perf: reduce needless allocations

Author: WillLillis

crates/cli/src/parse.rs

@@ -674,10 +674,9 @@ pub fn parse_file_at_path(
                 width = max_path_length
             )?;
             if let Some(node) = first_error {
-                let start = node.start_position();
-                let end = node.end_position();
-                let mut node_text = String::new();
-                for c in node.kind().chars() {
+                let node_kind = node.kind();
+                let mut node_text = String::with_capacity(node_kind.len());
+                for c in node_kind.chars() {
                     if let Some(escaped) = escape_invisible(c) {
                         node_text += escaped;
                     } else {
@@ -694,6 +693,9 @@ pub fn parse_file_at_path(
                 } else {
                     write!(&mut stdout, "{node_text}")?;
                 }
+
+                let start = node.start_position();
+                let end = node.end_position();
                 write!(
                     &mut stdout,
                     " [{}, {}] - [{}, {}])",

crates/generate/src/render.rs

@@ -34,6 +34,8 @@ macro_rules! add {
 
 macro_rules! add_whitespace {
     ($this:tt) => {{
+        // 4 bytes per char, 2 spaces per indent level
+        $this.buffer.reserve(4 * 2 * $this.indent_level);
         for _ in 0..$this.indent_level {
             write!(&mut $this.buffer, "  ").unwrap();
         }
@@ -688,13 +690,14 @@ impl Generator {
                         flat_field_map.push((field_name.clone(), *location));
                     }
                 }
+                let field_map_len = flat_field_map.len();
                 field_map_ids.push((
                     self.get_field_map_id(
-                        flat_field_map.clone(),
+                        flat_field_map,
                         &mut flat_field_maps,
                         &mut next_flat_field_map_index,
                     ),
-                    flat_field_map.len(),
+                    field_map_len,
                 ));
             }
         }
@@ -962,10 +965,7 @@ impl Generator {
                 large_char_set_ix = Some(char_set_ix);
             }
 
-            let mut line_break = "\n".to_string();
-            for _ in 0..self.indent_level + 2 {
-                line_break.push_str("  ");
-            }
+            let line_break = format!("\n{}", "  ".repeat(self.indent_level + 2));
 
             let has_positive_condition = large_char_set_ix.is_some() || !asserted_chars.is_empty();
             let has_negative_condition = !negated_chars.is_empty();

crates/highlight/src/highlight.rs

@@ -344,11 +344,13 @@ impl HighlightConfiguration {
         locals_query: &str,
     ) -> Result<Self, QueryError> {
         // Concatenate the query strings, keeping track of the start offset of each section.
-        let mut query_source = String::new();
+        let mut query_source = String::with_capacity(
+            injection_query.len() + locals_query.len() + highlights_query.len(),
+        );
         query_source.push_str(injection_query);
-        let locals_query_offset = query_source.len();
+        let locals_query_offset = injection_query.len();
         query_source.push_str(locals_query);
-        let highlights_query_offset = query_source.len();
+        let highlights_query_offset = injection_query.len() + locals_query.len();
         query_source.push_str(highlights_query);
 
         // Construct a single query by concatenating the three query strings, but record the