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Re: If statement vs short if statement
by Bugzilla from npiguet@romandie.com
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Can statements be broken up on multiple lines? If they can't, the easiest
solution you have is probably to treat end of lines just like any other token
in your grammar instead of ignoring them.
then you could just define your statement and if as
Statement = ( Whatever | IfStatement | WhileStatement | Declaration | ...)
<EOL>+
IfStatement = <IF> condition (LongIf | Statement)
LongIf = <EOL> Statement+ (<ELSE> statement+)? <ENDIF>
The advantage of this is that your parser won't need to do any deep,
complicated lookahead to decide which branch to take, so it should be fast
enough.
Are there any other cases that have a short form (say while and for loops, for
example)?
On Sunday 17 May 2009 11:03:22 pm Alex James wrote:
> Hi,
>
> I'm quite to new JavaCC and need a little help with the parsing of an
> if statement in the language I'm trying to replicate.
>
> The language has the following definition for if statements:
>
> <if> condition
> statement+
> (<else>
> statement+)?
> <endif>
>
> It also has a short if statement:
>
> <if> condition statement
>
> Trouble is I can't get my parser to recognise when the short if
> statement has been used as there is nothing to distinguish it from the
> long if statement. The language I'm trying to replicate generally
> ignores end of line characters but seems to take them into account
> when recognising the short if statement. Is there any way I can ignore
> end of line characters except in this one circumstance?
>
> Any help would be greatly appreciated.
>
> Cheers,
>
> Alex
>
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solution you have is probably to treat end of lines just like any other token
in your grammar instead of ignoring them.
then you could just define your statement and if as
Statement = ( Whatever | IfStatement | WhileStatement | Declaration | ...)
<EOL>+
IfStatement = <IF> condition (LongIf | Statement)
LongIf = <EOL> Statement+ (<ELSE> statement+)? <ENDIF>
The advantage of this is that your parser won't need to do any deep,
complicated lookahead to decide which branch to take, so it should be fast
enough.
Are there any other cases that have a short form (say while and for loops, for
example)?
On Sunday 17 May 2009 11:03:22 pm Alex James wrote:
> Hi,
>
> I'm quite to new JavaCC and need a little help with the parsing of an
> if statement in the language I'm trying to replicate.
>
> The language has the following definition for if statements:
>
> <if> condition
> statement+
> (<else>
> statement+)?
> <endif>
>
> It also has a short if statement:
>
> <if> condition statement
>
> Trouble is I can't get my parser to recognise when the short if
> statement has been used as there is nothing to distinguish it from the
> long if statement. The language I'm trying to replicate generally
> ignores end of line characters but seems to take them into account
> when recognising the short if statement. Is there any way I can ignore
> end of line characters except in this one circumstance?
>
> Any help would be greatly appreciated.
>
> Cheers,
>
> Alex
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: users-unsubscribe@...
> For additional commands, e-mail: users-help@...
---------------------------------------------------------------------
To unsubscribe, e-mail: users-unsubscribe@...
For additional commands, e-mail: users-help@...
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