TC-2 Optional GraphViz Dumper

The DumperDot class is optional, it is an optional visitor for TC-2. This visitor is accessible with the option --ast-dump. It displays a graph in dot format.

The --ast-dump command dumps the AST so that it can be exported to dot style.

This option will give you a better visual on your AST, to ease your debugging. If you wish to use it, you will need to fill the various FIXME in src/ast/dumper-dot.cc (The src/ast Directory). The instructions will always be in the same order. Take inspiration from the examples given in full. This option will be of great help in the following steps, especially TC3 and TC4.

void DumperDot::operator()(const FunctionDec& e)
{
  // Start html node, set the parent_id and return previous parent_id
  unsigned long old_parent_id = node_html_header(e, "FunctionDec");
  // Optional data field with name
  node_html_field("name", e.name_get());
  // List of children keys
  node_html_ports({"formals", "result", "body"});
  // End html node
  footer_and_link(old_parent_id);
  // Recursive call to every children using key
  dump("formals", e.formals_get());
  dump("result", e.result_get());
  dump("body", e.body_get());
  // Reset parent_id to previous parent_id
  parent_id = old_parent_id;
}

Some ASTs have attributes which contains a list of nodes. Due to that, two other member functions exist: node_html_port_list and dump_list. Here is an example for SeqExp which contains a list of Exp.

void DumperDot::operator()(const SeqExp& e)
{
  // Start html node, set the parent_id and return previous parent_id
  unsigned long old_parent_id = node_html_header(e, "SeqExp");
  // Optional data field with name is not present
  // Initialize children keys part
  node_html_ports();
  // Create a multi port, one for each exp of the list
  node_html_port_list("exps", e.exps_get());
  // End html node
  footer_and_link(old_parent_id);
  // Recursive call to every element of the list using helper dump_list
  dump_list("exps", e.exps_get());
  // Reset parent_id to previous parent_id
  parent_id = old_parent_id;
}

Here is a rather simple example of the steps to use your visitor.

print-42.tig

let
  var life := 42
in
  print_int(life);
  print("\n")
end

Generate dot using tc

$ tc -X --ast-dump print-42.tig > print-42.dot

You can now generate the image using dot.

Generate png using GraphViz

$ dot -Tpng print-42.dot -o print-42.png

print-42.png