Added more convenience methods and trait impls to `PluginTrust<"a>`.

Fortune for rng's current commit: Small blessing − 小吉

src/plugin/searcher.rs

@@ -5,7 +5,7 @@ use std::path::{
     Path,
 };
 use std::{
-    fs, io,
+    fs, io, ops,
     borrow::{
 	Cow, Borrow, 
     },
@@ -561,6 +561,32 @@ impl<P: AsRef<Path>> LookupVisitor<P>
     }
 }
 
+impl<'a, T: ToOwned<Owned = PathBuf> + 'a> From<(T, bool)> for PluginTrust<'a>
+{
+    fn from((from, trust): (T, bool)) -> Self
+    {
+	(if trust {
+	    Self::Trusted
+	} else {
+	    Self::Untrusted
+	})(Cow::Owned(from.to_owned()))
+	    .enforce_validity::<true>()
+    }
+}
+
+
+impl<'a> From<locations::PathTrust<'a>> for PluginTrust<'a>
+{
+    #[inline] 
+    fn from(from: locations::PathTrust<'a>) -> Self
+    {
+	match from {
+	    locations::PathTrust::Trusted(a) => PluginTrust::Trusted(Cow::from(Path::new(a))),
+	    locations::PathTrust::Untrusted(a) => PluginTrust::Untrusted(Cow::from(Path::new(a))),   
+	}.enforce_validity::<true>()
+    }
+}
+
 /// Denoted a plugin and if it was loaded from a trusted path or not
 #[derive(Debug, Clone, Eq, Hash, PartialOrd, Ord)]
 pub enum PluginTrust<'a>
@@ -569,6 +595,15 @@ pub enum PluginTrust<'a>
     Untrusted(Cow<'a, Path>)
 }
 
+impl<'a> ops::Deref for PluginTrust<'a>
+{
+    type Target = Path;
+    #[inline] 
+    fn deref(&self) -> &Self::Target {
+	self.as_path()
+    }
+}
+
 impl<'a> Borrow<Path> for PluginTrust<'a>
 {
     #[inline(always)] 
@@ -600,6 +635,15 @@ impl<'a> From<PluginTrust<'a>> for Cow<'a, Path>
     }
 }
 
+impl<'a> From<PluginTrust<'a>> for PathBuf
+{
+    #[inline] 
+    fn from(from: PluginTrust<'a>) -> Self {
+	let cow: Cow<Path> = from.into();
+	cow.into_owned()
+    }
+}
+
 impl<'a, T: AsRef<Path> + ?Sized> PartialEq<T> for PluginTrust<'a>
 {
     #[inline] 
@@ -628,15 +672,52 @@ impl<'a> PluginTrust<'a>
     {
 	!self.is_trusted()
     }
-}
 
-impl From<PluginTrust<'static>> for PathBuf
-{
+    /// Get the `Path`, trusted or otherwise.
+    #[inline(always)] 
+    fn as_path(&self) -> &Path
+    {
+	self.borrow()
+    }
+
+    /// Map this path to another.
+    ///
+    /// # Panics
+    /// If the output of `func` is not a file-like object or does not exist.
     #[inline] 
-    fn from(from: PluginTrust<'static>) -> Self
+    pub fn map<F, T: Into<Cow<'a, Path>>>(self, func: F) -> Self
+    where F: FnOnce(Cow<'a, Path>) -> T
     {
-	match from {
-	    PluginTrust::Trusted(a) | PluginTrust::Untrusted(a) => a.into_owned()
+	match self {
+	    Self::Trusted(yes) => Self::Trusted(func(yes).into()),
+	    Self::Untrusted(no) => Self::Untrusted(func(no).into())
+	}.enforce_validity::<false>()
+    }
+
+    #[inline(always)]
+    pub(super) fn is_valid(&self) -> bool
+    {
+	let path = self.as_path();
+	path.exists() && !path.is_dir() //XXX: Is this okay for validation for now? What about symlinked files?
+    }
+
+    #[inline(always)] 
+    fn enforce_validity<const DEBUG: bool>(self) -> Self
+    {
+	if !DEBUG || cfg!(debug_assertions) {
+	    #[inline(never)]
+	    #[cold]
+	    fn _panic_invalid(path: impl Into<PathBuf>) -> !
+	    {
+		panic!("Illegal plugin path name: {:?}", path.into())
+	    }
+	    if !self.is_valid() {
+		_panic_invalid(self)
+	    } else {
+		self
+	    }
+	} else {
+	    self
 	}
     }
 }