From 4a7bf893e643ee0f2e4069ffac144c6ddc6db6b4 Mon Sep 17 00:00:00 2001
From: Stephen Chung <Stephen.Chung@intexact.com>
Date: Mon, 3 Aug 2020 23:13:09 +0800
Subject: [PATCH] Refine flatten clone for scope.

---
 src/scope.rs | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/src/scope.rs b/src/scope.rs
index 836108c7..61f6fa17 100644
--- a/src/scope.rs
+++ b/src/scope.rs
@@ -4,9 +4,7 @@ use crate::any::{Dynamic, Variant};
 use crate::parser::{map_dynamic_to_expr, Expr};
 use crate::token::Position;
 
-use crate::stdlib::{
-    borrow::Cow, boxed::Box, collections::HashMap, iter, string::String, vec::Vec,
-};
+use crate::stdlib::{borrow::Cow, boxed::Box, iter, string::String, vec::Vec};
 
 /// Type of an entry in the Scope.
 #[derive(Debug, Eq, PartialEq, Hash, Copy, Clone)]
@@ -394,15 +392,19 @@ impl<'a> Scope<'a> {
     /// Clone the Scope, keeping only the last instances of each variable name.
     /// Shadowed variables are omitted in the copy.
     pub(crate) fn flatten_clone(&self) -> Self {
-        let mut entries: HashMap<&str, Entry> = Default::default();
+        let mut entries: Vec<Entry> = Default::default();
 
         self.0.iter().rev().for_each(|entry| {
-            entries
-                .entry(entry.name.as_ref())
-                .or_insert_with(|| entry.clone());
+            if entries
+                .iter()
+                .find(|Entry { name, .. }| &entry.name == name)
+                .is_none()
+            {
+                entries.push(entry.clone());
+            }
         });
 
-        Self(entries.into_iter().map(|(_, v)| v).collect())
+        Self(entries)
     }
 
     /// Get an iterator to entries in the Scope.