feat(bin) : max_values Macro for CLI args parsing

bin/reth/src/args/types.rs

@@ -1,6 +1,6 @@
 //! Additional helper types for CLI parsing.
 
-use std::{fmt, str::FromStr};
+use std::{fmt, num::ParseIntError, str::FromStr};
 
 /// A helper type that maps `0` to `None` when parsing CLI arguments.
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
@@ -36,6 +36,28 @@ impl FromStr for ZeroAsNone {
     }
 }
 
+/// A helper type for parsing "max" as `u32::MAX`.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct MaxU32(pub u32);
+
+impl fmt::Display for MaxU32 {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}", self.0)
+    }
+}
+
+impl FromStr for MaxU32 {
+    type Err = ParseIntError;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        if s == "max" {
+            Ok(MaxU32(u32::MAX))
+        } else {
+            s.parse::<u32>().map(MaxU32)
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -46,4 +68,16 @@ mod tests {
         assert_eq!(val, ZeroAsNone(None));
         assert_eq!(val.unwrap_or_max(), u64::MAX);
     }
+
+    #[test]
+    fn test_max_parse() {
+        let val = "max".parse::<MaxU32>().unwrap();
+        assert_eq!(val, MaxU32(u32::MAX));
+    }
+
+    #[test]
+    fn test_number_parse() {
+        let val = "123".parse::<MaxU32>().unwrap();
+        assert_eq!(val, MaxU32(123));
+    }
 }