[cup] Port over all the type-checking/pointer arithmetic stuff

There's still some work to be done when checking function call args,
etc, but the general mechanism of actually propagating the type back
up the AST is now here from the C compiler.

... Not to say that was very good, but it's passable enough for now.
More improvements to come in the future!

1 files changed, 43 insertions, 1 deletions

diff --git a/compiler/types.cup b/compiler/types.cup
index e6cb233..2addd95 100644
--- a/compiler/types.cup
+++ b/compiler/types.cup
@@ -89,4 +89,46 @@ fn create_type_string(typ: Type *): char* {
     else  die("type_to_string: unknown type");
 
     return buf;
-}
\ No newline at end of file
+}
+
+fn is_int_type(typ: Type*): int {
+    if (typ.typ == TYPE_INT) return true;
+    if (typ.typ == TYPE_CHAR) return true;
+    return false;
+}
+
+
+fn types_equal(a: Type*, b: Type*): int {
+    if (a == null && b == null)
+        return true;
+    if (a == null || b == null)
+        return false;
+    if (a.typ == TYPE_ANY || b.typ == TYPE_ANY)
+        return true;
+    return a.typ == b.typ && types_equal(a.ptr, b.ptr);
+}
+
+fn is_convertible(from: Type*, to: Type*): int {
+    if (from.typ == TYPE_ANY || to.typ == TYPE_ANY)
+        return true;
+
+    // Allow converstions to and from void* to any other pointer type
+    if (from.typ == TYPE_PTR && to.typ == TYPE_PTR)
+        if (from.ptr.typ == TYPE_VOID || to.ptr.typ == TYPE_VOID)
+            return true;
+
+    // TODO: Should we rause a warning if the target type is narrower
+    //       than the source type?
+    if (is_int_type(from) && is_int_type(to))
+        return true;
+    return types_equal(from, to);
+}
+
+fn is_struct_or_structptr(typ: Type*): int {
+    if (typ.typ == TYPE_STRUCT || typ.typ == TYPE_UNION)
+        return true;
+    if (typ.typ == TYPE_PTR)
+        if (typ.ptr.typ == TYPE_STRUCT || typ.ptr.typ == TYPE_UNION)
+            return true;
+    return false;
+}