Parse Input

[Mythran]

Sorry, this was originally posted in VB.Net newsgroup, but I meant for it to
be posted to the C# group initially, so I'm sorry for the multi-post, my
mistake.
-------------------------------------

I have a console app that accepts input from the user. This input can be a
command for the application, or a mathematical equation/formula. Currently,
I'm using a trick I found on the Internet that creates a dynamic JScript
assembly, loads it, which I then send any non-commands the user entered to a
method that simply passes this input to the val() function. This works, but
I'd like to go further and create my own (or somebody else's) val()
equivalent. I understand that it may be difficult and take awhile to do,
but every time I start on this trek, I just select all and delete because I
confuse myself too much...anyone have any pointers??

Thanks,
Mythran

[Fred Mellender]

Depending on exactly what you are trying to parse, your problem can be easy
or difficult. The easiest solution is a "recursive descent parser". Use
Google to find links. Search the usual places for implementations in C#.

E.G. http://en.wikipedia.org/wiki/Recursive_descent_parser

I wrote a more general purpose parser in C#, but it is probably overkill for
your problem. http://www.frontiernet.net/~fredm/pa...istWebPage.htm

"Mythran" <ki********@hot mail.comwrote in message
news:D8******** *************** ***********@mic rosoft.com...

Sorry, this was originally posted in VB.Net newsgroup, but I meant for it
to be posted to the C# group initially, so I'm sorry for the multi-post,
my mistake.
-------------------------------------

I have a console app that accepts input from the user. This input can be
a
command for the application, or a mathematical equation/formula.
Currently,
I'm using a trick I found on the Internet that creates a dynamic JScript
assembly, loads it, which I then send any non-commands the user entered to
a
method that simply passes this input to the val() function. This works,
but
I'd like to go further and create my own (or somebody else's) val()
equivalent. I understand that it may be difficult and take awhile to do,
but every time I start on this trek, I just select all and delete because
I
confuse myself too much...anyone have any pointers??

Thanks,
Mythran

[Brian Gideon]

On Jan 16, 1:36*pm, "Mythran" <kip_pot...@hot mail.comwrote:

Sorry, this was originally posted in VB.Net newsgroup, but I meant for it to
be posted to the C# group initially, so I'm sorry for the multi-post, my
mistake.
-------------------------------------

I have a console app that accepts input from the user. *This input can be a
command for the application, or a mathematical equation/formula. *Currently,
I'm using a trick I found on the Internet that creates a dynamic JScript
assembly, loads it, which I then send any non-commands the user entered toa
method that simply passes this input to the val() function. *This works,but
I'd like to go further and create my own (or somebody else's) val()
equivalent. *I understand that it may be difficult and take awhile to do,
but every time I start on this trek, I just select all and delete because I
confuse myself too much...anyone have any pointers??

Thanks,
Mythran

Those dynamic code variants make for easy work arounds, but they have
a lot of disadvantages. The infix to postfix techniques are pretty
easy, but if the expressions are too complex you'll have to explore
the more advanced parsing techniques.

There are a few compiler compilers out there for C#. ANTLR is one
example. However, I think they have a big learning curve and it's
probably overkill for an expression evaluator.

I was *very* disappointed with the expression evaluators in C# I found
the internet. Even the commercial ones were deficient in some way or
another. I eventually wrote my own. Maybe I should release it to the
public sometime...

[Mythran]

"Brian Gideon" <br*********@ya hoo.comwrote in message
news:f6******** *************** ***********@21g 2000hsj.googleg roups.com...

On Jan 16, 1:36 pm, "Mythran" <kip_pot...@hot mail.comwrote:

>Sorry, this was originally posted in VB.Net newsgroup, but I meant for it
to
be posted to the C# group initially, so I'm sorry for the multi-post, my
mistake.
-------------------------------------

I have a console app that accepts input from the user. This input can be
a
command for the application, or a mathematical equation/formula.
Currently,
I'm using a trick I found on the Internet that creates a dynamic JScript
assembly, loads it, which I then send any non-commands the user entered
to a
method that simply passes this input to the val() function. This works,
but
I'd like to go further and create my own (or somebody else's) val()
equivalent. I understand that it may be difficult and take awhile to do,
but every time I start on this trek, I just select all and delete because
I
confuse myself too much...anyone have any pointers??

Thanks,
Mythran

Those dynamic code variants make for easy work arounds, but they have
a lot of disadvantages. The infix to postfix techniques are pretty
easy, but if the expressions are too complex you'll have to explore
the more advanced parsing techniques.

There are a few compiler compilers out there for C#. ANTLR is one
example. However, I think they have a big learning curve and it's
probably overkill for an expression evaluator.

I was *very* disappointed with the expression evaluators in C# I found
the internet. Even the commercial ones were deficient in some way or
another. I eventually wrote my own. Maybe I should release it to the
public sometime...

Basically, I'm writing a console calculator that allows you to store
variables, write function addons that can be called from the console app
(which also needs to be parsed), set application commands (change
background/foreground color in application), etc. I got the function call
parsing to work (I successfully parse out these *commands* and run their
associated code blocks, but I don't have the 'addon' portion working yet).

<shrug Thanks for the reply :) I'll continue diggin and reviewing the
link(s) posted by Fred too...

Thanks again,
Mythran