Merge pull request #7702 from nyurik/iters

feat: optimize iter matching

src/uu/chroot/src/chroot.rs

@@ -53,22 +53,20 @@ struct Options {
 ///
 /// The `spec` must be of the form `[USER][:[GROUP]]`, otherwise an
 /// error is returned.
-fn parse_userspec(spec: &str) -> UResult<UserSpec> {
+fn parse_userspec(spec: &str) -> UserSpec {
-    match &spec.splitn(2, ':').collect::<Vec<&str>>()[..] {
+    match spec.split_once(':') {
         // ""
-        [""] => Ok(UserSpec::NeitherGroupNorUser),
+        None if spec.is_empty() => UserSpec::NeitherGroupNorUser,
         // "usr"
-        [usr] => Ok(UserSpec::UserOnly(usr.to_string())),
+        None => UserSpec::UserOnly(spec.to_string()),
         // ":"
-        ["", ""] => Ok(UserSpec::NeitherGroupNorUser),
+        Some(("", "")) => UserSpec::NeitherGroupNorUser,
         // ":grp"
-        ["", grp] => Ok(UserSpec::GroupOnly(grp.to_string())),
+        Some(("", grp)) => UserSpec::GroupOnly(grp.to_string()),
         // "usr:"
-        [usr, ""] => Ok(UserSpec::UserOnly(usr.to_string())),
+        Some((usr, "")) => UserSpec::UserOnly(usr.to_string()),
         // "usr:grp"
-        [usr, grp] => Ok(UserSpec::UserAndGroup(usr.to_string(), grp.to_string())),
+        Some((usr, grp)) => UserSpec::UserAndGroup(usr.to_string(), grp.to_string()),
-        // everything else
-        _ => Err(ChrootError::InvalidUserspec(spec.to_string()).into()),
     }
 }
 
@@ -144,10 +142,9 @@ impl Options {
             }
         };
         let skip_chdir = matches.get_flag(options::SKIP_CHDIR);
-        let userspec = match matches.get_one::<String>(options::USERSPEC) {
+        let userspec = matches
-            None => None,
+            .get_one::<String>(options::USERSPEC)
-            Some(s) => Some(parse_userspec(s)?),
+            .map(|s| parse_userspec(s));
-        };
         Ok(Self {
             newroot,
             skip_chdir,

src/uu/chroot/src/error.rs

@@ -34,10 +34,6 @@ pub enum ChrootError {
     #[error("invalid group list: {list}", list = .0.quote())]
     InvalidGroupList(String),
 
-    /// The given user and group specification was invalid.
-    #[error("invalid userspec: {spec}", spec = .0.quote())]
-    InvalidUserspec(String),
-
     /// The new root directory was not given.
     #[error(
         "Missing operand: NEWROOT\nTry '{0} --help' for more information.",

src/uu/nproc/src/nproc.rs

@@ -3,7 +3,7 @@
 // For the full copyright and license information, please view the LICENSE
 // file that was distributed with this source code.
 
-// spell-checker:ignore (ToDO) NPROCESSORS nprocs numstr threadstr sysconf
+// spell-checker:ignore (ToDO) NPROCESSORS nprocs numstr sysconf
 
 use clap::{Arg, ArgAction, Command};
 use std::{env, thread};
@@ -47,7 +47,7 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
         // Uses the OpenMP variable to limit the number of threads
         // If the parsing fails, returns the max size (so, no impact)
         // If OMP_THREAD_LIMIT=0, rejects the value
-        Ok(threadstr) => match threadstr.parse() {
+        Ok(threads) => match threads.parse() {
             Ok(0) | Err(_) => usize::MAX,
             Ok(n) => n,
         },
@@ -63,14 +63,13 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
         match env::var("OMP_NUM_THREADS") {
             // Uses the OpenMP variable to force the number of threads
             // If the parsing fails, returns the number of CPU
-            Ok(threadstr) => {
+            Ok(threads) => {
                 // In some cases, OMP_NUM_THREADS can be "x,y,z"
                 // In this case, only take the first one (like GNU)
                 // If OMP_NUM_THREADS=0, rejects the value
-                let thread: Vec<&str> = threadstr.split_terminator(',').collect();
+                match threads.split_terminator(',').next() {
-                match &thread[..] {
+                    None => available_parallelism(),
-                    [] => available_parallelism(),
+                    Some(s) => match s.parse() {
-                    [s, ..] => match s.parse() {
                         Ok(0) | Err(_) => available_parallelism(),
                         Ok(n) => n,
                     },

src/uu/split/src/strategy.rs

@@ -108,7 +108,7 @@ impl NumberType {
     /// # Errors
     ///
     /// If the string is not one of the valid number types,
-    /// if `K` is not a nonnegative integer,
+    /// if `K` is not a non-negative integer,
     /// or if `K` is 0,
     /// or if `N` is not a positive integer,
     /// or if `K` is greater than `N`
@@ -117,9 +117,9 @@ impl NumberType {
         fn is_invalid_chunk(chunk_number: u64, num_chunks: u64) -> bool {
             chunk_number > num_chunks || chunk_number == 0
         }
-        let parts: Vec<&str> = s.split('/').collect();
+        let mut parts = s.splitn(4, '/');
-        match &parts[..] {
+        match (parts.next(), parts.next(), parts.next(), parts.next()) {
-            [n_str] => {
+            (Some(n_str), None, None, None) => {
                 let num_chunks = parse_size_u64(n_str)
                     .map_err(|_| NumberTypeError::NumberOfChunks(n_str.to_string()))?;
                 if num_chunks > 0 {
@@ -128,7 +128,9 @@ impl NumberType {
                     Err(NumberTypeError::NumberOfChunks(s.to_string()))
                 }
             }
-            [k_str, n_str] if !k_str.starts_with('l') && !k_str.starts_with('r') => {
+            (Some(k_str), Some(n_str), None, None)
+                if !k_str.starts_with('l') && !k_str.starts_with('r') =>
+            {
                 let num_chunks = parse_size_u64(n_str)
                     .map_err(|_| NumberTypeError::NumberOfChunks(n_str.to_string()))?;
                 let chunk_number = parse_size_u64(k_str)
@@ -138,12 +140,12 @@ impl NumberType {
                 }
                 Ok(Self::KthBytes(chunk_number, num_chunks))
             }
-            ["l", n_str] => {
+            (Some("l"), Some(n_str), None, None) => {
                 let num_chunks = parse_size_u64(n_str)
                     .map_err(|_| NumberTypeError::NumberOfChunks(n_str.to_string()))?;
                 Ok(Self::Lines(num_chunks))
             }
-            ["l", k_str, n_str] => {
+            (Some("l"), Some(k_str), Some(n_str), None) => {
                 let num_chunks = parse_size_u64(n_str)
                     .map_err(|_| NumberTypeError::NumberOfChunks(n_str.to_string()))?;
                 let chunk_number = parse_size_u64(k_str)
@@ -153,12 +155,12 @@ impl NumberType {
                 }
                 Ok(Self::KthLines(chunk_number, num_chunks))
             }
-            ["r", n_str] => {
+            (Some("r"), Some(n_str), None, None) => {
                 let num_chunks = parse_size_u64(n_str)
                     .map_err(|_| NumberTypeError::NumberOfChunks(n_str.to_string()))?;
                 Ok(Self::RoundRobin(num_chunks))
             }
-            ["r", k_str, n_str] => {
+            (Some("r"), Some(k_str), Some(n_str), None) => {
                 let num_chunks = parse_size_u64(n_str)
                     .map_err(|_| NumberTypeError::NumberOfChunks(n_str.to_string()))?;
                 let chunk_number = parse_size_u64(k_str)