termwiz: recognize CSI > PP ; Pv m sequence

This is an xterm sequence that adjusts how the terminal
encodes keyboard output.

This commit teaches termwiz to parse and encode the sequence,
but doesn't teach the terminal emulator to do anything with it
at this time.

I'm adding this because vim sends these sequences and I wanted
to understand what they were for.

term/src/terminalstate.rs

@@ -1709,6 +1709,10 @@ impl TerminalState {
             Mode::SetMode(m) | Mode::ResetMode(m) => {
                 error!("unhandled TerminalMode {:?}", m);
             }
+
+            Mode::XtermKeyMode { resource, value } => {
+                error!("unhandled XtermKeyMode {:?} {:?}", resource, value);
+            }
         }
     }
 

termwiz/src/escape/csi.rs

@@ -46,6 +46,9 @@ pub struct Unspecified {
 
 impl Display for Unspecified {
     fn fmt(&self, f: &mut Formatter) -> Result<(), FmtError> {
+        for i in &self.intermediates {
+            write!(f, "{}", *i as char)?;
+        }
         for (idx, p) in self.params.iter().enumerate() {
             if idx > 0 {
                 write!(f, ";{}", p)?;
@@ -53,9 +56,6 @@ impl Display for Unspecified {
                 write!(f, "{}", p)?;
             }
         }
-        for i in &self.intermediates {
-            write!(f, "{}", *i as char)?;
-        }
         write!(f, "{}", self.control)
     }
 }
@@ -419,6 +419,26 @@ impl Display for MouseReport {
     }
 }
 
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum XtermKeyModifierResource {
+    Keyboard,
+    CursorKeys,
+    FunctionKeys,
+    OtherKeys,
+}
+
+impl XtermKeyModifierResource {
+    pub fn parse(value: i64) -> Option<Self> {
+        Some(match value {
+            0 => XtermKeyModifierResource::Keyboard,
+            1 => XtermKeyModifierResource::CursorKeys,
+            2 => XtermKeyModifierResource::FunctionKeys,
+            4 => XtermKeyModifierResource::OtherKeys,
+            _ => return None,
+        })
+    }
+}
+
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub enum Mode {
     SetDecPrivateMode(DecPrivateMode),
@@ -427,6 +447,10 @@ pub enum Mode {
     RestoreDecPrivateMode(DecPrivateMode),
     SetMode(TerminalMode),
     ResetMode(TerminalMode),
+    XtermKeyMode {
+        resource: XtermKeyModifierResource,
+        value: Option<i64>,
+    },
 }
 
 impl Display for Mode {
@@ -456,6 +480,22 @@ impl Display for Mode {
             Mode::RestoreDecPrivateMode(mode) => emit!("r", mode),
             Mode::SetMode(mode) => emit_mode!("h", mode),
             Mode::ResetMode(mode) => emit_mode!("l", mode),
+            Mode::XtermKeyMode { resource, value } => {
+                write!(
+                    f,
+                    ">{}",
+                    match resource {
+                        XtermKeyModifierResource::Keyboard => 0,
+                        XtermKeyModifierResource::CursorKeys => 1,
+                        XtermKeyModifierResource::FunctionKeys => 2,
+                        XtermKeyModifierResource::OtherKeys => 4,
+                    }
+                )?;
+                if let Some(value) = value {
+                    write!(f, ";{}", value)?;
+                }
+                write!(f, "m")
+            }
         }
     }
 }
@@ -1366,6 +1406,7 @@ impl<'a> CSIParser<'a> {
                 .map(|mode| CSI::Mode(Mode::SaveDecPrivateMode(mode))),
 
             ('m', &[b'<']) | ('M', &[b'<']) => self.mouse_sgr1006(params).map(CSI::Mouse),
+            ('m', &[b'>']) => self.xterm_key_modifier(params),
 
             ('c', &[]) => self
                 .req_primary_device_attributes(params)
@@ -1445,6 +1486,32 @@ impl<'a> CSIParser<'a> {
         }
     }
 
+    fn xterm_key_modifier(&mut self, params: &'a [i64]) -> Result<CSI, ()> {
+        if params.len() == 2 {
+            let resource = XtermKeyModifierResource::parse(params[0]).ok_or_else(|| ())?;
+            Ok(self.advance_by(
+                2,
+                params,
+                CSI::Mode(Mode::XtermKeyMode {
+                    resource,
+                    value: Some(params[1]),
+                }),
+            ))
+        } else if params.len() == 1 {
+            let resource = XtermKeyModifierResource::parse(params[0]).ok_or_else(|| ())?;
+            Ok(self.advance_by(
+                1,
+                params,
+                CSI::Mode(Mode::XtermKeyMode {
+                    resource,
+                    value: None,
+                }),
+            ))
+        } else {
+            Err(())
+        }
+    }
+
     fn decslrm(&mut self, params: &'a [i64]) -> Result<CSI, ()> {
         if params.is_empty() {
             // with no params this is a request to save the cursor