implemented FILTER, LIMIT and multi-star features

arangod/Aql/Ast.cpp

@@ -1406,6 +1406,7 @@ void Ast::validateAndOptimize () {
       if (static_cast<TraversalContext*>(data)->hasSeenWriteNode) {
         THROW_ARANGO_EXCEPTION(TRI_ERROR_QUERY_ACCESS_AFTER_MODIFICATION);
       }
+      return node;
     }
 
     // example

arangod/Aql/Executor.cpp

@@ -1050,7 +1050,7 @@ void Executor::generateCodeExpansion (AstNode const* node) {
     generateCodeNode(limitNode->getMember(0));
     _buffer->appendChar(',');
     generateCodeNode(limitNode->getMember(1));
-    _buffer->appendChar(')');
+    _buffer->appendText(",true)");
   }
 
   // RETURN

arangod/Aql/Expression.cpp

@@ -833,40 +833,166 @@ AqlValue Expression::executeSimpleExpression (AstNode const* node,
 
   else if (node->type == NODE_TYPE_EXPANSION) { 
     TRI_ASSERT(node->numMembers() == 5);
+
+    // LIMIT
+    int64_t offset = 0; 
+    int64_t count  = INT64_MAX;
+
+    auto limitNode = node->getMember(3);
+
+    if (limitNode->type != NODE_TYPE_NOP) {
+      TRI_document_collection_t const* subCollection = nullptr;
+      AqlValue sub = executeSimpleExpression(limitNode->getMember(0), &subCollection, trx, argv, startPos, vars, regs, false);
+      offset = sub.toInt64();
+      sub.destroy();
+
+      subCollection = nullptr;
+      sub = executeSimpleExpression(limitNode->getMember(1), &subCollection, trx, argv, startPos, vars, regs, false);
+      count = sub.toInt64();
+      sub.destroy();
+    }
+
+    if (offset < 0 || count <= 0) {
+      // no items to return... can already stop here
+      return AqlValue(new triagens::basics::Json(triagens::basics::Json::Array));
+    }
+
+    // FILTER
+    AstNode const* filterNode = node->getMember(2);
+
+    if (filterNode->type == NODE_TYPE_NOP) {
+      filterNode = nullptr;
+    }
+    else if (filterNode->isConstant()) {
+      if (filterNode->isTrue()) { 
+        // filter expression is always true
+        filterNode = nullptr;
+      }
+      else {
+        // filter expression is always false
+        return AqlValue(new triagens::basics::Json(triagens::basics::Json::Array));
+      }
+    }
+
     auto iterator = node->getMember(0);
     auto variable = static_cast<Variable*>(iterator->getMember(0)->getData());
-    // TODO: implement flatten!
     auto levels = node->getIntValue(true);
 
-    TRI_document_collection_t const* myCollection = nullptr;
-    AqlValue value = executeSimpleExpression(node->getMember(0), &myCollection, trx, argv, startPos, vars, regs, false);
+    AqlValue value;
 
-    if (! value.isArray()) {
+    if (levels > 1) {
+      // flatten value...
+
+      // generate a new temporary for the flattened array
+      std::unique_ptr<Json> flattened(new Json(Json::Array));
+
+      TRI_document_collection_t const* myCollection = nullptr;
+      value = executeSimpleExpression(node->getMember(0), &myCollection, trx, argv, startPos, vars, regs, false);
+
+      if (! value.isArray()) {
+        // must cast value to array first
+        FunctionParameters parameters{ std::make_pair(value, myCollection) };
+        auto res = Functions::ToArray(_ast->query(), trx, parameters);
+
+        // destroy old value and swap with function call result
+        value.destroy();
+        value = res;
+      }
+
+      std::function<void(TRI_json_t const*, int64_t)> flatten = [&] (TRI_json_t const* json, int64_t level) {
+        if (! TRI_IsArrayJson(json)) {
+          return;
+        }
+
+        size_t const n = TRI_LengthArrayJson(json);
+
+        for (size_t i = 0; i < n; ++i) {
+          auto item = static_cast<TRI_json_t const*>(TRI_AtVector(&json->_value._objects, i));
+        
+          bool const isArray = TRI_IsArrayJson(item);
+ 
+          if (! isArray || level == levels) {
+            flattened->add(TRI_CopyJson(TRI_UNKNOWN_MEM_ZONE, item));
+          } 
+          else if (isArray && level < levels) {
+            flatten(item, level + 1);
+          }
+        }
+      };
+
+      auto subJson = value.toJson(trx, myCollection, false);
+      flatten(subJson.json(), 1);
       value.destroy();
-      return AqlValue(new triagens::basics::Json(triagens::basics::Json::Array));
+
+      value = AqlValue(flattened.release());
+    }
+    else {
+      TRI_document_collection_t const* myCollection = nullptr;
+      value = executeSimpleExpression(node->getMember(0), &myCollection, trx, argv, startPos, vars, regs, false);
+
+      if (! value.isArray()) {
+        // must cast value to array first
+        FunctionParameters parameters{ std::make_pair(value, myCollection) };
+        auto res = Functions::ToArray(_ast->query(), trx, parameters);
+
+        // destroy old value and swap with function call result
+        value.destroy();
+        value = res;
+      }
+    }
+
+    // RETURN
+    // the default is to return array member unmodified 
+    AstNode const* projectionNode = node->getMember(1);
+
+    if (node->getMember(4)->type != NODE_TYPE_NOP) {
+      // return projection
+      projectionNode = node->getMember(4);
     }
 
     size_t const n = value.arraySize();
     std::unique_ptr<Json> array(new Json(Json::Array, n));
-  
-    size_t projectionNode = 1;
-    if (node->getMember(4)->type != NODE_TYPE_NOP) {
-      projectionNode = 4;
-    }
 
     for (size_t i = 0; i < n; ++i) {
       // TODO: check why we must copy the array member. will crash without copying!
+      TRI_document_collection_t const* myCollection = nullptr;
       auto arrayItem = value.extractArrayMember(trx, myCollection, i, true);
       
       setVariable(variable, arrayItem.json());
  
-      TRI_document_collection_t const* subCollection = nullptr;
-      AqlValue sub = executeSimpleExpression(node->getMember(projectionNode), &subCollection, trx, argv, startPos, vars, regs, true);
-      array->add(sub.toJson(trx, subCollection, true));
+      bool takeItem = true;
+
+      if (filterNode != nullptr) {
+        // have a filter
+        TRI_document_collection_t const* subCollection = nullptr;
+        AqlValue sub = executeSimpleExpression(filterNode, &subCollection, trx, argv, startPos, vars, regs, false);
+        takeItem = sub.isTrue();
+        sub.destroy();
+      }
+
+      if (takeItem && offset > 0) {
+        // there is an offset in place
+        --offset; 
+        takeItem = false;
+      }
+
+      if (takeItem) {
+        TRI_document_collection_t const* subCollection = nullptr;
+        AqlValue sub = executeSimpleExpression(projectionNode, &subCollection, trx, argv, startPos, vars, regs, true);
+        array->add(sub.toJson(trx, subCollection, true));
+      }
 
       clearVariable(variable);
 
       arrayItem.destroy();
+
+      if (takeItem && count > 0) {
+        // number of items to pick was restricted
+        if (--count == 0) {
+          // done
+          break;
+        }
+      }
     }
 
     value.destroy();

js/server/modules/org/arangodb/aql.js

@@ -3111,7 +3111,7 @@ function AQL_SHIFT (list) {
 /// @brief extract a slice from an array
 ////////////////////////////////////////////////////////////////////////////////
 
-function AQL_SLICE (value, from, to) {
+function AQL_SLICE (value, from, to, nonNegative) {
   'use strict';
 
   if (TYPEWEIGHT(value) !== TYPEWEIGHT_ARRAY) {
@@ -3122,6 +3122,10 @@ function AQL_SLICE (value, from, to) {
   from = AQL_TO_NUMBER(from);
   to   = AQL_TO_NUMBER(to);
 
+  if (nonNegative && (from < 0 || to < 0)) {
+    return [ ];
+  }
+
   if (TYPEWEIGHT(to) === TYPEWEIGHT_NULL) {
     to = undefined;
   }