digitalmars.D - Redundancy/conflicts in expression rules.

Iain Buclaw (81/81) Feb 12 2014 This might be because the rules I have in place are not complete

Brian Schott (3/7) Feb 12 2014 It's dangerous to go alone. Take this!

Iain Buclaw (18/27) Feb 12 2014 Thanks! Having a look at D.g4, I'm seeing that you do the same with the...
Iain Buclaw (3/17) Feb 12 2014 In any case, everything looks lean enough that I'll probably believe

Walter Bright (2/4) Feb 12 2014 Should issue pull requests for errors found in the grammar!

Iain Buclaw (2/7) Feb 12 2014 Will do ... in the morning.

Brian Schott (2/13) Feb 12 2014 See_also: http://d.puremagic.com/issues/show_bug.cgi?id=10233

Walter Bright (3/15) Feb 12 2014 Thank you. It's important to make such a log of all such errors you find...

Iain Buclaw (3/27) Feb 13 2014 I checked over the already existing reports, and this is what I'm seeing...

Brian Schott (8/13) Feb 12 2014 Use of my parser keeps finding places where my grammar is wrong.

Kenji Hara (4/25) Feb 12 2014 In git head, 'Grammar' page is added.
Iain Buclaw (2/27) Feb 13 2014 Bleh, that contains the same mistakes!

Walter Bright (4/10) Feb 14 2014 It should, because it should contain exactly the same grammar as is dist...

Dejan Lekic (3/12) Feb 18 2014 Brian's ANTLR grammar file is one that matches closely current
Marco Leise (5/15) Feb 18 2014 Is it a bad sign if I happen to remember the reference ? :p

Steven Schveighoffer (4/17) Feb 18 2014 No, but it is bad if the "da da da DAAAAA" sound plays in your head whil...

Rainer Schuetze (7/43) Feb 14 2014 I think this is by design to disallow comparison operators and binary

Iain Buclaw (22/28) Feb 15 2014 Yeah, I didn't buy that argument at first. Not least because it didn't
Iain Buclaw (12/22) Feb 18 2014 As soon as I introduced

"Iain Buclaw" <ibuclaw gdcproject.org> writes:

This might be because the rules I have in place are not complete 
(I'm not implementing a complete D expression parser), but I have 
my doubts on this, and currently leaning on a possible problem in 
the documentation.


I've built up rules in yacc based on what's documented here: 
http://dlang.org/expression.html

However I seem to be getting shift/reduce conflicts around:

AndAndExpression:
         OrExpression
|       AndAndExpression && OrExpression
         CmpExpression
|       AndAndExpression && CmpExpression
;

OrExpression:
         XorExpression
|       OrExpression | XorExpression
;

XorExpression:
         AndExpression
|       XorExpression ^ AndExpression
;

AndExpression:
         ShiftExpression
|       AndExpression & ShiftExpression
;

CmpExpression:
         ShiftExpression
|       EqualExpression
|       IdentityExpression
|       RelExpression
;

CmpExpression:
         ShiftExpression
|       EqualExpression
|       IdentityExpression
|       RelExpression
;


---
Conflict between 'XorExpression: XorExpression '^' AndExpression' 
and token '&'
Conflict between 'ShiftExpression: ShiftExpression RSH 
AddExpression' and token '+'
Conflict between 'ShiftExpression: ShiftExpression RSH 
AddExpression' and token '-'
Conflict between 'ShiftExpression: ShiftExpression LSH 
AddExpression' and token '+'
Conflict between 'ShiftExpression: ShiftExpression LSH 
AddExpression' and token '-'
Conflict between 'AddExpression: AddExpression '+' MulExpression' 
and token '*'
Conflict between 'AddExpression: AddExpression '-' MulExpression' 
and token '*'
---


It's not too much of a problem, I can tweak it (so it follows 
same-ish rules as Java) and it will pass just fine:

AndAndExpression:
         OrExpression
|       AndAndExpression && OrExpression
;

OrExpression:
         XorExpression
|       OrExpression | XorExpression
;

XorExpression:
         AndExpression
|       XorExpression ^ AndExpression
;

AndExpression:
         CmpExpression
|       AndExpression & CmpExpression
;

CmpExpression:
         ShiftExpression
|       EqualExpression
|       IdentityExpression
|       RelExpression
;


I'm just curious if anyone else has stumbled onto this, and 
whether or not it's just human error on my part.  :o)

Regards
Iain.

Feb 12 2014

"Brian Schott" <briancschott gmail.com> writes:

On Thursday, 13 February 2014 at 00:00:11 UTC, Iain Buclaw wrote:
 I'm just curious if anyone else has stumbled onto this, and 
 whether or not it's just human error on my part.  :o)

 Regards
 Iain.

It's dangerous to go alone. Take this!

https://github.com/Hackerpilot/DGrammar

Feb 12 2014

Iain Buclaw <ibuclaw gdcproject.org> writes:

On 13 February 2014 00:06, Brian Schott <briancschott gmail.com> wrote:
 On Thursday, 13 February 2014 at 00:00:11 UTC, Iain Buclaw wrote:
 I'm just curious if anyone else has stumbled onto this, and whether or not
 it's just human error on my part.  :o)

 Regards
 Iain.


 It's dangerous to go alone. Take this!

 https://github.com/Hackerpilot/DGrammar

Thanks!  Having a look at D.g4, I'm seeing that you do the same with the rules:

andAndExpression:
      orExpression
    | andAndExpression '&&' orExpression
    ;

/*...*/

andExpression:
      cmpExpression
    | andExpression '&' cmpExpression
    ;

cmpExpression:
      shiftExpression
    | equalExpression
    | identityExpression
    | relExpression
    | inExpression
    ;

Feb 12 2014

Iain Buclaw <ibuclaw gdcproject.org> writes:

On 13 February 2014 00:18, Iain Buclaw <ibuclaw gdcproject.org> wrote:
 On 13 February 2014 00:06, Brian Schott <briancschott gmail.com> wrote:
 On Thursday, 13 February 2014 at 00:00:11 UTC, Iain Buclaw wrote:
 I'm just curious if anyone else has stumbled onto this, and whether or not
 it's just human error on my part.  :o)

 Regards
 Iain.


 It's dangerous to go alone. Take this!

 https://github.com/Hackerpilot/DGrammar

 Thanks!  Having a look at D.g4, I'm seeing that you do the same with the rules:

In any case, everything looks lean enough that I'll probably believe
your documented grammar more than the official dlang site. ;-)

Feb 12 2014

Walter Bright <newshound2 digitalmars.com> writes:

On 2/12/2014 4:24 PM, Iain Buclaw wrote:
 In any case, everything looks lean enough that I'll probably believe
 your documented grammar more than the official dlang site. ;-)

Should issue pull requests for errors found in the grammar!

Feb 12 2014

Iain Buclaw <ibuclaw gdcproject.org> writes:

On 13 February 2014 01:16, Walter Bright <newshound2 digitalmars.com> wrote:
 On 2/12/2014 4:24 PM, Iain Buclaw wrote:
 In any case, everything looks lean enough that I'll probably believe
 your documented grammar more than the official dlang site. ;-)


 Should issue pull requests for errors found in the grammar!

Will do ... in the morning.

Feb 12 2014

"Brian Schott" <briancschott gmail.com> writes:

On Thursday, 13 February 2014 at 01:28:39 UTC, Iain Buclaw wrote:
 On 13 February 2014 01:16, Walter Bright 
 <newshound2 digitalmars.com> wrote:
 On 2/12/2014 4:24 PM, Iain Buclaw wrote:
 In any case, everything looks lean enough that I'll probably 
 believe
 your documented grammar more than the official dlang site. ;-)


 Should issue pull requests for errors found in the grammar!

 Will do ... in the morning.

See_also: http://d.puremagic.com/issues/show_bug.cgi?id=10233

Feb 12 2014

Walter Bright <newshound2 digitalmars.com> writes:

On 2/12/2014 5:37 PM, Brian Schott wrote:
 On Thursday, 13 February 2014 at 01:28:39 UTC, Iain Buclaw wrote:
 On 13 February 2014 01:16, Walter Bright <newshound2 digitalmars.com> wrote:
 On 2/12/2014 4:24 PM, Iain Buclaw wrote:
 In any case, everything looks lean enough that I'll probably believe
 your documented grammar more than the official dlang site. ;-)


 Should issue pull requests for errors found in the grammar!

 Will do ... in the morning.

 See_also: http://d.puremagic.com/issues/show_bug.cgi?id=10233

Thank you. It's important to make such a log of all such errors you find, 
otherwise the next poor soul will have to suffer through it all over again.

Feb 12 2014

Iain Buclaw <ibuclaw gdcproject.org> writes:

On 13 February 2014 02:23, Walter Bright <newshound2 digitalmars.com> wrote:
 On 2/12/2014 5:37 PM, Brian Schott wrote:
 On Thursday, 13 February 2014 at 01:28:39 UTC, Iain Buclaw wrote:
 On 13 February 2014 01:16, Walter Bright <newshound2 digitalmars.com>
 wrote:
 On 2/12/2014 4:24 PM, Iain Buclaw wrote:
 In any case, everything looks lean enough that I'll probably believe
 your documented grammar more than the official dlang site. ;-)



 Should issue pull requests for errors found in the grammar!


 Will do ... in the morning.


 See_also: http://d.puremagic.com/issues/show_bug.cgi?id=10233


 Thank you. It's important to make such a log of all such errors you find,
 otherwise the next poor soul will have to suffer through it all over again.

I checked over the already existing reports, and this is what I'm seeing:

http://d.puremagic.com/issues/show_bug.cgi?id=10232

Feb 13 2014

"Brian Schott" <briancschott gmail.com> writes:

On Thursday, 13 February 2014 at 01:16:47 UTC, Walter Bright 
wrote:
 On 2/12/2014 4:24 PM, Iain Buclaw wrote:
 In any case, everything looks lean enough that I'll probably 
 believe
 your documented grammar more than the official dlang site. ;-)

 Should issue pull requests for errors found in the grammar!

Use of my parser keeps finding places where my grammar is wrong. 
Here's an example from today:

https://github.com/Hackerpilot/Dscanner/commit/54118e905f55239fb7c03c101db84b22e4368e51#diff-6331f8b31e134d0bacb245c850fe5404

This reminds me that I haven't synchronized the parser's doc 
comments with that ANTLR file in a while. Hopefully I'll have 
time for that on the weekend.

Feb 12 2014

Kenji Hara <k.hara.pg gmail.com> writes:

2014-02-13 9:24 GMT+09:00 Iain Buclaw <ibuclaw gdcproject.org>:

 On 13 February 2014 00:18, Iain Buclaw <ibuclaw gdcproject.org> wrote:
 On 13 February 2014 00:06, Brian Schott <briancschott gmail.com> wrote:
 On Thursday, 13 February 2014 at 00:00:11 UTC, Iain Buclaw wrote:
 I'm just curious if anyone else has stumbled onto this, and whether or



 not
 it's just human error on my part.  :o)

 Regards
 Iain.


 It's dangerous to go alone. Take this!

 https://github.com/Hackerpilot/DGrammar

 Thanks!  Having a look at D.g4, I'm seeing that you do the same with the

 rules:

 In any case, everything looks lean enough that I'll probably believe
 your documented grammar more than the official dlang site. ;-)

In git head, 'Grammar' page is added.

https://github.com/D-Programming-Language/dlang.org/blob/master/grammar.dd

Kenji Hara

Feb 12 2014

Iain Buclaw <ibuclaw gdcproject.org> writes:

On 13 February 2014 06:17, Kenji Hara <k.hara.pg gmail.com> wrote:
 2014-02-13 9:24 GMT+09:00 Iain Buclaw <ibuclaw gdcproject.org>:

 On 13 February 2014 00:18, Iain Buclaw <ibuclaw gdcproject.org> wrote:
 On 13 February 2014 00:06, Brian Schott <briancschott gmail.com> wrote:
 On Thursday, 13 February 2014 at 00:00:11 UTC, Iain Buclaw wrote:
 I'm just curious if anyone else has stumbled onto this, and whether or
 not
 it's just human error on my part.  :o)

 Regards
 Iain.


 It's dangerous to go alone. Take this!

 https://github.com/Hackerpilot/DGrammar

 Thanks!  Having a look at D.g4, I'm seeing that you do the same with the
 rules:

 In any case, everything looks lean enough that I'll probably believe
 your documented grammar more than the official dlang site. ;-)


 In git head, 'Grammar' page is added.

 https://github.com/D-Programming-Language/dlang.org/blob/master/grammar.dd

Bleh, that contains the same mistakes!

Feb 13 2014

Walter Bright <newshound2 digitalmars.com> writes:

On 2/13/2014 12:42 AM, Iain Buclaw wrote:
 On 13 February 2014 06:17, Kenji Hara <k.hara.pg gmail.com> wrote:
 In git head, 'Grammar' page is added.

 https://github.com/D-Programming-Language/dlang.org/blob/master/grammar.dd

 Bleh, that contains the same mistakes!

It should, because it should contain exactly the same grammar as is distributed 
around the rest of the spec.

The two should be corrected in sync, not independently.

Feb 14 2014

"Dejan Lekic" <dejan.lekic gmail.com> writes:

On Thursday, 13 February 2014 at 00:06:11 UTC, Brian Schott wrote:
 On Thursday, 13 February 2014 at 00:00:11 UTC, Iain Buclaw 
 wrote:
 I'm just curious if anyone else has stumbled onto this, and 
 whether or not it's just human error on my part.  :o)

 Regards
 Iain.

 It's dangerous to go alone. Take this!

 https://github.com/Hackerpilot/DGrammar

Brian's ANTLR grammar file is one that matches closely current 
stat of affairs. I use it in two small Java apps. :)

Feb 18 2014

Marco Leise <Marco.Leise gmx.de> writes:

Am Thu, 13 Feb 2014 00:06:10 +0000
schrieb "Brian Schott" <briancschott gmail.com>:

 On Thursday, 13 February 2014 at 00:00:11 UTC, Iain Buclaw wrote:
 I'm just curious if anyone else has stumbled onto this, and 
 whether or not it's just human error on my part.  :o)

 Regards
 Iain.

 
 It's dangerous to go alone. Take this!
 
 https://github.com/Hackerpilot/DGrammar

Is it a bad sign if I happen to remember the reference ? :p

-- 
Marco

Feb 18 2014

"Steven Schveighoffer" <schveiguy yahoo.com> writes:

On Tue, 18 Feb 2014 13:18:00 -0500, Marco Leise <Marco.Leise gmx.de> wrote:

 Am Thu, 13 Feb 2014 00:06:10 +0000
 schrieb "Brian Schott" <briancschott gmail.com>:

 On Thursday, 13 February 2014 at 00:00:11 UTC, Iain Buclaw wrote:
 I'm just curious if anyone else has stumbled onto this, and
 whether or not it's just human error on my part.  :o)

 Regards
 Iain.

 It's dangerous to go alone. Take this!

 https://github.com/Hackerpilot/DGrammar

 Is it a bad sign if I happen to remember the reference ? :p

No, but it is bad if the "da da da DAAAAA" sound plays in your head while  
reading it :)

-Steve

Feb 18 2014

Rainer Schuetze <r.sagitario gmx.de> writes:

On 13.02.2014 01:00, Iain Buclaw wrote:
 This might be because the rules I have in place are not complete (I'm
 not implementing a complete D expression parser), but I have my doubts
 on this, and currently leaning on a possible problem in the documentation.


 I've built up rules in yacc based on what's documented here:
 http://dlang.org/expression.html

 However I seem to be getting shift/reduce conflicts around:

 AndAndExpression:
          OrExpression
 |       AndAndExpression && OrExpression
          CmpExpression
 |       AndAndExpression && CmpExpression
 ;

 OrExpression:
          XorExpression
 |       OrExpression | XorExpression
 ;

 XorExpression:
          AndExpression
 |       XorExpression ^ AndExpression
 ;

 AndExpression:
          ShiftExpression
 |       AndExpression & ShiftExpression
 ;

 CmpExpression:
          ShiftExpression
 |       EqualExpression
 |       IdentityExpression
 |       RelExpression
 ;

 CmpExpression:
          ShiftExpression
 |       EqualExpression
 |       IdentityExpression
 |       RelExpression
 ;

I think this is by design to disallow comparison operators and binary 
operators in the same expression without paranthesis:

int x = a & b < c;

op.d(2): Error: b < c must be parenthesized when next to operator &

The grammar in the spec doesn't play nice with generators and isn't 
always correct, but in this case, I think it is.

Feb 14 2014

Iain Buclaw <ibuclaw gdcproject.org> writes:

On 14 February 2014 19:40, Rainer Schuetze <r.sagitario gmx.de> wrote:
 I think this is by design to disallow comparison operators and binary
 operators in the same expression without paranthesis:

 int x = a & b < c;

Yeah, I didn't buy that argument at first. Not least because it didn't
look like the conflicts came from '&'


 op.d(2): Error: b < c must be parenthesized when next to operator &

 The grammar in the spec doesn't play nice with generators and isn't always
 correct, but in this case, I think it is.

Enforced brackets could be what is missing here...

---
AndAndExpression:
        ( OrExpression )
|       AndAndExpression && ( OrExpression )
|       CmpExpression
|       AndAndExpression && CmpExpression
;

/* ... */

AndExpression:
        CmpExpression
|       AndExpression & ( CmpExpression )
;
---

Bison likes it... however that seems to have broken expression parsing
in other ways.  I assume this is because I haven't yet introduced
brackets into the grammar yet.  :o)

Regards
Iain.

Feb 15 2014

Iain Buclaw <ibuclaw gdcproject.org> writes:

On 15 February 2014 20:09, Iain Buclaw <ibuclaw gdcproject.org> wrote:
 On 14 February 2014 19:40, Rainer Schuetze <r.sagitario gmx.de> wrote:
 I think this is by design to disallow comparison operators and binary
 operators in the same expression without paranthesis:

 int x = a & b < c;

 Yeah, I didn't buy that argument at first. Not least because it didn't
 look like the conflicts came from '&'

As soon as I introduced

PrimaryExpression:
        ( Expression )
;

I just ended up reverting it back, so the expression parser happily
accepts (a & b < c); as well as variants with multiple brackets
inside.

At the moment it's just good to get a D expression evaluator thats'
actually working, then worry about was is invalid D later. :o)

Regards
Iain.

Feb 18 2014

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