On 1/29/19 1:15 AM, Andy Goth wrote:
I wish to define custom aggregate functions in Tcl
Initial implementation:
https://chiselapp.com/user/andy/repository/sqlite-andy/info/e0689f05d1f8792d
Sample program, intended to be run from the root of a built SQLite tree:
#!/usr/bin/env tclsh
load .libs/libtclsqlite3.so
sqlite3 db
db function incr -deterministic {
apply {{arg} {
incr arg
}}
}
db function list -deterministic -aggregate {
apply {{state args} {
concat $state $args
}}
}
puts [db eval {
SELECT list(column1, ''), incr(42)
FROM (VALUES ('#'), ('#'), (' c '), ('\'), ('\\'), ('{ xx '),
('}'))
}]
db close
# vim: set sts=4 sw=4 tw=80 et ft=tcl:
Here's the output:
{{#} {} # {} { c } {} \\ {} {\\} {} \{\ xx\ {} \} {}} 43
Notice that the first # element is brace-quoted and the second one is
not. This demonstrates TIP 401 compliance (http://tip.tcl.tk/401) in
recent Tcl.
Before I can call this project finished, I need to update the test suite
and documentation. But I didn't want to wait for that to release the
code I've already written, so here you go.
As a separate project, I would like to improve the Tcl script dispatch.
For several reasons, safeToUseEvalObjv() doesn't really meet its stated
goal. I have a lot to say about this but should wait until another time
to go into detail. Let's finish the aggregate function project first.
Another good follow-on project would be adding support for window
functions. Before I can take that on, I need to gain some experience
using, let alone writing, window functions.
--
Andy Goth | <andrew.m.goth/at/gmail/dot/com>
_______________________________________________
sqlite-users mailing list
sqlite-users@mailinglists.sqlite.org
http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
