Add a "void *" passthrough pointer for psqlscan.l's callback functions.

The immediate motivation for this is to provide clean infrastructure
for the proposed \if...\endif patch for psql; but it seems like a good
thing to have even if that patch doesn't get in.  Previously the callback
functions could only make use of application-global state, which is a
pretty severe handicap.

For the moment, the pointer is only passed through to the get_variable
callback function.  I considered also passing it to the write_error
callback, but for now let's not.  Neither psql nor pgbench has a use
for that, and in the case of psql we'd have to invent a separate wrapper
function because we would certainly not want to change the signature of
psql_error().

Discussion: https://postgr.es/m/[email protected]

1 files changed, 17 insertions, 2 deletions

diff --git a/src/fe_utils/psqlscan.l b/src/fe_utils/psqlscan.l
index 1b29341fa87..19b3e57aa45 100644
--- a/src/fe_utils/psqlscan.l
+++ b/src/fe_utils/psqlscan.l
@@ -700,7 +700,8 @@ other			.
 					if (cur_state->callbacks->get_variable)
 						value = cur_state->callbacks->get_variable(varname,
 																   false,
-																   false);
+																   false,
+																   cur_state->cb_passthrough);
 					else
 						value = NULL;
 
@@ -923,6 +924,19 @@ psql_scan_destroy(PsqlScanState state)
 }
 
 /*
+ * Set the callback passthrough pointer for the lexer.
+ *
+ * This could have been integrated into psql_scan_create, but keeping it
+ * separate allows the application to change the pointer later, which might
+ * be useful.
+ */
+void
+psql_scan_set_passthrough(PsqlScanState state, void *passthrough)
+{
+	state->cb_passthrough = passthrough;
+}
+
+/*
  * Set up to perform lexing of the given input line.
  *
  * The text at *line, extending for line_len bytes, will be scanned by
@@ -1409,7 +1423,8 @@ psqlscan_escape_variable(PsqlScanState state, const char *txt, int len,
 	/* Variable lookup. */
 	varname = psqlscan_extract_substring(state, txt + 2, len - 3);
 	if (state->callbacks->get_variable)
-		value = state->callbacks->get_variable(varname, true, as_ident);
+		value = state->callbacks->get_variable(varname, true, as_ident,
+											   state->cb_passthrough);
 	else
 		value = NULL;
 	free(varname);