Simplify iterators

src/chains.rs

@@ -550,7 +550,7 @@ impl<'a> ChainFormatterShared<'a> {
         let almost_total = if extendable {
             prev_last_line_width
         } else {
-            self.rewrites.iter().fold(0, |a, b| a + b.len())
+            self.rewrites.iter().map(|a| a.len()).sum()
         } + last.tries;
         let one_line_budget = if self.child_count == 1 {
             shape.width

src/expr.rs

@@ -1,6 +1,7 @@
 use std::borrow::Cow;
 use std::cmp::min;
 
+use itertools::Itertools;
 use syntax::parse::token::DelimToken;
 use syntax::source_map::{BytePos, SourceMap, Span};
 use syntax::{ast, ptr};
@@ -1246,8 +1247,7 @@ fn rewrite_string_lit(context: &RewriteContext<'_>, span: Span, shape: Shape) ->
     if !context.config.format_strings() {
         if string_lit
             .lines()
-            .rev()
-            .skip(1)
+            .dropping_back(1)
             .all(|line| line.ends_with('\\'))
         {
             let new_indent = shape.visual_indent(1).indent;

src/lists.rs

@@ -577,13 +577,8 @@ pub fn extract_pre_comment(pre_snippet: &str) -> (Option<String>, ListItemCommen
     let has_block_comment = trimmed_pre_snippet.ends_with("*/");
     let has_single_line_comment = trimmed_pre_snippet.starts_with("//");
     if has_block_comment {
-        let comment_end = pre_snippet.chars().rev().position(|c| c == '/').unwrap();
-        if pre_snippet
-            .chars()
-            .rev()
-            .take(comment_end + 1)
-            .any(|c| c == '\n')
-        {
+        let comment_end = pre_snippet.rfind(|c| c == '/').unwrap();
+        if pre_snippet[comment_end..].contains('\n') {
             (
                 Some(trimmed_pre_snippet.to_owned()),
                 ListItemCommentStyle::DifferentLine,

src/overflow.rs

@@ -2,6 +2,7 @@
 
 use std::cmp::min;
 
+use itertools::Itertools;
 use syntax::parse::token::DelimToken;
 use syntax::source_map::Span;
 use syntax::{ast, ptr};
@@ -711,10 +712,14 @@ fn last_item_shape(
     if items.len() == 1 && !lists.get(0)?.is_nested_call() {
         return Some(shape);
     }
-    let offset = items.iter().rev().skip(1).fold(0, |acc, i| {
-        // 2 = ", "
-        acc + 2 + i.inner_as_ref().len()
-    });
+    let offset = items
+        .iter()
+        .dropping_back(1)
+        .map(|i| {
+            // 2 = ", "
+            2 + i.inner_as_ref().len()
+        })
+        .sum();
     Shape {
         width: min(args_max_width, shape.width),
         ..shape

src/vertical.rs

@@ -2,6 +2,7 @@
 
 use std::cmp;
 
+use itertools::Itertools;
 use syntax::ast;
 use syntax::source_map::{BytePos, Span};
 
@@ -190,11 +191,8 @@ fn struct_field_prefix_max_min_width<T: AlignedItem>(
                 }
             })
         })
-        .fold(Some((0, ::std::usize::MAX)), |acc, len| match (acc, len) {
-            (Some((max_len, min_len)), Some(len)) => {
-                Some((cmp::max(max_len, len), cmp::min(min_len, len)))
-            }
-            _ => None,
+        .fold_options((0, ::std::usize::MAX), |(max_len, min_len), len| {
+            (cmp::max(max_len, len), cmp::min(min_len, len))
         })
         .unwrap_or((0, 0))
 }
@@ -274,7 +272,11 @@ fn group_aligned_items<T: AlignedItem>(
             .skip(1)
             .collect::<Vec<_>>()
             .join("\n");
-        let spacings = if snippet.lines().rev().skip(1).any(|l| l.trim().is_empty()) {
+        let spacings = if snippet
+            .lines()
+            .dropping_back(1)
+            .any(|l| l.trim().is_empty())
+        {
             "\n"
         } else {
             ""