Refactoring a "runtime" language

I have been asked to start thinking about refactoring an existing
"runtime language" (as its called). It is essentially a scripting
language used to determine how data from an SQL Server database is
displayed (and manipulated)on screen using a Visual Basic application.


The process is something like this:


End user creates a text file which describes what data to pull from a
database and how that data will be positioned on a screen (form). This
file is then verified/compiled to a "byte code" if you like and is
stored within a database field (binary field). The user can then load
this compiled/processed data and the application will read the data
from the binary field, and from that pull out the required data from
the database and lay it out on a Visual Basic form as specified by the
user.


The scripting language is a bit like Basic, but more limited. For
example, it allows nested If/End IF, but no Else If. It also allows
the user to define variables of type string, integer and date. It
doesn't allow other tpes (eg. Boolean) or arrays. It is possible to
create procedures, but not functions, and so on.


A "source" file structure:


- Query to extract data (SQL)


- Variable declarations


- Form layout, this field here, this field there, this field this
colour, etc.


- "Event" handlers
      - Calls to in-built functions and procedures, eg. Hide this field,
make this field X width
      - Calls to user procedures


- User procedures, eg. Validate certain input (Total > $100) etc.




So there are, from what I have learned so far (which hasn't been
long), three main logical components to this area of the system, the
scripting/runtime language itself, the compilation/verification
process of parsing and converting the text to "byte code", and the
processing of byte code and displaying data/display elements to the
screen. All this is currently done in Visual Basic. I believe the idea
is to clean it up with a view to moving to VB.NET later.


I have never looked at anything like this before. Given this
information, does anyone have any recommended resources, such as books
(especially), websites, tutorials, code (free), algorithms, similar
languages, and so on that might be useful.


I was looking at some compiler design books, but I am thinking there
might be more specific resources than this???

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