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digitalmars.D.learn - first shot for a combinator library for d

reply =?ISO-8859-1?Q?Christian_K=F6stlin?= <christian.koestlin gmail.com> writes:
Hi,

I try to learn D and as a testproject I wanted to implement combinator 
parsing for D.

That's what I currently have: https://gist.github.com/736456#file_parser.d

It is a simple combinator library including simple matchers, 
alternatives, sequences, optional, transformations of the results and so 
on.

included is a unit-test that realizes a very simple expression evaluator 
(lexing, parsing and evaluation are all put together into one).

My questions are now:
* Starting from this, how should such a module be named?
* In which package structure should it be put?
* How could the language be made more convinient (e.g. I overloaded ~ 
and | operations to be able to write something like match("super") | 
match("not super"))?


Next steps for me would be to add support for different input that 
char[] aka strings.

happy to hear from you

christian
Dec 10 2010
parent reply Ellery Newcomer <ellery-newcomer utulsa.edu> writes:
Nice.

Maybe add support for predicated alternatives?

If you *really* want to make it more convenient, you could make a string 
mixin front for it, so that one could do something like

mixin(maek_parser("
   start -> s1 s2;

   s1 -> (`ab`|`cd`) `ef`;

   s2 -> (`1`|`2`|`3`);
"));

I don't recommend you do that, though, given D's current state of 
affairs regarding ctfe.

Though a runtime version would be doable.

Instead of adding support for char[], wchar[], string, etc, I would 
recommend you just make it support a dchar range interface.  This hits 
all of the above, and then some.

I looked at your code a bit, but I'm lazy. Why is ParseSuccess.fResults 
a Variant[] ?

Lastly, I can't help you with naming :)

On 12/10/2010 10:58 AM, Christian Köstlin wrote:

 Hi,

 I try to learn D and as a testproject I wanted to implement combinator
 parsing for D.

 That's what I currently have: https://gist.github.com/736456#file_parser.d

 It is a simple combinator library including simple matchers,
 alternatives, sequences, optional, transformations of the results and so
 on.

 included is a unit-test that realizes a very simple expression evaluator
 (lexing, parsing and evaluation are all put together into one).

 My questions are now:
 * Starting from this, how should such a module be named?
 * In which package structure should it be put?
 * How could the language be made more convinient (e.g. I overloaded ~
 and | operations to be able to write something like match("super") |
 match("not super"))?


 Next steps for me would be to add support for different input that
 char[] aka strings.

 happy to hear from you

 christian
Dec 10 2010
parent =?ISO-8859-1?Q?Christian_K=F6stlin?= <christian.koestlin gmail.com> writes:
thanks for your feedback!


 Maybe add support for predicated alternatives?


what is this :) ?


 If you *really* want to make it more convenient, you could make a string
 mixin front for it, so that one could do something like

 mixin(maek_parser("
 start -> s1 s2;

 s1 -> (`ab`|`cd`) `ef`;

 s2 -> (`1`|`2`|`3`);
 "));

 I don't recommend you do that, though, given D's current state of
 affairs regarding ctfe.

 Though a runtime version would be doable.

 Instead of adding support for char[], wchar[], string, etc, I would
 recommend you just make it support a dchar range interface. This hits
 all of the above, and then some.


yes ... i also think so ... i will try this today (but i want to go 
first with arrays of objects (templated) because then you could put a 
lexer in front of the parsers).


 I looked at your code a bit, but I'm lazy. Why is ParseSuccess.fResults
 a Variant[] ?


mhh .. thats one of the things i was not sure of. i wanted to be able to 
return different types from the parsers. e.g. an integer parser should 
return an array of ints (or in my case a variantarray containing ints). 
the use of the variants was the second thing which came to my mind and 
allowed for mixed returns from the parsers ... e.g. the result of 
parsing "private int i = 5" could be (by classes) [Modifier, Type, 
string, int].


 Lastly, I can't help you with naming :)


sure :) i just dont get it right now how people have their sources and 
libraries organized. because it seems that dsss is not any more for d2?

regards

christian
Dec 13 2010