From b10b837d18f14cbcd38d75680d0410dee3a66064 Mon Sep 17 00:00:00 2001
From: Joe Strout <joe@strout.net>
Date: Sat, 22 Oct 2022 17:12:39 -0700
Subject: [PATCH] Added `stackTrace` which was somehow missing.

---
 Farmtronics/M1/M1API.cs | 16 ++++++++++++++++
 Farmtronics/M1/Shell.cs | 23 ++++++++++++++++++-----
 2 files changed, 34 insertions(+), 5 deletions(-)

diff --git a/Farmtronics/M1/M1API.cs b/Farmtronics/M1/M1API.cs
index a29e04e..5f830bd 100644
--- a/Farmtronics/M1/M1API.cs
+++ b/Farmtronics/M1/M1API.cs
@@ -301,6 +301,22 @@ public static void Init(Shell shell) {
 			f.code = (context, partialResult) => {
 				return new Intrinsic.Result(WorldInfo());
 			};
+
+			// stackTrace: get a list describing the call stack.
+			f = Intrinsic.Create("stackTrace");
+			f.code = (context, partialResult) => {
+				TAC.Machine vm = context.vm;
+				if (vm.globalContext.variables.ContainsKey(_stackAtBreak)) {
+					// We have a stored stack from a break or exit.
+					// So, display that.  This gets cleared by 'run' so should never interfere with
+					// showing a more up-to-date stack during a run.
+					return new Intrinsic.Result(vm.globalContext.variables.map[_stackAtBreak]);
+				}
+				// Otherwise, build a stack now from the state of the VM.
+				ValList result = StackList(context.vm);
+				return new Intrinsic.Result(result);
+			};
+
 		}
 
 		static bool DisallowAllAssignment(Value key, Value value) {
diff --git a/Farmtronics/M1/Shell.cs b/Farmtronics/M1/Shell.cs
index 9a9f541..67d34e9 100644
--- a/Farmtronics/M1/Shell.cs
+++ b/Farmtronics/M1/Shell.cs
@@ -52,12 +52,14 @@ public bool allowControlCBreak {
 		ValString curScreenColor;
 
 		public TextDisplay textDisplay {  get {  return console.display; } }
-		
+
+		ValList stackAtLastErr;
+
 		public Shell() {
 			console = new Console(this);
 
 			// prepare the interpreter
-			interpreter = new Interpreter(null, PrintLineWithTaskCheck, PrintLine);
+			interpreter = new Interpreter(null, PrintLineWithTaskCheck, PrintErrLine);
 			interpreter.implicitOutput = PrintLine;
 			interpreter.hostData = this;
 		}
@@ -275,7 +277,8 @@ public void Break(bool silent=false) {
 			if (!silent && !allowControlCBreak) return;
 		
 			// grab the full stack and tuck it away for future reference
-			ValList stack = M1API.StackList(interpreter.vm);
+			ValList stack = stackAtLastErr;
+			if (stack == null) stack = M1API.StackList(interpreter.vm);
 		
 			// also find the first non-null entry, to display right away
 			SourceLoc loc = null;
@@ -349,8 +352,8 @@ void Clear() {
 	
 		public void Exit() {
 			if (interpreter.Running()) {
-				//interpreter.vm.globalContext.variables.SetElem(MiniMicroAPI._stackAtBreak, 
-				//	MiniMicroAPI.StackList(interpreter.vm));
+				interpreter.vm.globalContext.variables.SetElem(M1API._stackAtBreak, 
+					M1API.StackList(interpreter.vm));
 				interpreter.Stop();
 			}
 		}
@@ -361,6 +364,16 @@ public void PrintLine(string line) {
 			disp.Print(disp.delimiter);
 		}
 
+		public void PrintErrLine(string line) {
+			if (interpreter.vm != null) {
+				stackAtLastErr = M1API.StackList(interpreter.vm);
+				interpreter.vm.globalContext.variables.SetElem(M1API._stackAtBreak, stackAtLastErr);
+			} else {
+				stackAtLastErr = new ValList();	// empty list signifies error without a VM, e.g. at compile time.
+			}
+			PrintLine(line);
+		}
+
 		void PrintLineWithTaskCheck(string line) {
 			PrintLine(line);
 			ToDoManager.NotePrintOutput(line);