Array value syntax and escaping

Hello all,

I am currently adding array value handling to the PostgreSQL interface
for the Chicken Scheme compiler[*] and I was wondering if there's a more
detailed documentation for the exact syntax of arrays than the short
natural language explanation in the manual.

There doesn't appear to be a helper function in libpq to escape (and
unescape) string values for use inside array values and I'm concerned
that my homebrew procedures might not be foolproof.

If I understand correctly, the connection's character encoding is also
used to determine how strings sent by "PQsendQueryParams parameters"
(I don't know if there's an unambiguous name for those) are parsed, and
it is conceivable that either through bogus or malicous input a
multibyte array string could be wrongly escaped, which means one array
value could "break out" of its proper position in the array, resulting
in an array of different length or contents than intended.

IMHO, it would be a Good Thing to have helper procedures in libpq.
That would fix the problem once and for all in one place.

I briefly considered "abusing" the PQescapeIdentifier procedure for
escaping since the syntax for literals inside arrays seems to be exactly
like that of SQL identifiers, but I'm not 100% sure about that and I
also think the PQescapeIdentifier procedure shouldn't be overloaded for
this purpose.

Cheers,
Peter

[*] http://chicken.wiki.br/eggref/4/postgresql
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