fix: Provide convenient access for common cases

clap_complete/src/shells/zsh.rs

@@ -623,13 +623,14 @@ fn write_positionals_of(p: &Command) -> String {
         debug!("write_positionals_of:iter: arg={}", arg.get_id());
 
         let num_args = arg.get_num_args().expect("built");
-        let cardinality = if num_args != 1.into() && num_args != 0.into() {
+        let cardinality =
-            "*:"
+            if num_args != builder::ValueRange::EMPTY && num_args != builder::ValueRange::SINGLE {
-        } else if !arg.is_required_set() {
+                "*:"
-            ":"
+            } else if !arg.is_required_set() {
-        } else {
+                ":"
-            ""
+            } else {
-        };
+                ""
+            };
 
         let a = format!(
             "'{cardinality}:{name}{help}:{value_completion}' \\",

clap_complete_fig/src/fig.rs

@@ -335,7 +335,7 @@ fn gen_args(arg: &Arg, indent: usize) -> String {
     ));
 
     let num_args = arg.get_num_args().expect("built");
-    if num_args != 0.into() && num_args != 1.into() {
+    if num_args != builder::ValueRange::EMPTY && num_args != builder::ValueRange::SINGLE {
         buffer.push_str(&format!(
             "{:indent$}isVariadic: true,\n",
             "",

src/builder/arg.rs

@@ -3945,9 +3945,9 @@ impl<'help> Arg<'help> {
             self.num_vals.get_or_insert(val_names_len.into());
         } else {
             if self.is_takes_value_set() {
-                self.num_vals.get_or_insert(1.into());
+                self.num_vals.get_or_insert(ValueRange::SINGLE);
             } else {
-                self.num_vals.get_or_insert(0.into());
+                self.num_vals.get_or_insert(ValueRange::EMPTY);
             }
         }
     }

src/builder/debug_asserts.rs

@@ -3,6 +3,7 @@ use std::cmp::Ordering;
 use clap_lex::RawOsStr;
 
 use crate::builder::arg::ArgProvider;
+use crate::builder::ValueRange;
 use crate::mkeymap::KeyType;
 use crate::ArgAction;
 use crate::INTERNAL_ERROR_MSG;
@@ -693,7 +694,7 @@ fn assert_arg(arg: &Arg) {
 
     let num_vals = arg.get_num_args().expect(INTERNAL_ERROR_MSG);
     // This can be the cause of later asserts, so put this first
-    if num_vals != 0.into() {
+    if num_vals != ValueRange::EMPTY {
         // HACK: Don't check for flags to make the derive easier
         let num_val_names = arg.get_value_names().unwrap_or(&[]).len();
         if num_vals.max_values() < num_val_names {
@@ -728,7 +729,7 @@ fn assert_arg(arg: &Arg) {
         );
     }
 
-    if num_vals == 1.into() {
+    if num_vals == ValueRange::SINGLE {
         assert!(
             !arg.is_multiple_values_set(),
             "Argument {}: mismatch between `num_args` and `multiple_values`",

src/builder/range.rs

@@ -6,6 +6,18 @@ pub struct ValueRange {
 }
 
 impl ValueRange {
+    /// Nor argument values, or a flag
+    pub const EMPTY: Self = Self {
+        start_inclusive: 0,
+        end_inclusive: 0,
+    };
+
+    /// A single argument value, the most common case for options
+    pub const SINGLE: Self = Self {
+        start_inclusive: 1,
+        end_inclusive: 1,
+    };
+
     /// Create a range
     ///
     /// # Panics
@@ -96,7 +108,7 @@ impl std::ops::RangeBounds<usize> for ValueRange {
 
 impl Default for ValueRange {
     fn default() -> Self {
-        0.into()
+        Self::EMPTY
     }
 }