tamer: parse::trace: Include context

This is something that I had apparently forgotten to do, but is now useful
in debugging `ele_parse!` issues with the trampoline.

DEV-7145

tamer/src/parse/parser.rs

@@ -260,8 +260,11 @@ impl<S: ClosedParseState, I: TokenStream<S::Token>> Parser<S, I> {
             "lookahead token is available but was not consumed",
         );
 
-        self.tracer
-            .trace_tok_begin(self.state.as_ref().unwrap(), &tok);
+        self.tracer.trace_tok_begin(
+            self.state.as_ref().unwrap(),
+            &tok,
+            &self.ctx,
+        );
 
         // Parse a single token and perform the requested state transition.
         //
@@ -279,7 +282,7 @@ impl<S: ClosedParseState, I: TokenStream<S::Token>> Parser<S, I> {
         let TransitionResult(Transition(state), data) =
             self.state.take().unwrap().parse_token(tok, &mut self.ctx);
 
-        self.tracer.trace_tok_end(&state, &data);
+        self.tracer.trace_tok_end(&state, &data, &self.ctx);
         self.state.replace(state);
 
         use ParseStatus::{Incomplete, Object};

tamer/src/parse/trace.rs

@@ -47,7 +47,12 @@ pub(super) trait ParserTrace: Default {
     ///
     /// There is no means to return an error and a failure to output the
     ///   trace should not interrupt processing.
-    fn trace_tok_begin<S: ParseState>(&mut self, st_orig: &S, tok: &S::Token);
+    fn trace_tok_begin<S: ParseState>(
+        &mut self,
+        st_orig: &S,
+        tok: &S::Token,
+        ctx: &S::Context,
+    );
 
     /// Output the lower portion of a token trace.
     ///
@@ -60,6 +65,7 @@ pub(super) trait ParserTrace: Default {
         &mut self,
         st_new: &S,
         data: &TransitionData<S>,
+        ctx: &S::Context,
     );
 }
 
@@ -75,6 +81,7 @@ impl ParserTrace for VoidTrace {
         &mut self,
         _st_orig: &S,
         _tok: &S::Token,
+        _ctx: &S::Context,
     ) {
         // Do nothing at all.
     }
@@ -83,6 +90,7 @@ impl ParserTrace for VoidTrace {
         &mut self,
         _st_new: &S,
         _data: &TransitionData<S>,
+        _ctx: &S::Context,
     ) {
         // Do nothing at all.
     }
@@ -101,12 +109,18 @@ impl ParserTrace for VoidTrace {
 pub struct HumanReadableTrace<const REASON: &'static str>;
 
 impl<const REASON: &'static str> ParserTrace for HumanReadableTrace<REASON> {
-    fn trace_tok_begin<S: ParseState>(&mut self, st_orig: &S, tok: &S::Token) {
+    fn trace_tok_begin<S: ParseState>(
+        &mut self,
+        st_orig: &S,
+        tok: &S::Token,
+        ctx: &S::Context,
+    ) {
         eprint!(
             "\
 [Parser::feed_tok] (input IR: {ir})
 | ==> Parser before tok is {st_orig}.
 |  |  {st_orig:?}
+|  |  Context: {ctx:?}
 |
 | ==> {ir} tok: {tok}
 |  |  {tok:?}
@@ -119,12 +133,14 @@ impl<const REASON: &'static str> ParserTrace for HumanReadableTrace<REASON> {
         &mut self,
         st_new: &S,
         data: &TransitionData<S>,
+        ctx: &S::Context,
     ) {
         eprint!(
             "\
 | ==> Parser after tok is {st_new}.
 |  |  {st_new:?}
-|  |  Lookahead: {la:?}\n",
+|  |  Lookahead: {la:?}
+|  |  Context:   {ctx:?}\n",
             la = data.lookahead_ref(),
         );