expr: Do not parse arguments using clap

src/uu/expr/src/expr.rs

@@ -94,16 +94,29 @@ pub fn uu_app() -> Command {
 pub fn uumain(args: impl uucore::Args) -> UResult<()> {
     // For expr utility we do not want getopts.
     // The following usage should work without escaping hyphens: `expr -15 = 1 +  2 \* \( 3 - -4 \)`
-    let matches = uu_app().try_get_matches_from(args)?;
-    let token_strings: Vec<&str> = matches
-        .get_many::<String>(options::EXPRESSION)
-        .map(|v| v.into_iter().map(|s| s.as_ref()).collect::<Vec<_>>())
-        .unwrap_or_default();
+    let args: Vec<String> = args
+        .skip(1) // Skip binary name
+        .map(|a| a.to_string_lossy().to_string())
+        .collect();
 
-    let res: String = AstNode::parse(&token_strings)?.eval()?.eval_as_string();
+    if args.len() == 1 && args[0] == "--help" {
+        let _ = uu_app().print_help();
+    } else if args.len() == 1 && args[0] == "--version" {
+        println!("{} {}", uucore::util_name(), crate_version!())
+    } else {
+        // The first argument may be "--" and should be be ignored.
+        let args = if !args.is_empty() && args[0] == "--" {
+            &args[1..]
+        } else {
+            &args
+        };
+
+        let res: String = AstNode::parse(args)?.eval()?.eval_as_string();
         println!("{res}");
         if !is_truthy(&res.into()) {
             return Err(1.into());
         }
+    }
+
     Ok(())
 }

src/uu/expr/src/syntax_tree.rs

@@ -365,7 +365,7 @@ pub enum AstNode {
 }
 
 impl AstNode {
-    pub fn parse(input: &[&str]) -> ExprResult<Self> {
+    pub fn parse(input: &[impl AsRef<str>]) -> ExprResult<Self> {
         Parser::new(input).parse()
     }
 
@@ -427,13 +427,13 @@ impl AstNode {
     }
 }
 
-struct Parser<'a> {
-    input: &'a [&'a str],
+struct Parser<'a, S: AsRef<str>> {
+    input: &'a [S],
     index: usize,
 }
 
-impl<'a> Parser<'a> {
-    fn new(input: &'a [&'a str]) -> Self {
+impl<'a, S: AsRef<str>> Parser<'a, S> {
+    fn new(input: &'a [S]) -> Self {
         Self { input, index: 0 }
     }
 
@@ -441,19 +441,19 @@ impl<'a> Parser<'a> {
         let next = self.input.get(self.index);
         if let Some(next) = next {
             self.index += 1;
-            Ok(next)
+            Ok(next.as_ref())
         } else {
             // The indexing won't panic, because we know that the input size
             // is greater than zero.
             Err(ExprError::MissingArgument(
-                self.input[self.index - 1].into(),
+                self.input[self.index - 1].as_ref().into(),
             ))
         }
     }
 
     fn accept<T>(&mut self, f: impl Fn(&str) -> Option<T>) -> Option<T> {
         let next = self.input.get(self.index)?;
-        let tok = f(next);
+        let tok = f(next.as_ref());
         if let Some(tok) = tok {
             self.index += 1;
             Some(tok)
@@ -468,7 +468,7 @@ impl<'a> Parser<'a> {
         }
         let res = self.parse_expression()?;
         if let Some(arg) = self.input.get(self.index) {
-            return Err(ExprError::UnexpectedArgument(arg.to_string()));
+            return Err(ExprError::UnexpectedArgument(arg.as_ref().into()));
         }
         Ok(res)
     }
@@ -556,12 +556,12 @@ impl<'a> Parser<'a> {
                     // at `self.index - 1`. So this indexing won't panic.
                     Ok(_) => {
                         return Err(ExprError::ExpectedClosingBraceInsteadOf(
-                            self.input[self.index - 1].into(),
+                            self.input[self.index - 1].as_ref().into(),
                         ));
                     }
                     Err(ExprError::MissingArgument(_)) => {
                         return Err(ExprError::ExpectedClosingBraceAfter(
-                            self.input[self.index - 1].into(),
+                            self.input[self.index - 1].as_ref().into(),
                         ));
                     }
                     Err(e) => return Err(e),