src/Language/Parser.php
private function parseField()
    {
        $start       = $this->lexer->token;
        $nameOrAlias = $this->parseName();

        if ($this->skip(Token::COLON)) {
            $alias = $nameOrAlias;
            $name  = $this->parseName();
        } else {
            $alias = null;
            $name  = $nameOrAlias;
        }

        return new FieldNode([
            'alias'        => $alias,
            'name'         => $name,
            'arguments'    => $this->parseArguments(false),
            'directives'   => $this->parseDirectives(false),
            'selectionSet' => $this->peek(Token::BRACE_L) ? $this->parseSelectionSet() : null,
            'loc'          => $this->loc($start),
        ]);
    }
private function parseField()
    {
        $start       = $this->lexer->token;
        $nameOrAlias = $this->parseName();

        if ($this->skip(Token::COLON)) {
            $alias = $nameOrAlias;
            $name  = $this->parseName();
        } else {
            $alias = null;
            $name  = $nameOrAlias;
        }

        return new FieldNode([
            'alias'        => $alias,
            'name'         => $name,
            'arguments'    => $this->parseArguments(false),
            'directives'   => $this->parseDirectives(false),
            'selectionSet' => $this->peek(Token::BRACE_L) ? $this->parseSelectionSet() : null,
            'loc'          => $this->loc($start),
        ]);
    }
@return FieldNode

@throws SyntaxError