kdev-pg: Port to Flex / %member declarations

[Roberto Raggi]

Hi Jakob!

please commit your patches!! this stuff is very cool!
thanks a lot Jakob

ciao robe

On Monday 15 May 2006 10:43, Jakob Petsovits wrote:
> Hi Roberto and list,
>
> here's something I've been trying out, and I'm wondering if you like it.
>
>
> - One itch:
>
> kdev-pg writes all of the variables in the parse tree by itself, those are
> merely references to some tokens. That's ok for most AST nodes, but
> insufficient for others.
>
> For example, in my Java grammar I want to have a counter for the "multiple
> brackets" rule ("[][][]" - count: 3) instead of just having a list of 3
> left brackets in the node. Other example: I'd rather store the modifiers
> ("public", "static", "final", etc.) inside one modifier flag variable
> instead of storing one token for each of them. There are also loads of
> possible enum variables that would fit just fine into the AST.
>
> All of this makes for easier access to the AST after parsing.
>
>
> - Another itch:
>
> Currently, I can't make configuration variables a member of the parser
> class. For the Java grammar, that would be the Java compatibility mode
> (1.[3,4,5]) which is currently stored in a static class variable of a
> settings class, and that's hardly better than a global variable.
>
> I'd strongly prefer the compatibility mode belonging to the parser class
> itself, together with its accessor methods.
>
>
> - Approach:
>
> The main patch in here (kdev-pg-member.diff) adds a %member declaration to
> the syntax of a grammar file, where every %member occurrence can hold one
> of: - any public, protected or private declaration code,
> - code inserted into the constructor or the deconstructor.
>
> That code is then inserted into the body of either the parser class or an
> AST node struct, scratching both itches at once.
>
> This patch depends on the kdev-pg-flex-port.diff patch which replaces the
> hand-written lexer with a Flex one. This makes recognizing keywords and
> using lexer states much easier. The Flex port patch doesn't change any of
> the functionality though, error messages are also still working.
>
> With those two patches applied, I can make use of %member declarations in
> the Java grammar (kdev-pg-member-java.diff) in order to replace many
> token-storing variables with enums, bools or ints.
> Makes the AST much prettier. Also makes for happy grammar authors.
>
>
> - Syntax by example:
>
> %member ([target class/struct]: [where to go]) [: code; :]
>
> %member (parserclass: public declaration)
> [:
>   enum java_compatibility_mode {
>     java13_compatibility = 130,
>     java14_compatibility = 140,
>     java15_compatibility = 150,
>   };
>   java::java_compatibility_mode compatibility_mode();
>
> :]
>
> %member (parserclass: private declaration)
>   [: java::java_compatibility_mode _M_compatibility_mode; :]
> %member (parserclass: constructor)
>   [: _M_compatibility_mode = java15_compatibility; :]
>
> %member (optional_declarator_brackets: public declaration)
>   [: int bracket_count; :]
>
> %member (equality_expression_rest: public declaration)
> [:
>   enum equality_operator_enum {
>     op_equal,
>     op_not_equal
>   };
>   equality_operator_enum equality_operator;
>
> :]
>
> As this patch is a bit more intrusive than my previous ones, I'd like to
> have it reviewed before committing it. What do you think?
>
> Bye,
>   Jakob
>
>
> Patches:
> http://stud4.tuwien.ac.at/~e0127236/devel/kdev-pg-flex-port.diff
> http://stud4.tuwien.ac.at/~e0127236/devel/kdev-pg-member.diff
> http://stud4.tuwien.ac.at/~e0127236/devel/kdev-pg-member-java.diff
>
> P.S.:
> Amilcar, why is my mail with real attachments suppressed without any sign
> of waiting for moderation or deletion? That's kind of awkward.
>
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-- 
Roberto Raggi - roberto at kdevelop.org
KDevelop http://www.kdevelop.org