main, util: move get_version to util.rs

src/main.rs

@@ -3,11 +3,8 @@ mod util;
 use clap::Parser;
 use core::str;
 use log::{debug, error};
-use regex::Regex;
 use std::{
     collections::{HashMap, HashSet},
-    string::ToString,
-    sync::OnceLock,
     thread,
 };
 use yansi::Paint;
@@ -153,7 +150,7 @@ fn main() {
     let mut post = HashMap::<&str, HashSet<&str>>::new();
 
     for p in &package_list_pre {
-        match get_version(&**p) {
+        match util::get_version(&**p) {
             Ok((name, version)) => {
                 pre.entry(name).or_default().insert(version);
             }
@@ -164,7 +161,7 @@ fn main() {
     }
 
     for p in &package_list_post {
-        match get_version(&**p) {
+        match util::get_version(&**p) {
             Ok((name, version)) => {
                 post.entry(name).or_default().insert(version);
             }
@@ -247,58 +244,3 @@ fn main() {
         }
     }
 }
-
-// Returns a reference to the compiled regex pattern.
-// The regex is compiled only once.
-fn store_path_regex() -> &'static Regex {
-    static REGEX: OnceLock<Regex> = OnceLock::new();
-    REGEX.get_or_init(|| {
-        Regex::new(r"(.+?)(-([0-9].*?))?$")
-            .expect("Failed to compile regex pattern for nix store paths")
-    })
-}
-
-/// Parses a nix store path to extract the packages name and version
-///
-/// This function first drops the inputs first 44 chars, since that is exactly the length of the /nix/store/... prefix. Then it matches that against our store path regex.
-///
-/// # Returns
-///
-/// * Result<(&'a str, &'a str)> - The Package's name and version, or an error if
-///   one or both cannot be retrieved.
-fn get_version<'a>(pack: impl Into<&'a str>) -> Result<(&'a str, &'a str)> {
-    let path = pack.into();
-
-    // We can strip the path since it _always_ follows the format
-    // /nix/store/<...>-<program_name>-......
-    // This part is exactly 44 chars long, so we just remove it.
-    let stripped_path = &path[44..];
-    debug!("Stripped path: {stripped_path}");
-
-    // Match the regex against the input
-    if let Some(cap) = store_path_regex().captures(stripped_path) {
-        // Handle potential missing captures safely
-        let name = cap.get(1).map_or("", |m| m.as_str());
-        let mut version = cap.get(2).map_or("<none>", |m| m.as_str());
-
-        if version.starts_with('-') {
-            version = &version[1..];
-        }
-
-        if name.is_empty() {
-            return Err(AppError::ParseError {
-                message: format!("Failed to extract name from path: {path}"),
-                context: "get_version".to_string(),
-                source: None,
-            });
-        }
-
-        return Ok((name, version));
-    }
-
-    Err(AppError::ParseError {
-        message: format!("Path does not match expected nix store format: {path}"),
-        context: "get_version".to_string(),
-        source: None,
-    })
-}

src/util.rs

@@ -1,5 +1,18 @@
+use crate::error::AppError;
+use log::{debug, error};
+use regex::Regex;
 use std::cmp::Ordering;
 
+use std::{
+    collections::{HashMap, HashSet},
+    string::ToString,
+    sync::OnceLock,
+    thread,
+};
+
+// Use type alias for Result with our custom error type
+type Result<T> = std::result::Result<T, AppError>;
+
 #[derive(Eq, PartialEq, Debug)]
 enum VersionComponent {
     Number(u64),
@@ -114,3 +127,57 @@ mod test {
         );
     }
 }
+/// Parses a nix store path to extract the packages name and version
+///
+/// This function first drops the inputs first 44 chars, since that is exactly the length of the /nix/store/... prefix. Then it matches that against our store path regex.
+///
+/// # Returns
+///
+/// * Result<(&'a str, &'a str)> - The Package's name and version, or an error if
+///   one or both cannot be retrieved.
+pub fn get_version<'a>(pack: impl Into<&'a str>) -> Result<(&'a str, &'a str)> {
+    let path = pack.into();
+
+    // We can strip the path since it _always_ follows the format
+    // /nix/store/<...>-<program_name>-......
+    // This part is exactly 44 chars long, so we just remove it.
+    let stripped_path = &path[44..];
+    debug!("Stripped path: {stripped_path}");
+
+    // Match the regex against the input
+    if let Some(cap) = store_path_regex().captures(stripped_path) {
+        // Handle potential missing captures safely
+        let name = cap.get(1).map_or("", |m| m.as_str());
+        let mut version = cap.get(2).map_or("<none>", |m| m.as_str());
+
+        if version.starts_with('-') {
+            version = &version[1..];
+        }
+
+        if name.is_empty() {
+            return Err(AppError::ParseError {
+                message: format!("Failed to extract name from path: {path}"),
+                context: "get_version".to_string(),
+                source: None,
+            });
+        }
+
+        return Ok((name, version));
+    }
+
+    Err(AppError::ParseError {
+        message: format!("Path does not match expected nix store format: {path}"),
+        context: "get_version".to_string(),
+        source: None,
+    })
+}
+
+// Returns a reference to the compiled regex pattern.
+// The regex is compiled only once.
+fn store_path_regex() -> &'static Regex {
+    static REGEX: OnceLock<Regex> = OnceLock::new();
+    REGEX.get_or_init(|| {
+        Regex::new(r"(.+?)(-([0-9].*?))?$")
+            .expect("Failed to compile regex pattern for nix store paths")
+    })
+}