refactor/polish ~ fix cargo clippy complaints (use is_empty / is_none)

src/cut/ranges.rs

@@ -53,7 +53,7 @@ impl FromStr for Range {
                     Err(inval)
                 }
             }
-            (Some(n), Some(m)) if n.len() == 0 => {
+            (Some(n), Some(m)) if n.is_empty() => {
                 if let Ok(high) = m.parse::<usize>() {
                     if high > 0 {
                         Ok(Range { low: 1, high })

src/install/install.rs

@@ -259,7 +259,7 @@ fn behaviour(matches: &getopts::Matches) -> Result<Behaviour, i32> {
 /// Returns an integer intended as a program return code.
 ///
 fn directory(paths: &[PathBuf], b: Behaviour) -> i32 {
-    if paths.len() < 1 {
+    if paths.is_empty() {
         println!("{} with -d requires at least one argument.", NAME);
         1
     } else {

src/join/join.rs

@@ -186,7 +186,7 @@ impl Spec {
         let file_num = match chars.next() {
             Some('0') => {
                 // Must be all alone without a field specifier.
-                if let None = chars.next() {
+                if chars.next().is_none() {
                     return Spec::Key;
                 }
 

src/ln/ln.rs

@@ -159,7 +159,7 @@ pub fn uumain(args: Vec<String>) -> i32 {
 }
 
 fn exec(files: &[PathBuf], settings: &Settings) -> i32 {
-    if files.len() == 0 {
+    if files.is_empty() {
         show_error!(
             "missing file operand\nTry '{} --help' for more information.",
             NAME
@@ -201,7 +201,7 @@ fn exec(files: &[PathBuf], settings: &Settings) -> i32 {
         );
         return 1;
     }
-    assert!(files.len() != 0);
+    assert!(!files.is_empty());
 
     match link(&files[0], &files[1], settings) {
         Ok(_) => 0,

src/ls/ls.rs

@@ -531,7 +531,7 @@ fn get_file_name(name: &Path, strip: Option<&Path>) -> String {
         Some(prefix) => name.strip_prefix(prefix).unwrap_or(name),
         None => name,
     };
-    if name.as_os_str().len() == 0 {
+    if name.as_os_str().is_empty() {
         name = Path::new(".");
     }
     name.to_string_lossy().into_owned()

src/mv/mv.rs

@@ -426,7 +426,7 @@ fn existing_backup_path(path: &PathBuf, suffix: &str) -> PathBuf {
 fn is_empty_dir(path: &PathBuf) -> bool {
     match fs::read_dir(path) {
         Ok(contents) => {
-            return contents.peekable().peek().is_none();
+            contents.peekable().peek().is_none()
         },
         Err(_e) => { false }
     }

src/nl/nl.rs

@@ -363,7 +363,7 @@ fn pass_regex(line: &str, re: &regex::Regex) -> bool {
 }
 
 fn pass_nonempty(line: &str, _: &regex::Regex) -> bool {
-    line.len() > 0
+    !line.is_empty()
 }
 
 fn pass_none(_: &str, _: &regex::Regex) -> bool {

src/numfmt/numfmt.rs

@@ -353,7 +353,7 @@ pub fn uumain(args: Vec<String>) -> i32 {
 
     let options = parse_options(&matches).unwrap();
 
-    if matches.free.len() == 0 {
+    if matches.free.is_empty() {
         handle_stdin(options).unwrap()
     } else {
         handle_args(&matches.free, options).unwrap()

src/od/multifilereader.rs

@@ -36,7 +36,7 @@ impl<'b> MultifileReader<'b> {
     fn next_file(&mut self) {
         // loop retries with subsequent files if err - normally 'loops' once
         loop {
-            if self.ni.len() == 0 {
+            if self.ni.is_empty() {
                 self.curr_file = None;
                 break;
             }

src/od/parse_inputs.rs

@@ -73,7 +73,7 @@ pub fn parse_inputs(matches: &dyn CommandLineOpts) -> Result<CommandLineInputs,
         }
     }
 
-    if input_strings.len() == 0 {
+    if input_strings.is_empty() {
         input_strings.push("-".to_string());
     }
     Ok(CommandLineInputs::FileNames(input_strings))

src/pathchk/pathchk.rs

@@ -188,7 +188,7 @@ fn check_extra(path: &[String]) -> bool {
         }
     }
     // path length
-    if path.join("/").len() == 0 {
+    if path.join("/").is_empty() {
         writeln!(&mut std::io::stderr(), "empty file name");
         return false;
     }

src/printf/tokenize/num_format/formatters/cninetyninehexfloatf.rs

@@ -60,7 +60,7 @@ fn get_primitive_hex(
         Some(pos) => (&str_in[..pos], &str_in[pos + 1..]),
         None => (&str_in[..], "0"),
     };
-    if first_segment_raw.len() == 0 {
+    if first_segment_raw.is_empty() {
         first_segment_raw = "0";
     }
     // convert to string, hexifying if input is in dec.

src/printf/tokenize/num_format/formatters/float_common.rs

@@ -223,7 +223,7 @@ pub fn get_primitive_dec(
         Some(pos) => (&str_in[..pos], &str_in[pos + 1..]),
         None => (&str_in[..], "0"),
     };
-    if first_segment_raw.len() == 0 {
+    if first_segment_raw.is_empty() {
         first_segment_raw = "0";
     }
     // convert to string, de_hexifying if input is in hex.
@@ -317,7 +317,7 @@ pub fn primitive_to_str_common(prim: &FormatPrimitive, field: &FormatField) -> S
     let decimal_places = field.second_field.unwrap_or(6);
     match prim.post_decimal {
         Some(ref post_decimal) => {
-            if post_decimal.len() > 0 && decimal_places > 0 {
+            if !post_decimal.is_empty() && decimal_places > 0 {
                 final_str.push('.');
                 let len_avail = post_decimal.len() as u32;
 

src/printf/tokenize/num_format/num_format.rs

@@ -52,7 +52,7 @@ fn get_provided(str_in_opt: Option<&String>) -> Option<u8> {
                                 for cont in byte_it {
                                     ignored.push(cont);
                                 }
-                                if ignored.len() > 0 {
+                                if !ignored.is_empty() {
                                     warn_char_constant_ign(ignored);
                                 }
                                 second_byte as u8

src/printf/tokenize/sub.rs

@@ -190,7 +190,7 @@ impl SubParser {
                         }
                         match self.min_width_tmp.as_mut() {
                             Some(x) => {
-                                if (ch == '-' || ch == '*') && x.len() > 0 {
+                                if (ch == '-' || ch == '*') && !x.is_empty() {
                                     err_conv(&self.text_so_far);
                                 }
                                 if ch == '*' {
@@ -213,7 +213,7 @@ impl SubParser {
                         }
                         match self.second_field_tmp.as_mut() {
                             Some(x) => {
-                                if ch == '*' && x.len() > 0 {
+                                if ch == '*' && !x.is_empty() {
                                     err_conv(&self.text_so_far);
                                 }
                                 if ch == '*' {
@@ -252,7 +252,7 @@ impl SubParser {
                 }
             }
         }
-        if !self.field_char.is_some() {
+        if self.field_char.is_none() {
             err_conv(&self.text_so_far);
         }
         let field_char_retrieved = self.field_char.unwrap();

src/printf/tokenize/unescaped_text.rs

@@ -201,7 +201,7 @@ impl UnescapedText {
                         // on non hex or octal escapes is costly
                         // then we can make it faster/more complex
                         // with as-necessary draining.
-                        if tmp_str.len() > 0 {
+                        if !tmp_str.is_empty() {
                             new_vec.extend(tmp_str.bytes());
                             tmp_str = String::new();
                         }
@@ -228,7 +228,7 @@ impl UnescapedText {
                     }
                 }
             }
-            if tmp_str.len() > 0 {
+            if !tmp_str.is_empty() {
                 new_vec.extend(tmp_str.bytes());
             }
         }

src/seq/seq.rs

@@ -189,11 +189,11 @@ pub fn uumain(args: Vec<String>) -> i32 {
         Ok(m) => m,
         Err(f) => return f,
     };
-    if free.len() < 1 || free.len() > 3 {
+    if free.is_empty() || free.len() > 3 {
         crash!(
             1,
             "too {} operands.\nTry '{} --help' for more information.",
-            if free.len() < 1 { "few" } else { "many" },
+            if free.is_empty() { "few" } else { "many" },
             NAME
         );
     }

src/tail/tail.rs

@@ -276,7 +276,7 @@ pub fn parse_size(mut size_slice: &str) -> Result<u64, ParseSizeErr> {
         1024u64
     };
 
-    let exponent = if size_slice.len() > 0 {
+    let exponent = if !size_slice.is_empty() {
         let mut has_suffix = true;
         let exp = match size_slice.chars().last().unwrap_or('_') {
             'K' | 'k' => 1u64,

src/test/test.rs

@@ -53,7 +53,7 @@ pub fn uumain(_: Vec<String>) -> i32 {
 }
 
 fn one(args: &[&[u8]]) -> bool {
-    args[0].len() > 0
+    !args[0].is_empty()
 }
 
 fn two(args: &[&[u8]], error: &mut bool) -> bool {
@@ -212,13 +212,13 @@ enum Precedence {
 }
 
 fn parse_expr(mut args: &[&[u8]], error: &mut bool) -> bool {
-    if args.len() == 0 {
+    if args.is_empty() {
         false
     } else {
         let hashmap = setup_hashmap();
         let lhs = dispatch(&mut args, error);
 
-        if args.len() > 0 {
+        if !args.is_empty() {
             parse_expr_helper(&hashmap, &mut args, lhs, Precedence::Unknown, error)
         } else {
             lhs
@@ -237,11 +237,11 @@ fn parse_expr_helper<'a>(
         *error = true;
         &min_prec
     });
-    while !*error && args.len() > 0 && prec as usize >= min_prec as usize {
+    while !*error && !args.is_empty() && prec as usize >= min_prec as usize {
         let op = args[0];
         *args = &(*args)[1..];
         let mut rhs = dispatch(args, error);
-        while args.len() > 0 {
+        while !args.is_empty() {
             let subprec = *hashmap.get(&args[0]).unwrap_or_else(|| {
                 *error = true;
                 &min_prec
@@ -269,7 +269,7 @@ fn parse_expr_helper<'a>(
             Precedence::Paren => unimplemented!(), // TODO: implement parentheses
             _ => unreachable!(),
         };
-        if args.len() > 0 {
+        if !args.is_empty() {
             prec = *hashmap.get(&args[0]).unwrap_or_else(|| {
                 *error = true;
                 &min_prec

src/tr/expand.rs

@@ -43,7 +43,7 @@ impl<'a> Iterator for Unescape<'a> {
 
     #[inline]
     fn next(&mut self) -> Option<Self::Item> {
-        if self.string.len() == 0 {
+        if self.string.is_empty() {
             return None;
         }
 

src/truncate/truncate.rs

@@ -190,7 +190,7 @@ fn parse_size(size: &str) -> (u64, TruncateMode) {
         };
         if slice.chars().last().unwrap().is_alphabetic() {
             slice = &slice[..slice.len() - 1];
-            if slice.len() > 0 && slice.chars().last().unwrap().is_alphabetic() {
+            if !slice.is_empty() && slice.chars().last().unwrap().is_alphabetic() {
                 slice = &slice[..slice.len() - 1];
             }
         }

src/uutils/uutils.rs

@@ -70,7 +70,7 @@ fn main() {
     }
 
     // try first arg as util name.
-    if args.len() >= 1 {
+    if !args.is_empty() {
         let util = &args[0][..];
 
         match umap.get(util) {