perf: reduce allocations for split_into_lines (#103)

* perf: reduce allocations for `split_into_lines`

Author: h-a-n-a

src/helpers.rs

@@ -494,8 +494,8 @@ fn split(haystack: &str, needle: u8) -> impl Iterator<Item = &str> {
 }
 
 // /[^\n]+\n?|\n/g
-pub fn split_into_lines(source: &str) -> Vec<&str> {
-  split(source, b'\n').collect()
+pub fn split_into_lines(source: &str) -> impl Iterator<Item = &str> {
+  split(source, b'\n')
 }
 
 pub fn get_generated_source_info(source: &str) -> GeneratedInfo {
@@ -869,7 +869,7 @@ fn stream_chunks_of_source_map_lines_full(
   on_source: OnSource,
   _on_name: OnName,
 ) -> GeneratedInfo {
-  let lines = split_into_lines(source);
+  let lines: Vec<&str> = split_into_lines(source).collect();
   if lines.is_empty() {
     return GeneratedInfo {
       generated_line: 1,
@@ -1100,7 +1100,6 @@ pub fn stream_chunks_of_combined_source_map(
                 {
                   Some(Rc::new(
                     split_into_lines(original_source)
-                      .into_iter()
                       .map(|s| WithIndices::new(s.into()))
                       .collect(),
                   ))

src/replace_source.rs

@@ -398,7 +398,7 @@ impl<T: Source> StreamChunks for ReplaceSource<T> {
           }
           // Insert replacement content split into chunks by lines
           let repl = &repls[i];
-          let lines: Vec<&str> = split_into_lines(&repl.content);
+          let lines: Vec<&str> = split_into_lines(&repl.content).collect();
           let mut replacement_name_index = mapping
             .original
             .as_ref()
@@ -570,7 +570,6 @@ impl<T: Source> StreamChunks for ReplaceSource<T> {
         source_content_lines[source_index as usize] =
           source_content.map(|source_content| {
             split_into_lines(source_content)
-              .into_iter()
               .map(|line| line.to_string())
               .collect()
           });
@@ -600,7 +599,7 @@ impl<T: Source> StreamChunks for ReplaceSource<T> {
 
     // Insert remaining replacements content split into chunks by lines
     let mut line = result.generated_line as i64 + generated_line_offset;
-    let matches = split_into_lines(&remainder);
+    let matches: Vec<&str> = split_into_lines(&remainder).collect();
     for (m, content_line) in matches.iter().enumerate() {
       on_chunk(
         Some(content_line),