Fix some clippy lints

Some might actually improve perf

src/assets.rs

@@ -180,7 +180,7 @@ impl HighlightingAssets {
                         theme
                     );
                 }
-                &self.theme_set.themes[self.fallback_theme.unwrap_or(Self::default_theme())]
+                &self.theme_set.themes[self.fallback_theme.unwrap_or_else(|| Self::default_theme())]
             }
         }
     }
@@ -204,7 +204,7 @@ impl HighlightingAssets {
                     let path = Path::new(path_str);
                     let line_syntax = self.get_first_line_syntax(&mut input.reader);
 
-                    let absolute_path = path.canonicalize().ok().unwrap_or(path.to_owned());
+                    let absolute_path = path.canonicalize().ok().unwrap_or_else(|| path.to_owned());
                     match mapping.get_syntax_for(absolute_path) {
                         Some(MappingTarget::MapTo(syntax_name)) => {
                             // TODO: we should probably return an error here if this syntax can not be
@@ -221,7 +221,7 @@ impl HighlightingAssets {
                 OpenedInputKind::StdIn | OpenedInputKind::CustomReader => {
                     if let Some(ref name) = input.metadata.user_provided_name {
                         self.get_extension_syntax(&name)
-                            .or(self.get_first_line_syntax(&mut input.reader))
+                            .or_else(|| self.get_first_line_syntax(&mut input.reader))
                     } else {
                         self.get_first_line_syntax(&mut input.reader)
                     }

src/assets_metadata.rs

@@ -13,7 +13,7 @@ pub struct AssetsMetadata {
     creation_time: Option<SystemTime>,
 }
 
-const FILENAME: &'static str = "metadata.yaml";
+const FILENAME: &str = "metadata.yaml";
 
 impl AssetsMetadata {
     pub(crate) fn new(current_version: &str) -> AssetsMetadata {

src/bin/bat/app.rs

@@ -80,6 +80,7 @@ impl App {
         let paging_mode = match self.matches.value_of("paging") {
             Some("always") => PagingMode::Always,
             Some("never") => PagingMode::Never,
+            // FIXME: `_` will always cover in or patterns
             Some("auto") | _ => {
                 if self.matches.occurrences_of("plain") > 1 {
                     // If we have -pp as an option when in auto mode, the pager should be disabled.
@@ -147,6 +148,7 @@ impl App {
                 match self.matches.value_of("wrap") {
                     Some("character") => WrappingMode::Character,
                     Some("never") => WrappingMode::NoWrapping,
+                    // FIXME: `_` will always cover in or patterns
                     Some("auto") | _ => {
                         if style_components.plain() {
                             WrappingMode::NoWrapping
@@ -249,18 +251,18 @@ impl App {
 
         let mut filenames_or_none: Box<dyn Iterator<Item = _>> = match filenames {
             Some(ref filenames) => {
-                Box::new(filenames.into_iter().map(|name| Some(OsStr::new(*name))))
+                Box::new(filenames.iter().map(|name| Some(OsStr::new(*name))))
             }
             None => Box::new(std::iter::repeat(None)),
         };
         let files: Option<Vec<&OsStr>> = self.matches.values_of_os("FILE").map(|vs| vs.collect());
 
         if files.is_none() {
-            let input = Input::stdin().with_name(filenames_or_none.nth(0).unwrap_or(None));
+            let input = Input::stdin().with_name(filenames_or_none.next().unwrap_or(None));
             return Ok(vec![input]);
         }
         let files_or_none: Box<dyn Iterator<Item = _>> = match files {
-            Some(ref files) => Box::new(files.into_iter().map(|name| Some(*name))),
+            Some(ref files) => Box::new(files.iter().map(|name| Some(*name))),
             None => Box::new(std::iter::repeat(None)),
         };
 
@@ -274,7 +276,7 @@ impl App {
                 }
             }
         }
-        return Ok(file_input);
+        Ok(file_input)
     }
 
     fn style_components(&self) -> Result<StyleComponents> {

src/bin/bat/assets.rs

@@ -53,5 +53,5 @@ pub fn assets_from_cache_or_binary() -> Result<HighlightingAssets> {
         }
     }
 
-    Ok(HighlightingAssets::from_cache(&cache_dir).unwrap_or(HighlightingAssets::from_binary()))
+    Ok(HighlightingAssets::from_cache(&cache_dir).unwrap_or_else(|_| HighlightingAssets::from_binary()))
 }

src/bin/bat/clap_app.rs

@@ -180,7 +180,7 @@ pub fn build_app(interactive_output: bool) -> ClapApp<'static, 'static> {
                         t.parse::<i32>()
                             .map_err(|_e| "must be an offset or number")
                             .and_then(|v| if v == 0 && !is_offset {
-                                Err("terminal width cannot be zero".into())
+                                Err("terminal width cannot be zero")
                             } else {
                                 Ok(())
                             })

src/bin/bat/config.rs

@@ -35,10 +35,10 @@ pub fn generate_config_file() -> bat::error::Result<()> {
         match config_dir {
             Some(path) => fs::create_dir_all(path)?,
             None => {
-                return Ok(Err(format!(
+                return Err(format!(
                     "Unable to write config file to: {}",
                     config_file.to_string_lossy()
-                ))?)
+                ).into());
             }
         }
     }
@@ -77,7 +77,7 @@ pub fn generate_config_file() -> bat::error::Result<()> {
         config_file.to_string_lossy()
     );
 
-    return Ok(());
+    Ok(())
 }
 
 pub fn get_args_from_config_file() -> Result<Vec<OsString>, shell_words::ParseError> {

src/bin/bat/main.rs

@@ -70,7 +70,7 @@ pub fn list_languages(config: &Config) -> Result<()> {
 
     if config.loop_through {
         for lang in languages {
-            write!(stdout, "{}:{}\n", lang.name, lang.file_extensions.join(","))?;
+            writeln!(stdout, "{}:{}", lang.name, lang.file_extensions.join(","))?;
         }
     } else {
         let longest = languages

src/controller.rs

@@ -45,9 +45,9 @@ impl<'b> Controller<'b> {
             if self.config.paging_mode != PagingMode::Never {
                 let call_pager = inputs.iter().any(|ref input| {
                     if let InputKind::OrdinaryFile(ref path) = input.kind {
-                        return Path::new(path).exists();
+                        Path::new(path).exists()
                     } else {
-                        return true;
+                        true
                     }
                 });
                 if !call_pager {

src/line_range.rs

@@ -30,7 +30,7 @@ impl LineRange {
     fn parse_range(range_raw: &str) -> Result<LineRange> {
         let mut new_range = LineRange::default();
 
-        if range_raw.bytes().nth(0).ok_or("Empty line range")? == b':' {
+        if range_raw.bytes().next().ok_or("Empty line range")? == b':' {
             new_range.upper = range_raw[1..].parse()?;
             return Ok(new_range);
         } else if range_raw.bytes().last().ok_or("Empty line range")? == b':' {

src/preprocessor.rs

@@ -36,15 +36,12 @@ pub fn expand_tabs(line: &str, width: usize, cursor: &mut usize) -> String {
 fn try_parse_utf8_char(input: &[u8]) -> Option<(char, usize)> {
     let str_from_utf8 = |seq| std::str::from_utf8(seq).ok();
 
-    let decoded = None
+    let decoded = input.get(0..1).and_then(str_from_utf8).map(|c| (c, 1))
-        .or(input.get(0..1).and_then(str_from_utf8).map(|c| (c, 1)))
+        .or_else(|| input.get(0..2).and_then(str_from_utf8).map(|c| (c, 2)))
-        .or(input.get(0..2).and_then(str_from_utf8).map(|c| (c, 2)))
+        .or_else(|| input.get(0..3).and_then(str_from_utf8).map(|c| (c, 3)))
-        .or(input.get(0..3).and_then(str_from_utf8).map(|c| (c, 3)))
+        .or_else(|| input.get(0..4).and_then(str_from_utf8).map(|c| (c, 4)));
-        .or(input.get(0..4).and_then(str_from_utf8).map(|c| (c, 4)));
 
-    let decoded_char = decoded.map(|(seq, n)| (seq.chars().next().unwrap(), n));
+    decoded.map(|(seq, n)| (seq.chars().next().unwrap(), n))
-
-    decoded_char
 }
 
 pub fn replace_nonprintable(input: &[u8], tab_width: usize) -> String {

src/printer.rs

@@ -202,7 +202,7 @@ impl<'a> InteractivePrinter<'a> {
             if self.config.style_components.grid() {
                 format!("{} │ ", text_filled)
             } else {
-                format!("{}", text_filled)
+                text_filled
             }
         }
     }
@@ -229,10 +229,8 @@ impl<'a> Printer for InteractivePrinter<'a> {
                     Yellow.paint("[bat warning]"),
                     input.description().full,
                 )?;
-            } else {
+            } else if self.config.style_components.grid() {
-                if self.config.style_components.grid() {
+                self.print_horizontal_line(handle, '┬')?;
-                    self.print_horizontal_line(handle, '┬')?;
-                }
             }
             return Ok(());
         }
@@ -304,9 +302,9 @@ impl<'a> Printer for InteractivePrinter<'a> {
         let snip_right =
             " ─".repeat((self.config.term_width - panel_count - snip_left_count - title_count) / 2);
 
-        write!(
+        writeln!(
             handle,
-            "{}\n",
+            "{}",
             self.colors
                 .grid
                 .paint(format!("{}{}{}{}", panel, snip_left, title, snip_right))

tests/no_duplicate_extensions.rs

@@ -4,7 +4,7 @@ use bat::assets::HighlightingAssets;
 
 #[test]
 fn no_duplicate_extensions() {
-    const KNOWN_EXCEPTIONS: &[&'static str] = &[
+    const KNOWN_EXCEPTIONS: &[&str] = &[
         // The '.h' extension currently appears in multiple syntaxes: C, C++, Objective C,
         // Objective C++
         "h",