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["Guth, Dwight" <dguth2 AT illinois.edu>]

The #parse command makes use of whatever parser you pass as a flag with 
--parser. It also sets the sort information provided as its second argument 
on the command line as the envirionment variable "KRUN_SORT". So if I say:

krun programName --parser "parserName"

and programName contains a require statement that calls #parse, it will call 
parserName with the string you passed to #parse and set the KRUN_SORT 
variable with the sort you passed to #parse. So it should work, and if you 
want to read that environment variable in your external parser and parse 
differently based on its value, you can.

There is one caveat here though. If your external parser takes the name of a 
file on the command line and outputs the AST on stdout, you will need to make 
a slight adjustment to it in order for this to work. There is in general no 
great way of deciding whether or not a particular external parser takes the 
name of a file or the contents of a program itself (since the two are, from 
the perspective of krun, indistinguishable). So it's the job of the external 
parser to be able to handle the program itself being passed on the command 
line if necessary, because the #parse command calls the external parser with 
exactly one argument, which is the string of the text to be parsed. This is 
done by means of another environment variable, KRUN_IS_NOT_FILE, which is set 
to the string "true". You will need to modify your external parser to check 
the value of this environment variable, and if it is present with the value 
"true", treat the argument passed to the parser as text to be parsed, rather 
than as a filename.
________________________________________
From: Daniele Filaretti 
[dfilaretti AT gmail.com]
Sent: Wednesday, May 22, 2013 2:21 PM
To: Guth, Dwight
Cc: Daniele Filaretti; 
k-user AT cs.uiuc.edu
Subject: Re: [K-user] 'include' statement

Nice, thanks!

But I actually forgot to mention an important detail: I'm using an external 
parser? Will it work? I haven't tried yet.

Daniele

On 22 May 2013, at 19:59, "Guth, Dwight" 
<dguth2 AT illinois.edu>
 wrote:

> Hi, please consider the following code. It might not do exactly what you 
> want, but it captures the general idea and should illustrate to you the 
> features you will need to use to implement this:
>
> syntax Stmt ::= "require" String
> rule require S:String => #parse(readFile(#open(S)), "Stmt")
>
> syntax String ::= readFile(Int) [function]
> syntax Int ::= "BUFFER_SIZE"
> rule BUFFER_SIZE => 1000 [macro]
> rule readFile(Fd:Int) => readFile(#fReadBytes(Fd, BUFFER_SIZE), Fd)
> syntax String ::= readFile(K, Int) [function]
> rule readFile(S:String, Fd) => S +String readFile(Fd)
> rule readFile(#EOF, Fd) => closeFile(#close(Fd))
> syntax String ::= closeFile(K) [function]
> rule closeFile(.K) => ""
>
> Everything except the first two lines of this code fragment consists of 
> code designed to read a file given a file descriptor, close the file, and 
> return a String of its contents. The first rule then opens the file given a 
> path, calls the readFile function to get a string back, and then tells the 
> K framework to parse it as a term of sort Stmt and return it as a term. The 
> term will then be at the top of the K cell and get evaluated according to 
> your semantics. If you need to do something different with the term, you 
> can equally well put #parse inside another piece of syntax and provide 
> whatever semantics to that syntax you choose.
> ________________________________________
> From: 
> k-user-bounces AT cs.uiuc.edu
>  
> [k-user-bounces AT cs.uiuc.edu]
>  on behalf of Daniele Filaretti 
> [daniele.filaretti AT gmail.com]
> Sent: Wednesday, May 22, 2013 1:44 PM
> To: 
> k-user AT cs.uiuc.edu
> Subject: [K-user] 'include' statement
>
> Hi all,
> is there a builtin function that make it possible to simulate 'include' or 
> 'require' functionalities in a language? (i.e. something that takes a 
> filename, parse the content and put the result into the current file)
>
> I'm sure there is (at least in the C semantics, and in Java --- I'm having 
> a look at the code but I cannot find where the import in done :/)
>
> Thanks a lot,
>
> Daniele
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