Lexer and parser generators using CTFE

[Nick Sabalausky]

"Nick Sabalausky" <a at a.a> wrote in message 
news:jikcca$1vq7$1 at digitalmars.com...
> "H. S. Teoh" <hsteoh at quickfur.ath.cx> wrote in message 
> news:mailman.215.1330472867.24984.digitalmars-d at puremagic.com...
>> On Tue, Feb 28, 2012 at 10:03:42PM +0100, Martin Nowak wrote:
>> [...]
>>> I won't deny that the combination of CTFE text processing and static
>>> introspection could improve on this. It could be made more feasible by
>>> some conventions, e.g. parse result always uses structs or classes and
>>> built-in arrays.
>>
>> Excellent idea, I like this.
>>
>>
>>> class Module
>>> {
>>>     this(Declaration[]);
>>> }
>>>
>>> class StructDeclaration : Declaration
>>> {
>>>     enum _enbf = "struct $1=Identifier { $2=Declaration* }";
>>>
>>>     this(Identifier, Declaration[]);
>>> }
>>>
>>> ...
>>>
>>> Parser!(Module, StructDeclaration, ...) parser;
>>> Module m = parser.parse(read("file.d"));
>>
>> I like this! Definitely an improvement over yacc syntax.
>>
>
> In Goldie, I've taken an inverted approach, which IMHO is easier to use: 
> The types are automatically generated from the grammar, not the other way 
> around. So applying that approach to the above code, it'd be more like 
> this:
>
> mixin genGrammar!("myGrammar", `
>    Identifier = [a-zA-Z_][a-zA-Z_0-9]*
>    Module = Declaration+
>    Declaration = StructDeclaration
>    StructDeclaration = 'struct' Identifier '{' Declaration* '}'
> `);
>
> Which generates these classes:
>
> Parser!"myGrammar"
> Symbol!("myGrammar.Identifier")
> Symbol!("myGrammar.Module")
> Symbol!("myGrammar.Declaration")
> Symbol!("myGrammar.StructDeclaration")
>
> and/or these:
>
> Parser_myGrammar
> Symbol_myGrammar!"Identifier"
> Symbol_myGrammar!"Module"
> Symbol_myGrammar!"Declaration"
> Symbol_myGrammar!"StructDeclaration"
>
> would could then be aliased by the user however they wanted:
>
> alias Symbol_myGrammar MySym;
>
> And there can still be hooks (delegates, subclassing, whatever) to add 
> customized behavior/functionality.
>

Hmm, maybe I need to think about what it would take to make Goldie able to 
parse at compile-time...