From 291af1a7056be934ed2cbe875f3e252f63ba2baf Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=81lvaro=20Mond=C3=A9jar=20Rubio?=
 <mondejar1994@gmail.com>
Date: Mon, 26 Aug 2024 01:42:04 +0200
Subject: [PATCH] Implement dummy sorting for `LanguageIdentifier`'s variants

---
 unic-langid-impl/src/lib.rs             | 11 +++-------
 unic-langid-impl/src/parser/mod.rs      |  4 +---
 unic-langid-impl/src/subtags/variant.rs | 28 +++++++++++++++++++++++++
 3 files changed, 32 insertions(+), 11 deletions(-)

diff --git a/unic-langid-impl/src/lib.rs b/unic-langid-impl/src/lib.rs
index ece89a9b..d69c195a 100644
--- a/unic-langid-impl/src/lib.rs
+++ b/unic-langid-impl/src/lib.rs
@@ -130,9 +130,7 @@ impl LanguageIdentifier {
         variants: &[subtags::Variant],
     ) -> Self {
         let variants = if !variants.is_empty() {
-            let mut v = variants.to_vec();
-            v.sort_unstable();
-            v.dedup();
+            let v = subtags::Variant::sort_and_deduplicate(variants);
             Some(v.into_boxed_slice())
         } else {
             None
@@ -298,13 +296,10 @@ impl LanguageIdentifier {
     /// assert_eq!(li.to_string(), "ca-ES-valencia");
     /// ```
     pub fn set_variants(&mut self, variants: &[subtags::Variant]) {
-        let mut v = variants.to_vec();
-
-        if v.is_empty() {
+        if variants.is_empty() {
             self.variants = None;
         } else {
-            v.sort_unstable();
-            v.dedup();
+            let v = subtags::Variant::sort_and_deduplicate(variants);
             self.variants = Some(v.into_boxed_slice());
         }
     }
diff --git a/unic-langid-impl/src/parser/mod.rs b/unic-langid-impl/src/parser/mod.rs
index d750ebba..c22a0ff0 100644
--- a/unic-langid-impl/src/parser/mod.rs
+++ b/unic-langid-impl/src/parser/mod.rs
@@ -49,7 +49,7 @@ pub fn parse_language_identifier_from_iter<'a>(
         } else {
             // Variants
             if let Ok(v) = subtags::Variant::from_bytes(subtag) {
-                variants.push(v);
+                subtags::Variant::push_sorted_and_deduplicated(v, &mut variants);
             } else {
                 break;
             }
@@ -64,8 +64,6 @@ pub fn parse_language_identifier_from_iter<'a>(
     let variants = if variants.is_empty() {
         None
     } else {
-        variants.sort_unstable();
-        variants.dedup();
         Some(variants.into_boxed_slice())
     };
 
diff --git a/unic-langid-impl/src/subtags/variant.rs b/unic-langid-impl/src/subtags/variant.rs
index 5df930d6..ddbd85e0 100644
--- a/unic-langid-impl/src/subtags/variant.rs
+++ b/unic-langid-impl/src/subtags/variant.rs
@@ -1,5 +1,6 @@
 use crate::parser::errors::ParserError;
 use std::str::FromStr;
+use core::cmp::Ordering;
 use tinystr::TinyStr8;
 
 #[derive(Debug, PartialEq, Eq, Clone, Hash, PartialOrd, Ord, Copy)]
@@ -37,6 +38,33 @@ impl Variant {
     pub const unsafe fn from_raw_unchecked(v: u64) -> Self {
         Self(TinyStr8::from_bytes_unchecked(v.to_le_bytes()))
     }
+
+    // Utility function to push a variant to a vector, keeping it sorted and deduplicated.
+    #[inline]
+    pub(crate) fn push_sorted_and_deduplicated(
+        item: Variant,
+        vec: &mut Vec<Variant>,
+    ) {
+        let mut i = 0;
+        while i < vec.len() {
+            match vec[i].cmp(&item) {
+                Ordering::Less => i += 1,
+                Ordering::Equal => return,
+                Ordering::Greater => break,
+            }
+        }
+        vec.insert(i, item);
+    }
+
+    // Utility function to sort and deduplicate a vector of variants.
+    #[inline]
+    pub(crate) fn sort_and_deduplicate(vec: &[Variant]) -> Vec<Variant> {
+        let mut new_vec = Vec::with_capacity(vec.len());
+        for item in vec {
+            Self::push_sorted_and_deduplicated(*item, &mut new_vec);
+        }
+        new_vec
+    }
 }
 
 impl From<Variant> for u64 {