Convert translation table to a single Vec

crates/oxc_ast/src/utf8_to_utf16.rs

@@ -7,11 +7,17 @@ use crate::{ast::Program, visit::VisitMut};
 /// Convert UTF8 span offsets to UTF16.
 #[derive(Default)]
 pub struct Utf8ToUtf16 {
+    translations: Vec<Translation>,
+}
+
+#[derive(Clone, Copy)]
+#[repr(align(8))]
+struct Translation {
     // UTF8 byte offset
-    utf8_offsets: Vec<u32>,
+    utf8_offset: u32,
     // Number to subtract from UTF8 byte offset to get UTF16 char offset
     // for offsets *after* `utf8_offset`
-    utf16_differences: Vec<u32>,
+    utf16_difference: u32,
 }
 
 impl Utf8ToUtf16 {
@@ -24,7 +30,7 @@ impl Utf8ToUtf16 {
     pub fn convert(mut self, program: &mut Program<'_>) {
         self.build_table(program.source_text);
         // Skip if unicode is absent.
-        if self.utf8_offsets.is_empty() {
+        if self.translations.is_empty() {
             return;
         }
         self.visit_program(program);
@@ -40,8 +46,8 @@ impl Utf8ToUtf16 {
             if byte >= 0xC0 {
                 let difference_for_this_byte = u32::from(byte >= 0xE0) + 1;
                 utf16_difference += difference_for_this_byte;
-                self.utf8_offsets.push(utf8_offset as u32);
-                self.utf16_differences.push(utf16_difference);
+                self.translations
+                    .push(Translation { utf8_offset: utf8_offset as u32, utf16_difference });
             }
         }
     }
@@ -54,9 +60,10 @@ impl Utf8ToUtf16 {
     fn convert_offset(&self, utf8_offset: u32) -> u32 {
         // FIXME:
         let mut utf16_offset = utf8_offset;
-        let index = self.utf8_offsets.partition_point(|&offset| offset < utf8_offset);
-        if let Some(&utf16_difference) = self.utf16_differences.get(index) {
-            utf16_offset -= utf16_difference;
+        let index =
+            self.translations.partition_point(|&translation| translation.utf8_offset < utf8_offset);
+        if let Some(&translation) = self.translations.get(index) {
+            utf16_offset -= translation.utf16_difference;
         }
         utf16_offset
     }