title: Make bison start parsing with a rule other than the start rule
body: <p>Currently I'm working on a source-to-source compiler and I have already written a bison parser that creates the AST for the input correctly. I need to do several transformations on the syntax tree now and therefore I need to insert many nodes to the tree.</p>
  
  <p>I could create all the structs/unions that I want to add to the syntax tree manually, but this seems to be <strong>very</strong> much work.</p>
  
  <p>It would be much easier for me to create a string and I want this string to be parsed by the parser I already have. The parser should then return the tree for this string, which I can insert in my original syntax tree.</p>
  
  <p>Unfortunately, the string cannot be parsed with the start rule of my parser, since it must be parsed by a subrule (e.g. my parser parses a list of functions containing statements, the string is a single statement).</p>
  
  <p>How can I make bison parse a string, starting with a rule different from the start rule?</p>
  
  <p>Thanks in advance!</p>