From 9bb18e54380250f3fb931028952379c3ab2dec29 Mon Sep 17 00:00:00 2001
From: antirez <antirez@gmail.com>
Date: Mon, 20 Nov 2017 11:25:05 +0100
Subject: [PATCH] Streams: XRANGE REV option -> XREVRANGE command.

---
 src/server.c   |  1 +
 src/server.h   |  1 +
 src/t_stream.c | 23 ++++++++++++++++-------
 3 files changed, 18 insertions(+), 7 deletions(-)

diff --git a/src/server.c b/src/server.c
index f1fd06ca..af19b5a3 100644
--- a/src/server.c
+++ b/src/server.c
@@ -304,6 +304,7 @@ struct redisCommand redisCommandTable[] = {
     {"pfdebug",pfdebugCommand,-3,"w",0,NULL,0,0,0,0,0},
     {"xadd",xaddCommand,-5,"wmF",0,NULL,1,1,1,0,0},
     {"xrange",xrangeCommand,-4,"r",0,NULL,1,1,1,0,0},
+    {"xrevrange",xrevrangeCommand,-4,"r",0,NULL,1,1,1,0,0},
     {"xlen",xlenCommand,2,"rF",0,NULL,1,1,1,0,0},
     {"xread",xreadCommand,-3,"rs",0,xreadGetKeys,1,1,1,0,0},
     {"post",securityWarningCommand,-1,"lt",0,NULL,0,0,0,0,0},
diff --git a/src/server.h b/src/server.h
index bc572b1e..d65fd0c5 100644
--- a/src/server.h
+++ b/src/server.h
@@ -2010,6 +2010,7 @@ void moduleCommand(client *c);
 void securityWarningCommand(client *c);
 void xaddCommand(client *c);
 void xrangeCommand(client *c);
+void xrevrangeCommand(client *c);
 void xlenCommand(client *c);
 void xreadCommand(client *c);
 
diff --git a/src/t_stream.c b/src/t_stream.c
index efb01ef6..837a812a 100644
--- a/src/t_stream.c
+++ b/src/t_stream.c
@@ -856,16 +856,17 @@ void xaddCommand(client *c) {
         signalKeyAsReady(c->db, c->argv[1]);
 }
 
-/* XRANGE key start end [COUNT <n>] [REV] */
-void xrangeCommand(client *c) {
+/* XRANGE/XREVRANGE actual implementation. */
+void xrangeGenericCommand(client *c, int rev) {
     robj *o;
     stream *s;
     streamID startid, endid;
     long long count = 0;
-    int rev = 0;
+    robj *startarg = rev ? c->argv[3] : c->argv[2];
+    robj *endarg = rev ? c->argv[2] : c->argv[3];
 
-    if (streamParseIDOrReply(c,c->argv[2],&startid,0) == C_ERR) return;
-    if (streamParseIDOrReply(c,c->argv[3],&endid,UINT64_MAX) == C_ERR) return;
+    if (streamParseIDOrReply(c,startarg,&startid,0) == C_ERR) return;
+    if (streamParseIDOrReply(c,endarg,&endid,UINT64_MAX) == C_ERR) return;
 
     /* Parse the COUNT option if any. */
     if (c->argc > 4) {
@@ -876,8 +877,6 @@ void xrangeCommand(client *c) {
                     != C_OK) return;
                 if (count < 0) count = 0;
                 j++; /* Consume additional arg. */
-            } else if (strcasecmp(c->argv[j]->ptr,"REV") == 0) {
-                rev = 1;
             } else {
                 addReply(c,shared.syntaxerr);
                 return;
@@ -892,6 +891,16 @@ void xrangeCommand(client *c) {
     streamReplyWithRange(c,s,&startid,&endid,count,rev);
 }
 
+/* XRANGE key start end [COUNT <n>] */
+void xrangeCommand(client *c) {
+    xrangeGenericCommand(c,0);
+}
+
+/* XREVRANGE key end start [COUNT <n>] */
+void xrevrangeCommand(client *c) {
+    xrangeGenericCommand(c,1);
+}
+
 /* XLEN */
 void xlenCommand(client *c) {
     robj *o;