parse.y (Yacc) - next step

Uses the ANSI C yacc grammar and creates an AST on per-function basis.
Already described in previous times but quick example:

selection_statement
        : IF '(' expr ')' { sequence_num++; } statement else_statement {
                $$ = createIf($3, $6, $7);
        }

/* AST Prototype */
ast *
createIf(ast *conditional, ast *if_body, ast *else_body)

What does that do?