3 files changed, 67 insertions, 9 deletions

diff --git a/src/loading/fs.rs b/src/loading/fs.rs
index 70ab5e53..55aa967b 100644
--- a/src/loading/fs.rs
+++ b/src/loading/fs.rs
@@ -6,7 +6,7 @@ use memmap2::Mmap;
 use same_file::Handle;
 use walkdir::WalkDir;
 
-use super::{FileHash, Loader};
+use super::{Buffer, FileHash, Loader};
 use crate::font::FontInfo;
 
 /// Loads fonts and files from the local file system.
@@ -130,7 +130,7 @@ impl Loader for FsLoader {
         }
     }
 
-    fn load(&self, path: &Path) -> io::Result<Vec<u8>> {
-        fs::read(path)
+    fn load(&self, path: &Path) -> io::Result<Buffer> {
+        Ok(fs::read(path)?.into())
     }
 }
diff --git a/src/loading/mem.rs b/src/loading/mem.rs
index 320de349..36e920d9 100644
--- a/src/loading/mem.rs
+++ b/src/loading/mem.rs
@@ -3,7 +3,7 @@ use std::collections::HashMap;
 use std::io;
 use std::path::{Path, PathBuf};
 
-use super::{FileHash, Loader};
+use super::{Buffer, FileHash, Loader};
 use crate::font::FontInfo;
 use crate::util::PathExt;
 
@@ -61,10 +61,10 @@ impl Loader for MemLoader {
         }
     }
 
-    fn load(&self, path: &Path) -> io::Result<Vec<u8>> {
+    fn load(&self, path: &Path) -> io::Result<Buffer> {
         self.files
             .get(&path.normalize())
-            .map(|cow| cow.clone().into_owned())
+            .map(|cow| cow.clone().into_owned().into())
             .ok_or_else(|| io::ErrorKind::NotFound.into())
     }
 }
@@ -90,7 +90,7 @@ mod tests {
 
         // Test that the file can be loaded.
         assert_eq!(
-            loader.load(Path::new("directory/../PTSans.ttf")).unwrap(),
+            loader.load(Path::new("directory/../PTSans.ttf")).unwrap().as_slice(),
             data
         );
     }
diff --git a/src/loading/mod.rs b/src/loading/mod.rs
index d37dd1fc..ecc1e8d5 100644
--- a/src/loading/mod.rs
+++ b/src/loading/mod.rs
@@ -8,10 +8,14 @@ mod mem;
 pub use fs::*;
 pub use mem::*;
 
+use std::fmt::{self, Debug, Formatter};
 use std::io;
+use std::ops::Deref;
 use std::path::Path;
+use std::sync::Arc;
 
 use crate::font::FontInfo;
+use crate::util::Prehashed;
 
 /// A hash that identifies a file.
 ///
@@ -29,7 +33,7 @@ pub trait Loader {
     fn resolve(&self, path: &Path) -> io::Result<FileHash>;
 
     /// Load a file from a path.
-    fn load(&self, path: &Path) -> io::Result<Vec<u8>>;
+    fn load(&self, path: &Path) -> io::Result<Buffer>;
 }
 
 /// A loader which serves nothing.
@@ -44,7 +48,61 @@ impl Loader for BlankLoader {
         Err(io::ErrorKind::NotFound.into())
     }
 
-    fn load(&self, _: &Path) -> io::Result<Vec<u8>> {
+    fn load(&self, _: &Path) -> io::Result<Buffer> {
         Err(io::ErrorKind::NotFound.into())
     }
 }
+
+/// A shared buffer that is cheap to clone.
+#[derive(Clone, Hash, Eq, PartialEq)]
+pub struct Buffer(Prehashed<Arc<Vec<u8>>>);
+
+impl Buffer {
+    /// Return a view into the buffer.
+    pub fn as_slice(&self) -> &[u8] {
+        self
+    }
+
+    /// Return a copy of the buffer as a vector.
+    pub fn to_vec(&self) -> Vec<u8> {
+        self.0.to_vec()
+    }
+}
+
+impl From<&[u8]> for Buffer {
+    fn from(slice: &[u8]) -> Self {
+        Self(Prehashed::new(Arc::new(slice.to_vec())))
+    }
+}
+
+impl From<Vec<u8>> for Buffer {
+    fn from(vec: Vec<u8>) -> Self {
+        Self(Prehashed::new(Arc::new(vec)))
+    }
+}
+
+impl From<Arc<Vec<u8>>> for Buffer {
+    fn from(arc: Arc<Vec<u8>>) -> Self {
+        Self(Prehashed::new(arc))
+    }
+}
+
+impl Deref for Buffer {
+    type Target = [u8];
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl AsRef<[u8]> for Buffer {
+    fn as_ref(&self) -> &[u8] {
+        self
+    }
+}
+
+impl Debug for Buffer {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        f.pad("Buffer(..)")
+    }
+}