Enhance CLI arguments with new options, validation, and detailed help messages

src/util/fs.rs

@@ -1,6 +1,27 @@
+use regex::Regex;
 use std::path::PathBuf;
+use once_cell::sync::Lazy;
+
+static PATH_REGEX: Lazy<Regex> = Lazy::new(|| {
+    Regex::new(r"^[+-]?(\d+(\.\d*)?|\.\d+)([eE][+-]?\d+)?$").unwrap()
+});
 
 pub fn path_exists(s: &str) -> Result<PathBuf, String> {
     let p = PathBuf::from(s);
     p.exists().then_some(p).ok_or("path does not exist".to_string())
 }
+
+pub fn valid_possible_path(s: &str) -> Result<PathBuf, String>
+{
+    let lower = s.to_ascii_lowercase();
+
+    if lower == "true" || lower == "false" {
+        return Err("boolean literal is not allowed".into());
+    }
+
+    if PATH_REGEX.is_match(s) {
+        return Err("numeric literal is not allowed".into());
+    }
+
+    Ok(PathBuf::from(s))
+}