[explorer] Add zobrist command

It prints the hash of the board!

explorer/src/main.rs

@@ -90,6 +90,7 @@ fn command_line() -> Command {
         )
         .subcommand(Command::new("print").about("Print the board"))
         .subcommand(Command::new("quit").alias("exit").about("Quit the program"))
+        .subcommand(Command::new("zobrist").about("Print the Zobrist hash of the current board"))
 }
 
 #[derive(Clone, Debug, Error, Eq, PartialEq)]
@@ -175,6 +176,7 @@ fn respond(line: &str, state: &mut State) -> anyhow::Result<CommandResult> {
         Some(("moves", matches)) => result = do_moves_command(state, matches)?,
         Some(("movement", matches)) => result = do_movement_command(state, matches)?,
         Some(("reset", matches)) => result = do_reset_command(state, matches)?,
+        Some(("zobrist", matches)) => result = do_zobrist_command(state, matches),
         Some((name, _matches)) => unimplemented!("{name}"),
         None => unreachable!("Subcommand required"),
     }
@@ -269,6 +271,19 @@ fn do_movement_command(
     })
 }
 
+fn do_zobrist_command(state: &mut State, _matches: &clap::ArgMatches) -> CommandResult {
+    if let Some(hash) = state.position.zobrist_hash() {
+        println!("hash:{hash}");
+    } else {
+        println!("No Zobrist hash available");
+    }
+
+    CommandResult {
+        should_continue: true,
+        should_print_position: false,
+    }
+}
+
 fn main() -> Result<(), String> {
     let mut editor = DefaultEditor::new().map_err(|err| format!("Error: {err}"))?;