From d97f3f7ec44b31b8321077de30d0ee00a6924f62 Mon Sep 17 00:00:00 2001
From: Stephen Chung <schungx@live.com>
Date: Sat, 29 Oct 2022 15:17:12 +0800
Subject: [PATCH] Merge variables in Stmt::Share.

---
 src/ast/stmt.rs  | 13 +++++--------
 src/eval/stmt.rs | 34 ++++++++++++++++++----------------
 src/parser.rs    | 12 +++++++-----
 3 files changed, 30 insertions(+), 29 deletions(-)

diff --git a/src/ast/stmt.rs b/src/ast/stmt.rs
index ed6c51a3..e272e1e9 100644
--- a/src/ast/stmt.rs
+++ b/src/ast/stmt.rs
@@ -605,19 +605,16 @@ pub enum Stmt {
     /// Not available under `no_module`.
     #[cfg(not(feature = "no_module"))]
     Export(Box<(Ident, Ident)>, Position),
-    /// Convert a variable to shared.
+    /// Convert a list of variables to shared.
     ///
     /// Not available under `no_closure`.
     ///
     /// # Notes
     ///
     /// This variant does not map to any language structure.  It is currently only used only to
-    /// convert a normal variable into a shared variable when the variable is _captured_ by a closure.
+    /// convert normal variables into shared variables when they are _captured_ by a closure.
     #[cfg(not(feature = "no_closure"))]
-    Share(
-        Box<(crate::ImmutableString, Option<NonZeroUsize>)>,
-        Position,
-    ),
+    Share(Box<crate::FnArgsVec<(crate::ImmutableString, Option<NonZeroUsize>, Position)>>),
 }
 
 impl Default for Stmt {
@@ -684,7 +681,7 @@ impl Stmt {
             Self::Export(.., pos) => *pos,
 
             #[cfg(not(feature = "no_closure"))]
-            Self::Share(.., pos) => *pos,
+            Self::Share(x) => x[0].2,
         }
     }
     /// Override the [position][Position] of this statement.
@@ -716,7 +713,7 @@ impl Stmt {
             Self::Export(.., pos) => *pos = new_pos,
 
             #[cfg(not(feature = "no_closure"))]
-            Self::Share(.., pos) => *pos = new_pos,
+            Self::Share(x) => x.iter_mut().for_each(|(_, _, pos)| *pos = new_pos),
         }
 
         self
diff --git a/src/eval/stmt.rs b/src/eval/stmt.rs
index 4eecbf88..0a302ee6 100644
--- a/src/eval/stmt.rs
+++ b/src/eval/stmt.rs
@@ -977,23 +977,25 @@ impl Engine {
 
             // Share statement
             #[cfg(not(feature = "no_closure"))]
-            Stmt::Share(x, pos) => {
-                let (name, index) = &**x;
+            Stmt::Share(x) => {
+                x.iter()
+                    .try_for_each(|(name, index, pos)| {
+                        if let Some(index) = index
+                            .map(|n| scope.len() - n.get())
+                            .or_else(|| scope.search(name))
+                        {
+                            let val = scope.get_mut_by_index(index);
 
-                if let Some(index) = index
-                    .map(|n| scope.len() - n.get())
-                    .or_else(|| scope.search(name))
-                {
-                    let val = scope.get_mut_by_index(index);
-
-                    if !val.is_shared() {
-                        // Replace the variable with a shared value.
-                        *val = std::mem::take(val).into_shared();
-                    }
-                    Ok(Dynamic::UNIT)
-                } else {
-                    Err(ERR::ErrorVariableNotFound(name.to_string(), *pos).into())
-                }
+                            if !val.is_shared() {
+                                // Replace the variable with a shared value.
+                                *val = std::mem::take(val).into_shared();
+                            }
+                            Ok(())
+                        } else {
+                            Err(ERR::ErrorVariableNotFound(name.to_string(), *pos).into())
+                        }
+                    })
+                    .map(|_| Dynamic::UNIT)
             }
 
             _ => unreachable!("statement cannot be evaluated: {:?}", stmt),
diff --git a/src/parser.rs b/src/parser.rs
index 9ca3a8a0..c2e02aa7 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -3739,15 +3739,17 @@ impl Engine {
 
         // Convert the entire expression into a statement block, then insert the relevant
         // [`Share`][Stmt::Share] statements.
-        let mut statements = StaticVec::with_capacity(externals.len() + 1);
-        statements.extend(
+        let mut statements = StaticVec::with_capacity(2);
+        statements.push(Stmt::Share(
             externals
                 .into_iter()
                 .map(|crate::ast::Ident { name, pos }| {
                     let (index, _) = parent.access_var(&name, lib, pos);
-                    Stmt::Share((name, index).into(), pos)
-                }),
-        );
+                    (name, index, pos)
+                })
+                .collect::<crate::FnArgsVec<_>>()
+                .into(),
+        ));
         statements.push(Stmt::Expr(expr.into()));
         Expr::Stmt(crate::ast::StmtBlock::new(statements, pos, Position::NONE).into())
     }