feat: add ability to add extra paths to search for icons

The cache retry logic had last_check.duration_since(Instant::now()) which
is backwards - duration_since computes self - earlier, so past.duration_since(future)
always returns Duration::ZERO (saturates to 0). This caused icons marked NotFound
to never be retried, breaking the intended 5-second retry window.

Using last_check.elapsed() is equivalent to Instant::now().duration_since(last_check)
and correctly measures how much time has passed since the cache entry was created.

Cargo.toml

@@ -10,17 +10,16 @@ readme = "README.md"
 keywords = ["icons", "gui", "freedesktop"]
 
 [dependencies]
-dirs = "6.0"
-thiserror = "2.0"
-xdg = "3.0"
-tracing = "0.1.41"
-ini_core = "0.2.0"
+bstr = "1.12.1"
+btoi = "0.5.0"
+memchr = "2.7.6"
 memmap2 = "0.9"
+thiserror = "2.0"
+tracing = { version = "0.1.41", default-features = false }
+xdg = "3.0"
 
 [dev-dependencies]
 speculoos = "0.13.0"
-linicon = "2.3.0"
-gtk4 = "0.10"
 criterion = "0.7"
 
 [features]

benches/simple_lookup.rs

@@ -1,9 +1,8 @@
+use cosmic_freedesktop_icons::lookup;
 use criterion::{
-    AxisScale, BenchmarkId, Criterion, PlotConfiguration, black_box, criterion_group,
-    criterion_main,
+    AxisScale, BenchmarkId, Criterion, PlotConfiguration, criterion_group, criterion_main,
 };
-use freedesktop_icons::lookup;
-use gtk4::{IconLookupFlags, IconTheme, TextDirection};
+use std::hint::black_box;
 
 pub fn bench_lookups(c: &mut Criterion) {
     let mut group = c.benchmark_group("ComparisonsLookups");
@@ -11,21 +10,13 @@ pub fn bench_lookups(c: &mut Criterion) {
     group.plot_config(plot_config);
 
     let args = [
-        "user-home",      // (Best case) An icon that can be found in the current theme
-        "firefox",        // An icon that can be found in the hicolor default theme
-        "archlinux-logo", // An icon that resides in /usr/share/pixmaps
-        "not-found",      // (Worst case) An icon that does not exist
+        "user-home",               // (Best case) An icon that can be found in the current theme
+        "firefox",                 // An icon that can be found in the hicolor default theme
+        "com.valvesoftware.Steam", // An icon that resides in /usr/share/pixmaps
+        "not-found",               // (Worst case) An icon that does not exist
     ];
 
     for arg in args {
-        group.bench_with_input(BenchmarkId::new("freedesktop-icons", arg), arg, |b, arg| {
-            b.iter(|| {
-                lookup(black_box(arg))
-                    .with_theme(black_box("Adwaita"))
-                    .find()
-            });
-        });
-
         group.bench_with_input(
             BenchmarkId::new("freedesktop-icons-cache", arg),
             arg,
@@ -40,33 +31,6 @@ pub fn bench_lookups(c: &mut Criterion) {
                 });
             },
         );
-
-        group.bench_with_input(BenchmarkId::new("linicon", arg), arg, |b, arg| {
-            b.iter(|| {
-                linicon::lookup_icon(black_box(arg))
-                    .from_theme(black_box("Adwaita"))
-                    .with_scale(black_box(1))
-                    .with_size(black_box(24))
-                    .next()
-            });
-        });
-
-        group.bench_with_input(BenchmarkId::new("gtk", arg), arg, |b, arg| {
-            gtk4::init().unwrap();
-            let theme = IconTheme::new();
-            b.iter(|| {
-                theme
-                    .lookup_icon(
-                        black_box(arg),
-                        black_box(&[]),
-                        black_box(24),
-                        black_box(1),
-                        black_box(TextDirection::None),
-                        black_box(IconLookupFlags::empty()),
-                    )
-                    .icon_name()
-            });
-        });
     }
 
     group.finish();

benches/tests.rs

@@ -1,105 +0,0 @@
-use freedesktop_icons::lookup;
-use gtk4::{IconLookupFlags, IconTheme, TextDirection};
-use speculoos::prelude::*;
-use std::path::PathBuf;
-
-#[test]
-fn gtk_lookup() {
-    gtk4::init().unwrap();
-    let theme = IconTheme::new();
-
-    let x = theme.lookup_icon(
-        "firefox",
-        &[],
-        24,
-        1,
-        TextDirection::None,
-        IconLookupFlags::empty(),
-    );
-
-    assert!(x.icon_name().is_some())
-}
-
-// Linicon sometimes fails with theme that have unknown parents
-// This test only ensure we are running the correct function in the benchmarks
-// And results are identical.
-#[test]
-fn linicon() {
-    // Current theme
-    let lin_user_home = linicon::lookup_icon("user-home")
-        .from_theme("Adwaita")
-        .with_size(24)
-        .with_scale(1)
-        .next();
-
-    let user_home = lookup("user-home")
-        .with_theme("Adwaita")
-        .with_size(24)
-        .with_scale(1)
-        .find();
-
-    asserting!("Linicon return some icon")
-        .that(&lin_user_home.unwrap())
-        .is_ok()
-        .map(|icon| &icon.path)
-        .is_equal_to(PathBuf::from(
-            "/usr/share/icons/Adwaita/24x24/places/user-home.png",
-        ));
-
-    asserting!("Our implementation should return the same result as linicon")
-        .that(&user_home)
-        .is_some()
-        .is_equal_to(PathBuf::from(
-            "/usr/share/icons/Adwaita/24x24/places/user-home.png",
-        ));
-
-    // Fallback to hicolor
-    let lin_firefox = linicon::lookup_icon("firefox")
-        .from_theme("Adwaita")
-        .with_size(24)
-        .with_scale(1)
-        .next();
-
-    let firefox = lookup("firefox")
-        .with_theme("Adwaita")
-        .with_size(24)
-        .with_scale(1)
-        .find();
-
-    asserting!("Linicon return some icon")
-        .that(&lin_firefox.unwrap())
-        .is_ok()
-        .map(|icon| &icon.path)
-        .is_equal_to(PathBuf::from(
-            "/usr/share/icons/hicolor/22x22/apps/firefox.png",
-        ));
-
-    asserting!("Our implementation should return the same result as linicon")
-        .that(&firefox)
-        .is_some()
-        .is_equal_to(PathBuf::from(
-            "/usr/share/icons/hicolor/22x22/apps/firefox.png",
-        ));
-
-    // pixmaps
-    let lin_archlinux = linicon::lookup_icon("archlinux-logo")
-        .from_theme("Adwaita")
-        .with_size(24)
-        .with_scale(1)
-        .next();
-
-    let archlinux = lookup("archlinux-logo")
-        .with_theme("Adwaita")
-        .with_size(24)
-        .with_scale(1)
-        .find();
-
-    asserting!("Linicon fails to fallback to pixmaps")
-        .that(&lin_archlinux)
-        .is_none();
-
-    asserting!("But we succeed")
-        .that(&archlinux)
-        .is_some()
-        .is_equal_to(PathBuf::from("/usr/share/pixmaps/archlinux-logo.png"));
-}

src/cache.rs

@@ -1,15 +1,17 @@
 use std::collections::BTreeMap;
 use std::path::{Path, PathBuf};
-use std::sync::LazyLock;
-use std::sync::Mutex;
+use std::sync::{LazyLock, RwLock};
 use std::time::Instant;
 
 pub(crate) static CACHE: LazyLock<Cache> = LazyLock::new(Cache::default);
-type IconMap = BTreeMap<(String, u16, u16), CacheEntry>;
-type ThemeMap = BTreeMap<String, IconMap>;
+type Theme = Box<str>;
+type Icon = Box<str>;
+type SizedMap = BTreeMap<(u16, u16), CacheEntry>;
+type IconMap = BTreeMap<Icon, SizedMap>;
+type ThemeMap = BTreeMap<Theme, IconMap>;
 
 #[derive(Default)]
-pub(crate) struct Cache(Mutex<ThemeMap>);
+pub(crate) struct Cache(RwLock<ThemeMap>);
 
 #[derive(Debug, Clone, PartialEq)]
 pub enum CacheEntry {
@@ -23,7 +25,7 @@ pub enum CacheEntry {
 
 impl Cache {
     pub fn clear(&self) {
-        self.0.lock().unwrap().clear();
+        self.0.write().unwrap().clear();
     }
 
     pub fn insert<P: AsRef<Path>>(
@@ -34,41 +36,38 @@ impl Cache {
         icon_name: &str,
         icon_path: &Option<P>,
     ) {
-        let mut theme_map = self.0.lock().unwrap();
+        let mut inner = self.0.write().unwrap();
         let entry = icon_path
             .as_ref()
             .map(|path| CacheEntry::Found(path.as_ref().to_path_buf()))
             .unwrap_or(CacheEntry::NotFound(Instant::now()));
 
-        match theme_map.get_mut(theme) {
-            Some(icon_map) => {
-                icon_map.insert((icon_name.to_string(), size, scale), entry);
-            }
-            None => {
-                let mut icon_map = BTreeMap::new();
-                icon_map.insert((icon_name.to_string(), size, scale), entry);
-                theme_map.insert(theme.to_string(), icon_map);
-            }
-        }
+        inner
+            .entry(theme.into())
+            .or_insert_with(IconMap::default)
+            .entry(icon_name.into())
+            .or_insert_with(BTreeMap::default)
+            .insert((size, scale), entry);
     }
 
     pub fn get(&self, theme: &str, size: u16, scale: u16, icon_name: &str) -> CacheEntry {
-        let theme_map = self.0.lock().unwrap();
+        let inner = self.0.read().unwrap();
 
-        theme_map
+        inner
             .get(theme)
-            .map(|icon_map| icon_map.get(&(icon_name.to_string(), size, scale)))
-            .and_then(|path| path.cloned())
+            .and_then(|icon_map| icon_map.get(icon_name))
+            .and_then(|icon_map| icon_map.get(&(size, scale)).cloned())
             .unwrap_or(CacheEntry::Unknown)
     }
 
     pub fn reset_none(&self) {
-        let mut theme_map = self.0.lock().unwrap();
-
-        for (_theme_name, theme) in theme_map.iter_mut() {
-            for (_icon_data, cached_icon) in theme.iter_mut() {
-                if matches!(cached_icon, CacheEntry::NotFound(_)) {
-                    *cached_icon = CacheEntry::Unknown;
+        let mut inner = self.0.write().unwrap();
+        for (_theme_name, theme) in inner.iter_mut() {
+            for (_, cached_icons) in theme.iter_mut() {
+                for (_, cached_icon) in cached_icons.iter_mut() {
+                    if matches!(cached_icon, CacheEntry::NotFound(_)) {
+                        *cached_icon = CacheEntry::Unknown;
+                    }
                 }
             }
         }

src/lib.rs

@@ -51,11 +51,14 @@
 //!     .find();
 //! # }
 //! ```
+use memmap2::Mmap;
 use theme::BASE_PATHS;
 
 use crate::cache::{CACHE, CacheEntry};
-use crate::theme::{THEMES, try_build_icon_path};
+use crate::theme::{THEMES, Theme, try_build_icon_path};
+use std::hash::{Hash, Hasher};
 use std::io::BufRead;
+use std::ops::ControlFlow;
 use std::path::PathBuf;
 use std::time::Instant;
 
@@ -82,8 +85,10 @@ pub fn list_themes() -> Vec<String> {
         .flatten()
         .map(|path| &path.index)
         .filter_map(|index| {
-            let file = std::fs::File::open(index).ok()?;
-            let mut reader = std::io::BufReader::new(file);
+            let file = std::fs::File::open(index)
+                .and_then(|file| unsafe { Mmap::map(&file) })
+                .ok()?;
+            let mut reader = std::io::Cursor::new(file.as_ref());
 
             let mut line = String::new();
             while let Ok(read) = reader.read_line(&mut line) {
@@ -105,56 +110,6 @@ pub fn list_themes() -> Vec<String> {
     themes
 }
 
-/// Return the default GTK theme if set.
-///
-/// ## Example
-/// ```rust, no_run
-/// use cosmic_freedesktop_icons::default_theme_gtk;
-///
-/// let theme = default_theme_gtk();
-///
-/// assert_eq!(Some("Adwaita"), theme.as_deref());
-/// ```
-pub fn default_theme_gtk() -> Option<String> {
-    // Calling gsettings is the simplest way to retrieve the default icon theme without adding
-    // GTK as a dependency. There seems to be several ways to set the default GTK theme
-    // including a file in XDG_CONFIG_HOME as well as an env var. Gsettings is the most
-    // straightforward method.
-    let gsettings = std::process::Command::new("gsettings")
-        .args(["get", "org.gnome.desktop.interface", "icon-theme"])
-        .output()
-        .ok()?;
-
-    // Only return the theme if it's in the cache.
-    if gsettings.status.success() {
-        let name = String::from_utf8(gsettings.stdout).ok()?;
-        let name = name.trim().trim_matches('\'');
-        THEMES.get(name).and_then(|themes| {
-            themes.first().and_then(|path| {
-                let file = std::fs::File::open(&path.index).ok()?;
-                let mut reader = std::io::BufReader::new(file);
-
-                let mut line = String::new();
-                while let Ok(read) = reader.read_line(&mut line) {
-                    if read == 0 {
-                        break;
-                    }
-
-                    if let Some(name) = line.strip_prefix("Name=") {
-                        return Some(name.trim().to_owned());
-                    }
-
-                    line.clear();
-                }
-
-                None
-            })
-        })
-    } else {
-        None
-    }
-}
-
 /// The lookup builder struct, holding all the lookup query parameters.
 pub struct LookupBuilder<'a> {
     name: &'a str,
@@ -163,6 +118,7 @@ pub struct LookupBuilder<'a> {
     scale: u16,
     size: u16,
     theme: &'a str,
+    extra_paths: &'a [PathBuf],
 }
 
 /// Build an icon lookup for the given icon name.
@@ -269,6 +225,14 @@ impl<'a> LookupBuilder<'a> {
         self
     }
 
+    /// Search additional directories for the icon as flat paths (no theme hierarchy).
+    /// These paths are searched before the theme chain.
+    #[inline]
+    pub fn with_extra_paths<'b: 'a>(mut self, paths: &'b [PathBuf]) -> Self {
+        self.extra_paths = paths;
+        self
+    }
+
     /// Execute the current lookup
     /// if no icon is found in the current theme fallback to
     /// `/usr/share/icons/hicolor` theme and then to `/usr/share/pixmaps`.
@@ -290,6 +254,7 @@ impl<'a> LookupBuilder<'a> {
             scale: 1,
             size: 24,
             theme: "hicolor",
+            extra_paths: &[],
         }
     }
 
@@ -301,80 +266,91 @@ impl<'a> LookupBuilder<'a> {
         if self.cache {
             match self.cache_lookup(self.theme) {
                 CacheEntry::Found(icon) => return Some(icon),
-                CacheEntry::NotFound(last_check)
-                    if last_check.duration_since(Instant::now()).as_secs() < 5 =>
-                {
+                CacheEntry::NotFound(last_check) if last_check.elapsed().as_secs() < 5 => {
                     return None;
                 }
                 _ => (),
             }
         }
 
+        if !self.extra_paths.is_empty() {
+            let extensions = if self.force_svg {
+                [".svg", ".png", ".xpm"]
+            } else {
+                [".png", ".svg", ".xpm"]
+            };
+            let mut name_buf = String::new();
+
+            let result = extensions
+                .into_iter()
+                .try_for_each(|ext| {
+                    self.extra_paths.iter().try_for_each(|dir| {
+                        let mut path = dir.clone();
+                        if try_build_icon_path(&mut path, &mut name_buf, self.name, ext) {
+                            return ControlFlow::Break(path);
+                        }
+                        name_buf.clear();
+                        ControlFlow::Continue(())
+                    })
+                })
+                .break_value();
+
+            if result.is_some() {
+                return result;
+            }
+        }
+
+        // Records theme paths that have already been searched.
+        let searched_themes = &mut Vec::new();
+        // Record themes whose inherits have been searched.
+        let search_inherits = &mut Vec::new();
+
         // Then lookup in the given theme
         THEMES
-            .get(self.theme)
-            .or_else(|| THEMES.get("hicolor"))
+            .get(self.theme.as_bytes())
+            .or_else(|| THEMES.get("hicolor".as_bytes()))
             .and_then(|icon_themes| {
                 let icon = icon_themes
                     .iter()
-                    .find_map(|theme| {
-                        theme.try_get_icon(self.name, self.size, self.scale, self.force_svg)
-                    })
+                    // Search the active icon themes
+                    .find_map(|theme| self.search_theme(searched_themes, theme))
+                    // Search the inherits of those icon themes.
                     .or_else(|| {
-                        // Fallback to the parent themes recursively
-                        let mut parents = icon_themes
-                            .iter()
-                            .flat_map(|t| {
-                                let Ok(file) = theme::read_ini_theme(&t.index) else {
-                                    return Vec::new();
-                                };
+                        icon_themes.iter().find_map(|t| {
+                            self.search_theme_inherits(search_inherits, searched_themes, t)
+                        })
+                    })
+                    // Search the cosmic icon theme
+                    .or_else(|| self.search_inherited_theme(searched_themes, "Cosmic".as_bytes()))
+                    // Search the hicolor icon theme if it was not previously searched
+                    .or_else(|| self.search_inherited_theme(searched_themes, "hicolor".as_bytes()))
+                    // GNOME applications may rely on the gnome theme
+                    .or_else(|| self.search_inherited_theme(searched_themes, "gnome".as_bytes()))
+                    // Ubuntu applications may require Yaru
+                    .or_else(|| self.search_inherited_theme(searched_themes, "Yaru".as_bytes()))
+                    .or_else(|| {
+                        let extensions = if self.force_svg {
+                            [".svg", ".png", ".xpm"]
+                        } else {
+                            [".png", ".svg", ".xpm"]
+                        };
 
-                                let Ok(file) = std::str::from_utf8(file.as_ref()) else {
-                                    return Vec::new();
-                                };
+                        let mut name_buf = String::new();
 
-                                t.inherits(file)
-                                    .into_iter()
-                                    .map(String::from)
-                                    .collect::<Vec<String>>()
-                            })
-                            .collect::<Vec<_>>();
-                        parents.dedup();
-                        parents.into_iter().find_map(|parent| {
-                            THEMES.get(&parent).and_then(|parent| {
-                                parent.iter().find_map(|t| {
-                                    t.try_get_icon(self.name, self.size, self.scale, self.force_svg)
+                        extensions
+                            .into_iter()
+                            .try_for_each(|ext| {
+                                BASE_PATHS.iter().try_for_each(|theme_base_dir| {
+                                    let mut path = theme_base_dir.clone();
+                                    if try_build_icon_path(&mut path, &mut name_buf, self.name, ext)
+                                    {
+                                        return ControlFlow::Break(path);
+                                    }
+                                    name_buf.clear();
+                                    ControlFlow::Continue(())
                                 })
                             })
-                        })
-                    })
-                    .or_else(|| {
-                        THEMES.get("hicolor").and_then(|icon_themes| {
-                            icon_themes.iter().find_map(|theme| {
-                                theme.try_get_icon(self.name, self.size, self.scale, self.force_svg)
-                            })
-                        })
-                    })
-                    .or_else(|| {
-                        for theme_base_dir in BASE_PATHS.iter() {
-                            if let Some(icon) =
-                                try_build_icon_path(self.name, theme_base_dir, self.force_svg)
-                            {
-                                return Some(icon);
-                            }
-                        }
-                        None
-                    })
-                    .or_else(|| {
-                        try_build_icon_path(self.name, "/usr/share/pixmaps", self.force_svg)
-                    })
-                    .or_else(|| {
-                        let p = PathBuf::from(&self.name);
-                        if let (Some(name), Some(parent)) = (p.file_stem(), p.parent()) {
-                            try_build_icon_path(&name.to_string_lossy(), parent, self.force_svg)
-                        } else {
-                            None
-                        }
+                            .break_value()
                     });
 
                 if self.cache {
@@ -405,30 +381,190 @@ impl<'a> LookupBuilder<'a> {
         CACHE.insert(theme, self.size, self.scale, self.name, &icon);
         icon
     }
+
+    /// Search a theme by its path for a matching icon if not already searched.
+    fn search_theme(&self, searched_themes: &mut Vec<u64>, theme: &Theme) -> Option<PathBuf> {
+        // Store hash of the theme.
+        let theme_hash = {
+            let mut hasher = std::hash::DefaultHasher::new();
+            theme.path.0.hash(&mut hasher);
+            hasher.finish()
+        };
+
+        if let Err(pos) = searched_themes.binary_search(&theme_hash) {
+            searched_themes.insert(pos, theme_hash);
+            return theme.try_get_icon(self.name, self.size, self.scale, self.force_svg);
+        }
+
+        None
+    }
+
+    // Search the inherits of a theme if not already searched.
+    fn search_theme_inherits(
+        &self,
+        search_inherits: &mut Vec<u64>,
+        searched_themes: &mut Vec<u64>,
+        theme: &Theme,
+    ) -> Option<PathBuf> {
+        // Store hash of the theme.
+        let theme_hash = {
+            let mut hasher = std::hash::DefaultHasher::new();
+            theme.path.0.hash(&mut hasher);
+            hasher.finish()
+        };
+
+        if let Err(pos) = search_inherits.binary_search(&theme_hash) {
+            search_inherits.insert(pos, theme_hash);
+            let Ok(file) = theme::read_ini_theme(&theme.index) else {
+                return None;
+            };
+
+            // Search all inherited themes that we haven't already searched
+            return theme
+                .inherits(file.as_ref())
+                .into_iter()
+                .find_map(|parent| self.search_inherited_theme(searched_themes, parent));
+        }
+
+        None
+    }
+
+    /// Search the inherits of a theme by its name if not already searched.
+    fn search_inherited_theme(
+        &self,
+        searched_themes: &mut Vec<u64>,
+        theme: &[u8],
+    ) -> Option<PathBuf> {
+        THEMES
+            .get(theme)?
+            .iter()
+            .find_map(|t| self.search_theme(searched_themes, t))
+    }
 }
 
 // WARNING: these test are highly dependent on your installed icon-themes.
 // If you want to run them, make sure you have 'Papirus' and 'Arc' icon-themes installed.
 #[cfg(test)]
-#[cfg(feature = "local_tests")]
 mod test {
     use crate::{CACHE, CacheEntry, lookup};
     use speculoos::prelude::*;
     use std::path::PathBuf;
 
     #[test]
-    fn simple_lookup() {
+    fn hicolor_firefox_24_png() {
         let firefox = lookup("firefox").find();
 
+        asserting!("Firefox contains only a 16x16 and 32x32 icon, so 16x16 should be returned")
+            .that(&firefox)
+            .is_some()
+            .is_equal_to(PathBuf::from(
+                "/usr/share/icons/hicolor/16x16/apps/firefox.png",
+            ));
+    }
+
+    #[test]
+    fn hicolor_firefox_48_png() {
+        let firefox = lookup("firefox").with_size(48).find();
+
+        asserting!("Firefox has a 48x48 icon, so that should be returned")
+            .that(&firefox)
+            .is_some()
+            .is_equal_to(PathBuf::from(
+                "/usr/share/icons/hicolor/48x48/apps/firefox.png",
+            ));
+    }
+
+    #[test]
+    fn hicolor_firefox_svg_fallback_to_png() {
+        let firefox = lookup("firefox").force_svg().find();
+
         asserting!("Lookup with no parameters should return an existing icon")
             .that(&firefox)
             .is_some()
             .is_equal_to(PathBuf::from(
-                "/usr/share/icons/hicolor/22x22/apps/firefox.png",
+                "/usr/share/icons/hicolor/16x16/apps/firefox.png",
             ));
     }
 
     #[test]
+    fn cosmic_weather_storm_symbolic() {
+        let firefox = lookup("weather-storm-symbolic").find();
+
+        asserting!("Is the cosmic icon theme installed?")
+            .that(&firefox)
+            .is_some()
+            .is_equal_to(PathBuf::from(
+                "/usr/share/icons/Cosmic/scalable/status/weather-storm-symbolic.svg",
+            ));
+    }
+
+    #[test]
+    fn cosmic_weather_storm_symbolic_force_svg() {
+        let firefox = lookup("weather-storm-symbolic").force_svg().find();
+
+        asserting!("Is the cosmic icon theme installed?")
+            .that(&firefox)
+            .is_some()
+            .is_equal_to(PathBuf::from(
+                "/usr/share/icons/Cosmic/scalable/status/weather-storm-symbolic.svg",
+            ));
+    }
+
+    #[test]
+    fn flatpak_slack() {
+        let home = std::env::home_dir().unwrap();
+
+        assert_eq!(
+            lookup("com.slack.Slack").find(),
+            Some(home.join(
+                ".local/share/flatpak/exports/share/icons/hicolor/scalable/apps/com.slack.Slack.svg"
+            )),
+            "Is the Slack flatpak installed locally?"
+        );
+    }
+
+    #[test]
+    fn vscode_pixmap() {
+        assert_eq!(
+            lookup("vscode").find(),
+            Some(PathBuf::from("/usr/share/pixmaps/vscode.png")),
+            "Is VS Code installed locally on the host?"
+        );
+    }
+
+    #[test]
+    fn libreoffice_startcenter() {
+        assert_eq!(
+            lookup("libreoffice-startcenter").find(),
+            Some(PathBuf::from(
+                "/usr/share/icons/hicolor/24x24/apps/libreoffice-startcenter.png"
+            )),
+            "Is libreoffice installed locally on the host?"
+        );
+    }
+
+    #[test]
+    fn gnome_advanced_network() {
+        assert_eq!(
+            lookup("preferences-system-network").find(),
+            Some(PathBuf::from(
+                "/usr/share/icons/gnome/24x24/categories/preferences-system-network.png"
+            )),
+            "Is the gnome icon theme installed?"
+        );
+    }
+
+    #[test]
+    fn ubuntu_additional_drivers() {
+        assert_eq!(
+            lookup("jockey").find(),
+            Some(PathBuf::from("/usr/share/icons/Yaru/24x24/apps/jockey.png")),
+            "Is the gnome icon theme installed?"
+        );
+    }
+
+    #[test]
+    #[cfg(feature = "local_tests")]
     fn theme_lookup() {
         let firefox = lookup("firefox").with_theme("Papirus").find();
 
@@ -441,6 +577,7 @@ mod test {
     }
 
     #[test]
+    #[cfg(feature = "local_tests")]
     fn should_fallback_to_parent_theme() {
         let icon = lookup("video-single-display-symbolic")
             .with_theme("Arc")
@@ -455,6 +592,7 @@ mod test {
     }
 
     #[test]
+    #[cfg(feature = "local_tests")]
     fn should_fallback_to_pixmaps_utlimately() {
         let archlinux_logo = lookup("archlinux-logo")
             .with_size(16)
@@ -468,26 +606,6 @@ mod test {
             .is_equal_to(PathBuf::from("/usr/share/pixmaps/archlinux-logo.png"));
     }
 
-    #[test]
-    fn compare_to_linincon_with_theme() {
-        let lin_wireshark = linicon::lookup_icon("wireshark")
-            .next()
-            .unwrap()
-            .unwrap()
-            .path;
-
-        let wireshark = lookup("wireshark")
-            .with_size(16)
-            .with_scale(1)
-            .with_theme("Papirus")
-            .find();
-
-        asserting!("Given the same input parameter, lookup should output be the same as linincon")
-            .that(&wireshark)
-            .is_some()
-            .is_equal_to(lin_wireshark);
-    }
-
     #[test]
     fn should_not_attempt_to_lookup_a_not_found_cached_icon() {
         let not_found = lookup("not-found").with_cache().find();
@@ -496,8 +614,9 @@ mod test {
 
         let expected_cache_result = CACHE.get("hicolor", 24, 1, "not-found");
 
-        asserting!("When lookup fails a first time, subsequent attempts should fail from cache")
-            .that(&expected_cache_result)
-            .is_equal_to(CacheEntry::NotFound);
+        assert!(
+            matches!(expected_cache_result, CacheEntry::NotFound(..)),
+            "When lookup fails a first time, subsequent attempts should fail from cache"
+        );
     }
 }

src/theme/directories.rs

@@ -10,47 +10,31 @@ pub struct Directory<'a> {
 }
 
 impl Directory<'_> {
-    pub fn match_size(&self, size: u16, scale: u16) -> bool {
-        let scale = scale as i16;
-        let size = size as i16;
-
-        if self.scale != scale {
-            false
-        } else {
-            match self.type_ {
-                DirectoryType::Fixed => self.size == size,
-                DirectoryType::Scalable => self.minsize <= size && size <= self.maxsize,
-                DirectoryType::Threshold => {
-                    self.size - self.threshold <= size && size <= self.size + self.threshold
-                }
-            }
-        }
-    }
-
-    pub fn directory_size_distance(&self, size: u16, scale: u16) -> i16 {
-        let scaled_size = self.size * self.scale;
-        let min_scaled_size = self.minsize * self.scale;
-        let max_scaled_size = self.maxsize * self.scale;
-        let scale = scale as i16;
-        let size = size as i16;
-        let scaled_requested_size = size * scale;
-
+    pub fn directory_size_distance(&self, size: i16, scale: i16) -> i16 {
         match self.type_ {
-            DirectoryType::Fixed => scaled_size - scaled_requested_size,
+            DirectoryType::Fixed => self.size * self.scale - size * scale,
+
             DirectoryType::Scalable => {
+                let scaled_requested_size = size * scale;
+                let min_scaled_size = self.minsize * self.scale;
                 if scaled_requested_size < min_scaled_size {
                     min_scaled_size - scaled_requested_size
-                } else if scaled_requested_size < max_scaled_size {
-                    scaled_requested_size - max_scaled_size
                 } else {
-                    0
+                    let max_scaled_size = self.maxsize * self.scale;
+                    if scaled_requested_size < max_scaled_size {
+                        scaled_requested_size - max_scaled_size
+                    } else {
+                        0
+                    }
                 }
             }
+
             DirectoryType::Threshold => {
+                let scaled_requested_size = size * scale;
                 if scaled_requested_size < (self.size - self.threshold) * scale {
-                    min_scaled_size - scaled_requested_size
+                    self.minsize * self.scale - scaled_requested_size
                 } else if scaled_requested_size > (self.size + self.threshold) * scale {
-                    scaled_requested_size - max_scaled_size
+                    scaled_requested_size - self.maxsize * self.scale
                 } else {
                     0
                 }
@@ -72,11 +56,11 @@ impl Default for DirectoryType {
     }
 }
 
-impl From<&str> for DirectoryType {
-    fn from(value: &str) -> Self {
-        match value {
-            "Fixed" => DirectoryType::Fixed,
-            "Scalable" => DirectoryType::Scalable,
+impl From<&[u8]> for DirectoryType {
+    fn from(value: &[u8]) -> Self {
+        match value[0] {
+            b'F' => DirectoryType::Fixed,
+            b'S' => DirectoryType::Scalable,
             _ => DirectoryType::Threshold,
         }
     }

src/theme/error.rs

@@ -1,11 +0,0 @@
-use std::io;
-use std::path::PathBuf;
-use thiserror::Error;
-
-#[derive(Error, Debug)]
-pub(crate) enum ThemeError {
-    #[error("No 'index.theme' file for {0}")]
-    ThemeIndexNotFound(PathBuf),
-    #[error("IoError: {0}")]
-    IoError(#[from] io::Error),
-}

src/theme/mod.rs

@@ -1,19 +1,19 @@
-use crate::theme::error::ThemeError;
+use crate::theme::directories::DirectoryType;
 use crate::theme::paths::ThemePath;
 use memmap2::Mmap;
 pub(crate) use paths::BASE_PATHS;
+use std::cmp::Ordering;
 use std::collections::BTreeMap;
+use std::ops::ControlFlow;
+use std::os::unix::ffi::OsStrExt;
 use std::path::{Path, PathBuf};
 use std::sync::LazyLock;
 
 mod directories;
-pub mod error;
 mod parse;
 mod paths;
 
-type Result<T> = std::result::Result<T, ThemeError>;
-
-pub static THEMES: LazyLock<BTreeMap<String, Vec<Theme>>> = LazyLock::new(get_all_themes);
+pub static THEMES: LazyLock<BTreeMap<Vec<u8>, Vec<Theme>>> = LazyLock::new(get_all_themes);
 
 #[inline]
 pub fn read_ini_theme(path: &Path) -> std::io::Result<Mmap> {
@@ -33,76 +33,99 @@ impl Theme {
         name: &str,
         size: u16,
         scale: u16,
-        force_svg: bool,
+        prefer_svg: bool,
     ) -> Option<PathBuf> {
         let file = read_ini_theme(&self.index).ok()?;
-        let file = std::str::from_utf8(file.as_ref()).ok()?;
-        self.try_get_icon_exact_size(file, name, size, scale, force_svg)
-            .or_else(|| self.try_get_icon_closest_size(file, name, size, scale, force_svg))
-    }
-
-    #[inline]
-    fn try_get_icon_exact_size(
-        &self,
-        file: &str,
-        name: &str,
-        size: u16,
-        scale: u16,
-        force_svg: bool,
-    ) -> Option<PathBuf> {
-        self.match_size(file, size, scale)
-            .find_map(|path| try_build_icon_path(name, path, force_svg))
-    }
-
-    #[inline]
-    fn match_size<'a>(
-        &'a self,
-        file: &'a str,
-        size: u16,
-        scale: u16,
-    ) -> impl Iterator<Item = PathBuf> + 'a {
-        let dirs = self.get_all_directories(file);
-
-        dirs.filter(move |directory| directory.match_size(size, scale))
-            .map(|dir| dir.name)
-            .map(|dir| self.path().join(dir))
+        self.try_get_icon_closest_size(file.as_ref(), name, size, scale, prefer_svg)
     }
 
     #[inline]
     fn try_get_icon_closest_size(
         &self,
-        file: &str,
+        file: &[u8],
         name: &str,
         size: u16,
         scale: u16,
-        force_svg: bool,
+        prefer_svg: bool,
     ) -> Option<PathBuf> {
-        self.closest_match_size(file, size, scale)
-            .iter()
-            .find_map(|path| try_build_icon_path(name, path, force_svg))
+        self.try_fold_icon_path(
+            self.closest_match_size(file, size, scale, prefer_svg),
+            name,
+            prefer_svg,
+        )
     }
 
-    fn closest_match_size(&self, file: &str, size: u16, scale: u16) -> Vec<PathBuf> {
-        let dirs = self.get_all_directories(file);
+    fn try_fold_icon_path<'a>(
+        &self,
+        dir_names: Vec<(&'a str, i16, bool)>,
+        name: &str,
+        prefer_svg: bool,
+    ) -> Option<PathBuf> {
+        let extensions = if prefer_svg {
+            [".svg", ".png", ".xpm"]
+        } else {
+            [".png", ".svg", ".xpm"]
+        };
 
-        let mut dirs: Vec<_> = dirs
-            .filter_map(|directory| {
-                let distance = directory.directory_size_distance(size, scale);
-                if distance < i16::MAX {
-                    Some((directory, distance.abs()))
-                } else {
-                    None
-                }
-            })
-            .collect();
+        extensions.into_iter().find_map(|ext| {
+            dir_names
+                .iter()
+                .try_fold(
+                    (self.path().clone(), String::new()),
+                    move |(mut path, mut name_buf), (dir_name, _, _)| {
+                        path.push(dir_name);
+                        if try_build_icon_path(&mut path, &mut name_buf, name, ext) {
+                            ControlFlow::Break(path)
+                        } else {
+                            name_buf.clear();
+                            let components = dir_name
+                                .as_bytes()
+                                .iter()
+                                .fold(2, |n, c| n + (*c == b'/') as u32)
+                                as usize;
 
-        dirs.sort_by(|(_, a), (_, b)| a.cmp(b));
+                            for _ in 0..components {
+                                path.pop();
+                            }
 
-        dirs.iter()
-            .map(|(dir, _)| dir)
-            .map(|dir| dir.name)
-            .map(|dir| self.path().join(dir))
-            .collect()
+                            ControlFlow::Continue((path, name_buf))
+                        }
+                    },
+                )
+                .break_value()
+        })
+    }
+
+    fn closest_match_size<'a>(
+        &'a self,
+        file: &'a [u8],
+        size: u16,
+        scale: u16,
+        prefer_svg: bool,
+    ) -> Vec<(&'a str, i16, bool)> {
+        let mut unsorted = self.get_all_directories(file).fold(
+            Vec::<(&'a str, i16, bool)>::new(),
+            |mut unsorted, directory| {
+                let is_scalable = matches!(directory.type_, DirectoryType::Scalable);
+                let distance = directory.directory_size_distance(size as i16, scale as i16);
+                unsorted.push((directory.name, distance.abs(), is_scalable));
+                unsorted
+            },
+        );
+
+        unsorted.sort_by(|a, b| {
+            let ordering = if prefer_svg {
+                b.2.cmp(&a.2)
+            } else {
+                a.2.cmp(&b.2)
+            };
+            match ordering {
+                Ordering::Equal => a.1.cmp(&b.1),
+                _ => ordering,
+            }
+        });
+
+        unsorted
     }
 
     fn path(&self) -> &PathBuf {
@@ -110,45 +133,28 @@ impl Theme {
     }
 }
 
-pub(super) fn try_build_icon_path<P: AsRef<Path>>(
+pub(super) fn try_build_icon_path<'a>(
+    path: &'a mut PathBuf,
+    name_buf: &'a mut String,
     name: &str,
-    path: P,
-    force_svg: bool,
-) -> Option<PathBuf> {
-    if force_svg {
-        try_build_svg(name, path.as_ref())
-            .or_else(|| try_build_png(name, path.as_ref()))
-            .or_else(|| try_build_xmp(name, path.as_ref()))
-    } else {
-        try_build_png(name, path.as_ref())
-            .or_else(|| try_build_svg(name, path.as_ref()))
-            .or_else(|| try_build_xmp(name, path.as_ref()))
-    }
+    extension: &'static str,
+) -> bool {
+    name_buf.push_str(name);
+    path.push(name);
+    try_build_ext(path, name_buf, name, extension)
 }
 
-fn try_build_svg<P: AsRef<Path>>(name: &str, path: P) -> Option<PathBuf> {
-    let path = path.as_ref();
-    let svg = path.join(format!("{name}.svg"));
-
-    if svg.exists() { Some(svg) } else { None }
-}
-
-fn try_build_png<P: AsRef<Path>>(name: &str, path: P) -> Option<PathBuf> {
-    let path = path.as_ref();
-    let png = path.join(format!("{name}.png"));
-
-    if png.exists() { Some(png) } else { None }
-}
-
-fn try_build_xmp<P: AsRef<Path>>(name: &str, path: P) -> Option<PathBuf> {
-    let path = path.as_ref();
-    let xmp = path.join(format!("{name}.xmp"));
-    if xmp.exists() { Some(xmp) } else { None }
+#[inline]
+fn try_build_ext(path: &mut PathBuf, name_buf: &mut String, name: &str, ext: &'static str) -> bool {
+    name_buf.truncate(name.len());
+    name_buf.push_str(ext);
+    path.set_file_name(&name_buf);
+    path.exists()
 }
 
 // Iter through the base paths and get all theme directories
-pub(super) fn get_all_themes() -> BTreeMap<String, Vec<Theme>> {
-    let mut icon_themes = BTreeMap::<_, Vec<_>>::new();
+pub(super) fn get_all_themes() -> BTreeMap<Vec<u8>, Vec<Theme>> {
+    let mut icon_themes = BTreeMap::<Vec<u8>, Vec<_>>::new();
     let mut found_indices = BTreeMap::new();
     let mut to_revisit = Vec::new();
 
@@ -168,8 +174,10 @@ pub(super) fn get_all_themes() -> BTreeMap<String, Vec<Theme>> {
                 if fallback_index.is_none() {
                     found_indices.insert(name.clone(), theme.index.clone());
                 }
-                let name = name.to_string_lossy().to_string();
-                icon_themes.entry(name).or_default().push(theme);
+                icon_themes
+                    .entry(name.as_bytes().to_owned())
+                    .or_default()
+                    .push(theme);
             } else if entry.path().is_dir() {
                 to_revisit.push(entry);
             }
@@ -180,8 +188,10 @@ pub(super) fn get_all_themes() -> BTreeMap<String, Vec<Theme>> {
         let name = entry.file_name();
         let fallback_index = found_indices.get(&name);
         if let Some(theme) = Theme::from_path(entry.path(), fallback_index) {
-            let name = name.to_string_lossy().to_string();
-            icon_themes.entry(name).or_default().push(theme);
+            icon_themes
+                .entry(name.as_bytes().to_owned())
+                .or_default()
+                .push(theme);
         }
     }
 
@@ -190,24 +200,26 @@ pub(super) fn get_all_themes() -> BTreeMap<String, Vec<Theme>> {
 
 impl Theme {
     pub(crate) fn from_path<P: AsRef<Path>>(path: P, index: Option<&PathBuf>) -> Option<Self> {
-        let path = path.as_ref();
+        let mut path = path.as_ref().to_path_buf();
+        let is_dir = path.is_dir();
+        path.push("index.theme");
+        let local_index_exists = path.exists();
+        let has_index = local_index_exists || index.is_some();
 
-        let has_index = path.join("index.theme").exists() || index.is_some();
-
-        if !has_index || !path.is_dir() {
+        if !has_index || !is_dir {
             return None;
         }
 
-        let path = ThemePath(path.into());
-
-        match (index, path.index()) {
-            (Some(index), _) => Some(Theme {
-                path,
-                index: index.clone(),
-            }),
-            (None, Ok(index)) => Some(Theme { path, index }),
-            _ => None,
-        }
+        index
+            .cloned()
+            .or_else(|| local_index_exists.then_some(path.clone()))
+            .map(|index| Theme {
+                path: ThemePath({
+                    path.pop();
+                    path
+                }),
+                index,
+            })
     }
 }
 
@@ -219,24 +231,22 @@ mod test {
 
     #[test]
     fn get_one_icon() {
-        let themes = THEMES.get("Adwaita").unwrap();
+        let themes = THEMES.get(&b"Adwaita"[..]).unwrap();
         println!(
             "{:?}",
             themes.iter().find_map(|t| {
                 let file = super::read_ini_theme(&t.index).ok()?;
-                let file = std::str::from_utf8(file.as_ref()).ok()?;
-                t.try_get_icon_exact_size(file, "edit-delete-symbolic", 24, 1, false)
+                t.try_get_icon_closest_size(file.as_ref(), "edit-delete-symbolic", 24, 1, false)
             })
         );
     }
 
     #[test]
     fn should_get_png_first() {
-        let themes = THEMES.get("hicolor").unwrap();
+        let themes = THEMES.get(&b"hicolor"[..]).unwrap();
         let icon = themes.iter().find_map(|t| {
             let file = super::read_ini_theme(&t.index).ok()?;
-            let file = std::str::from_utf8(file.as_ref()).ok()?;
-            t.try_get_icon_exact_size(file, "blueman", 24, 1, true)
+            t.try_get_icon_closest_size(file.as_ref(), "blueman", 22, 1, false)
         });
         assert_that!(icon).is_some().is_equal_to(PathBuf::from(
             "/usr/share/icons/hicolor/22x22/apps/blueman.png",
@@ -244,15 +254,38 @@ mod test {
     }
 
     #[test]
-    fn should_get_svg_first() {
-        let themes = THEMES.get("hicolor").unwrap();
+    fn should_get_png_first_92() {
+        let themes = THEMES.get(&b"hicolor"[..]).unwrap();
         let icon = themes.iter().find_map(|t| {
             let file = super::read_ini_theme(&t.index).ok()?;
-            let file = std::str::from_utf8(file.as_ref()).ok()?;
-            t.try_get_icon_exact_size(file, "blueman", 24, 1, false)
+            t.try_get_icon_closest_size(file.as_ref(), "blueman", 92, 1, false)
         });
         assert_that!(icon).is_some().is_equal_to(PathBuf::from(
-            "/usr/share/icons/hicolor/22x22/apps/blueman.png",
+            "/usr/share/icons/hicolor/96x96/apps/blueman.png",
+        ));
+    }
+
+    #[test]
+    fn should_get_svg_first() {
+        let themes = THEMES.get(&b"hicolor"[..]).unwrap();
+        let icon = themes.iter().find_map(|t| {
+            let file = super::read_ini_theme(&t.index).ok()?;
+            t.try_get_icon_closest_size(file.as_ref(), "blueman", 24, 1, true)
+        });
+        assert_that!(icon).is_some().is_equal_to(PathBuf::from(
+            "/usr/share/icons/hicolor/scalable/apps/blueman.svg",
+        ));
+    }
+
+    #[test]
+    fn should_get_svg_first_96() {
+        let themes = THEMES.get(&b"hicolor"[..]).unwrap();
+        let icon = themes.iter().find_map(|t| {
+            let file = super::read_ini_theme(&t.index).ok()?;
+            t.try_get_icon_closest_size(file.as_ref(), "blueman", 96, 1, true)
+        });
+        assert_that!(icon).is_some().is_equal_to(PathBuf::from(
+            "/usr/share/icons/hicolor/scalable/apps/blueman.svg",
         ));
     }
 }

src/theme/parse.rs

@@ -1,76 +1,48 @@
 use crate::theme::Theme;
 use crate::theme::directories::{Directory, DirectoryType};
-
-fn icon_theme_section(file: &str) -> impl Iterator<Item = (&str, &str)> + '_ {
-    ini_core::Parser::new(file)
-        .skip_while(|item| *item != ini_core::Item::Section("Icon Theme"))
-        .take_while(|item| match item {
-            ini_core::Item::Section(value) => *value == "Icon Theme",
-            _ => true,
-        })
-        .filter_map(|item| {
-            if let ini_core::Item::Property(key, value) = item {
-                Some((key, value?))
-            } else {
-                None
-            }
-        })
-}
-
-#[derive(Debug)]
-enum DirectorySection<'a> {
-    Property(&'a str, &'a str),
-    EndSection,
-    Section(&'a str),
-}
-
-fn sections(file: &str) -> impl Iterator<Item = DirectorySection<'_>> {
-    ini_core::Parser::new(file).filter_map(move |item| match item {
-        ini_core::Item::Property(key, Some(value)) => Some(DirectorySection::Property(key, value)),
-        ini_core::Item::Section(section) => Some(DirectorySection::Section(section)),
-        ini_core::Item::SectionEnd => Some(DirectorySection::EndSection),
-        _ => None,
-    })
-}
+use bstr::BStr;
 
 impl Theme {
     pub(super) fn get_all_directories<'a>(
         &'a self,
-        file: &'a str,
+        file: &'a [u8],
     ) -> impl Iterator<Item = Directory<'a>> + 'a {
         let mut iterator = sections(file);
 
         std::iter::from_fn(move || {
+            let mut is_icon_theme = false;
             let mut name = "";
             let mut size = None;
             let mut max_size = None;
             let mut min_size = None;
             let mut threshold = None;
             let mut scale = None;
-            // let mut context = None;
             let mut dtype = DirectoryType::default();
 
             #[allow(clippy::while_let_on_iterator)]
             while let Some(event) = iterator.next() {
                 match event {
                     DirectorySection::Property(key, value) => {
-                        if name.is_empty() || name == "Icon Theme" {
+                        if is_icon_theme {
                             continue;
                         }
 
                         match key {
-                            "Size" => size = str::parse(value).ok(),
-                            "Scale" => scale = str::parse(value).ok(),
-                            // "Context" => context = Some(value),
-                            "Type" => dtype = DirectoryType::from(value),
-                            "MaxSize" => max_size = str::parse(value).ok(),
-                            "MinSize" => min_size = str::parse(value).ok(),
-                            "Threshold" => threshold = str::parse(value).ok(),
+                            b"Size" => size = btoi::btoi(value).ok(),
+                            b"Scale" => scale = btoi::btoi(value).ok(),
+                            b"Type" => dtype = DirectoryType::from(value),
+                            b"MaxSize" => max_size = btoi::btoi(value).ok(),
+                            b"MinSize" => min_size = btoi::btoi(value).ok(),
+                            b"Threshold" => threshold = btoi::btoi(value).ok(),
                             _ => (),
                         }
                     }
 
                     DirectorySection::Section(new_name) => {
+                        let Ok(new_name) = std::str::from_utf8(new_name) else {
+                            return None;
+                        };
+                        is_icon_theme = new_name == "Icon Theme";
                         name = new_name;
                         size = None;
                         max_size = None;
@@ -81,7 +53,7 @@ impl Theme {
                     }
 
                     DirectorySection::EndSection => {
-                        if name.is_empty() || name == "Icon Theme" {
+                        if is_icon_theme {
                             continue;
                         }
 
@@ -91,7 +63,6 @@ impl Theme {
                             name,
                             size,
                             scale: scale.unwrap_or(1),
-                            // context,
                             type_: dtype,
                             maxsize: max_size.unwrap_or(size),
                             minsize: min_size.unwrap_or(size),
@@ -105,29 +76,391 @@ impl Theme {
         })
     }
 
-    pub fn inherits<'a>(&self, file: &'a str) -> Vec<&'a str> {
+    pub fn inherits<'a>(&self, file: &'a [u8]) -> impl Iterator<Item = &'a [u8]> {
         icon_theme_section(file)
-            .find(|&(key, _)| key == "Inherits")
-            .map(|(_, parents)| {
-                parents
-                    .split(',')
+            .find(|&(key, _)| key == b"Inherits")
+            .into_iter()
+            .flat_map(|(_, parents)| {
+                BStr::new(parents)
+                    .split(|&char| char == b',')
                     // Filtering out 'hicolor' since we are going to fallback there anyway
-                    .filter(|parent| parent != &"hicolor")
-                    .collect()
+                    .filter(|parent| parent != &b"hicolor")
             })
-            .unwrap_or_default()
     }
 }
 
+#[derive(Debug)]
+enum DirectorySection<'a> {
+    Property(&'a [u8], &'a [u8]),
+    EndSection,
+    Section(&'a [u8]),
+}
+
+fn sections(file: &[u8]) -> impl Iterator<Item = DirectorySection<'_>> {
+    let mut finished = false;
+    let mut table_found = false;
+    let mut section: &[u8] = b"";
+    let mut prev = 0;
+    let mut line_indices = memchr::memchr_iter(b'\n', file);
+
+    std::iter::from_fn(move || {
+        if finished {
+            return None;
+        }
+
+        if !section.is_empty() {
+            let new_section = section;
+            section = b"";
+            return Some(DirectorySection::Section(new_section));
+        }
+
+        loop {
+            let line_pos = match line_indices.next() {
+                Some(pos) => pos,
+                None => {
+                    let value = if !finished {
+                        Some(DirectorySection::EndSection)
+                    } else {
+                        None
+                    };
+                    finished = true;
+                    return value;
+                }
+            };
+
+            let line = BStr::new(unsafe {
+                // Indices from memchr are valid.
+                file.get_unchecked(prev..line_pos)
+            })
+            .trim_ascii();
+            prev = line_pos + 1;
+
+            if line.is_empty() {
+                continue;
+            }
+
+            if line[0] == b'[' {
+                section = &line[1..line.len() - 1];
+                if table_found {
+                    return Some(DirectorySection::EndSection);
+                } else {
+                    table_found = true;
+                    return Some(DirectorySection::Section(section));
+                }
+            }
+
+            if let Some((key, value)) = memchr::memchr(b'=', line).map(|pos| unsafe {
+                // Position was already validated by memchr.
+                line.split_at_unchecked(pos)
+            }) {
+                return Some(DirectorySection::Property(key, &value[1..]));
+            }
+        }
+    })
+}
+
+fn icon_theme_section(file: &[u8]) -> impl Iterator<Item = (&[u8], &[u8])> + '_ {
+    let mut found_table = false;
+    let mut prev = 0;
+    let mut line_indices = memchr::memchr_iter(b'\n', file);
+
+    std::iter::from_fn(move || {
+        loop {
+            let line_pos = line_indices.next()?;
+            let line = BStr::new(unsafe {
+                // Indices from memchr are valid.
+                file.get_unchecked(prev..line_pos)
+            })
+            .trim_ascii();
+            prev = line_pos + 1;
+
+            if line.is_empty() {
+                continue;
+            }
+
+            if line[0] == b'[' {
+                if found_table {
+                    return None;
+                } else {
+                    let section = &line[1..line.len() - 1];
+                    found_table = true;
+                    if section != b"Icon Theme" {
+                        return None;
+                    }
+                }
+            }
+
+            if let Some((key, value)) = memchr::memchr(b'=', line).map(|pos| unsafe {
+                // Position was already validated by memchr.
+                line.split_at_unchecked(pos)
+            }) {
+                return Some((key, &value[1..]));
+            }
+        }
+    })
+}
+
 #[cfg(test)]
+
 mod test {
-    use crate::THEMES;
-    use speculoos::prelude::*;
+    const ADWAITA_INDEX: &str = "[Icon Theme]
+Name=Adwaita\u{0020}
+Comment=The Only One
+Example=folder
+Inherits=hicolor
+
+# KDE Specific Stuff
+DisplayDepth=32
+
+# Directory list
+Directories=16x16/actions,16x16/apps,16x16/categories,16x16/devices,16x16/emblems,16x16/emotes,16x16/legacy,16x16/mimetypes,16x16/places,16x16/status,16x16/ui,scalable/devices,scalable/mimetypes,scalable/places,scalable/status,scalable/actions,scalable/apps,scalable/categories,scalable/emblems,scalable/emotes,scalable/legacy,scalable/ui,symbolic-up-to-32/status,symbolic/actions,symbolic/apps,symbolic/categories,symbolic/devices,symbolic/emblems,symbolic/emotes,symbolic/mimetypes,symbolic/places,symbolic/status,symbolic/legacy,symbolic/ui,
+
+[16x16/actions]
+Context=Actions
+Size=16
+Type=Fixed
+
+[16x16/apps]
+Context=Applications
+Size=16
+Type=Fixed
+
+[16x16/categories]
+Context=Categories
+Size=16
+Type=Fixed
+
+[16x16/devices]
+Context=Devices
+Size=16
+Type=Fixed
+
+[16x16/emblems]
+Context=Emblems
+Size=16
+Type=Fixed
+
+[16x16/emotes]
+Context=Emotes
+Size=16
+Type=Fixed
+
+[16x16/legacy]
+Context=Legacy
+Size=16
+Type=Fixed
+
+[16x16/mimetypes]
+Context=MimeTypes
+Size=16
+Type=Fixed
+
+[16x16/places]
+Context=Places
+Size=16
+Type=Fixed
+
+[16x16/status]
+Context=Status
+Size=16
+Type=Fixed
+
+[16x16/ui]
+Context=UI
+Size=16
+Type=Fixed
+
+[scalable/devices]
+Context=Devices
+Size=128
+MinSize=8
+MaxSize=512
+Type=Scalable
+
+[scalable/mimetypes]
+Context=MimeTypes
+Size=128
+MinSize=8
+MaxSize=512
+Type=Scalable
+
+[scalable/places]
+Context=Places
+Size=128
+MinSize=8
+MaxSize=512
+Type=Scalable
+
+[scalable/status]
+Context=Status
+Size=128
+MinSize=8
+MaxSize=512
+Type=Scalable
+
+[scalable/actions]
+Context=Actions
+Size=128
+MinSize=8
+MaxSize=512
+Type=Scalable
+
+[scalable/apps]
+Context=Applications
+Size=128
+MinSize=8
+MaxSize=512
+Type=Scalable
+
+[scalable/categories]
+Context=Categories
+Size=128
+MinSize=8
+MaxSize=512
+Type=Scalable
+
+[scalable/emblems]
+Context=Emblems
+Size=128
+MinSize=8
+MaxSize=512
+Type=Scalable
+
+[scalable/emotes]
+Context=Emotes
+Size=128
+MinSize=8
+MaxSize=512
+Type=Scalable
+
+[scalable/legacy]
+Context=Legacy
+Size=128
+MinSize=8
+MaxSize=512
+Type=Scalable
+
+[scalable/ui]
+Context=UI
+Size=128
+MinSize=8
+MaxSize=512
+Type=Scalable
+
+[symbolic-up-to-32/status]
+Context=Status
+Size=16
+MinSize=16
+MaxSize=32
+Type=Scalable
+
+[symbolic/actions]
+Context=Actions
+Size=16
+MinSize=8
+MaxSize=512
+Type=Scalable
+
+[symbolic/apps]
+Context=Applications
+Size=16
+MinSize=8
+MaxSize=512
+Type=Scalable
+
+[symbolic/categories]
+Context=Categories
+Size=16
+MinSize=8
+MaxSize=512
+Type=Scalable
+
+[symbolic/devices]
+Context=Devices
+Size=16
+MinSize=8
+MaxSize=512
+Type=Scalable
+
+[symbolic/emblems]
+Context=Emblems
+Size=16
+MinSize=8
+MaxSize=512
+Type=Scalable
+
+[symbolic/emotes]
+Context=Emotes
+Size=16
+MinSize=8
+MaxSize=512
+Type=Scalable
+
+[symbolic/mimetypes]
+Context=MimeTypes
+Size=16
+MinSize=8
+MaxSize=512
+Type=Scalable
+
+[symbolic/places]
+Context=Places
+Size=16
+MinSize=8
+MaxSize=512
+Type=Scalable
+
+[symbolic/status]
+Context=Status
+Size=16
+MinSize=8
+MaxSize=512
+Type=Scalable
+
+[symbolic/legacy]
+Context=Legacy
+Size=16
+MinSize=8
+MaxSize=512
+Type=Scalable
+
+[symbolic/ui]
+Context=UI
+Size=16
+MinSize=8
+MaxSize=512
+Type=Scalable";
+
+    #[test]
+    fn icon_theme_section() {
+        let mut iterator = super::icon_theme_section(ADWAITA_INDEX.as_bytes());
+
+        let (key, value) = iterator.next().unwrap();
+        assert_eq!(key, b"Name");
+        assert_eq!(value, b"Adwaita");
+        let (key, value) = iterator.next().unwrap();
+        assert_eq!(key, b"Comment");
+        assert_eq!(value, b"The Only One");
+        let (key, value) = iterator.next().unwrap();
+        assert_eq!(key, b"Example");
+        assert_eq!(value, b"folder");
+        let (key, value) = iterator.next().unwrap();
+        assert_eq!(key, b"Inherits");
+        assert_eq!(value, b"hicolor");
+        let (key, value) = iterator.next().unwrap();
+        assert_eq!(key, b"DisplayDepth");
+        assert_eq!(value, b"32");
+        let (key, value) = iterator.next().unwrap();
+        assert_eq!(key, b"Directories");
+        assert_eq!(value, b"16x16/actions,16x16/apps,16x16/categories,16x16/devices,16x16/emblems,16x16/emotes,16x16/legacy,16x16/mimetypes,16x16/places,16x16/status,16x16/ui,scalable/devices,scalable/mimetypes,scalable/places,scalable/status,scalable/actions,scalable/apps,scalable/categories,scalable/emblems,scalable/emotes,scalable/legacy,scalable/ui,symbolic-up-to-32/status,symbolic/actions,symbolic/apps,symbolic/categories,symbolic/devices,symbolic/emblems,symbolic/emotes,symbolic/mimetypes,symbolic/places,symbolic/status,symbolic/legacy,symbolic/ui,");
+        assert_eq!(iterator.next(), None);
+    }
 
     #[test]
     #[cfg(feature = "local_tests")]
     fn should_get_theme_parents() {
-        for theme in THEMES.get("Arc").unwrap() {
+        use speculoos::prelude::*;
+        for theme in crate::THEMES.get("Arc").unwrap() {
             let file = crate::theme::read_ini_theme(&theme.index).ok().unwrap();
             let file = std::str::from_utf8(file.as_ref()).ok().unwrap();
             let parents = theme.inherits(file);

src/theme/paths.rs

@@ -1,50 +1,38 @@
-use dirs::home_dir;
 use std::path::PathBuf;
 use std::sync::LazyLock;
 use xdg::BaseDirectories;
 
-use crate::theme;
-use crate::theme::error::ThemeError;
-
 pub(crate) static BASE_PATHS: LazyLock<Vec<PathBuf>> = LazyLock::new(icon_theme_base_paths);
 
 /// Look in $HOME/.icons (for backwards compatibility), in $XDG_DATA_DIRS/icons, in $XDG_DATA_DIRS/pixmaps and in /usr/share/pixmaps (in that order).
 /// Paths that are not found are filtered out.
 fn icon_theme_base_paths() -> Vec<PathBuf> {
     let base_dirs = BaseDirectories::new();
-    let mut data_dirs: Vec<_> = base_dirs
+
+    let data_dirs = base_dirs
         .get_data_dirs()
         .into_iter()
-        .flat_map(|p| [p.join("icons"), p.join("pixmaps")])
-        .collect();
+        .flat_map(|p| [p.join("icons"), p.join("pixmaps")]);
 
-    if let Some(data_home) = base_dirs.get_data_home() {
-        data_dirs.push(data_home.join("icons"));
-        data_dirs.push(data_home.join("pixmaps"));
-    }
+    let data_home_dirs = base_dirs
+        .get_data_home()
+        .into_iter()
+        .flat_map(|data_home| [data_home.join("icons"), data_home.join("pixmaps")].into_iter());
 
-    match home_dir().map(|home| home.join(".icons")) {
-        Some(home_icon_dir) => data_dirs.push(home_icon_dir),
-        None => tracing::warn!("No $HOME directory found"),
-    }
-    data_dirs.into_iter().filter(|p| p.exists()).collect()
+    let home_dir = std::env::home_dir()
+        .into_iter()
+        .map(|home| home.join(".icons"));
+
+    data_dirs
+        .chain(data_home_dirs)
+        .chain(home_dir)
+        .filter(|p| p.exists())
+        .collect()
 }
 
 #[derive(Clone, Debug)]
 pub struct ThemePath(pub PathBuf);
 
-impl ThemePath {
-    pub(super) fn index(&self) -> theme::Result<PathBuf> {
-        let index = self.0.join("index.theme");
-
-        if !index.exists() {
-            return Err(ThemeError::ThemeIndexNotFound(index));
-        }
-
-        Ok(index)
-    }
-}
-
 #[cfg(test)]
 mod test {
     use crate::theme::paths::icon_theme_base_paths;
@@ -54,7 +42,7 @@ mod test {
     #[test]
     fn should_get_all_themes() {
         let themes = get_all_themes();
-        assert_that!(themes.get("hicolor")).is_some();
+        assert_that!(themes.get(&b"hicolor"[..])).is_some();
     }
 
     #[test]