PetitParser problem with plus
There is something about plus that I donât understand. In the following code if I parse for (x , x) then I get what I expect. If I parse for (x plus) then the image hangs. What am I doing wrong? James | a notA x y | a := $a asParser. notA := $a asParser negate star flatten. x := a / notA. y := x , x. âworks fineâ y := x plus. ânever finishesâ ^y end parse: 'abâ.
With x, x it will only go to 2 level deep. With the plus you allow to go as far as the x rule succeed and your x rule always succeed because notA always succeed due to the star without consuming anything so you fall into infinite loop. 2014-12-18 6:47 GMT+01:00 James Foster <Smalltalk@jgfoster.net>:
There is something about plus that I donât understand. In the following code if I parse for (x , x) then I get what I expect. If I parse for (x plus) then the image hangs. What am I doing wrong?
James
| a notA x y | a := $a asParser. notA := $a asParser negate star flatten. x := a / notA. y := x , x. âworks fineâ y := x plus. ânever finishesâ ^y end parse: 'abâ.
-- *Guillaume Larcheveque*
So you just have to remove the #star in notA or replace it by #plus to makes it succeed only when it consume at least one character 2014-12-18 7:54 GMT+01:00 Guillaume Larcheveque < guillaume.larcheveque@gmail.com>:
With x, x it will only go to 2 level deep.
With the plus you allow to go as far as the x rule succeed and your x rule always succeed because notA always succeed due to the star without consuming anything so you fall into infinite loop.
2014-12-18 6:47 GMT+01:00 James Foster <Smalltalk@jgfoster.net>:
There is something about plus that I donât understand. In the following code if I parse for (x , x) then I get what I expect. If I parse for (x plus) then the image hangs. What am I doing wrong?
James
| a notA x y | a := $a asParser. notA := $a asParser negate star flatten. x := a / notA. y := x , x. âworks fineâ y := x plus. ânever finishesâ ^y end parse: 'abâ.
-- *Guillaume Larcheveque*
-- *Guillaume Larcheveque*
Exactly... This happens so often that we should add some warning somewhere in these cases.... Cheers, Jan On 18 December 2014 at 08:36, Guillaume Larcheveque < guillaume.larcheveque@gmail.com> wrote:
So you just have to remove the #star in notA or replace it by #plus to makes it succeed only when it consume at least one character
2014-12-18 7:54 GMT+01:00 Guillaume Larcheveque < guillaume.larcheveque@gmail.com>:
With x, x it will only go to 2 level deep.
With the plus you allow to go as far as the x rule succeed and your x rule always succeed because notA always succeed due to the star without consuming anything so you fall into infinite loop.
2014-12-18 6:47 GMT+01:00 James Foster <Smalltalk@jgfoster.net>:
There is something about plus that I donât understand. In the following code if I parse for (x , x) then I get what I expect. If I parse for (x plus) then the image hangs. What am I doing wrong?
James
| a notA x y | a := $a asParser. notA := $a asParser negate star flatten. x := a / notA. y := x , x. âworks fineâ y := x plus. ânever finishesâ ^y end parse: 'abâ.
-- *Guillaume Larcheveque*
-- *Guillaume Larcheveque*
Could one of you write a small paragraph for the petit parser chapter? Le 18/12/14 09:07, Jan Kurš a écrit :
Exactly...
This happens so often that we should add some warning somewhere in these cases....
Cheers, Jan
On 18 December 2014 at 08:36, Guillaume Larcheveque <guillaume.larcheveque@gmail.com <mailto:guillaume.larcheveque@gmail.com>> wrote:
So you just have to remove the #star in notA or replace it by #plus to makes it succeed only when it consume at least one character
2014-12-18 7:54 GMT+01:00 Guillaume Larcheveque <guillaume.larcheveque@gmail.com <mailto:guillaume.larcheveque@gmail.com>>:
With x, x it will only go to 2 level deep.
With the plus you allow to go as far as the x rule succeed and your x rule always succeed because notA always succeed due to the star without consuming anything so you fall into infinite loop.
2014-12-18 6:47 GMT+01:00 James Foster <Smalltalk@jgfoster.net <mailto:Smalltalk@jgfoster.net>>:
There is something about plus that I donât understand. In the following code if I parse for (x , x) then I get what I expect. If I parse for (x plus) then the image hangs. What am I doing wrong?
James
| a notA x y | a := $a asParser. notA := $a asParser negate star flatten. x := a / notA. y := x , x. âworks fineâ y := x plus. ânever finishesâ ^y end parse: 'abâ.
-- *Guillaume Larcheveque*
-- *Guillaume Larcheveque*
You mean deep into pharo? Or something else? I can do this... On 21 December 2014 at 13:27, stepharo <stepharo@free.fr> wrote:
Could one of you write a small paragraph for the petit parser chapter?
Le 18/12/14 09:07, Jan Kurš a écrit :
Exactly...
This happens so often that we should add some warning somewhere in these cases....
Cheers, Jan
On 18 December 2014 at 08:36, Guillaume Larcheveque < guillaume.larcheveque@gmail.com> wrote:
So you just have to remove the #star in notA or replace it by #plus to makes it succeed only when it consume at least one character
2014-12-18 7:54 GMT+01:00 Guillaume Larcheveque < guillaume.larcheveque@gmail.com>:
With x, x it will only go to 2 level deep.
With the plus you allow to go as far as the x rule succeed and your x rule always succeed because notA always succeed due to the star without consuming anything so you fall into infinite loop.
2014-12-18 6:47 GMT+01:00 James Foster <Smalltalk@jgfoster.net>:
There is something about plus that I donât understand. In the following code if I parse for (x , x) then I get what I expect. If I parse for (x plus) then the image hangs. What am I doing wrong?
James
| a notA x y | a := $a asParser. notA := $a asParser negate star flatten. x := a / notA. y := x , x. âworks fineâ y := x plus. ânever finishesâ ^y end parse: 'abâ.
-- *Guillaume Larcheveque*
-- *Guillaume Larcheveque*
Le 31/12/14 16:37, Jan Kurš a écrit :
You mean deep into pharo? Or something else? I can do this...
Yes I mean let us improve **OUR** documentation. Soon we will release an official version of Deep into Pharo. Then we will convert it to pillar and this means that we will all the Pharo books online and on different formats. Stef
On 21 December 2014 at 13:27, stepharo <stepharo@free.fr <mailto:stepharo@free.fr>> wrote:
Could one of you write a small paragraph for the petit parser chapter?
Le 18/12/14 09:07, Jan Kurš a écrit :
Exactly...
This happens so often that we should add some warning somewhere in these cases....
Cheers, Jan
On 18 December 2014 at 08:36, Guillaume Larcheveque <guillaume.larcheveque@gmail.com <mailto:guillaume.larcheveque@gmail.com>> wrote:
So you just have to remove the #star in notA or replace it by #plus to makes it succeed only when it consume at least one character
2014-12-18 7:54 GMT+01:00 Guillaume Larcheveque <guillaume.larcheveque@gmail.com <mailto:guillaume.larcheveque@gmail.com>>:
With x, x it will only go to 2 level deep.
With the plus you allow to go as far as the x rule succeed and your x rule always succeed because notA always succeed due to the star without consuming anything so you fall into infinite loop.
2014-12-18 6:47 GMT+01:00 James Foster <Smalltalk@jgfoster.net <mailto:Smalltalk@jgfoster.net>>:
There is something about plus that I donât understand. In the following code if I parse for (x , x) then I get what I expect. If I parse for (x plus) then the image hangs. What am I doing wrong?
James
| a notA x y | a := $a asParser. notA := $a asParser negate star flatten. x := a / notA. y := x , x. âworks fineâ y := x plus. ânever finishesâ ^y end parse: 'abâ.
-- *Guillaume Larcheveque*
-- *Guillaume Larcheveque*
That did it and it makes sense. Thanks so much!
On Dec 17, 2014, at 11:36 PM, Guillaume Larcheveque <guillaume.larcheveque@gmail.com> wrote:
So you just have to remove the #star in notA or replace it by #plus to makes it succeed only when it consume at least one character
2014-12-18 7:54 GMT+01:00 Guillaume Larcheveque <guillaume.larcheveque@gmail.com <mailto:guillaume.larcheveque@gmail.com>>: With x, x it will only go to 2 level deep.
With the plus you allow to go as far as the x rule succeed and your x rule always succeed because notA always succeed due to the star without consuming anything so you fall into infinite loop.
2014-12-18 6:47 GMT+01:00 James Foster <Smalltalk@jgfoster.net <mailto:Smalltalk@jgfoster.net>>: There is something about plus that I donât understand. In the following code if I parse for (x , x) then I get what I expect. If I parse for (x plus) then the image hangs. What am I doing wrong?
James
| a notA x y | a := $a asParser. notA := $a asParser negate star flatten. x := a / notA. y := x , x. âworks fineâ y := x plus. ânever finishesâ ^y end parse: 'abâ.
-- Guillaume Larcheveque
-- Guillaume Larcheveque
participants (4)
-
Guillaume Larcheveque -
James Foster -
Jan Kurš -
stepharo