1 files changed, 47 insertions, 0 deletions
diff --git a/tiger-compiler/src/type/nil.hh b/tiger-compiler/src/type/nil.hh
new file mode 100644
index 0000000..4807ac0
--- /dev/null
+++ b/tiger-compiler/src/type/nil.hh
@@ -0,0 +1,47 @@
+/**
+ ** \file type/nil.hh
+ ** \brief The Nil type.
+ */
+#pragma once
+
+#include <type/fwd.hh>
+#include <type/type.hh>
+
+namespace type
+{
+  /*------.
+  | Nil.  |
+  `------*/
+
+  class Record;
+
+  /// The builtin type of `nil'.
+  /// The Nil type is the type of a `nil` expression.
+  class Nil : public Type
+  {
+  public:
+    /// \name Visitors entry point.
+    /** \{ */
+    /// Accept a const visitor \a v.
+    void accept(ConstVisitor& v) const override;
+    /// Accept a non-const visitor \a v.
+    void accept(Visitor& v) override;
+    /** \} */
+
+    bool compatible_with(const Type& other) const override;
+
+    /// Get the associated record type.
+    const Type* record_type_get() const;
+
+    /// Set the record type used with the nil.
+    void record_type_set(const Type& type) const;
+
+  private:
+    /// The actual record_type that it represents.
+    /// Nil types are either compatible with `type::Record` or `type::Class`.
+    /// record_type represents the actual type that the `nil` was meant to be
+    /// used with.
+    mutable const Type* record_type_ = nullptr;
+  };
+
+} // namespace type