Re: proposal: unescape_text function - Mailing list pgsql-hackers

st 2. 12. 2020 v 9:23 odesílatel Peter Eisentraut <peter.eisentraut@enterprisedb.com> napsal:

On 2020-11-30 22:15, Pavel Stehule wrote:
>     I would like some supporting documentation on this.  So far we only
>     have
>     one stackoverflow question, and then this implementation, and they are
>     not even the same format.  My worry is that if there is not precise
>     specification, then people are going to want to add things in the
>     future, and there will be no way to analyze such requests in a
>     principled way.
>
>
> I checked this and it is "prefix backslash-u hex" used by Java,
> JavaScript  or RTF -
> https://billposer.org/Software/ListOfRepresentations.html

Heh.  The fact that there is a table of two dozen possible
representations kind of proves my point that we should be deliberate in
picking one.

I do see Oracle unistr() on that list, which appears to be very similar
to what you are trying to do here.  Maybe look into aligning with that.

unistr is a primitive form of proposed function.  But it can be used as a base. The format is compatible with our  "4.1.2.3. String Constants with Unicode Escapes".

What do you think about the following proposal?

1. unistr(text) .. compatible with Postgres unicode escapes - it is enhanced against Oracle, because Oracle's unistr doesn't support 6 digits unicodes.

2. there can be optional parameter "prefix" with default "\". But with "\u" it can be compatible with Java or Python.

What do you think about it?

Pavel