile_regex(pattern)?;
+            let re = compile_regex(&pattern)?;
 
             Ok(Arc::new(Int64Array::from_iter_values(
                 values
@@ -357,7 +357,7 @@ where
             };
 
             let pattern = get_pattern(regex, flags_scalar)?;
-            let re = compile_regex(pattern)?;
+            let re = compile_regex(&pattern)?;
             let start_array = start_array.unwrap();
 
             Ok(Arc::new(Int64Array::from_iter_values(
@@ -560,7 +560,7 @@ fn compile_and_cache_regex<'a>(
         return Ok(regex_cache.get(&pattern).unwrap());
     }
 
-    let re = compile_regex(pattern.clone())?;
+    let re = compile_regex(&pattern)?;
     regex_cache.insert(pattern.clone(), re);
     Ok(regex_cache.get(&pattern).unwrap())
 }
@@ -579,8 +579,8 @@ fn get_pattern(regex: &str, flags: Option<&str>) -> Result<String, ArrowError> {
     }
 }
 
-fn compile_regex(pattern: String) -> Result<Regex, ArrowError> {
-    Regex::new(&pattern).map_err(|_| {
+fn compile_regex(pattern: &str) -> Result<Regex, ArrowError> {
+    Regex::new(pattern).map_err(|_| {
         ArrowError::ComputeError(format!(
             "Regular expression did not compile: {}",
             pattern