From 1957ef668d4c1de68ce6b4a55775129a7a623d7f Mon Sep 17 00:00:00 2001
From: Michael Hackstein <michael@arangodb.com>
Date: Tue, 3 Nov 2015 17:36:28 +0100
Subject: [PATCH] Added CXX implementation of SHIFT

---
 arangod/Aql/Executor.cpp  |  2 +-
 arangod/Aql/Functions.cpp | 31 +++++++++++++++++++++++++++++++
 arangod/Aql/Functions.h   |  1 +
 3 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/arangod/Aql/Executor.cpp b/arangod/Aql/Executor.cpp
index 2467bd9fe3..b84360a8e1 100644
--- a/arangod/Aql/Executor.cpp
+++ b/arangod/Aql/Executor.cpp
@@ -180,7 +180,7 @@ std::unordered_map<std::string, Function const> const Executor::FunctionNames{
   { "PUSH",                        Function("PUSH",                        "AQL_PUSH", "l,.|b", true, true, false, true, false, &Functions::Push) },
   { "APPEND",                      Function("APPEND",                      "AQL_APPEND", "l,lz|b", true, true, false, true, true, &Functions::Append) },
   { "POP",                         Function("POP",                         "AQL_POP", "l", true, true, false, true, true, &Functions::Pop) },
-  { "SHIFT",                       Function("SHIFT",                       "AQL_SHIFT", "l", true, true, false, true, true) },
+  { "SHIFT",                       Function("SHIFT",                       "AQL_SHIFT", "l", true, true, false, true, true, &Functions::Shift) },
   { "UNSHIFT",                     Function("UNSHIFT",                     "AQL_UNSHIFT", "l,.|b", true, true, false, true, true, &Functions::Unshift) },
   { "REMOVE_VALUE",                Function("REMOVE_VALUE",                "AQL_REMOVE_VALUE", "l,.|n", true, true, false, true, true) },
   { "REMOVE_VALUES",               Function("REMOVE_VALUES",               "AQL_REMOVE_VALUES", "l,lz", true, true, false, true, true) },
diff --git a/arangod/Aql/Functions.cpp b/arangod/Aql/Functions.cpp
index 4f696fa266..15f771011f 100644
--- a/arangod/Aql/Functions.cpp
+++ b/arangod/Aql/Functions.cpp
@@ -3530,6 +3530,37 @@ AqlValue Functions::Unshift (triagens::aql::Query* query,
   return AqlValue(new Json(Json::Null));
 }
 
+////////////////////////////////////////////////////////////////////////////////
+/// @brief function SHIFT
+////////////////////////////////////////////////////////////////////////////////
+
+AqlValue Functions::Shift (triagens::aql::Query* query,
+                           triagens::arango::AqlTransaction* trx,
+                           FunctionParameters const& parameters) {
+  size_t const n = parameters.size();
+
+  if (n != 1) {
+    THROW_ARANGO_EXCEPTION_PARAMS(TRI_ERROR_QUERY_FUNCTION_ARGUMENT_NUMBER_MISMATCH, "SHIFT", (int) 1, (int) 1);
+  }
+
+  Json list = ExtractFunctionParameter(trx, parameters, 0, false);
+  if (list.isNull()) {
+    return AqlValue(new Json(Json::Null));
+  }
+  if (list.isArray()) {
+    if (list.size() == 0) {
+      return AqlValue(new Json(Json::Array, 0));
+    }
+    if (!TRI_DeleteArrayJson(TRI_UNKNOWN_MEM_ZONE, list.json(), 0)) {
+      THROW_ARANGO_EXCEPTION(TRI_ERROR_OUT_OF_MEMORY);
+    }
+    return AqlValue(new Json(TRI_UNKNOWN_MEM_ZONE, list.copy().steal()));
+  }
+
+  RegisterInvalidArgumentWarning(query, "SHIFT");
+  return AqlValue(new Json(Json::Null));
+}
+
 // -----------------------------------------------------------------------------
 // --SECTION--                                                       END-OF-FILE
 // -----------------------------------------------------------------------------
diff --git a/arangod/Aql/Functions.h b/arangod/Aql/Functions.h
index b750b36e83..314aa4b9df 100644
--- a/arangod/Aql/Functions.h
+++ b/arangod/Aql/Functions.h
@@ -135,6 +135,7 @@ namespace triagens {
       static AqlValue Pop             (triagens::aql::Query*, triagens::arango::AqlTransaction*, FunctionParameters const&);
       static AqlValue Append          (triagens::aql::Query*, triagens::arango::AqlTransaction*, FunctionParameters const&);
       static AqlValue Unshift         (triagens::aql::Query*, triagens::arango::AqlTransaction*, FunctionParameters const&);
+      static AqlValue Shift           (triagens::aql::Query*, triagens::arango::AqlTransaction*, FunctionParameters const&);
     };
 
   }