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digitalmars.D.announce - Pegged v0.4: longest-match, left-recursion, and expandable parse trees

reply Philippe Sigaud <philippe.sigaud gmail.com> writes:
Hi,

Pegged is a parser generator based on Parsing Expression Grammars 
(PEG) written in D, that aims to be both simple to use and work 
at compile-time.

See: https://github.com/PhilippeSigaud/Pegged

To use Pegged, just call the grammar function with a PEG and mix 
it in your module. For example:

import pegged.grammar;

mixin(grammar(`
Arithmetic:
     Term     < Factor (Add / Sub)*
     Add      < "+" Factor
     Sub      < "-" Factor
     Factor   < Primary (Mul / Div)*
     Mul      < "*" Primary
     Div      < "/" Primary
     Primary  < Parens / Neg / Pos / Number / Variable
     Parens   < "(" Term ")"
     Neg      < "-" Primary
     Pos      < "+" Primary
     Number   < ~([0-9]+)

     Variable <- identifier
`));

This will create the `Arithmetic` parser, that can parse your 
usual arithmetic expresion at runtime or compile-time.

// Parsing at compile-time:
enum parseTree1 = Arithmetic("1 + 2 - (3*x-5)*6");
// Runtime:
auto parseTree2 = Arithmetic("1 + 2 - (3*x-5)*6");

-----


This minor release v0.4 (v0.4.1 right now) is on dub 
(code.dlang.org) right now and introduces the following new 
features:

  * A longest-match alternation operator, |, which will always 
choose the longest match during a parse. See 
[https://github.com/PhilippeSigaud/Pegged/wiki/Extended-PEG-Syntax] for more
details and the interest of this operator for grammar writers.

  * The left-recursion engine, introduced in version v0.3.0 is now 
fully documented in the wiki at 
[https://github.com/PhilippeSigaud/Pegged/wiki/Left-Recursion]. 
Pegged can deal with left recursion, hidden left recursion and 
indirect left recursion. Try it!

  * These improvements allow Pegged to generate a parser that 
fully parses Extended Pascal files, based on the official ISO 
10206:1990 grammar. Have a look at it in the 
[https://github.com/PhilippeSigaud/Pegged/tree/master/pegged/examp
es/extended_pascal] directory.

  * The new toHTML function can be used to generate an HTML file 
containing an expandable tree view that can be manipulated with 
an HTML5-compliant browser. See 
[https://github.com/PhilippeSigaud/Pegged/wiki/Parse-Result] for 
more details on this new fun way to explore parse results (and 
parse failures!).


Pegged documentation can be found on the wiki 
[https://github.com/PhilippeSigaud/Pegged/wiki], along with a 
tutorial 
[https://github.com/PhilippeSigaud/Pegged/wiki/Pegged-Tutorial].


Thanks a lot for Bastiaan Veelo for these wonderful improvements 
to Pegged!
Mar 02
next sibling parent mogu <mogucpp 163.com> writes:
On Thursday, 2 March 2017 at 20:42:56 UTC, Philippe Sigaud wrote:
 Hi,

 Pegged is a parser generator based on Parsing Expression 
 Grammars (PEG) written in D, that aims to be both simple to use 
 and work at compile-time.

 See: https://github.com/PhilippeSigaud/Pegged
 ...
Excellent! I love pegged. Thanks for your brilliant works.
Mar 02
prev sibling next sibling parent lobo <swamp.lobo gmail.com> writes:
On Thursday, 2 March 2017 at 20:42:56 UTC, Philippe Sigaud wrote:
 Hi,

 Pegged is a parser generator based on Parsing Expression 
 Grammars (PEG) written in D, that aims to be both simple to use 
 and work at compile-time.

 [...]
Thanks! This is my all time favourite D library.
Mar 02
prev sibling parent reply Moritz Maxeiner <moritz ucworks.org> writes:
On Thursday, 2 March 2017 at 20:42:56 UTC, Philippe Sigaud wrote:
 Hi,

 Pegged is a parser generator based on Parsing Expression 
 Grammars (PEG) written in D, that aims to be both simple to use 
 and work at compile-time.

 See: https://github.com/PhilippeSigaud/Pegged

 [...]
Thank you very much for Pegged, if I end up choosing D for the implementation part of my master thesis, Pegged will be very helpful to me.
Mar 03
parent reply Philippe Sigaud <philippe.sigaud gmail.com> writes:
Thank you all for the positive comments!
Mar 03
parent Bastiaan Veelo <Bastiaan Veelo.net> writes:
On Friday, 3 March 2017 at 20:37:33 UTC, Philippe Sigaud wrote:
 Thank you all for the positive comments!
Indeed, I subscribe to that! (Literally, I am subscribed to this thread :-))
Mar 03