df: remove use of FsSelector abstraction

Remove the use of the `FsSelector` struct when deciding whether a
filesystem type should be included or excluded from the output
table. Instead, just maintain optional `Vec`s of filesystem types to
exclude and include, and check whether the filesystem type is
contained in one of those. This reduces the amount of code required to
implement these checks, and since the number of types given in the
`include` or `exclude` lists is likely to be small, there should not
be much of a difference in performance.

src/uu/df/src/df.rs

@@ -18,10 +18,7 @@ use uucore::fsext::{read_fs_list, FsUsage, MountInfo};
 
 use clap::{crate_version, App, AppSettings, Arg, ArgMatches};
 
-use std::collections::HashSet;
 use std::fmt;
-use std::iter::FromIterator;
-
 use std::path::Path;
 
 use crate::blocks::{block_size_from_matches, BlockSize};
@@ -54,14 +51,6 @@ static OUTPUT_FIELD_LIST: [&str; 12] = [
     "file", "target",
 ];
 
-/// Store names of file systems as a selector.
-/// Note: `exclude` takes priority over `include`.
-#[derive(Default)]
-struct FsSelector {
-    include: HashSet<String>,
-    exclude: HashSet<String>,
-}
-
 /// Parameters that control the behavior of `df`.
 ///
 /// Most of these parameters control which rows and which columns are
@@ -72,9 +61,22 @@ struct Options {
     show_all_fs: bool,
     show_listed_fs: bool,
     block_size: BlockSize,
-    fs_selector: FsSelector,
+
+    /// Optional list of filesystem types to include in the output table.
+    ///
+    /// If this is not `None`, only filesystems that match one of
+    /// these types will be listed.
+    include: Option<Vec<String>>,
+
+    /// Optional list of filesystem types to exclude from the output table.
+    ///
+    /// If this is not `None`, filesystems that match one of these
+    /// types will *not* be listed.
+    exclude: Option<Vec<String>>,
+
     /// Whether to show a final row comprising the totals for each column.
     show_total: bool,
+
     /// Sequence of columns to display in the output table.
     columns: Vec<Column>,
 }
@@ -86,7 +88,8 @@ impl Default for Options {
             show_all_fs: Default::default(),
             show_listed_fs: Default::default(),
             block_size: Default::default(),
-            fs_selector: Default::default(),
+            include: Default::default(),
+            exclude: Default::default(),
             show_total: Default::default(),
             columns: vec![
                 Column::Source,
@@ -125,7 +128,8 @@ impl Options {
             show_listed_fs: false,
             block_size: block_size_from_matches(matches)
                 .map_err(|_| OptionsError::InvalidBlockSize)?,
-            fs_selector: FsSelector::from(matches),
+            include: matches.values_of_lossy(OPT_TYPE),
+            exclude: matches.values_of_lossy(OPT_EXCLUDE_TYPE),
             show_total: matches.is_present(OPT_TOTAL),
             columns: Column::from_matches(matches),
         })
@@ -138,30 +142,6 @@ struct Filesystem {
     usage: FsUsage,
 }
 
-impl FsSelector {
-    /// Convert command-line arguments into a [`FsSelector`].
-    ///
-    /// This function reads the include and exclude sets from
-    /// [`ArgMatches`] and returns the corresponding [`FsSelector`]
-    /// instance.
-    fn from(matches: &ArgMatches) -> Self {
-        let include = HashSet::from_iter(matches.values_of_lossy(OPT_TYPE).unwrap_or_default());
-        let exclude = HashSet::from_iter(
-            matches
-                .values_of_lossy(OPT_EXCLUDE_TYPE)
-                .unwrap_or_default(),
-        );
-        Self { include, exclude }
-    }
-
-    fn should_select(&self, fs_type: &str) -> bool {
-        if self.exclude.contains(fs_type) {
-            return false;
-        }
-        self.include.is_empty() || self.include.contains(fs_type)
-    }
-}
-
 impl Filesystem {
     // TODO: resolve uuid in `mount_info.dev_name` if exists
     fn new(mount_info: MountInfo) -> Option<Self> {
@@ -199,8 +179,15 @@ fn is_included(mi: &MountInfo, opt: &Options) -> bool {
     }
 
     // Don't show filesystems if they have been explicitly excluded.
-    if !opt.fs_selector.should_select(&mi.fs_type) {
+    if let Some(ref excludes) = opt.exclude {
-        return false;
+        if excludes.contains(&mi.fs_type) {
+            return false;
+        }
+    }
+    if let Some(ref includes) = opt.include {
+        if !includes.contains(&mi.fs_type) {
+            return false;
+        }
     }
 
     true
@@ -562,8 +549,7 @@ mod tests {
 
     mod is_included {
 
-        use crate::{is_included, FsSelector, Options};
+        use crate::{is_included, Options};
-        use std::collections::HashSet;
         use uucore::fsext::MountInfo;
 
         /// Instantiate a [`MountInfo`] with the given fields.
@@ -617,13 +603,9 @@ mod tests {
 
         #[test]
         fn test_exclude_match() {
-            let exclude = HashSet::from([String::from("ext4")]);
+            let exclude = Some(vec![String::from("ext4")]);
-            let fs_selector = FsSelector {
-                exclude,
-                ..Default::default()
-            };
             let opt = Options {
-                fs_selector,
+                exclude,
                 ..Default::default()
             };
             let m = mount_info("ext4", "/mnt/foo", false, false);
@@ -632,13 +614,9 @@ mod tests {
 
         #[test]
         fn test_exclude_no_match() {
-            let exclude = HashSet::from([String::from("tmpfs")]);
+            let exclude = Some(vec![String::from("tmpfs")]);
-            let fs_selector = FsSelector {
-                exclude,
-                ..Default::default()
-            };
             let opt = Options {
-                fs_selector,
+                exclude,
                 ..Default::default()
             };
             let m = mount_info("ext4", "/mnt/foo", false, false);
@@ -647,13 +625,9 @@ mod tests {
 
         #[test]
         fn test_include_match() {
-            let include = HashSet::from([String::from("ext4")]);
+            let include = Some(vec![String::from("ext4")]);
-            let fs_selector = FsSelector {
-                include,
-                ..Default::default()
-            };
             let opt = Options {
-                fs_selector,
+                include,
                 ..Default::default()
             };
             let m = mount_info("ext4", "/mnt/foo", false, false);
@@ -662,13 +636,9 @@ mod tests {
 
         #[test]
         fn test_include_no_match() {
-            let include = HashSet::from([String::from("tmpfs")]);
+            let include = Some(vec![String::from("tmpfs")]);
-            let fs_selector = FsSelector {
-                include,
-                ..Default::default()
-            };
             let opt = Options {
-                fs_selector,
+                include,
                 ..Default::default()
             };
             let m = mount_info("ext4", "/mnt/foo", false, false);
@@ -677,11 +647,11 @@ mod tests {
 
         #[test]
         fn test_include_and_exclude_match_neither() {
-            let include = HashSet::from([String::from("tmpfs")]);
+            let include = Some(vec![String::from("tmpfs")]);
-            let exclude = HashSet::from([String::from("squashfs")]);
+            let exclude = Some(vec![String::from("squashfs")]);
-            let fs_selector = FsSelector { include, exclude };
             let opt = Options {
-                fs_selector,
+                include,
+                exclude,
                 ..Default::default()
             };
             let m = mount_info("ext4", "/mnt/foo", false, false);
@@ -690,11 +660,11 @@ mod tests {
 
         #[test]
         fn test_include_and_exclude_match_exclude() {
-            let include = HashSet::from([String::from("tmpfs")]);
+            let include = Some(vec![String::from("tmpfs")]);
-            let exclude = HashSet::from([String::from("ext4")]);
+            let exclude = Some(vec![String::from("ext4")]);
-            let fs_selector = FsSelector { include, exclude };
             let opt = Options {
-                fs_selector,
+                include,
+                exclude,
                 ..Default::default()
             };
             let m = mount_info("ext4", "/mnt/foo", false, false);
@@ -703,11 +673,11 @@ mod tests {
 
         #[test]
         fn test_include_and_exclude_match_include() {
-            let include = HashSet::from([String::from("ext4")]);
+            let include = Some(vec![String::from("ext4")]);
-            let exclude = HashSet::from([String::from("squashfs")]);
+            let exclude = Some(vec![String::from("squashfs")]);
-            let fs_selector = FsSelector { include, exclude };
             let opt = Options {
-                fs_selector,
+                include,
+                exclude,
                 ..Default::default()
             };
             let m = mount_info("ext4", "/mnt/foo", false, false);
@@ -719,11 +689,11 @@ mod tests {
             // TODO The same filesystem type in both `include` and
             // `exclude` should cause an error, but currently does
             // not.
-            let include = HashSet::from([String::from("ext4")]);
+            let include = Some(vec![String::from("ext4")]);
-            let exclude = HashSet::from([String::from("ext4")]);
+            let exclude = Some(vec![String::from("ext4")]);
-            let fs_selector = FsSelector { include, exclude };
             let opt = Options {
-                fs_selector,
+                include,
+                exclude,
                 ..Default::default()
             };
             let m = mount_info("ext4", "/mnt/foo", false, false);