Allow primary selection for sharing

Adds a feature flag to use the primary selection instead of the
clipboard. Only works on Linux.

src/sharing.rs

@@ -0,0 +1,35 @@
+#![cfg(feature = "share_clipboard")]
+
+#[cfg(not(feature = "share_selection"))]
+use clipboard::ClipboardContext;
+use clipboard::ClipboardProvider;
+#[cfg(feature = "share_selection")]
+use clipboard::x11_clipboard::{X11ClipboardContext, Primary};
+
+#[cfg(not(feature = "share_selection"))]
+pub fn read_share() -> Option<String> {
+    ClipboardProvider::new()
+        .and_then(|mut ctx: ClipboardContext| ctx.get_contents())
+        .ok()
+}
+
+#[cfg(feature = "share_selection")]
+pub fn read_share() -> Option<String> {
+    ClipboardProvider::new()
+        .and_then(|mut ctx: X11ClipboardContext<Primary>| ctx.get_contents())
+        .ok()
+}
+
+#[cfg(not(feature = "share_selection"))]
+pub fn write_share(url: String) -> Option<()> {
+    ClipboardProvider::new()
+        .and_then(|mut ctx: ClipboardContext| ctx.set_contents(url))
+        .ok()
+}
+
+#[cfg(feature = "share_selection")]
+pub fn write_share(url: String) -> Option<()> {
+    ClipboardProvider::new()
+        .and_then(|mut ctx: X11ClipboardContext<Primary>| ctx.set_contents(url))
+        .ok()
+}