From 780c36e675824e446411faf6df31770dda3a3b31 Mon Sep 17 00:00:00 2001
From: Stephen Chung <schungx@live.com>
Date: Sun, 12 Dec 2021 12:33:22 +0800
Subject: [PATCH] Simplify if let.

---
 CHANGELOG.md     |  2 +-
 src/func/call.rs | 11 ++++++-----
 src/optimizer.rs |  8 +++-----
 src/parser.rs    | 40 +++++++++++++++++++---------------------
 src/tokenizer.rs |  7 +++----
 5 files changed, 32 insertions(+), 36 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index eacb2b1d..4192ccc6 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -28,7 +28,7 @@ Enhancements
 * Added `Engine::register_type_with_name_raw` to register a custom type based on a fully-qualified type path.
 * Added `into_array` and `into_typed_array` for `Dynamic`.
 * Added `FnPtr::call` and `FnPtr::call_within_context` to simplify calling a function pointer.
-* A function's hashes are included in its JSON metadata to assist in debugging. Each function's `hashBase` field in the JSON object should map directly to the pre-calculated hash in the function call.
+* A function's hashes are included in its JSON metadata to assist in debugging. Each function's `baseHash` field in the JSON object should map directly to the pre-calculated hash in the function call.
 * `Expression` now derefs to `Expr`.
 
 Deprecated and Gated API's
diff --git a/src/func/call.rs b/src/func/call.rs
index a4f679e9..7db44596 100644
--- a/src/func/call.rs
+++ b/src/func/call.rs
@@ -577,11 +577,12 @@ impl Engine {
             }
 
             let mut empty_scope;
-            let scope = if let Some(scope) = _scope {
-                scope
-            } else {
-                empty_scope = Scope::new();
-                &mut empty_scope
+            let scope = match _scope {
+                Some(scope) => scope,
+                None => {
+                    empty_scope = Scope::new();
+                    &mut empty_scope
+                }
             };
 
             let result = if _is_method_call {
diff --git a/src/optimizer.rs b/src/optimizer.rs
index 3dbbc75b..0e8040f7 100644
--- a/src/optimizer.rs
+++ b/src/optimizer.rs
@@ -304,11 +304,9 @@ fn optimize_stmt_block(
                         if reduce_return && !options.contains(AST_OPTION_BREAK_OUT) =>
                     {
                         state.set_dirty();
-                        *statements.last_mut().expect(">= 2 elements") = if let Some(expr) = expr {
-                            Stmt::Expr(mem::take(expr))
-                        } else {
-                            Stmt::Noop(pos)
-                        };
+                        *statements.last_mut().expect(">= 2 elements") = expr
+                            .as_mut()
+                            .map_or_else(|| Stmt::Noop(pos), |e| Stmt::Expr(mem::take(e)));
                     }
                     // { ...; stmt; noop } -> done
                     [.., ref second_last_stmt, Stmt::Noop(_)]
diff --git a/src/parser.rs b/src/parser.rs
index 92e36a2b..25bc5272 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -1048,19 +1048,18 @@ fn parse_switch(
         };
 
         let hash = if let Some(expr) = expr {
-            if let Some(value) = expr.get_literal_value() {
-                let hasher = &mut get_hasher();
-                value.hash(hasher);
-                let hash = hasher.finish();
+            let value = expr.get_literal_value().ok_or_else(|| {
+                PERR::ExprExpected("a literal".to_string()).into_err(expr.position())
+            })?;
+            let hasher = &mut get_hasher();
+            value.hash(hasher);
+            let hash = hasher.finish();
 
-                if table.contains_key(&hash) {
-                    return Err(PERR::DuplicatedSwitchCase.into_err(expr.position()));
-                }
-
-                Some(hash)
-            } else {
-                return Err(PERR::ExprExpected("a literal".to_string()).into_err(expr.position()));
+            if table.contains_key(&hash) {
+                return Err(PERR::DuplicatedSwitchCase.into_err(expr.position()));
             }
+
+            Some(hash)
         } else {
             None
         };
@@ -1081,11 +1080,12 @@ fn parse_switch(
 
         let need_comma = !stmt.is_self_terminated();
 
-        def_stmt = if let Some(hash) = hash {
-            table.insert(hash, (condition, stmt.into()).into());
-            None
-        } else {
-            Some(stmt.into())
+        def_stmt = match hash {
+            Some(hash) => {
+                table.insert(hash, (condition, stmt.into()).into());
+                None
+            }
+            None => Some(stmt.into()),
         };
 
         match input.peek().expect(NEVER_ENDS) {
@@ -2461,14 +2461,12 @@ fn parse_for(
 
     let prev_stack_len = state.stack.len();
 
-    let counter_var = if let Some(name) = counter_name {
+    let counter_var = counter_name.map(|name| {
         let name = state.get_identifier(name);
         let pos = counter_pos.expect("`Some`");
         state.stack.push((name.clone(), AccessMode::ReadWrite));
-        Some(Ident { name, pos })
-    } else {
-        None
-    };
+        Ident { name, pos }
+    });
 
     let loop_var = state.get_identifier(name);
     state.stack.push((loop_var.clone(), AccessMode::ReadWrite));
diff --git a/src/tokenizer.rs b/src/tokenizer.rs
index 79018371..c039a8dc 100644
--- a/src/tokenizer.rs
+++ b/src/tokenizer.rs
@@ -2223,10 +2223,9 @@ impl<'a> Iterator for TokenIterator<'a> {
         };
 
         // Run the mapper, if any
-        let token = if let Some(map_func) = self.token_mapper {
-            map_func(token, pos, &self.state)
-        } else {
-            token
+        let token = match self.token_mapper {
+            Some(map_func) => map_func(token, pos, &self.state),
+            None => token,
         };
 
         Some((token, pos))