问题
I have compiled ruby 64 bit on an AIX Box. There doesn't seem to be any issue except when I use some specific regular expressions in my code. Here is an example:
/([0-9]){1000}/.match("2")
results in:
RegexpError: too big quantifier in {,}: /([0-9]*){1000}/
When I try reducing the number of repetitions, it seems to work.
I tried digging into the ruby code. But could not understand the reason. Is this some dependency or restriction that we have in AIX/64 bit ruby?
Thanks in advance :)
回答1:
I almost immediately found the answer.
The first thing I did was to search in the ruby source code for the error being thrown. I found that regex.h was responsible for this.
In regex.h, the code flow is something like this:
/* Maximum number of duplicates an interval can allow. */
#ifndef RE_DUP_MAX
#define RE_DUP_MAX ((1 << 15) - 1)
#endif
Now the problem here is RE_DUP_MAX. On AIX box, the same constant has been defined somewhere in /usr/include. I searched for it and found in
/usr/include/NLregexp.h
/usr/include/sys/limits.h
/usr/include/unistd.h
I am not sure which of the three is being used(most probably NLregexp.h). In these headers, the value of RE_DUP_MAX has been set to 255! So there is a cap placed on the number of repetitions of a regex!
In short, the reason is the compilation taking the system defined value than that we define in regex.h!
Hence the issue was solved by reassigning the value of RE_DUP_MAX in regex.h i.e
# ifdef RE_DUP_MAX
# undef RE_DUP_MAX
# endif
# define RE_DUP_MAX ((1 << 15) - 1)
Cheers!
来源：https://stackoverflow.com/questions/8924762/regex-limit-in-ruby-64-bit-aix-compilation