refactor: Introduce ConfigurationOptions::get method

crates/ruff/src/settings/options_base.rs

@@ -1,5 +1,30 @@
 pub trait ConfigurationOptions {
     fn get_available_options() -> Vec<(&'static str, OptionEntry)>;
+
+    /// Get an option entry by its fully-qualified name
+    /// (e.g. `foo.bar` refers to the `bar` option in the `foo` group).
+    fn get(name: Option<&str>) -> Option<OptionEntry> {
+        let mut entries = Self::get_available_options();
+
+        let mut parts_iter = name.into_iter().flat_map(|s| s.split('.'));
+
+        while let Some(part) = parts_iter.next() {
+            let (_, field) = entries.into_iter().find(|(name, _)| *name == part)?;
+            match field {
+                OptionEntry::Field(..) => {
+                    if parts_iter.next().is_some() {
+                        return None;
+                    }
+
+                    return Some(field);
+                }
+                OptionEntry::Group(fields) => {
+                    entries = fields;
+                }
+            }
+        }
+        Some(OptionEntry::Group(entries))
+    }
 }
 
 #[derive(Debug)]

crates/ruff_cli/src/commands/config.rs

@@ -6,43 +6,31 @@ use ruff::settings::{
 use crate::ExitStatus;
 
 #[allow(clippy::print_stdout)]
-pub(crate) fn config(option: Option<&str>) -> ExitStatus {
+pub(crate) fn config(key: Option<&str>) -> ExitStatus {
-    let entries = Options::get_available_options();
+    let Some(entry) = Options::get(key) else {
-    let mut entries = &entries;
-
-    let mut parts_iter = option.iter().flat_map(|s| s.split('.'));
-
-    while let Some(part) = parts_iter.next() {
-        let Some((_, field)) = entries.iter().find(|(name, _)| *name == part) else {
         println!("Unknown option");
         return ExitStatus::Error;
     };
-        match field {
+
+    match entry {
         OptionEntry::Field(OptionField {
             doc,
             default,
             value_type,
             example,
         }) => {
-                if parts_iter.next().is_some() {
-                    println!("Unknown option");
-                    return ExitStatus::Error;
-                }
-
             println!("{doc}");
             println!();
             println!("Default value: {default}");
             println!("Type: {value_type}");
             println!("Example usage:\n```toml\n{example}\n```");
-                return ExitStatus::Success;
-            }
-            OptionEntry::Group(fields) => {
-                entries = fields;
-            }
-        }
         }
+        OptionEntry::Group(entries) => {
             for (name, _) in entries {
                 println!("{name}");
             }
+        }
+    }
+
     ExitStatus::Success
 }