Translator – Functions

Now that the translation arrays have been defined, it's time to define the translation of functions. Functions (whether Internal, one-line Defined or User) have arguments separated by commas. Take the example MID$(A$+B$,INT(A+0.5),I+5) containing two internal function calls where the tokens will be parsed as:

MID$( A$ + B$ , INT( A + 0.5 ) , I + 5 )

Again there are tokens for commas and closing parentheses. This expression will be translated to RPN as:

A$ B$ + A 0.5 INT( I 5 + MID$(

The functions are found after their associated arguments. Functions will pop their already evaluated arguments off of the run-time stack (which will be in reverse order), perform there operations, and then push their result back onto the run-time for the next part of the expression.

Though this example contains only internal functions, one-line defined functions and user functions work the same way. The big difference is that Translator (using Table) will know the number of arguments that internal functions have and can perform error checking for the number of arguments. However, this can't be done for one-line defined (FN) functions and user functions. This job will be left for the Encoder (which will access the Dictionary for this information).