Manlio Perillo ha scritto:
Hi.
I'm starting to write a CSS parser with Alex and Happy.
The grammar is defined here:
http://www.w3.org/TR/CSS21/grammar.html
However I have noted that there are some difference in the syntax
between Alex and Flex?
What is the rationale?
One more thing.
Here: http://www.haskell.org/alex/doc/html/alex-files.html
it seems that there is an error with
macrodef := @smac '=' set
| @rmac '=' regexp
it should be
macrodef := $smac '=' set
| @rmac '=' regexp
Ok, this is not an error, sorry.
By the way, here is the list of differences between Alex and Flex I have
found, for people interested:
1) Alex make a distinction between "character set macros" and
"regular expression macros".
2) Alex support the
set '#' set0
syntax for "character set macros"
3) Alex does not support
[_a-z0-9-]
that must be rewritten as
[_a-z0-9\-]
4) In Alex the order of macro definitions is important.
A macro must be defined before it is used in another macro
definition.
5) For reasons I still don't understand, this:
\"([^\n\r\f\\"]|[EMAIL PROTECTED]|@escape)*\"
cause a parse error, but these are ok:
\'([^\n\r\f\\']|[EMAIL PROTECTED]|@escape)*\'
\"([^\n\r\f\\"]|[EMAIL PROTECTED]|@escape)*
6) As with 3), these are not parsed:
[^*]
[^/*]
and must be rewritten as
[^\*]
[^\/\*]
7) I don't understand why, but this is not parsed:
[EMAIL PROTECTED]@nmchar*
The -? at the beginning must be removed.
How can I fix this?
Thanks Manlio Perillo
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