Recognize clicks on hyperlinks

There's plumbing for handling these events in the TerminalHost
trait, but we don't do anything beyond printing them at the moment.

src/xwin.rs

@@ -13,6 +13,7 @@ use std::slice;
 use term::{self, CellAttributes, CursorPosition, KeyCode, KeyModifiers, Line, MouseButton,
            MouseEvent, MouseEventKind, TerminalHost, Underline};
 use term::color::RgbColor;
+use term::hyperlink::Hyperlink;
 use xcb;
 use xcb_util;
 use xgfx::{self, BitmapImage, Connection, Drawable};
@@ -112,6 +113,10 @@ impl<'a> term::TerminalHost for Host<'a> {
         &mut self.pty
     }
 
+    fn click_link(&mut self, link: &Rc<Hyperlink>) {
+        println!("clicked on link: {:?}", link);
+    }
+
     // Check out https://tronche.com/gui/x/icccm/sec-2.html for some deep and complex
     // background on what's happening in here.
     fn get_clipboard(&mut self) -> Result<String, Error> {

term/src/terminal.rs

@@ -16,6 +16,9 @@ pub trait TerminalHost {
 
     /// Change the title of the window
     fn set_title(&mut self, title: &str);
+
+    /// Called when a URL is clicked
+    fn click_link(&mut self, link: &Rc<Hyperlink>);
 }
 
 pub struct Terminal {

term/src/terminalstate.rs

@@ -327,12 +327,20 @@ impl TerminalState {
                         // The double/triple click cases are handled above.
                         Some(&LastMouseClick { streak: 1, .. }) => {
                             let text = self.get_selection_text();
+                            if text.len() > 0 {
                                 debug!(
                                     "finish drag selection {:?} '{}'",
                                     self.selection_range,
                                     text
                                 );
                                 host.set_clipboard(Some(text))?;
+                            } else {
+                                // If the button release wasn't a drag, consider
+                                // whether it was a click on a hyperlink
+                                if let Some(link) = self.current_highlight() {
+                                    host.click_link(&link);
+                                }
+                            }
                             return Ok(());
                         }
                         _ => {}

term/src/test/mod.rs

@@ -33,6 +33,8 @@ impl TerminalHost for TestHost {
     fn writer(&mut self) -> &mut std::io::Write {
         panic!("no writer support in TestHost");
     }
+
+    fn click_link(&mut self, _link: &Rc<Hyperlink>) {}
 }
 
 macro_rules! assert_cursor_pos {