From 30252e58633ba1292afdc0e71413a21dee82d4cf Mon Sep 17 00:00:00 2001
From: Tijmen van Nesselrooij <tijmen_222@hotmail.com>
Date: Sat, 16 May 2020 11:54:49 +0200
Subject: [PATCH] Improve runtime error handling

---
 include/execute/error.hpp      | 29 +++++++++++++++++++-----
 src/execute/error.cpp          | 40 +++++++++++++++++++++++++++++++++-
 src/execute/virtualmachine.cpp | 14 +++++++++++-
 src/interpret/statement.cpp    |  4 ++--
 4 files changed, 77 insertions(+), 10 deletions(-)

diff --git a/include/execute/error.hpp b/include/execute/error.hpp
index 2b3b26c..5e899d6 100644
--- a/include/execute/error.hpp
+++ b/include/execute/error.hpp
@@ -1,27 +1,44 @@
 #pragma once
+#include <string>
 
 namespace Execute
 {
-	struct RuntimeError
+	class RuntimeError
 	{
+	protected:
+		std::string message;
 
+	public:
+		std::string const & GetMessage() const;
+
+		RuntimeError();
+		RuntimeError(std::string const & what);
 	};
 
-	struct StackUnderflow : RuntimeError
+	class StackUnderflow : public RuntimeError
 	{
-
+	public:
+		StackUnderflow();
 	};
 
-	struct StackOverflow : RuntimeError
+	class StackOverflow : public RuntimeError
 	{
+	public:
+		StackOverflow();
+	};
 
+	class MissingLabel : public RuntimeError
+	{
+	public:
+		MissingLabel(std::string const & label);
 	};
 
 	namespace Internal
 	{
-		struct BadValueType : RuntimeError
+		class BadValueType : public RuntimeError
 		{
-
+		public:
+			BadValueType();
 		};
 	}
 }
\ No newline at end of file
diff --git a/src/execute/error.cpp b/src/execute/error.cpp
index e83a30a..b4876b2 100644
--- a/src/execute/error.cpp
+++ b/src/execute/error.cpp
@@ -2,5 +2,43 @@
 
 namespace Execute
 {
-	
+	std::string const & RuntimeError::GetMessage() const
+	{
+		return message;
+	}
+
+	RuntimeError::RuntimeError()
+		: message("Undocumented runtime error")
+	{
+	}
+
+	RuntimeError::RuntimeError(std::string const & what)
+		: message(what)
+	{
+	}
+
+	StackUnderflow::StackUnderflow()
+		: RuntimeError("Stack underflow error")
+	{
+	}
+
+	StackOverflow::StackOverflow()
+		: RuntimeError("Stack overflow error")
+	{
+	}
+
+	MissingLabel::MissingLabel(std::string const & label)
+	{
+		message = "Missing jump/function label \"";
+		message += label;
+		message += '"';
+	}
+
+	namespace Internal
+	{
+		BadValueType::BadValueType()
+			: RuntimeError("Internal error: bad value type")
+		{
+		}
+	}
 }
\ No newline at end of file
diff --git a/src/execute/virtualmachine.cpp b/src/execute/virtualmachine.cpp
index 02267e6..b0a999d 100644
--- a/src/execute/virtualmachine.cpp
+++ b/src/execute/virtualmachine.cpp
@@ -1,4 +1,5 @@
 #include <execute/virtualmachine.hpp>
+#include <execute/error.hpp>
 
 namespace Execute
 {
@@ -6,7 +7,18 @@ namespace Execute
 	{
 		state.nextStatement = state.currentStatement + 1u;
 
-		code.statements[state.currentStatement]->Execute(flags, state, registers);
+		try
+		{
+			code.statements[state.currentStatement]->Execute(flags, state, registers);
+		}
+		catch(RuntimeError & ex)
+		{
+			terminated = true;
+			std::puts("\nA fatal error occurred and execution has been halted:");
+			std::printf("%s\n", ex.GetMessage().c_str());
+
+			return;
+		}
 
 		state.currentStatement = state.nextStatement;
 		if (state.currentStatement >= code.statements.size())
diff --git a/src/interpret/statement.cpp b/src/interpret/statement.cpp
index df1655e..87a902c 100644
--- a/src/interpret/statement.cpp
+++ b/src/interpret/statement.cpp
@@ -33,7 +33,7 @@ namespace Interpret
 		}
 		else
 		{
-			throw std::runtime_error("Attempted jump to nonexisting label");
+			throw Execute::MissingLabel(label);
 		}
 	}
 
@@ -47,7 +47,7 @@ namespace Interpret
 		auto const & elem = state.labelStatementIndice.find(label);
 		if (elem == state.labelStatementIndice.end())
 		{
-			throw std::runtime_error("Attempted call nonexisting function (missing label)");
+			throw Execute::MissingLabel(label);
 		}
 
 		if ((state.memory.size() - state.stackPointer) < sizeof(unsigned))