Reduce nesting in if blocks by short circuiting

src/assets.rs

@@ -255,18 +255,18 @@ impl HighlightingAssets {
     ) -> Result<SyntaxReferenceInSet> {
         if let Some(language) = language {
             let syntax_set = self.get_syntax_set_by_name(language)?;
-            syntax_set
+            return syntax_set
                 .find_syntax_by_token(language)
                 .map(|syntax| SyntaxReferenceInSet { syntax, syntax_set })
-                .ok_or_else(|| Error::UnknownSyntax(language.to_owned()))
-        } else {
+                .ok_or_else(|| Error::UnknownSyntax(language.to_owned()));
+        }
+
         let line_syntax = self.get_first_line_syntax(&mut input.reader)?;
 
         // Get the path of the file:
         // If this was set by the metadata, that will take priority.
         // If it wasn't, it will use the real file path (if available).
-            let path_str =
-                input
+        let path_str = input
             .metadata
             .user_provided_name
             .as_ref()
@@ -307,7 +307,6 @@ impl HighlightingAssets {
             line_syntax.ok_or_else(|| Error::UndetectedSyntax("[unknown]".into()))
         }
     }
-    }
 
     fn get_extension_syntax(&self, file_name: &OsStr) -> Result<Option<SyntaxReferenceInSet>> {
         let mut syntax = self.find_syntax_by_file_name(file_name)?;

src/bin/bat/main.rs

@@ -100,17 +100,14 @@ pub fn get_languages(config: &Config) -> Result<String> {
             // Also skip if the 'extension' contains another real extension, likely
             // that is a full match file name like 'CMakeLists.txt' and 'Cargo.lock'
             if extension.starts_with('.') || Path::new(extension).extension().is_some() {
-                true
-            } else {
+                return true;
+            }
+
             let test_file = Path::new("test").with_extension(extension);
             let syntax_in_set = assets
                 .get_syntax_for_file_name(test_file, &config.syntax_mapping)
                 .unwrap(); // safe since .get_syntaxes() above worked
-                match syntax_in_set {
-                    Some(syntax_in_set) => syntax_in_set.syntax.name == lang_name,
-                    None => false,
-                }
-            }
+            matches!(syntax_in_set, Some(syntax_in_set) if syntax_in_set.syntax.name == lang_name)
         });
     }
 

src/input.rs

@@ -256,18 +256,18 @@ impl<'a> InputReader<'a> {
     }
 
     pub(crate) fn read_line(&mut self, buf: &mut Vec<u8>) -> io::Result<bool> {
-        if self.first_line.is_empty() {
+        if !self.first_line.is_empty() {
+            buf.append(&mut self.first_line);
+            return Ok(true);
+        }
+
         let res = self.inner.read_until(b'\n', buf).map(|size| size > 0)?;
 
         if self.content_type == Some(ContentType::UTF_16LE) {
-                self.inner.read_until(0x00, buf).ok();
+            let _ = self.inner.read_until(0x00, buf);
         }
 
         Ok(res)
-        } else {
-            buf.append(&mut self.first_line);
-            Ok(true)
-        }
     }
 }
 

src/less.rs

@@ -11,13 +11,13 @@ pub fn retrieve_less_version(less_path: &dyn AsRef<OsStr>) -> Option<usize> {
 }
 
 fn parse_less_version(output: &[u8]) -> Option<usize> {
-    if output.starts_with(b"less ") {
+    if !output.starts_with(b"less ") {
+        return None;
+    }
+
     let version = std::str::from_utf8(&output[5..]).ok()?;
     let end = version.find(|c: char| !c.is_ascii_digit())?;
     version[..end].parse::<usize>().ok()
-    } else {
-        None
-    }
 }
 
 #[test]

src/printer.rs

@@ -226,8 +226,9 @@ impl<'a> InteractivePrinter<'a> {
 
     fn create_fake_panel(&self, text: &str) -> String {
         if self.panel_width == 0 {
-            "".to_string()
-        } else {
+            return "".to_string();
+        }
+
         let text_truncated: String = text.chars().take(self.panel_width - 1).collect();
         let text_filled: String = format!(
             "{}{}",
@@ -240,17 +241,16 @@ impl<'a> InteractivePrinter<'a> {
             text_filled
         }
     }
-    }
 
     fn preprocess(&self, text: &str, cursor: &mut usize) -> String {
         if self.config.tab_width > 0 {
-            expand_tabs(text, self.config.tab_width, cursor)
-        } else {
+            return expand_tabs(text, self.config.tab_width, cursor);
+        }
+
         *cursor += text.len();
         text.to_string()
     }
 }
-}
 
 impl<'a> Printer for InteractivePrinter<'a> {
     fn print_header(