fix reading group sections

src/backend/mod.rs

@@ -103,7 +103,7 @@ pub(crate) trait Backend {
             .skip(1)
             .filter(|line| !line.starts_with('['))
             .fuse()
-            .map(Package::from)
+            .filter_map(Package::try_from)
             .collect()
     }
 

src/backend/pacman.rs

@@ -47,7 +47,7 @@ fn get_explicitly_installed_packages_from_alpm() -> HashSet<String> {
 }
 
 fn convert_to_pacdef_packages(packages: HashSet<String>) -> HashSet<Package> {
-    packages.into_iter().map(Package::from).collect()
+    packages.into_iter().filter_map(Package::try_from).collect()
 }
 
 impl Pacman {

src/backend/rust.rs

@@ -17,7 +17,7 @@ impl Backend for Rust {
 
     fn get_all_installed_packages(&self) -> HashSet<Package> {
         extract_packages_names(&run_cargo_install_list())
-            .map(Package::from)
+            .filter_map(Package::try_from)
             .collect()
     }
 

src/group.rs

@@ -1,13 +1,11 @@
 use std::collections::HashSet;
-use std::fs::{read_to_string, File};
+use std::fs::read_to_string;
 use std::hash::Hash;
-use std::io::{BufRead, BufReader};
 use std::path::Path;
 
-use anyhow::{anyhow, Context, Result};
+use anyhow::{Context, Result};
 
 use crate::section::Section;
-use crate::Package;
 
 #[derive(Debug)]
 pub struct Group {
@@ -21,10 +19,11 @@ impl Group {
 
         let path = crate::path::get_pacdef_group_dir().context("getting pacdef group dir")?;
         for entry in path.read_dir().context("reading group dir")? {
-            let file = entry.context("getting a file")?;
+            let file = entry.context("getting group file")?;
             let path = file.path();
 
-            let group = Group::try_from(path)?;
+            let group =
+                Group::try_from(&path).with_context(|| format!("reading group file {:?}", path))?;
             result.insert(group);
         }
 
@@ -63,11 +62,11 @@ impl Eq for Group {
     fn assert_receiver_is_total_eq(&self) {}
 }
 
-impl<P> From<P> for Group
-where
+impl Group {
+    fn try_from<P>(p: P) -> Result<Self>
+    where
         P: AsRef<Path>,
-{
-    fn from(p: P) -> Self {
+    {
         let path = p.as_ref();
         let content = read_to_string(path).unwrap();
         let name = path.file_name().unwrap().to_string_lossy().to_string();
@@ -76,10 +75,11 @@ where
         let mut sections = HashSet::new();
 
         while lines.peek().is_some() {
-            let section = Section::from_lines(&mut lines);
+            if let Ok(section) = Section::try_from_lines(&mut lines).context("reading section") {
                 sections.insert(section);
             }
+        }
 
-        Self { name, sections }
+        Ok(Self { name, sections })
     }
 }

src/package.rs

@@ -8,21 +8,6 @@ pub struct Package {
     repo: Option<String>,
 }
 
-impl From<&str> for Package {
-    fn from(s: &str) -> Self {
-        let trimmed = remove_all_but_package_name(s);
-
-        let (name, repo) = Self::split_into_name_and_repo(trimmed);
-        Self { name, repo }
-    }
-}
-
-impl From<String> for Package {
-    fn from(value: String) -> Self {
-        Package::from(value.as_ref())
-    }
-}
-
 fn remove_all_but_package_name(s: &str) -> &str {
     s.split('#') // remove comment
         .next()
@@ -36,7 +21,7 @@ impl Package {
     ) -> HashSet<Self> {
         lines
             .into_iter()
-            .map(|l| Package::from(l.unwrap()))
+            .filter_map(|l| Package::try_from(l.unwrap()))
             .collect()
     }
 
@@ -46,6 +31,19 @@ impl Package {
         let repo = iter.next().map(|s| s.to_string());
         (name, repo)
     }
+
+    pub(crate) fn try_from<S>(s: S) -> Option<Self>
+    where
+        S: AsRef<str>,
+    {
+        let trimmed = remove_all_but_package_name(s.as_ref());
+        if trimmed.is_empty() {
+            return None;
+        }
+
+        let (name, repo) = Self::split_into_name_and_repo(trimmed);
+        Some(Self { name, repo })
+    }
 }
 
 impl PartialEq for Package {
@@ -100,7 +98,7 @@ mod tests {
     #[test]
     fn from() {
         let x = "myrepo/somepackage  #  ".to_string();
-        let p = Package::from(x);
+        let p = Package::try_from(x).unwrap();
         assert_eq!(p.name, "somepackage");
         assert_eq!(p.repo, Some("myrepo".to_string()));
     }

src/section.rs

@@ -1,4 +1,6 @@
-use std::{collections::HashSet, hash::Hash};
+use std::{collections::HashSet, hash::Hash, iter::Peekable};
+
+use anyhow::{Context, Result};
 
 use crate::Package;
 
@@ -13,22 +15,25 @@ impl Section {
         Self { name, packages }
     }
 
-    pub fn from_lines<'a>(iter: &mut (impl Iterator<Item = &'a str> + std::fmt::Debug)) -> Self {
+    pub(crate) fn try_from_lines<'a>(
+        iter: &mut Peekable<(impl Iterator<Item = &'a str> + std::fmt::Debug)>,
+    ) -> Result<Self> {
         let name = iter
             .find(|line| line.starts_with('['))
-            .unwrap()
+            .context("finding beginning of next section")?
             .trim()
             .trim_start_matches('[')
             .trim_end_matches(']')
             .to_string();
 
-        let packages = iter
-            .take_while(|line| !line.starts_with('['))
-            .map(Package::try_from)
-            .filter_map(|p| p.ok())
-            .collect();
-
-        Self::new(name, packages)
+        let mut packages = HashSet::new();
+        // `while let` is unstable, unfortunately
+        while iter.peek().is_some() && !iter.peek().unwrap().starts_with('[') {
+            if let Some(package) = Package::try_from(iter.next().unwrap()) {
+                packages.insert(package);
+            }
+        }
+        Ok(Self::new(name, packages))
     }
 }