Function getRoot

dql/parser.go:2819–3065

getRoot gets the root graph query object after parsing the args.

(it *lex.ItemIterator)

// getRoot gets the root graph query object after parsing the args.
func getRoot(it *lex.ItemIterator) (gq *GraphQuery, rerr error) {
	gq = &GraphQuery{
		Args: make(map[string]string),
	}
	if !it.Next() {
		return nil, it.Errorf("Invalid query")
	}
	item := it.Item()
	if item.Typ != itemName {
		return nil, item.Errorf("Expected some name. Got: %v", item)
	}

	peekIt, err := it.Peek(1)
	if err != nil {
		return nil, it.Errorf("Invalid Query")
	}
	if peekIt[0].Typ == itemName && strings.ToLower(peekIt[0].Val) == "as" {
		gq.Var = item.Val
		it.Next() // Consume the "AS".
		it.Next()
		item = it.Item()
	}

	gq.Alias = item.Val
	if !it.Next() {
		return nil, item.Errorf("Invalid query")
	}
	item = it.Item()
	if item.Typ != itemLeftRound {
		return nil, item.Errorf("Expected Left round brackets. Got: %v", item)
	}

	expectArg := true
	order := make(map[string]bool)
	// Parse in KV fashion. Depending on the value of key, decide the path.
loop:
	for it.Next() {
		var key string
		// Get key.
		item := it.Item()
		switch item.Typ {
		case itemName:
			if !expectArg {
				return nil, item.Errorf("Not expecting argument. Got: %v", item)
			}
			key = item.Val
			expectArg = false
		case itemRightRound:
			if isEmpty(gq) {
				// Used to do aggregation at root which would be fetched in another block.
				gq.IsEmpty = true
			}
			break loop
		case itemComma:
			if expectArg {
				return nil, item.Errorf("Expected Argument but got comma.")
			}
			expectArg = true