From 9cf44b3092890553a50b7038a4d7f480293bcace Mon Sep 17 00:00:00 2001
From: Johan Wikman <johan.wikman@mariadb.com>
Date: Thu, 26 Apr 2018 13:03:54 +0300
Subject: [PATCH] MXS-1829 Recognise PREVIOUS in addition to NEXT

Earlier only "SELECT NEXT VALUE FOR SEQ" was parsed
properly, while "SELECT PREVIOUS VALUE FOR SEQ" was not.
Now the latter statement is also parsed properly.
---
 query_classifier/qc_sqlite/sqlite-src-3110100/src/parse.y   | 6 +++++-
 .../qc_sqlite/sqlite-src-3110100/tool/mkkeywordhash.c       | 1 +
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/query_classifier/qc_sqlite/sqlite-src-3110100/src/parse.y b/query_classifier/qc_sqlite/sqlite-src-3110100/src/parse.y
index a765bec97..d4498cf37 100644
--- a/query_classifier/qc_sqlite/sqlite-src-3110100/src/parse.y
+++ b/query_classifier/qc_sqlite/sqlite-src-3110100/src/parse.y
@@ -626,6 +626,7 @@ columnid(A) ::= nm(X). {
   NAMES NEXT
   NO
   OF OFFSET OPEN
+  PREVIOUS
   QUICK
   RAISE RECURSIVE /*REINDEX*/ RELEASE /*RENAME*/ /*REPLACE*/ RESTRICT ROLLBACK ROLLUP ROW
   SAVEPOINT SELECT_OPTIONS_KW /*SEQUENCE*/ SLAVE /*START*/ STATUS
@@ -1207,7 +1208,10 @@ selcollist(A) ::= sclp(P) nm(X) DOT STAR(Y). {
   A = sqlite3ExprListAppend(pParse,P, pDot);
 }
 %ifdef MAXSCALE
-selcollist(A) ::= sclp(P) NEXT VALUE FOR nm(X) as(Y).     {
+next_or_previous(A) ::= NEXT(X). {A = X;}
+next_or_previous(A) ::= PREVIOUS(X). {A = X;}
+
+selcollist(A) ::= sclp(P) next_or_previous VALUE FOR nm(X) as(Y).     {
   Expr* pSeq = sqlite3PExpr(pParse, TK_ID, 0, 0, &X);
   ExprList* pArgs = sqlite3ExprListAppend(pParse, NULL, pSeq);
   Token nextval = { "nextval", 7 };
diff --git a/query_classifier/qc_sqlite/sqlite-src-3110100/tool/mkkeywordhash.c b/query_classifier/qc_sqlite/sqlite-src-3110100/tool/mkkeywordhash.c
index d8723ea16..5d51ea86a 100644
--- a/query_classifier/qc_sqlite/sqlite-src-3110100/tool/mkkeywordhash.c
+++ b/query_classifier/qc_sqlite/sqlite-src-3110100/tool/mkkeywordhash.c
@@ -383,6 +383,7 @@ static Keyword aKeywordTable[] = {
 #ifdef MAXSCALE
   { "PRECEDING",        "TK_PRECEDING",    ALWAYS                 },
   { "PREPARE",          "TK_PREPARE",      ALWAYS                 },
+  { "PREVIOUS",         "TK_PREVIOUS",     ALWAYS                 },
 #endif
   { "PRIMARY",          "TK_PRIMARY",      ALWAYS                 },
 #ifdef MAXSCALE