1 files changed, 57 insertions, 0 deletions
diff --git a/tiger-compiler/src/type/visitor.hh b/tiger-compiler/src/type/visitor.hh
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+++ b/tiger-compiler/src/type/visitor.hh
@@ -0,0 +1,57 @@
+/**
+ ** \file type/visitor.hh
+ ** \brief Definition of type::Visitor.
+ */
+#pragma once
+
+#include <misc/select-const.hh>
+#include <type/fwd.hh>
+
+namespace type
+{
+  /** \brief Root class of all Type visitors.
+   **
+   ** GenVisitor<CONSTIFY> is the root class of all Type visitors. */
+  template <template <typename> class Const> class GenVisitor
+  {
+    /** \name Ctor & dtor.
+     ** \{ */
+  public:
+    /// Convenient abbreviation.
+    template <typename T> using const_t = typename Const<T>::type;
+
+    /// Destroy a GenVisitor.
+    virtual ~GenVisitor();
+    /** \} */
+
+    /// The entry point: visit \a e.
+    virtual void operator()(const_t<Type>& e);
+    virtual void operator()(const_t<Nil>&) = 0;
+    virtual void operator()(const_t<Void>&) = 0;
+    virtual void operator()(const_t<Int>&) = 0;
+    virtual void operator()(const_t<String>&) = 0;
+    virtual void operator()(const_t<Named>&) = 0;
+    virtual void operator()(const_t<Array>&) = 0;
+    virtual void operator()(const_t<Record>&) = 0;
+    virtual void operator()(const_t<Class>&) = 0;
+    virtual void operator()(const_t<Function>&) = 0;
+    virtual void operator()(const_t<Method>&) = 0;
+
+    /// Helper to visit nodes manipulated via a pointer.
+    template <class E> void operator()(E* e);
+  };
+
+  /// Shorthand for a const visitor.
+  using ConstVisitor = GenVisitor<misc::constify_traits>;
+  /// Shorthand for a non const visitor.
+  using Visitor = GenVisitor<misc::id_traits>;
+
+#ifdef SWIG
+  /// Shorthand for a const visitor.
+  %template(GenConstVisitor) GenVisitor<misc::constify_traits>;
+  /// Shorthand for a non const visitor.
+  %template(GenVisitor) GenVisitor<misc::id_traits>;
+#endif
+} // namespace type
+
+#include <type/visitor.hxx>