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[Daniele Filaretti <dfilaretti AT gmail.com>]

On 22 May 2013, at 20:38, "Guth, Dwight" 
<dguth2 AT illinois.edu>
 wrote:

> 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.

What version of K are you using? The latest stable I guess? I'm using the 
latest build and it doesn't work. In particular it seems that '#fReadBytes' 
doesn't exists (I inspected k/include/modules/uris.k), while with '#parse()' 
I got an 'unexpected end of rule' error (even if '#parse' seems to exists). 

Thanks for the info and explanation, it's very useful - I'll work more on it 
when I'll have some time. 

Daniele






> ________________________________________
> 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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>> k-user AT cs.uiuc.edu
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