Valve Data Format (.vdf) Reader and Writer in C++

Valve uses its own JSON-like data format: KeyValue, also known as vdf. e.g. in game manifest files or as SteamCMD output. This header-only file provides a parser and writer to load and save the given data.

Features:

read and write vdf data in C++
build-in encodings: char and wchar_t
supports custom character sets
support for C++ (//) and C (/**/) comments
#include/#base keyword (note: searches for files in the current working directory)
platform independent
header-only

Requirements

C++11

Test Requirements

C++14 (uses catch2)

(works with the C++11 features of vs120/"Visual Studio 2013" and newer)

How-To Use

First, you have to include the main file vdf-Parser.h. This file provides several functions and data-structures which are in the namespace tyti::vdf.

All functions and data structures supports wide characters. The wide character data structure is indicated by the commonly known w-prefix. Functions are templates and don't need a prefix.

To read an file, create a stream e.g. std::ifsteam or std::wifstream and call the tyti::vdf::read function.

std::ifstream file("PathToMyFile");
auto root = tyti::vdf::read(file);

You can also define a sequence of character defined by a range.

std::string blob;
...
auto root = tyti::vdf::read(std::cbegin(blob), std::cend(blob));

//given .vdf below, following holds
assert(root.name == "name");
const std::shared_ptr<tyti::vdf::object> child = root.childs["child0"];
assert(child->name == "child0");
const std::string& k = root[0].attribs["attrib0"];
assert(k == "value");

The tyti::vdf::object is a tree like data structure. It has its name, some attributes as a pair of key and value and its object childs. Below you can see a vdf data structure and how it is stored by naming:

"name"
{
    "attrib0" "value" // saved as a pair, first -> key, second -> value
    "#base" "includeFile.vdf" // appends object defined in the file to childs
    "child0"
    {
    ...
    }
    ...
}

Given such an object, you can also write it into vdf files via:

tyti::vdf::write(file, object);

Multi-Key and Custom Output Type

It is also possible to customize your output dataformat. Per default, the parser stores all items in a std::unordered_map, which, per definition, doesn't allow different entries with the same key.

However, the Valve vdf format supports multiple keys. Therefore, the output data format has to store all items in e.g. a std::unordered_multimap.

You can change the output format by passing the output type via template argument to the read function

namespace tyti;
vdf::object       no_multi_key = vdf::read(file);
vdf::multikey_object multi_key = vdf::read<vdf::multikey_object>(file);

Note: The interface of std::unordered_map and std::unordered_multimap are different when you access the elements.

It is also possible to create your own data structure which is used by the parser. Your output class needs to define 3 functions with the following signature:

void add_attribute(std::basic_string<CHAR> key, std::basic_string<CHAR> value);
void add_child(std::unique_ptr< MYCLASS > child);
void set_name(std::basic_string<CHAR> n);

where MYCLASS is the tpe of your class and CHAR the type of your character set. Also, the type has to be default constructible and move constructible.

This also allows you, to inspect the file without storing it in a data structure. Lets say, for example, you want to count all attributes of a file without storing it. You can do this by using this class

struct counter
{
    size_t num_attributes = 0;
    void add_attribute(std::string key, std::string value)
    {
        ++num_attributes;
    }
    void add_child(std::unique_ptr< counter > child)
    {
        num_attributes += child->num_attributes;
    }
    void set_name(std::string n)
    {}
};

and then call the read function

std::vector<counter> num = tyti::vdf::read<counter>(file);

Options (experimental)

You can configure the parser, the non default options are not well tested yet.

struct Options
{
    bool strip_escape_symbols; //default true
    bool ignore_all_platform_conditionals; // default false
    bool ignore_includes; //default false
};

Reference

/////////////////////////////////////////////////////////////
// pre-defined output classes
/////////////////////////////////////////////////////////////
  // default output object
  template<typename T>
  basic_object<T>
  {
    std::basic_string<char_type> name;
    std::unordered_map<std::basic_string<char_type>, std::basic_string<char_type> > attribs;
    std::unordered_map<std::basic_string<char_type>, std::shared_ptr< basic_object<char_type> > > childs;
  };
  typedef basic_object<char> object;
  typedef basic_object<wchar_t> wobject

  // output object with multikey support
  template<typename T>
  basic_multikey_object<T>
  {
    std::basic_string<char_type> name;
    std::unordered_multimap<std::basic_string<char_type>, std::basic_string<char_type> > attribs;
    std::unordered_multimap<std::basic_string<char_type>, std::shared_ptr< basic_object<char_type> > > childs;
  };
  typedef basic_multikey_object<char> multikey_object;
  typedef basic_multikey_object<wchar_t> wmultikey_object

/////////////////////////////////////////////////////////////
// error codes
/////////////////////////////////////////////////////////////
/*
  Possible error codes:
    std::errc::protocol_error: file is mailformatted
    std::errc::not_enough_memory: not enough space
    std::errc::invalid_argument: iterators throws e.g. out of range
*/

/////////////////////////////////////////////////////////////
// read from stream
/////////////////////////////////////////////////////////////

  /** \brief Loads a stream (e.g. filestream) into the memory and parses the vdf formatted data.
      throws "std::bad_alloc" if file buffer could not be allocated
      throws "std::runtime_error" if a parsing error occured
  */
  template<ytpename OutputT, typename iStreamT>
  std::vector<OutputT> read(iStreamT& inStream, const Options &opt = Options{});

  template<typename iStreamT>
   std::vector<basic_object<typename iStreamT::char_type>> read(iStreamT& inStream, const Options &opt = Options{});

  /** \brief Loads a stream (e.g. filestream) into the memory and parses the vdf formatted data.
      throws "std::bad_alloc" if file buffer could not be allocated
      ok == false, if a parsing error occured
  */
  template<typename OutputT, typename iStreamT>
  std::vector<OutputT> read(iStreamT& inStream, bool* ok, const Options &opt = Options{});

  template<typename iStreamT>
   std::vector<basic_object<typename iStreamT::char_type>> read(iStreamT& inStream, bool* ok, const Options &opt = Options{});
  
  /** \brief Loads a stream (e.g. filestream) into the memory and parses the vdf formatted data.
      throws "std::bad_alloc" if file buffer could not be allocated
  */
  template<typename OutputT, typename iStreamT>
   std::vector<OutputT> read(iStreamT& inStream, std::error_code& ec, const Options &opt = Options{});

  template<typename iStreamT>
   std::vector<basic_object<iStreamT::char_type>> read(iStreamT& inStream, std::error_code& ec, const Options &opt = Options{});

/////////////////////////////////////////////////////////////
// read from memory
/////////////////////////////////////////////////////////////

  /** \brief Read VDF formatted sequences defined by the range [first, last).
  If the file is mailformatted, parser will try to read it until it can.
  @param first begin iterator
  @param end end iterator
  
  throws "std::runtime_error" if a parsing error occured
  throws "std::bad_alloc" if not enough memory could be allocated
  */
  template<typename OutputT, typename IterT>
   std::vector<OutputT> read(IterT first, IterT last, const Options &opt = Options{});

  template<typename IterT>
   std::vector<basic_object<typename std::iterator_traits<IterT>::value_type>> read(IterT first, IterT last, const Options &opt = Options{});
 
  /** \brief Read VDF formatted sequences defined by the range [first, last).
  If the file is mailformatted, parser will try to read it until it can.
  @param first begin iterator
  @param end end iterator
  @param ok output bool. true, if parser successed, false, if parser failed
  */
  template<typename OutputT, typename IterT>
   std::vector<OutputT> read(IterT first, IterT last, bool* ok, const Options &opt = Options{}) noexcept;
  
  template<typename IterT>
   std::vector<basic_object<typename std::iterator_traits<IterT>::value_type>> read(IterT first, IterT last, bool* ok, const Options &opt = Options{}) noexcept;
  


  /** \brief Read VDF formatted sequences defined by the range [first, last).
  If the file is mailformatted, parser will try to read it until it can.
  @param first begin iterator
  @param end end iterator
  @param ec output bool. 0 if ok, otherwise, holds an system error code
  */
  template<typename OutputT, typename IterT>
  std::vector<OutputT> read(IterT first, IterT last, std::error_code& ec, const Options &opt = Options{}) noexcept;
  
  template<typename IterT>
  std::vector<basic_object<typename std::iterator_traits<IterT>::value_type>> read(IterT first, IterT last, std::error_code& ec, const Options &opt = Options{}) noexcept;
  

/////////////////////////////////////////////////////////////////////////////
  // Writer functions
  /// writes given obj into out in vdf style 
  /// Output is prettyfied, using tabs
  template<typename oStreamT, typename T>
  void write(oStreamT& out, const T& obj, const Options &opt = Options{});

Remarks for Errors

The current version is a greedy implementation and jumps over unrecognized fields. Therefore, the error detection is very imprecise an does not give the line, where the error occurs.

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