==== Compilers Exam, 2016-12-20 ====
=== Programming Part ===

The following tasks should be solved in the order below. Write tests for each step!

  * Grade 2: Add a new regular expression to the lexer in order to separate the name of the program from the name of the variables! The name of the program has to start with a "@" character, then an upper case letter and a non-empty sequence of lower case letters. The variable names do not change.
  * Grade 3: Change the grammar to include the new program name token!
  * Grade 4: Add the ''?'' and '':'' tokens to the lexical analyser! Extend the grammar with the following new expression type:
    * Examples:
      * ''a := (x<3 ? 0 : 1) + 1''
      * ''write(2 * (b ? x : y+1))''
    * The open and close parentheses are mandatory around these expressions.
    * The meaning of ''(x<3 ? 0 : 1)'': If x<3, then the result is 0 and 1 otherwise.
  * Grade 5: Extend the semantic analysis to check if
    * The expressions before ''?'' has to be booleans.
    * The expressions before and after the '':'' have to have the same type.
    * The type of the full ''(a?b:c)'' expression is the type of ''b'' (and ''c'').