Not able to use x3::skip(skipper)[some recursive rule] in its rule definition
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I've posted the same question in stackoverflow.
https://stackoverflow.com/questions/45282293/spirit-not-able-to-use-x3skipskippersome-recursive-rule-in-its-rule-defin Let's say we want to parse a recursive block like this. When " skip_comments_tag" is prefixed to the block, we skip all comments(/*...*/) within this block recursively.It's easy to come up with a recursive parser as in Coliru. But it doesn't compile (when the Questions:
BTW: TU seperation doesn't solve this. ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Spirit-general mailing list [hidden email] https://lists.sourceforge.net/lists/listinfo/spirit-general |
Re: Not able to use x3::skip(skipper)[some recursive rule] in its rule definition
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On 07/25/2017 03:40 AM, Han Wang wrote:
> I've posted the same question in stackoverflow. > > https://stackoverflow.com/questions/45282293/spirit-not-able-to-use-x3skipskippersome-recursive-rule-in-its-rule-defin > > Let's say we want to parse a recursive block like this. When > "|skip_comments_tag|" is prefixed to the block, we skip all > comments(|/*...*/|) within this block recursively. > > |{{}{skip_comments_tag{{}/*comments*/{/*comments*/}}}}| > > It's easy to come up with a recursive parser as in Coliru > <http://coliru.stacked-crooked.com/a/31fb17064091fae3>. > > |namespaceParser{autoconstruleComment =x3::lit("/*")>>*(x3::char_ > -"*/")>>"*/"|x3::space;x3::rule<structSBlockId>construleBlock;autoconstruleBlock_def > =x3::lit('{')>>*(ruleBlock > |"skip_comments_tag">>x3::skip(ruleComment)[ruleBlock])>>'}';BOOST_SPIRIT_DEFINE(ruleBlock)}| > > But it doesn't compile (when the |parse| function is called) because it > will generate an infinite context (by |x3::make_context| in > |x3::skip_directive|). |x3::no_case| and |x3::with| also have this > problem because they all use |x3::make_context| in the implementation. > > Questions: > > 1. Is there always a better way to write parsers for this kind of > questions to avoid such compile error and how? > 2. Or is the |x3::make_context| implementation considered to be flawed > for this kind of questions? > > BTW: TU seperation doesn't solve this. > You might try the get_rhs branch of a spirit fork here: https://github.com/cppljevans/spirit/tree/get_rhs and then #define BOOST_SPIRIT_GET_RHS_CRTP. As you can see from here: https://github.com/cppljevans/spirit/blob/get_rhs/include/boost/spirit/home/x3/nonterminal/detail/rule.hpp#L140 that will disable the x3::make_context calls. Please let me know if that works. If so, I might be encouraged enough to go to the trouble of creating a pull request despite the need (as pointed out in a private email) that I'll need to document the rationale for the pull request. HTH. -regards, Larry ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Spirit-general mailing list [hidden email] https://lists.sourceforge.net/lists/listinfo/spirit-general |
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Hi Larry, Thanks. I've tried this get_rhs branch but it doesn't solve this problem. Still get the same error. Best regards, Han On Tue, Jul 25, 2017 at 1:21 PM, Larry Evans <[hidden email]> wrote: On 07/25/2017 03:40 AM, Han Wang wrote: ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Spirit-general mailing list [hidden email] https://lists.sourceforge.net/lists/listinfo/spirit-general |
Re: Not able to use x3::skip(skipper)[some recursive rule] in its rule definition
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On 07/25/2017 07:43 AM, Han Wang wrote:
> Hi Larry, > > Thanks. I've tried this get_rhs branch but it doesn't solve this > problem. Still get the same error. > > Best regards, > Han > [snip] OPPS. Sorry about that. I should have read where you say in OP: it will generate an infinite context (by x3::make_context in x3::skip_directive). I just saw the x3::make_context and remembered that was causing long compile times. There's a make_unique_context which avoids the infinite recursion. When that's applied, as shown here: https://github.com/cppljevans/spirit/blob/get_rhs/include/boost/spirit/home/x3/directive/skip.hpp#L40 Compile succeeds fast: make compile time /home/evansl/dwnlds/llvm/3.9/prebuilt/clang+llvm-3.9.0-x86_64-linux-gnu-ubuntu-16.04/bin/clang++ -c -O0 -stdlib=libc++ -std=c++1z -ftemplate-backtrace-limit=0 -fdiagnostics-show-template-tree -fno-elide-type -fmacro-backtrace-limit=0 -c -std=c++14 -ftemplate-depth=1024 -I/home/evansl/prog_dev/boost/releases/ro/boost_1_64_0/sandbox/pull_requests/context_debug_fix.fork/spirit/include -I/home/evansl/prog_dev/boost/releases/ro/boost_1_64_0 -DBOOST_SPIRIT_GET_RHS_CRTP=0 -DBOOST_SPIRIT_ATTR_XFORM_IN_RULE=0 main.cpp In file included from main.cpp:7: In file included from /home/evansl/prog_dev/boost/releases/ro/boost_1_64_0/sandbox/pull_requests/context_debug_fix.fork/spirit/include/boost/spirit/home/x3.hpp:17: In file included from /home/evansl/prog_dev/boost/releases/ro/boost_1_64_0/sandbox/pull_requests/context_debug_fix.fork/spirit/include/boost/spirit/home/x3/nonterminal.hpp:10: /home/evansl/prog_dev/boost/releases/ro/boost_1_64_0/sandbox/pull_requests/context_debug_fix.fork/spirit/include/boost/spirit/home/x3/nonterminal/rule.hpp:18:11: warning: deprecated. May cause link error when using BOOST_SPIRIT_INSTANTIATE. [-W#pragma-messages] #pragma message "deprecated. May cause link error when using BOOST_SPIRIT_INSTANTIATE." ^ /home/evansl/prog_dev/boost/releases/ro/boost_1_64_0/sandbox/pull_requests/context_debug_fix.fork/spirit/include/boost/spirit/home/x3/nonterminal/rule.hpp:22:11: warning: deprecated. May cause excessive compile times when many rules. [-W#pragma-messages] #pragma message "deprecated. May cause excessive compile times when many rules." ^ 2 warnings generated. real 0m2.351s user 0m1.372s sys 0m0.072s Compilation finished at Tue Jul 25 08:53:02 HTH. -regards, Larry ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Spirit-general mailing list [hidden email] https://lists.sourceforge.net/lists/listinfo/spirit-general |
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Hi Larry, I think we cannot just change make_context to make_unique_context here in x3::skip_directive. If there already is a skipper in the context (x3::space e.g), the new skipper (ruleComment) will be ignored (because x3::make_unique_context will simply return the original context). Best regards, Han On Tue, Jul 25, 2017 at 4:02 PM, Larry Evans <[hidden email]> wrote: On 07/25/2017 07:43 AM, Han Wang wrote: ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Spirit-general mailing list [hidden email] https://lists.sourceforge.net/lists/listinfo/spirit-general |
Re: Not able to use x3::skip(skipper)[some recursive rule] in its rule definition
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On 07/25/2017 09:18 AM, Han Wang wrote:
> Hi Larry, > > I think we cannot just change make_context to make_unique_context here > in x3::skip_directive. If there already is a skipper in the context > (x3::space e.g), the new skipper (ruleComment) will be ignored (because > x3::make_unique_context will simply return the original context). > [snip] Good catch. I had assumed that context<ID,val,NEXT> was a dictionary with only 1 value for given ID. However, I guess there could be several entries where ID==skipper_tag and only the 1st one is retrieved by the context.get<ID_>(ID_) member function. I guess there's some method to pop the top value with given ID off the context stack. In that case, I've no idea how to solve the problem. Sorry :( -regards, Larry ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Spirit-general mailing list [hidden email] https://lists.sourceforge.net/lists/listinfo/spirit-general |
Re: Not able to use x3::skip(skipper)[some recursive rule] in its rule definition
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On 07/25/2017 09:54 AM, Larry Evans wrote:
> On 07/25/2017 09:18 AM, Han Wang wrote: >> Hi Larry, >> >> I think we cannot just change make_context to make_unique_context here >> in x3::skip_directive. If there already is a skipper in the context >> (x3::space e.g), the new skipper (ruleComment) will be ignored >> (because x3::make_unique_context will simply return the original >> context). >> > [snip] > Good catch. I had assumed that context<ID,val,NEXT> was a dictionary > with only 1 value for given ID. However, I guess there could be > several entries where ID==skipper_tag and only the 1st one is retrieved > by the context.get<ID_>(ID_) member function. I guess there's some > method to pop the top value with given ID off the context stack. > > In that case, I've no idea how to solve the problem. > > Sorry :( > > -regards, > Larry > I kept trying and *maybe* this: https://github.com/cppljevans/spirit/blob/get_rhs/include/boost/spirit/home/x3/directive/skip.hpp#L85 will solve problem. It did successfully compile & run your test program. HTH. -regards, Larry ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Spirit-general mailing list [hidden email] https://lists.sourceforge.net/lists/listinfo/spirit-general |
Re: Not able to use x3::skip(skipper)[some recursive rule] in its rule definition
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On 07/26/2017 08:37 AM, Larry Evans wrote:
> On 07/25/2017 09:54 AM, Larry Evans wrote: >> On 07/25/2017 09:18 AM, Han Wang wrote: >>> Hi Larry, >>> >>> I think we cannot just change make_context to make_unique_context >>> here in x3::skip_directive. If there already is a skipper in the >>> context (x3::space e.g), the new skipper (ruleComment) will be >>> ignored (because x3::make_unique_context will simply return the >>> original context). >>> >> [snip] >> Good catch. I had assumed that context<ID,val,NEXT> was a dictionary >> with only 1 value for given ID. However, I guess there could be >> several entries where ID==skipper_tag and only the 1st one is retrieved >> by the context.get<ID_>(ID_) member function. I guess there's some >> method to pop the top value with given ID off the context stack. >> >> In that case, I've no idea how to solve the problem. >> >> Sorry :( >> >> -regards, >> Larry >> > > I kept trying and *maybe* this: > > https://github.com/cppljevans/spirit/blob/get_rhs/include/boost/spirit/home/x3/directive/skip.hpp#L85 > > > will solve problem. It did successfully compile & run your test > program. > > HTH. > essentially, close duplication of code in context.hpp. This was done by just modifying the context.hpp detail::make_unique_context slightly. HTH. -regards, Larry ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Spirit-general mailing list [hidden email] https://lists.sourceforge.net/lists/listinfo/spirit-general |
Re: Not able to use x3::skip(skipper)[some recursive rule] in its rule definition
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On 07/27/2017 02:48 AM, Larry Evans wrote:
> On 07/26/2017 08:37 AM, Larry Evans wrote: >> On 07/25/2017 09:54 AM, Larry Evans wrote: >>> On 07/25/2017 09:18 AM, Han Wang wrote: >>>> Hi Larry, >>>> >>>> I think we cannot just change make_context to make_unique_context >>>> here in x3::skip_directive. If there already is a skipper in the >>>> context (x3::space e.g), the new skipper (ruleComment) will be >>>> ignored (because x3::make_unique_context will simply return the >>>> original context). >>>> >>> [snip] >>> Good catch. I had assumed that context<ID,val,NEXT> was a dictionary >>> with only 1 value for given ID. However, I guess there could be >>> several entries where ID==skipper_tag and only the 1st one is retrieved >>> by the context.get<ID_>(ID_) member function. I guess there's some >>> method to pop the top value with given ID off the context stack. >>> >>> In that case, I've no idea how to solve the problem. >>> >>> Sorry :( >>> >>> -regards, >>> Larry >>> >> >> I kept trying and *maybe* this: >> >> https://github.com/cppljevans/spirit/blob/get_rhs/include/boost/spirit/home/x3/directive/skip.hpp#L85 >> >> >> will solve problem. It did successfully compile & run your test >> program. >> >> HTH. >> > Further revision were made to remove the code in skip.hpp which was, > essentially, close duplication of code in context.hpp. This was done > by just modifying the context.hpp detail::make_unique_context slightly. > After further thought, the proposed solution may not always work. I think it *may* suffer the same problem as before in some cases. One such case maybe where the: make_unique_context<skipper_tag>(skipper,context) is called with alternate values for skipper, say, skipper1, skipper2. Then the context would be: context<skipper_tag> ( skipper1 , context<skipper_tag> ( skipper2 , context<skipper_tag> ( skipper1 , unused_type ) ) ) I've no idea what type of grammar might produce this; however, before this thread started, I had no idea would type of grammar would produce your particular problem, which, simplified, produces: context<skipper_tag> ( skipper1 , context<skipper_tag> ( skipper1 , context<skipper_tag> ( skipper1 , unused_type ) ) ) IOW, each time the skip_directive::parse is called, the context is extended. If the skip_directive is in a recursive rule, then it get's extended without end. I've no idea, yet, how to solve this problem. Also, I've not made a test case either so I may be completely wrong. I hope someone else will solve problem. -regards, Larry ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Spirit-general mailing list [hidden email] https://lists.sourceforge.net/lists/listinfo/spirit-general |
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