clean up backend

src/backend/actual/pacman.rs

@@ -0,0 +1,75 @@
+use std::collections::HashSet;
+
+use alpm::Alpm;
+use alpm::PackageReason::Explicit;
+use anyhow::{Context, Result};
+
+use crate::backend::backend_trait::*;
+use crate::{impl_backend_constants, Group, Package};
+
+pub(crate) struct Pacman {
+    pub(crate) packages: HashSet<Package>,
+}
+
+const BINARY: Text = "paru";
+const SECTION: Text = "pacman";
+const SWITCHES_INSTALL: Switches = &["-S"];
+const SWITCHES_REMOVE: Switches = &["-Rsn"];
+
+impl Backend for Pacman {
+    impl_backend_constants!();
+
+    fn get_all_installed_packages(&self) -> Result<HashSet<Package>> {
+        let alpm_packages = get_all_installed_packages_from_alpm()
+            .context("getting all installed packages from alpm")?;
+
+        let result = convert_to_pacdef_packages(alpm_packages);
+        Ok(result)
+    }
+
+    fn get_explicitly_installed_packages(&self) -> Result<HashSet<Package>> {
+        let alpm_packages = get_explicitly_installed_packages_from_alpm()
+            .context("getting all installed packages from alpm")?;
+        let result = convert_to_pacdef_packages(alpm_packages);
+        Ok(result)
+    }
+}
+
+fn get_all_installed_packages_from_alpm() -> Result<HashSet<String>> {
+    let db = get_db_handle().context("getting DB handle")?;
+    let result = db
+        .localdb()
+        .pkgs()
+        .iter()
+        .map(|p| p.name().to_string())
+        .collect();
+    Ok(result)
+}
+
+fn get_explicitly_installed_packages_from_alpm() -> Result<HashSet<String>> {
+    let db = get_db_handle().context("getting DB handle")?;
+    let result = db
+        .localdb()
+        .pkgs()
+        .iter()
+        .filter(|p| p.reason() == Explicit)
+        .map(|p| p.name().to_string())
+        .collect();
+    Ok(result)
+}
+
+fn convert_to_pacdef_packages(packages: HashSet<String>) -> HashSet<Package> {
+    packages.into_iter().map(Package::from).collect()
+}
+
+fn get_db_handle() -> Result<Alpm> {
+    Alpm::new("/", "/var/lib/pacman").context("connecting to DB using expected default values")
+}
+
+impl Pacman {
+    pub(crate) fn new() -> Self {
+        Self {
+            packages: HashSet::new(),
+        }
+    }
+}