[Cider 2 | Debugger] Preserve debugger info and command history on re…

…start (#2213)

A small patch that makes the new `restart` command preserve the
watchpoints, breakpoints, and command history of the debugger rather
than fully resetting it.

interp/src/debugger/commands/core.rs

@@ -422,7 +422,7 @@ lazy_static! {
             CIBuilder::new().invocation("explain")
                 .description("Show examples of commands which take arguments").build(),
             CIBuilder::new().invocation("restart")
-                .description("Restart the debugger from the beginning of the execution. This will reset all breakpoints, watchpoints, and the command history").build(),
+                .description("Restart the debugger from the beginning of the execution. Command history, breakpoints, watchpoints, etc. are preserved").build(),
             // exit/quit
             CIBuilder::new().invocation("exit")
                 .invocation("quit")

interp/src/debugger/debugger_core.rs

@@ -55,8 +55,14 @@ impl ProgramStatus {
     }
 }
 
+/// An opaque wrapper type for internal debugging information
+pub struct DebuggerInfo {
+    ctx: DebuggingContext,
+    input_stream: Input,
+}
+
 pub enum DebuggerReturnStatus {
-    Restart,
+    Restart(Box<DebuggerInfo>),
     Exit,
 }
 
@@ -177,8 +183,20 @@ impl<C: AsRef<Context> + Clone> Debugger<C> {
 
     // so on and so forth
 
-    pub fn main_loop(mut self) -> InterpreterResult<DebuggerReturnStatus> {
-        let mut input_stream = Input::new()?;
+    pub fn main_loop(
+        mut self,
+        info: Option<DebuggerInfo>,
+    ) -> InterpreterResult<DebuggerReturnStatus> {
+        let (input_stream, dbg_ctx) = info
+            .map(|x| (Some(x.input_stream), Some(x.ctx)))
+            .unwrap_or_else(|| (None, None));
+
+        if let Some(dbg_ctx) = dbg_ctx {
+            self.debugging_context = dbg_ctx;
+        }
+
+        let mut input_stream =
+            input_stream.map(Ok).unwrap_or_else(Input::new)?;
 
         println!(
             "==== {}: The {}alyx {}nterpreter and {}bugge{} ====",
@@ -275,7 +293,12 @@ impl<C: AsRef<Context> + Clone> Debugger<C> {
                 }
 
                 Command::Restart => {
-                    return Ok(DebuggerReturnStatus::Restart);
+                    return Ok(DebuggerReturnStatus::Restart(Box::new(
+                        DebuggerInfo {
+                            ctx: self.debugging_context,
+                            input_stream,
+                        },
+                    )));
                 }
             }
         }
@@ -322,7 +345,12 @@ impl<C: AsRef<Context> + Clone> Debugger<C> {
                     print!("{}", Command::get_explain_string().blue().bold())
                 }
                 Command::Restart => {
-                    return Ok(DebuggerReturnStatus::Restart);
+                    return Ok(DebuggerReturnStatus::Restart(Box::new(
+                        DebuggerInfo {
+                            ctx: self.debugging_context,
+                            input_stream,
+                        },
+                    )));
                 }
                 _ => {
                     println!(

interp/src/debugger/debugging_context/context.rs

@@ -739,3 +739,9 @@ impl DebuggingContext {
         }
     }
 }
+
+impl Default for DebuggingContext {
+    fn default() -> Self {
+        Self::new()
+    }
+}

interp/src/debugger/mod.rs

@@ -5,9 +5,8 @@ mod io_utils;
 mod macros;
 pub mod source;
 
-pub use debugger_core::Debugger;
-pub use debugger_core::DebuggerReturnStatus;
-pub use debugger_core::OwnedDebugger;
-pub use debugger_core::ProgramStatus;
+pub use debugger_core::{
+    Debugger, DebuggerInfo, DebuggerReturnStatus, OwnedDebugger, ProgramStatus,
+};
 
 pub(crate) use macros::unwrap_error_message;

interp/src/main.rs

@@ -3,7 +3,7 @@ use argh::FromArgs;
 use calyx_utils::OutputFile;
 use interp::{
     configuration,
-    debugger::{Debugger, DebuggerReturnStatus},
+    debugger::{Debugger, DebuggerInfo, DebuggerReturnStatus},
     errors::InterpreterResult,
     flatten::structures::environment::Simulator,
 };
@@ -128,13 +128,16 @@ fn main() -> InterpreterResult<()> {
             Ok(())
         }
         Command::Debug(_) => {
+            let mut info: Option<DebuggerInfo> = None;
             loop {
                 let debugger = Debugger::new(&i_ctx, &opts.data_file)?;
 
-                let result = debugger.main_loop()?;
+                let result = debugger.main_loop(info)?;
                 match result {
                     DebuggerReturnStatus::Exit => break,
-                    DebuggerReturnStatus::Restart => continue,
+                    DebuggerReturnStatus::Restart(new_info) => {
+                        info = Some(*new_info);
+                    }
                 }
             }
             Ok(())