The Pegged parser does not build anymore

[PhilippeSigaud]

Uh oh.

The Pegged parser, generated from regenerate.d does not work any more. DMD says there is a recursive expansion in a getName. The failed rule comes from the small D grammar embedded in the Pegged grammar to read direct code between { } brackets.

That's a mighty regression.

callumenator, could get an eye on this? I'll try to rebuild everything by ditching the D grammar part and see if that fails or not.

[PhilippeSigaud]

Looking a this a bit more:

commit 35a3fc9acf17fdd1d5a109d98fab36abb61c577f works. This was before cal's addition to the Pegged grammar.

But commit d2f522ee5e6c5fc6da8781ddb6374cbf303302a6 (the merging) also works.

Hmmm.

[callumenator]

rdmd regenerate.d works for me at 466a1c4be0f4e637ce3f41c895601dc214a7f7dd but not 99e759bbc87f2e423aac913638f307538b66590c, where I get the same error as you mentioned.

[PhilippeSigaud]

Same here, confirmed. So, my mistake :)

Thanks a lot for the search, I wanted to do that on Sunday, now I can concentrate on correcting this bug.

[PhilippeSigaud]

I did a lot of surgery on the project and stashed a bunch of recent changes into another branch (macro2).

The current master regenerates the Pegged parser OK.

[callumenator]

Have the semantic action changes to the pegged grammar been retained somewhere? It looks like they are no longer in examples.peggedgrammar.d?

[PhilippeSigaud]

On Wed, Jan 23, 2013 at 1:46 AM, callumenator notifications@github.comwrote:

Have the semantic action changes to the pegged grammar been retained somewhere? It looks like they are no longer in examples.peggedgrammar.d?

I dropped them a few commits ago (yesterday or the day before), for that was the only mean I found to get the parser to still function.

The are still there:

git checkout 35e8f7ab4e4636b2e43550fc7beb5c37d3f0e64a

Or, here in raw form:

Action Rule

Action <- :ACTIONOPEN Spacing ((Lambda / qualifiedIdentifier) (:SEPARATOR (Lambda / qualifiedIdentifier))) Spacing :ACTIONCLOSE Lambda <~ (!(ACTIONCLOSE/SEPARATOR) (LambdaItems / NestedList('{',LambdaItems,'}') / .))

LambdaItems <- ~DComment / ~DString / ~DParamList DString <- WYSString / DBQString / TKNString / DLMString

WYSString <- 'r' doublequote (!doublequote .)* doublequote / backquote (!backquote .)* backquote

DBQString <- doublequote (!doublequote Char)* doublequote

TKNString <- (&'q{' ('q' NestedList('{',DString,'}')))

DLMString <- ('q' doublequote) ( (&'{' NestedList('{',DString,'}')) / (&'',DString,') / (&'(' NestedList('(',DString,')')) / (&'<' NestedList('<',DString,'>')) ) doublequote

DComment <- DLineComment / DBlockComment / DNestingBlockComment

DLineComment <- "//" (!endOfLine .)* endOfLine DBlockComment <- "/" (!"/" .)* "*/" DNestingBlockComment <- NestedList("/+","+/")

DParamList <- NestedList('(',')')

Linear nested lists with and without special items

NestedList(L,Items,R) <- ^L ( !(L/R/Items) . )* ( Items / NestedList(L,Items,R) / ( !(L/R/Items) . ) )* ( !(L/R/Items) . )\ ^R

NestedList(L,R) <- ^L ( !(L/R) . )* (NestedList(L,R) / ( !(L/R) . ) )* ( !(L/R) . )\ ^R

[PhilippeSigaud]

An idea I wanted to test was to make {{ ... }} (double curly, no space) the delimiter for raw D code (that would have to contain no pair of no-spaces closing curly braces). That way, the grammar simply become:

# Action Rule
Action      <- SimpleAction / RawCode
SimpleAction <- :ACTIONOPEN Spacing qualifiedIdentifier (:SEPARATOR qualifiedIdentifier)* Spacing :ACTIONCLOSE
RawCode <~ :ACTIONOPEN :ACTIONOPEN (!(ACTIONCLOSE ACTIONCLOSE) .)* :ACTIONCLOSE :ACTIONCLOSE

And RawCode directly produce the string to be mixed in. The only limit is the code must not contain a }} pair, which I deem acceptable. That drastically simplify the grammar and we get back the capacity to insert D code in the grammar.

I thought we had tested the grammar, that's really strange.

[callumenator]

I thought we had tested the grammar, that's really strange.

Well it works at 466a1c4be0f4e637ce3f41c895601dc214a7f7dd, which was only a few days ago, I just thought it was some of the dynamic grammar changes that were causing the trouble.

[PhilippeSigaud]

On Wed, Jan 23, 2013 at 7:25 AM, callumenator notifications@github.comwrote:

I thought we had tested the grammar, that's really strange.

Well it works at 466a1c4https://github.com/PhilippeSigaud/Pegged/commit/466a1c4be0f4e637ce3f41c895601dc214a7f7dd, which was only a few days ago, I just thought it was some of the dynamic grammar changes that were causing the trouble.

I was certain to have tested this commit. Sigh. OK, here we go again.

[PhilippeSigaud]

OK, bad day: my newly generated DMD chokes on to!(string) conversions. Bahhh!

[PhilippeSigaud]

Ahhh.

OK, this seems to work! The Pegged grammar has cal's additions back and I can still dynamically graft new rules to a static parser. Maybe this is a "macros, here we come" moment.

That's commit 0b5ce1bc07541dbb5d407d90a227f42f3bf3194b