Executing regex in C code
Hi,
I'm trying to execute the equivalent to '~' with regexp from within C code.
According to pg_operator
<https://github.com/postgres/postgres/blob/c7b8998ebbf310a156aa38022555a24d98fdbfb4/src/include/catalog/pg_operator.h>this
operator for type text corresponds to textregexeq:
DATA(insert OID = 641 ( "~" PGNSP PGUID b f f 25 25 16 0 642 textregexeq
regexeqsel regexeqjoinsel ));
DESCR("matches regular expression, case-sensitive");
I've tried to execute it from the C code:
text * s = cstring_to_text("aa");
text * p = cstring_to_text("a");
return DatumGetBool(DirectFunctionCall2(textregexeq, PointerGetDatum(s),
PointerGetDatum(p)));
But I'm getting an error with collate:
ERROR: could not determine which collation to use for regular expression
HINT: Use the COLLATE clause to set the collation explicitly.
Any hints on how to proceed? Of course if I do select 'aa'~'a'; from psql
it works like a charm.
Thanks in advance.
Gabriel Furstenheim Milerud <furstenheim@gmail.com> writes:
I'm trying to execute the equivalent to '~' with regexp from within C code.
text * s = cstring_to_text("aa");
text * p = cstring_to_text("a");
return DatumGetBool(DirectFunctionCall2(textregexeq, PointerGetDatum(s),
PointerGetDatum(p)));
But I'm getting an error with collate:
ERROR: could not determine which collation to use for regular expression
HINT: Use the COLLATE clause to set the collation explicitly.
Yes, you need to use DirectFunctionCall2Coll() if you're trying to invoke
a collation-aware function. It's probably good enough to pass
DEFAULT_COLLATION_OID, although if you're inside a SQL function of
your own, passing down whatever collation was passed to you would
be a better plan.
regards, tom lane
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Thanks a lot,
That did the trick
Best regards
On 30 July 2017 at 18:26, Tom Lane <tgl@sss.pgh.pa.us> wrote:
Show quoted text
Gabriel Furstenheim Milerud <furstenheim@gmail.com> writes:
I'm trying to execute the equivalent to '~' with regexp from within C
code.
text * s = cstring_to_text("aa");
text * p = cstring_to_text("a");
return DatumGetBool(DirectFunctionCall2(textregexeq,PointerGetDatum(s),
PointerGetDatum(p)));
But I'm getting an error with collate:
ERROR: could not determine which collation to use for regular expression
HINT: Use the COLLATE clause to set the collation explicitly.Yes, you need to use DirectFunctionCall2Coll() if you're trying to invoke
a collation-aware function. It's probably good enough to pass
DEFAULT_COLLATION_OID, although if you're inside a SQL function of
your own, passing down whatever collation was passed to you would
be a better plan.regards, tom lane