These changes allow backtick command evaluation and psql variable
interpolation to happen on substrings of a single meta-command argument.
Formerly, no such evaluations happened at all if the backtick or colon
wasn't the first character of the argument, and we considered an argument
completed as soon as we'd processed one backtick, variable reference, or
quoted substring. A string like 'FOO'BAR was thus taken as two arguments
not one, not exactly what one would expect. In the new coding, an argument
is considered terminated only by unquoted whitespace or backslash.
Also, clean up a bunch of omissions, infelicities and outright errors in
the psql documentation of variables and metacommand argument syntax.
This has been the only documented and encouraged syntax for a long time, and
with extension facilities such as aliases being proposed, it is a good time to
clean up the legacy syntax a bit.
Author: Bernd Helmle <mailings@oopsware.de>
after an unknown or failed psql backslash command, and also while
discarding "extra" arguments of a putatively valid backslash command.
In the case of an unknown/failed command, make sure we discard the
whole rest of the line, rather than trying to resume at the next
backslash. Per discussion with Thomer Gil.
recent discussion. The lexer is used for both SQL command text and
backslash commands. The purpose of this change is to make it easier to
track the behavior of the backend's SQL lexer --- essentially identical
flex rules are now used by psql. Also, this cleans up a lot of very
squirrelly code in mainloop.c and command.c. The flex code is somewhat
bulkier than the removed code, but should be lots easier to maintain.
