refactor: Cow is better

Author: SyMind

src/concat_source.rs

@@ -159,7 +159,7 @@ impl<'a> StreamChunks<'a> for ConcatSource {
     }
     let mut current_line_offset = 0;
     let mut current_column_offset = 0;
-    let mut source_mapping: HashMap<String, u32> = HashMap::default();
+    let mut source_mapping: HashMap<Cow<str>, u32> = HashMap::default();
     let mut name_mapping: HashMap<&str, u32> = HashMap::default();
     let mut need_to_close_mapping = false;
 
@@ -262,10 +262,10 @@ impl<'a> StreamChunks<'a> for ConcatSource {
           }
         },
         &mut |i, source, source_content| {
-          let mut global_index = source_mapping.get(source).copied();
+          let mut global_index = source_mapping.get(&source).copied();
           if global_index.is_none() {
             let len = source_mapping.len() as u32;
-            source_mapping.insert(source.to_owned(), len);
+            source_mapping.insert(source.clone(), len);
             on_source(len, source, source_content);
             global_index = Some(len);
           }

src/helpers.rs

@@ -35,7 +35,7 @@ pub fn get_map<'a, S: StreamChunks<'a>>(
       mappings.push(mapping);
     },
     // on_source
-    &mut |source_index, source: &str, source_content: Option<&str>| {
+    &mut |source_index, source, source_content| {
       let source_index = source_index as usize;
       if sources.len() <= source_index {
         sources.resize(source_index + 1, Cow::Borrowed(""));
@@ -49,7 +49,7 @@ pub fn get_map<'a, S: StreamChunks<'a>>(
       }
     },
     // on_name
-    &mut |name_index, name: &str| {
+    &mut |name_index, name| {
       let name_index = name_index as usize;
       if names.len() <= name_index {
         names.resize(name_index + 1, Cow::Borrowed(""));
@@ -78,7 +78,7 @@ pub trait StreamChunks<'a> {
 pub type OnChunk<'a, 'b> = &'a mut dyn FnMut(Option<&'b str>, Mapping);
 
 /// [OnSource] abstraction, see [webpack-sources onSource](https://github.com/webpack/webpack-sources/blob/9f98066311d53a153fdc7c633422a1d086528027/lib/helpers/streamChunks.js#L13).
-pub type OnSource<'a, 'b> = &'a mut dyn FnMut(u32, &str, Option<&'b str>);
+pub type OnSource<'a, 'b> = &'a mut dyn FnMut(u32, Cow<'b, str>, Option<&'b str>);
 
 /// [OnName] abstraction, see [webpack-sources onName](https://github.com/webpack/webpack-sources/blob/9f98066311d53a153fdc7c633422a1d086528027/lib/helpers/streamChunks.js#L13).
 pub type OnName<'a, 'b> = &'a mut dyn FnMut(u32, &'b str);
@@ -580,13 +580,13 @@ pub fn stream_chunks_of_source_map<'a>(
   }
 }
 
-fn get_source(source_map: &SourceMap, source: &str) -> String {
+fn get_source<'a>(source_map: &SourceMap, source: &'a str) -> Cow<'a, str> {
   let source_root = source_map.source_root();
   match source_root {
-    Some(root) if root.is_empty() => source.to_string(),
-    Some(root) if root.ends_with('/') => format!("{}{}", root, source),
-    Some(root) => format!("{}/{}", root, source),
-    None => source.to_string(),
+    Some(root) if root.is_empty() => Cow::Borrowed(source),
+    Some(root) if root.ends_with('/') => Cow::Owned(format!("{}{}", root, source)),
+    Some(root) => Cow::Owned(format!("{}/{}", root, source)),
+    None => Cow::Borrowed(source),
   }
 }
 
@@ -604,7 +604,7 @@ fn stream_chunks_of_source_map_final<'a>(
   for (i, source) in source_map.sources().iter().enumerate() {
     on_source(
       i as u32,
-      &get_source(source_map, source),
+      get_source(source_map, source),
       source_map.get_source_content(i),
     )
   }
@@ -656,7 +656,7 @@ fn stream_chunks_of_source_map_full<'a>(
   for (i, source) in source_map.sources().iter().enumerate() {
     on_source(
       i as u32,
-      &get_source(source_map, source),
+      get_source(source_map, source),
       source_map.get_source_content(i),
     )
   }
@@ -764,7 +764,7 @@ fn stream_chunks_of_source_map_lines_final<'a>(
   for (i, source) in source_map.sources().iter().enumerate() {
     on_source(
       i as u32,
-      &get_source(source_map, source),
+      get_source(source_map, source),
       source_map.get_source_content(i),
     )
   }
@@ -819,7 +819,7 @@ fn stream_chunks_of_source_map_lines_full<'a>(
   for (i, source) in source_map.sources().iter().enumerate() {
     on_source(
       i as u32,
-      &get_source(source_map, source),
+      get_source(source_map, source),
       source_map.get_source_content(i),
     )
   }
@@ -918,6 +918,8 @@ impl<'a> SourceMapLineChunk<'a> {
   }
 }
 
+type InnerSourceIndexValueMapping<'a> = HashMap<i64, (Cow<'a, str>, Option<&'a str>)>;
+
 #[allow(clippy::too_many_arguments)]
 pub fn stream_chunks_of_combined_source_map<'a>(
   source: &'a str,
@@ -933,7 +935,7 @@ pub fn stream_chunks_of_combined_source_map<'a>(
 ) -> GeneratedInfo {
   let on_source = RefCell::new(on_source);
   let inner_source: RefCell<Option<&str>> = RefCell::new(inner_source);
-  let source_mapping: RefCell<HashMap<String, u32>> =
+  let source_mapping: RefCell<HashMap<Cow<str>, u32>> =
     RefCell::new(HashMap::default());
   let mut name_mapping: HashMap<&str, u32> = HashMap::default();
   let source_index_mapping: RefCell<HashMap<i64, i64>> =
@@ -945,9 +947,7 @@ pub fn stream_chunks_of_combined_source_map<'a>(
   let inner_source_index: RefCell<i64> = RefCell::new(-2);
   let inner_source_index_mapping: RefCell<HashMap<i64, i64>> =
     RefCell::new(HashMap::default());
-  let inner_source_index_value_mapping: RefCell<
-    HashMap<i64, (String, Option<&str>)>,
-  > = RefCell::new(HashMap::default());
+  let inner_source_index_value_mapping: RefCell<InnerSourceIndexValueMapping> = RefCell::new(HashMap::default());
   let inner_source_contents: RefCell<HashMap<i64, Option<&str>>> =
     RefCell::new(HashMap::default());
   let inner_source_content_lines: InnerSourceContentLine =
@@ -1080,11 +1080,11 @@ pub fn stream_chunks_of_combined_source_map<'a>(
                 .unwrap_or(("".into(), None));
               let mut source_mapping = source_mapping.borrow_mut();
               let mut global_index =
-                source_mapping.get(&source.to_string()).copied();
+                source_mapping.get(&source).copied();
               if global_index.is_none() {
                 let len = source_mapping.len() as u32;
-                source_mapping.insert(source.to_string(), len);
-                on_source.borrow_mut()(len, &source, source_content);
+                source_mapping.insert(source.clone(), len);
+                on_source.borrow_mut()(len, source, source_content);
                 global_index = Some(len);
               }
               source_index = global_index.unwrap() as i64;
@@ -1225,7 +1225,7 @@ pub fn stream_chunks_of_combined_source_map<'a>(
               source_mapping.insert(source.into(), len);
               on_source.borrow_mut()(
                 len,
-                inner_source_name,
+                Cow::Borrowed(inner_source_name),
                 *inner_source.borrow(),
               );
               global_index = Some(len);
@@ -1360,7 +1360,7 @@ pub fn stream_chunks_of_combined_source_map<'a>(
             inner_source_index_mapping.borrow_mut().insert(i, -2);
             inner_source_index_value_mapping
               .borrow_mut()
-              .insert(i, (source.to_string(), source_content));
+              .insert(i, (source, source_content));
           },
           &mut |i, name| {
             let i = i as i64;
@@ -1374,10 +1374,10 @@ pub fn stream_chunks_of_combined_source_map<'a>(
         );
       } else {
         let mut source_mapping = source_mapping.borrow_mut();
-        let mut global_index = source_mapping.get(source).copied();
+        let mut global_index = source_mapping.get(&source).copied();
         if global_index.is_none() {
           let len = source_mapping.len() as u32;
-          source_mapping.insert(source.to_string(), len);
+          source_mapping.insert(source.clone(), len);
           on_source.borrow_mut()(len, source, source_content);
           global_index = Some(len);
         }

src/original_source.rs

@@ -106,7 +106,7 @@ impl<'a> StreamChunks<'a> for OriginalSource {
     on_source: OnSource<'_, 'a>,
     _on_name: OnName,
   ) -> crate::helpers::GeneratedInfo {
-    on_source(0, &self.name, Some(&self.value));
+    on_source(0, Cow::Borrowed(&self.name), Some(&self.value));
     if options.columns {
       // With column info we need to read all lines and split them
       let mut line = 1;