22 Jun
2015
22 Jun
'15
10:42 a.m.
Hi,
is it possible to add such a parser that would consume input, but wouldn't
return anything?
Right now I do things like...
MyParser>>rule
^ ($[ asParser, anotherRule, $] asParser) ==> [ :nodes | nodes second ]
Of course when the rules are more complex, so is the block; however it
seems that this is how it's done in the example parsers...
So, would it be possible to add some kind of Null/Void/Ignore/Throwaway
parser, that would consume the input, but would be omitted from the result?
so the above method could be written as
MyParser>>rule
^ $[ asNullPaser, anotherRule, $] asNullParser
or
MyParser>>rule
^ $[ asParser ignore, anotherRule, $[ asParser ignore
or something else.
Thanks,
Peter
22 Jun
22 Jun
12:59 p.m.
not sure what is the probleme exactly.
if you don't put any semantic action "==> [....]"
then the parser does not produce anything, no?
nicolas
On 22/06/2015 10:42, Peter Uhnák wrote:
Hi,
is it possible to add such a parser that would consume input, but
wouldn't return anything?
Right now I do things like...
MyParser>>rule
^ ($[ asParser, anotherRule, $] asParser) ==> [ :nodes | nodes
second ]
Of course when the rules are more complex, so is the block; however it
seems that this is how it's done in the example parsers...
So, would it be possible to add some kind of
Null/Void/Ignore/Throwaway parser, that would consume the input, but
would be omitted from the result?
so the above method could be written as
MyParser>>rule
^ $[ asNullPaser, anotherRule, $] asNullParser
or
MyParser>>rule
^ $[ asParser ignore, anotherRule, $[ asParser ignore
or something else.
Thanks,
Peter
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1:27 p.m.
The problem is, that in syntax there are often many symbols that are no
longer needed once the string is parsed so I want to get rid of them.
For example imagine a string representation of an JSON array:
'[ 1, 2, 3 ]'
Once the string is parsed, the brackets are no longer needed so I can get
rid of them with a block
MyJsonParser>>array
^ ($[ asParser, arrayElements, $] asParser) ==> [ :nodes | nodes second
]
This way the result of the array will not contain those $[ $] symbols
because I am not interested in them after the parsing.
So, I would prefer to explicitly state that I am not interested in certain
parser after it has done its job.
MyJsonParser>>array
^ $[ asParser ignore, arrayElements, $] asParser ignore
(or the other alternative mentioned in the first post)
Is what I am trying to accomplish clearer?
Peter
7 Jul
7 Jul
2:38 p.m.
Hey, you can achieve your goal by extending the petit parser API as follows;
PPParser>>nullParser
" transforms whatever result to null "
^ self ==> [:e | NullResult instance ]
PPParser>>ignoreNulls
" removes NullResults from result "
^ self ==> [:e | e isCollection
ifTrue: [ e reject: [ :item | item isNullResult ]
ifFalse: [ e ] ]
Cheers,
Jan
On Mon, Jun 22, 2015 at 1:27 PM Peter Uhnák <i.uhnak(a)gmail.com> wrote:
The problem is, that in syntax there are often many
symbols that are no
longer needed once the string is parsed so I want to get rid of them.
For example imagine a string representation of an JSON array:
'[ 1, 2, 3 ]'
Once the string is parsed, the brackets are no longer needed so I can get
rid of them with a block
MyJsonParser>>array
^ ($[ asParser, arrayElements, $] asParser) ==> [ :nodes | nodes
second ]
This way the result of the array will not contain those $[ $] symbols
because I am not interested in them after the parsing.
So, I would prefer to explicitly state that I am not interested in certain
parser after it has done its job.
MyJsonParser>>array
^ $[ asParser ignore, arrayElements, $] asParser ignore
(or the other alternative mentioned in the first post)
Is what I am trying to accomplish clearer?
Peter
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days inactive
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days old
3 comments
3 participants
participants (3)
-
Jan Kurš -
Nicolas Anquetil -
Peter Uhnák