This gets us to a point where psqlscan.l can be used by other frontend
programs for the same purpose psql uses it for, ie to detect when it's
collected a complete SQL command from input that is divided across
line boundaries. Moreover, other programs can supply their own lexers
for backslash commands of their own choosing. A follow-on patch will
use this in pgbench.
The end result here is roughly the same as in Kyotaro Horiguchi's
0001-Make-SQL-parser-part-of-psqlscan-independent-from-ps.patch, although
the details of the method for switching between lexers are quite different.
Basically, in this patch we share the entire PsqlScanState, YY_BUFFER_STATE
stack, *and* yyscan_t between different lexers. The only thing we need
to do to switch to a different lexer is to make sure the start_state is
valid for the new lexer. This works because flex doesn't keep any other
persistent state that depends on the specific lexing tables generated for
a particular .l file. (We are assuming that both lexers are built with
the same flex version, or at least versions that are compatible with
respect to the contents of yyscan_t; but that doesn't seem likely to
be a big problem in practice, considering how slowly flex changes.)
Aside from being more efficient than Horiguchi-san's original solution,
this avoids possible corner-case changes in semantics: the original code
was capable of popping the input buffer stack while still staying in
backslash-related parsing states. I'm not sure that that equates to any
useful user-visible behaviors, but I'm not sure it doesn't either, so
I'm loath to assume that we only need to consider the topmost buffer when
parsing a backslash command.
I've attempted to update the MSVC build scripts for the added .l file,
but will rely on the buildfarm to see if I missed anything.
Kyotaro Horiguchi and Tom Lane
Remove assorted external references from psqlscan.l in preparation for
making it usable by other frontend programs. This mostly involves
getting rid of direct calls to psql_error() and GetVariable() in favor
of introducing a callback-functions struct to encapsulate variable
fetching and error printing. In addition, pass the current encoding
and standard-strings status as additional parameters to psql_scan_setup
instead of looking directly at "pset" or calling additional functions.
I did not bother to change some references to psql_error that are in
functions that will soon migrate to a psql-specific backslash-command
lexer. Other than that, this version of psqlscan.l is capable of
compiling standalone. It still depends on assorted src/common functions
as well as some encoding-related libpq functions, but we expect that
all programs using it will be happy with those dependencies.
Kyotaro Horiguchi, somewhat editorialized on by me
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.
