feat(*): distinguish between error and unset clipboard

src/common.rs

@@ -39,5 +39,5 @@ pub trait ClipboardProvider: Sized {
     /// Method to set the clipboard contents as a String
     fn set_contents(&mut self, String) -> Result<(), Box<Error>>;
     /// Method to get clipboard contents not necessarily string
-    fn get_binary_contents(&mut self) -> Result<ClipboardContent, Box<Error>>;
+    fn get_binary_contents(&mut self) -> Result<Option<ClipboardContent>, Box<Error>>;
 }

src/lib.rs

@@ -35,6 +35,7 @@ extern crate objc_foundation;
 
 mod common;
 pub use common::ClipboardProvider;
+pub use common::ClipboardContent;
 
 #[cfg(all(unix, not(any(target_os="macos", target_os="android"))))]
 pub mod x11_clipboard;

src/nop_clipboard.rs

@@ -29,10 +29,10 @@ impl ClipboardProvider for NopClipboardContext {
                   implemented on this platform.");
         Ok("".to_string())
     }
-    fn get_binary_contents(&mut self) -> Result<ClipboardContent, Box<Error>> {
+    fn get_binary_contents(&mut self) -> Result<Option<ClipboardContent>, Box<Error>> {
         println!("Attempting to get the contents of the clipboard, which hasn't yet been \
                   implemented on this platform.");
-        Ok(ClipboardContent::__Nonexhaustive)
+        Ok(None)
     }
     fn set_contents(&mut self, _: String) -> Result<(), Box<Error>> {
         println!("Attempting to set the contents of the clipboard, which hasn't yet been \

src/osx_clipboard.rs

@@ -61,7 +61,7 @@ impl ClipboardProvider for OSXClipboardContext {
             Ok(string_array[0].as_str().to_owned())
         }
     }
-    fn get_binary_contents(&mut self) -> Result<ClipboardContent, Box<Error>> {
+    fn get_binary_contents(&mut self) -> Result<Option<ClipboardContent>, Box<Error>> {
         let string_class: Id<NSObject> = {
             let cls: Id<Class> = unsafe { Id::from_ptr(class("NSString")) };
             unsafe { transmute(cls) }
@@ -86,12 +86,12 @@ impl ClipboardProvider for OSXClipboardContext {
             Id::from_ptr(obj)
         };
         if contents.count() == 0 {
-            Err(err("pasteboard#readObjectsForClasses:options: returned empty"))
+            Ok(None)
         } else {
             let obj = &contents[0];
             if obj.is_kind_of(Class::get("NSString").unwrap()) {
                 let s: &NSString = unsafe { transmute(obj) };
-                Ok(ClipboardContent::Utf8(s.as_str().to_owned()))
+                Ok(Some(ClipboardContent::Utf8(s.as_str().to_owned())))
             } else if obj.is_kind_of(Class::get("NSImage").unwrap()) {
                 let tiff: &NSArray<NSObject> = unsafe { msg_send![obj, TIFFRepresentation] };
                 let len: usize = unsafe { msg_send![tiff, length] };
@@ -99,10 +99,10 @@ impl ClipboardProvider for OSXClipboardContext {
                 let vec = unsafe { std::slice::from_raw_parts(bytes, len) };
                 // Here we copy the entire &[u8] into a new owned `Vec`
                 // Is there another way that doesn't copy multiple megabytes?
-                Ok(ClipboardContent::Tiff(vec.into()))
+                Ok(Some(ClipboardContent::Tiff(vec.into())))
             } else if obj.is_kind_of(Class::get("NSURL").unwrap()) {
                 let s: &NSString = unsafe { msg_send![obj, absoluteString] };
-                Ok(ClipboardContent::Utf8(s.as_str().to_owned()))
+                Ok(Some(ClipboardContent::Utf8(s.as_str().to_owned())))
             } else {
                 // let cls: &Class = unsafe { msg_send![obj, class] };
                 // println!("{}", cls.name());