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SunSoft, Inc. 2550 Garcia Avenue Mountain View, California 94043 NOTE: SunOS, SunSoft, Sun, Solaris, Sun Microsystems or the Sun logo are trademarks or registered trademarks of Sun Microsystems, Inc. */ // EXPLANATION: The CORBA spec says that the only legal use of recursive types is // in a manifest sequence declared inside a struct or union whose base type is // the struct or union. // ALGORITHM FOR CHECK: // Sequences push a NULL on the scope stack to mark where in the scope nesting // they appear. // - If the type is not a struct or union, return FALSE (legal use of type). // - Otherwise check up the scope stack, looking for this base type. If we // find a NULL return FALSE (legal use of type, since it is inside some // sequence). If we find the type on the stack, return TRUE (illegal use // since it was not bracketed by a sequence). If we don't find the base // type nor a sequence, return FALSE (legal use, since we're not nested). #include "ast_union.h" #include "utl_stack.h" #include "global_extern.h" #include "nr_extern.h" bool AST_illegal_interface_recursion (AST_Decl *t) { // Can't be 0 since we know we have an interface or valuetype. AST_Decl *d = nullptr; // If we encounter the argument in an enclosing scope, it's illegal. for (UTL_ScopeStackActiveIterator i (idl_global->scopes ()); !i.is_done (); i.next ()) { d = ScopeAsDecl (i.item ()); // Exceptions cannot be recursive, but may contain a reference // to the interface they are defined in. if (d->node_type () == AST_Decl::NT_except) { return false; } if (d == t) { return true; } } return false; } bool AST_illegal_recursive_type (AST_Decl *t) { if (t == nullptr) { return false; } AST_Decl::NodeType nt; AST_Type *ut = dynamic_cast (t); if (ut != nullptr) { ut = ut->unaliased_type (); nt = ut->node_type (); } else { nt = t->node_type (); } if (nt == AST_Decl::NT_interface) { // Check for interface->struct/union->....->interface nesting. // return AST_illegal_interface_recursion (t); } else if (nt != AST_Decl::NT_struct && nt != AST_Decl::NT_union) { // Structs and unions fall through to the check below. return false; // NOT ILLEGAL. } bool check_for_struct = false; bool check_for_union = false; AST_Structure *st1 = nullptr; AST_Union *un1 = nullptr; // Narrow the type appropriately so comparison will work. if (t->node_type () == AST_Decl::NT_struct) { check_for_struct = true; st1 = dynamic_cast (t); if (st1 == nullptr) { return false; // NOT ILLEGAL. } } else if (t->node_type () == AST_Decl::NT_union) { check_for_union = true; un1 = dynamic_cast (t); if (un1 == nullptr) { return false; // NOT ILLEGAL. } } UTL_Scope *s = nullptr; AST_Structure *st2 = nullptr; AST_Union *un2 = nullptr; // OK, iterate up the stack. for (UTL_ScopeStackActiveIterator i (idl_global->scopes ()); !i.is_done (); i.next ()) { s = i.item (); // If we hit a NULL we're done since it means that we're nested inside // a sequence, where recursive types may be used. if (s == nullptr) { return false; // NOT ILLEGAL. } // OK, must check this scope. if (s->scope_node_type () == AST_Decl::NT_struct && check_for_struct == true) { st2 = dynamic_cast (s); if (st2 != nullptr && st2 == st1) { return true; // ILLEGAL RECURSIVE TYPE USE. } } else if (s->scope_node_type () == AST_Decl::NT_union && check_for_union == true) { un2 = dynamic_cast (s); if (un2 != nullptr && un2 == un1) { return true; // ILLEGAL RECURSIVE TYPE USE. } } } // No more scopes to check. This type was used legally. return false; // NOT ILLEGAL. }