[Mesa-dev] [PATCH 2/2] glcpp: Fix so that trailing punctuation does not prevent macro expansion

[Ian Romanick]

On Sat, Jan 21, 2012 at 09:34:26AM -0800, Carl Worth wrote:
> The trick here is that flex always chooses the rule that matches the most
> text. So with a input text of "two:" which we want to be lexed as an
> IDENTIFIER token "two" followed by an OTHER token ":" the previous OTHER
> rule would match longer as a single token of "two:" which we don't want.
> 
> We prevent this by forcing the OTHER pattern to never match a string which
> has a first character that could be an identifier (that is _, a-z, or A-Z).
> This way the ambiguity is eliminated and this case is lexed correctly.
> ---
>  src/glsl/glcpp/glcpp-lex.l |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/src/glsl/glcpp/glcpp-lex.l b/src/glsl/glcpp/glcpp-lex.l
> index 8661887..20d7fc1 100644
> --- a/src/glsl/glcpp/glcpp-lex.l
> +++ b/src/glsl/glcpp/glcpp-lex.l
> @@ -70,7 +70,7 @@ HSPACE		[ \t]
>  HASH		^{HSPACE}*#{HSPACE}*
>  IDENTIFIER	[_a-zA-Z][_a-zA-Z0-9]*
>  PUNCTUATION	[][(){}.&*~!/%<>^|;,=+-]
> -OTHER		[^][(){}.&*~!/%<>^|;,=#[:space:]+-]+
> +OTHER		[^][_a-zA-Z(){}.&*~!/%<>^|;,=#[:space:]+-][^][(){}.&*~!/%<>^|;,=#[:space:]+-]*

The fix seems correct, but reading that regex made my head hurt.  Is
there a way to refactor the character classes to be more readable?
OTHER is basically
[{PUNCTUATION}{IDENTIFIER_FIRST_CHAR}[:space:]][{PUNCTUATION}[:space:]]*,
right?

>  DIGITS			[0-9][0-9]*
>  DECIMAL_INTEGER		[1-9][0-9]*[uU]?
> -- 
> 1.7.8.3
> 
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