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How to achieve context-sensitive char syntax?

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Adrian Aichner

Friday, 6 August 1999 Fri, 6 Aug '99

3:51 p.m.

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Hello All, I try to define a syntax table for a language which uses " for string-quotes. Inside of strings " is used to char-quote ". To get a string of two consecutive double-quotes one would write: """""" My conclusion is that this cannot be done with elisp syntax tables. Am I correct? Any suggestions? Regards, Adrian

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Kyle Jones

Friday, 6 August Fri, 6 Aug

8:17 p.m.

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Adrian Aichner writes:

Hello All, I try to define a syntax table for a language which uses " for string-quotes. Inside of strings " is used to char-quote ". To get a string of two consecutive double-quotes one would write: """"""

Yuck! Unless the langauge disallows empty strings, your example could be parsed four different ways! """""" "" """" """" "" "" "" ""

My conclusion is that this cannot be done with elisp syntax tables. Am I correct?

Yes. The syntax you describe requires the " character to be in two different syntax classes. Not possible.

Any suggestions?

Hack XEmacs to add an ad hoc syntax class for this language. It's not without precedent. The syntax class for ' is tailored for Lisp usage.

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Justin Vallon

Sunday, 8 August Sun, 8 Aug

12:56 a.m.

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On Fri, 6 Aug 1999, Kyle Jones wrote:

Adrian Aichner writes: > > Hello All, > > I try to define a syntax table for a language which uses " for > string-quotes. Inside of strings " is used to char-quote ". > > To get a string of two consecutive double-quotes one would write: > > """"""

SQL, for example: Select "He said ""Quote me"".". Particularly, it makes escaping simple: s/"/""/.

Yuck! Unless the langauge disallows empty strings, your example could be parsed four different ways!

Probably not. The language would most likely disallow two strings without any intervening lexical tokens. I don't see any ambiguity.

"""""" "" """" """" "" "" "" ""

2-4 are strings followed by strings. The first is a single string of two double quotes.

> My conclusion is that this cannot be done with elisp syntax tables. > Am I correct? Yes. The syntax you describe requires the " character to be in two different syntax classes. Not possible. > Any suggestions? Hack XEmacs to add an ad hoc syntax class for this language. It's not without precedent. The syntax class for ' is tailored for Lisp usage.

You could treat "testing""123" as two strings concatenated: "testing" followed by "123". Unless you want to treat the "" specially, it should be easy enough the ignore the special language construct (ie: it becomes "). Disclaimer: I know nothing about xemacs syntax tables. -Justin vallon(a)mindspring.com

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Adrian Aichner
Justin Vallon
Kyle Jones