+ virtual void visit(FunctionCall &);
+ virtual void visit(VariableDeclaration &);
+ virtual void visit(InterfaceBlock &);
+ virtual void visit(FunctionDeclaration &);
+};
+
+/** Verifies that expressions are valid. In most cases an invalid expression
+is indicated by a null result type. */
+class ExpressionValidator: private Validator
+{
+private:
+ FunctionDeclaration *current_function = 0;
+ bool constant_expression = false;
+
+public:
+ void apply(Stage &s) { stage = &s; s.content.visit(*this); }
+
+private:
+ virtual void visit(VariableReference &);
+ virtual void visit(InterfaceBlockReference &);
+ virtual void visit(Swizzle &);
+ virtual void visit(UnaryExpression &);
+ virtual void visit(BinaryExpression &);
+ virtual void visit(Assignment &);
+ virtual void visit(TernaryExpression &);
+ virtual void visit(VariableDeclaration &);
+ virtual void visit(FunctionDeclaration &);
+ virtual void visit(Conditional &);
+ virtual void visit(Iteration &);
+ virtual void visit(Return &);
+};
+
+/** Verifies flow control constructs. Functions returning non-void must have
+return statements. Warnings are given about dead code. */
+class FlowControlValidator: private Validator
+{
+private:
+ bool reachable = true;
+
+public:
+ void apply(Stage &s) { stage = &s; s.content.visit(*this); }
+
+private:
+ virtual void visit(Block &);
+ virtual void visit(FunctionDeclaration &);
+ virtual void visit(Conditional &);
+ virtual void visit(Iteration &);
+ virtual void visit(Return &) { reachable = false; }
+ virtual void visit(Jump &) { reachable = false; }
+};
+
+/** Verifies that stage input and output interfaces are valid. Linked
+variables must have matching types and locations and there must not be any
+overlap in locations. */
+class StageInterfaceValidator: private Validator
+{
+private:
+ std::map<std::string, std::map<unsigned, VariableDeclaration *> > used_locations;
+
+public:
+ void apply(Stage &s) { stage = &s; s.content.visit(*this); }
+
+private:
+ int get_location(const Layout &);
+