Avoid using to_expr as much as possible

3 files changed, 54 insertions, 38 deletions

diff --git a/src/closures.rs b/src/closures.rs
index 153f3413f10..bde08931d18 100644
--- a/src/closures.rs
+++ b/src/closures.rs
@@ -361,13 +361,10 @@ pub fn rewrite_last_closure(
 /// Returns true if the given vector of arguments has more than one `ast::ExprKind::Closure`.
 pub fn args_have_many_closure(args: &[OverflowableItem]) -> bool {
     args.iter()
-        .filter(|arg| {
-            arg.to_expr()
-                .map(|e| match e.node {
-                    ast::ExprKind::Closure(..) => true,
-                    _ => false,
-                })
-                .unwrap_or(false)
+        .filter_map(|arg| arg.to_expr())
+        .filter(|expr| match expr.node {
+            ast::ExprKind::Closure(..) => true,
+            _ => false,
         })
         .count()
         > 1
diff --git a/src/expr.rs b/src/expr.rs
index 102fab346d7..06c9d355906 100644
--- a/src/expr.rs
+++ b/src/expr.rs
@@ -1337,7 +1337,7 @@ pub fn rewrite_call(
     )
 }
 
-fn is_simple_expr(expr: &ast::Expr) -> bool {
+pub fn is_simple_expr(expr: &ast::Expr) -> bool {
     match expr.node {
         ast::ExprKind::Lit(..) => true,
         ast::ExprKind::Path(ref qself, ref path) => qself.is_none() && path.segments.len() <= 1,
@@ -1356,9 +1356,7 @@ fn is_simple_expr(expr: &ast::Expr) -> bool {
 }
 
 pub fn is_every_expr_simple(lists: &[OverflowableItem]) -> bool {
-    lists
-        .iter()
-        .all(|arg| arg.to_expr().map_or(false, is_simple_expr))
+    lists.iter().all(OverflowableItem::is_simple)
 }
 
 pub fn can_be_overflowed_expr(context: &RewriteContext, expr: &ast::Expr, args_len: usize) -> bool {
diff --git a/src/overflow.rs b/src/overflow.rs
index 37d070cfd40..22b07fbc178 100644
--- a/src/overflow.rs
+++ b/src/overflow.rs
@@ -17,7 +17,7 @@ use syntax::{ast, ptr};
 
 use closures;
 use expr::{
-    can_be_overflowed_expr, is_every_expr_simple, is_method_call, is_nested_call,
+    can_be_overflowed_expr, is_every_expr_simple, is_method_call, is_nested_call, is_simple_expr,
     maybe_get_args_offset,
 };
 use lists::{definitive_tactic, itemize_list, write_list, ListFormatting, ListItem, Separator};
@@ -70,6 +70,30 @@ impl<'a> OverflowableItem<'a> {
         }
     }
 
+    pub fn is_simple(&self) -> bool {
+        match self {
+            OverflowableItem::Expr(expr) => is_simple_expr(expr),
+            OverflowableItem::MacroArg(MacroArg::Expr(expr)) => is_simple_expr(expr),
+            _ => false,
+        }
+    }
+
+    pub fn is_expr(&self) -> bool {
+        match self {
+            OverflowableItem::Expr(..) => true,
+            OverflowableItem::MacroArg(MacroArg::Expr(..)) => true,
+            _ => false,
+        }
+    }
+
+    pub fn is_nested_call(&self) -> bool {
+        match self {
+            OverflowableItem::Expr(expr) => is_nested_call(expr),
+            OverflowableItem::MacroArg(MacroArg::Expr(expr)) => is_nested_call(expr),
+            _ => false,
+        }
+    }
+
     pub fn to_expr(&self) -> Option<&'a ast::Expr> {
         match self {
             OverflowableItem::Expr(expr) => Some(expr),
@@ -303,23 +327,24 @@ impl<'a> Context<'a> {
         shape: Shape,
     ) -> Option<String> {
         let last_item = self.last_item()?;
-        let rewrite = if let Some(expr) = last_item.to_expr() {
-            match expr.node {
-                // When overflowing the closure which consists of a single control flow expression,
-                // force to use block if its condition uses multi line.
-                ast::ExprKind::Closure(..) => {
-                    // If the argument consists of multiple closures, we do not overflow
-                    // the last closure.
-                    if closures::args_have_many_closure(&self.items) {
-                        None
-                    } else {
-                        closures::rewrite_last_closure(self.context, expr, shape)
+        let rewrite = match last_item {
+            OverflowableItem::Expr(ref expr) => {
+                match expr.node {
+                    // When overflowing the closure which consists of a single control flow
+                    // expression, force to use block if its condition uses multi line.
+                    ast::ExprKind::Closure(..) => {
+                        // If the argument consists of multiple closures, we do not overflow
+                        // the last closure.
+                        if closures::args_have_many_closure(&self.items) {
+                            None
+                        } else {
+                            closures::rewrite_last_closure(self.context, expr, shape)
+                        }
                     }
+                    _ => expr.rewrite(self.context, shape),
                 }
-                _ => expr.rewrite(self.context, shape),
             }
-        } else {
-            last_item.rewrite(self.context, shape)
+            item @ _ => item.rewrite(self.context, shape),
         };
 
         if let Some(rewrite) = rewrite {
@@ -343,7 +368,7 @@ impl<'a> Context<'a> {
     fn try_overflow_last_item(&self, list_items: &mut Vec<ListItem>) -> DefinitiveListTactic {
         // 1 = "("
         let combine_arg_with_callee = self.items.len() == 1
-            && self.items[0].to_expr().is_some()
+            && self.items[0].is_expr()
             && self.ident.len() < self.context.config.tab_spaces();
         let overflow_last = combine_arg_with_callee || can_be_overflowed(self.context, &self.items);
 
@@ -351,12 +376,13 @@ impl<'a> Context<'a> {
         // first arguments.
         let placeholder = if overflow_last {
             let old_value = *self.context.force_one_line_chain.borrow();
-            if !combine_arg_with_callee {
-                if let Some(ref expr) = self.last_item().and_then(|item| item.to_expr()) {
-                    if is_method_call(expr) {
-                        self.context.force_one_line_chain.replace(true);
-                    }
+            match self.last_item() {
+                Some(OverflowableItem::Expr(expr))
+                    if !combine_arg_with_callee && is_method_call(expr) =>
+                {
+                    self.context.force_one_line_chain.replace(true);
                 }
+                _ => (),
             }
             let result = last_item_shape(
                 &self.items,
@@ -596,12 +622,7 @@ fn last_item_shape(
     shape: Shape,
     args_max_width: usize,
 ) -> Option<Shape> {
-    let is_nested_call = lists
-        .iter()
-        .next()
-        .and_then(|item| item.to_expr())
-        .map_or(false, is_nested_call);
-    if items.len() == 1 && !is_nested_call {
+    if items.len() == 1 && !lists.iter().next()?.is_nested_call() {
         return Some(shape);
     }
     let offset = items.iter().rev().skip(1).fold(0, |acc, i| {