Aul: Split assignment op from standard BinOp

Assignment was special-cased everywhere, so it can just as well get a
separate AST node.

src/script/C4AulAST.h

@@ -37,6 +37,7 @@ namespace aul { namespace ast {
 	class VarExpr;
 	class UnOpExpr;
 	class BinOpExpr;
+	class AssignmentExpr;
 	class SubscriptExpr;
 	class SliceExpr;
 	class CallExpr;
@@ -75,6 +76,7 @@ public:
 	virtual void visit(const ::aul::ast::VarExpr *n) {}
 	virtual void visit(const ::aul::ast::UnOpExpr *) {}
 	virtual void visit(const ::aul::ast::BinOpExpr *) {}
+	virtual void visit(const ::aul::ast::AssignmentExpr *) {}
 	virtual void visit(const ::aul::ast::SubscriptExpr *) {}
 	virtual void visit(const ::aul::ast::SliceExpr *) {}
 	virtual void visit(const ::aul::ast::CallExpr *) {}
@@ -224,9 +226,14 @@ public:
 	BinOpExpr(int op, ExprPtr &&lhs, ExprPtr &&rhs) : op(op), lhs(std::move(lhs)), rhs(std::move(rhs)) {}
 	ExprPtr lhs, rhs;
 	int op; // TODO: Make this a proper operator type
+};
 
-	// Marker for '='
+class AssignmentExpr : public Expr
-	enum { AssignmentOp = -1 };
+{
+	AST_NODE(AssignmentExpr);
+public:
+	AssignmentExpr(ExprPtr &&lhs, ExprPtr &&rhs) : lhs(std::move(lhs)), rhs(std::move(rhs)) {}
+	ExprPtr lhs, rhs;
 };
 
 class SubscriptExpr : public Expr
@@ -456,6 +463,11 @@ public:
 		n->lhs->accept(this);
 		n->rhs->accept(this);
 	}
+	virtual void visit(const ::aul::ast::AssignmentExpr *n) override
+	{
+		n->lhs->accept(this);
+		n->rhs->accept(this);
+	}
 	virtual void visit(const ::aul::ast::SubscriptExpr *n) override
 	{
 		n->object->accept(this);

src/script/C4AulCompiler.cpp

@@ -228,6 +228,7 @@ public:
 	virtual void visit(const ::aul::ast::VarExpr *n) override;
 	virtual void visit(const ::aul::ast::UnOpExpr *n) override;
 	virtual void visit(const ::aul::ast::BinOpExpr *n) override;
+	virtual void visit(const ::aul::ast::AssignmentExpr *n) override;
 	virtual void visit(const ::aul::ast::SubscriptExpr *n) override;
 	virtual void visit(const ::aul::ast::SliceExpr *n) override;
 	virtual void visit(const ::aul::ast::CallExpr *n) override;
@@ -315,6 +316,7 @@ public:
 	virtual void visit(const ::aul::ast::VarExpr *n) override;
 	virtual void visit(const ::aul::ast::UnOpExpr *n) override;
 	virtual void visit(const ::aul::ast::BinOpExpr *n) override;
+	virtual void visit(const ::aul::ast::AssignmentExpr *n) override;
 	virtual void visit(const ::aul::ast::SubscriptExpr *n) override;
 	virtual void visit(const ::aul::ast::SliceExpr *n) override;
 	virtual void visit(const ::aul::ast::CallExpr *n) override;
@@ -985,14 +987,6 @@ void C4AulCompiler::CodegenAstVisitor::visit(const ::aul::ast::BinOpExpr *n)
 {
 	n->lhs->accept(this);
 
-	if (n->op == ::aul::ast::BinOpExpr::AssignmentOp)
-	{
-		C4AulBCC setter = MakeSetter(n->loc, false);
-		n->rhs->accept(this);
-		AddBCC(n->loc, setter);
-		return;
-	}
-
 	const auto &op = C4ScriptOpMap[n->op];
 	if (op.Code == AB_JUMPAND || op.Code == AB_JUMPOR || op.Code == AB_JUMPNNIL)
 	{
@@ -1017,6 +1011,14 @@ void C4AulCompiler::CodegenAstVisitor::visit(const ::aul::ast::BinOpExpr *n)
 	}
 }
 
+void C4AulCompiler::CodegenAstVisitor::visit(const ::aul::ast::AssignmentExpr *n)
+{
+	n->lhs->accept(this);
+	C4AulBCC setter = MakeSetter(n->loc, false);
+	n->rhs->accept(this);
+	AddBCC(n->loc, setter);
+}
+
 void C4AulCompiler::CodegenAstVisitor::visit(const ::aul::ast::SubscriptExpr *n)
 {
 	n->object->accept(this);
@@ -1588,9 +1590,6 @@ void C4AulCompiler::ConstexprEvaluator::visit(const ::aul::ast::UnOpExpr *n)
 
 void C4AulCompiler::ConstexprEvaluator::visit(const ::aul::ast::BinOpExpr *n)
 {
-	if (n->op == ::aul::ast::BinOpExpr::AssignmentOp)
-		nonconst(n);
-
 	assert(n->op > 0);
 	const auto &op = C4ScriptOpMap[n->op];
 	if (op.Changer)
@@ -1662,6 +1661,11 @@ void C4AulCompiler::ConstexprEvaluator::visit(const ::aul::ast::BinOpExpr *n)
 	}
 }
 
+void C4AulCompiler::ConstexprEvaluator::visit(const ::aul::ast::AssignmentExpr *n)
+{
+	nonconst(n);
+}
+
 void C4AulCompiler::ConstexprEvaluator::visit(const ::aul::ast::SubscriptExpr *n)
 {
 	n->object->accept(this);

src/script/C4AulParse.cpp

@@ -1460,7 +1460,7 @@ std::unique_ptr<::aul::ast::Expr> C4AulParse::Parse_Expression(int iParentPrio)
 				if (iParentPrio > 1)
 					return expr;
 				Shift();
-				expr = ::aul::ast::BinOpExpr::New(NodeStart, ::aul::ast::BinOpExpr::AssignmentOp, std::move(expr), Parse_Expression(1));
+				expr = ::aul::ast::AssignmentExpr::New(NodeStart, std::move(expr), Parse_Expression(1));
 				break;
 			}
 		case ATT_OPERATOR: