Function push_stmt_mcontext

src/pl/plpgsql/src/pl_exec.c:1524–1535

* Push down the current stmt_mcontext so that called statements won't use it. * This is needed by statements that have statement-lifespan data and need to * preserve it across some inner statements. The caller should eventually do * pop_stmt_mcontext(). */

 * pop_stmt_mcontext().
 */
static void
push_stmt_mcontext(PLpgSQL_execstate *estate)
{
	/* Should have done get_stmt_mcontext() first */
	Assert(estate->stmt_mcontext != NULL);
	/* Assert we've not messed up the stack linkage */
	Assert(MemoryContextGetParent(estate->stmt_mcontext) == estate->stmt_mcontext_parent);
	/* Push it down to become the parent of any nested stmt mcontext */
	estate->stmt_mcontext_parent = estate->stmt_mcontext;
	/* And make it not available for use directly */
	estate->stmt_mcontext = NULL;
}

/*
 * Undo push_stmt_mcontext().  We assume this is done just before or after