Package com.prineside.luaj.lib

Class OsLib

java.lang.Object
com.prineside.luaj.Varargs
com.prineside.luaj.LuaValue
com.prineside.luaj.LuaFunction
com.prineside.luaj.lib.LibFunction
com.prineside.luaj.lib.TwoArgFunction
com.prineside.luaj.lib.OsLib
All Implemented Interfaces:
com.esotericsoftware.kryo.KryoSerializable
Direct Known Subclasses:
JseOsLib
public class OsLib extends TwoArgFunction
Subclass of LibFunction which implements the standard lua os library.

It is a usable base with simplified stub functions for library functions that cannot be implemented uniformly on Jse and Jme.

This can be installed as-is on either platform, or extended and refined to be used in a complete Jse implementation.

Because the nature of the os library is to encapsulate os-specific features, the behavior of these functions varies considerably from their counterparts in the C platform.

The following functions have limited implementations of features that are not supported well on Jme:

  • execute()
  • remove()
  • rename()
  • tmpname()

Typically, this library is included as part of a call to either org.luaj.vm2.lib.jse.JsePlatform#standardGlobals() or org.luaj.vm2.lib.jme.JmePlatform#standardGlobals() 

 
 Globals globals = JsePlatform.standardGlobals();
 System.out.println( globals.get("os").get("time").call() );
In this example the platform-specific org.luaj.vm2.lib.jse.JseOsLib library will be loaded, which will include the base functionality provided by this class.

To instantiate and use it directly, link it into your globals table via LuaValue.load(LuaValue) using code such as: 

 
 Globals globals = new Globals();
 globals.load(new JseBaseLib());
 globals.load(new PackageLib());
 globals.load(new OsLib());
 System.out.println( globals.get("os").get("time").call() );

See Also:

  • Field Details

  • Constructor Details

    • OsLib

      public OsLib()
      Create and OsLib instance.

  • Method Details

    • write

      public void write(com.esotericsoftware.kryo.Kryo kryo, com.esotericsoftware.kryo.io.Output output)
      Specified by:
      write in interface com.esotericsoftware.kryo.KryoSerializable
      Overrides:
      write in class LibFunction

    • read

      public void read(com.esotericsoftware.kryo.Kryo kryo, com.esotericsoftware.kryo.io.Input input)
      Specified by:
      read in interface com.esotericsoftware.kryo.KryoSerializable
      Overrides:
      read in class LibFunction

    • call

      public LuaValue call(LuaValue modname, LuaValue env)
      Perform one-time initialization on the library by creating a table containing the library functions, adding that table to the supplied environment, adding the table to package.loaded, and returning table as the return value.
      Specified by:
      call in class TwoArgFunction
      Parameters:
      modname - the module name supplied if this is loaded via 'require'.
      env - the environment to load into, typically a Globals instance.
      Returns:
      First return value (this(arg1,arg2)), or LuaValue.NIL if there were none.
      See Also:

    • clock

      protected double clock()
      Returns:
      an approximation of the amount in seconds of CPU time used by the program. For luaj this simple returns the elapsed time since the OsLib class was loaded.

    • difftime

      protected double difftime(double t2, double t1)
      Returns the number of seconds from time t1 to time t2. In POSIX, Windows, and some other systems, this value is exactly t2-t1.
      Parameters:
      t2 -
      t1 -
      Returns:
      diffeence in time values, in seconds

    • date

      public String date(String format, double time)
      If the time argument is present, this is the time to be formatted (see the os.time function for a description of this value). Otherwise, date formats the current time. Date returns the date as a string, formatted according to the same rules as ANSII strftime, but without support for %g, %G, or %V. When called without arguments, date returns a reasonable date and time representation that depends on the host system and on the current locale (that is, os.date() is equivalent to os.date("%c")).
      Parameters:
      format -
      time - time since epoch, or -1 if not supplied
      Returns:
      a LString or a LTable containing date and time, formatted according to the given string format.

    • execute

      protected Varargs execute(String command)
      This function is equivalent to the C function system. It passes command to be executed by an operating system shell. It returns a status code, which is system-dependent. If command is absent, then it returns nonzero if a shell is available and zero otherwise.
      Parameters:
      command - command to pass to the system

    • exit

      protected void exit(int code)
      Calls the C function exit, with an optional code, to terminate the host program.
      Parameters:
      code -

    • getenv

      protected String getenv(String varname)
      Returns the value of the process environment variable varname, or the System property value for varname, or null if the variable is not defined in either environment. The default implementation, which is used by the JmePlatform, only queryies System.getProperty(). The JsePlatform overrides this behavior and returns the environment variable value using System.getenv() if it exists, or the System property value if it does not. A SecurityException may be thrown if access is not allowed for 'varname'.
      Parameters:
      varname -
      Returns:
      String value, or null if not defined

    • remove

      protected void remove(String filename) throws IOException
      Deletes the file or directory with the given name. Directories must be empty to be removed. If this function fails, it throws and IOException
      Parameters:
      filename -
      Throws:
      IOException - if it fails

    • rename

      protected void rename(String oldname, String newname) throws IOException
      Renames file or directory named oldname to newname. If this function fails,it throws and IOException
      Parameters:
      oldname - old file name
      newname - new file name
      Throws:
      IOException - if it fails

    • setlocale

      protected String setlocale(String locale, String category)
      Sets the current locale of the program. locale is a string specifying a locale; category is an optional string describing which category to change: "all", "collate", "ctype", "monetary", "numeric", or "time"; the default category is "all". If locale is the empty string, the current locale is set to an implementation- defined native locale. If locale is the string "C", the current locale is set to the standard C locale. When called with null as the first argument, this function only returns the name of the current locale for the given category.
      Parameters:
      locale -
      category -
      Returns:
      the name of the new locale, or null if the request cannot be honored.

    • time

      protected double time(LuaTable table)
      Returns the current time when called without arguments, or a time representing the date and time specified by the given table. This table must have fields year, month, and day, and may have fields hour, min, sec, and isdst (for a description of these fields, see the os.date function).
      Parameters:
      table -
      Returns:
      long value for the time

    • tmpname

      protected String tmpname()
      Returns a string with a file name that can be used for a temporary file. The file must be explicitly opened before its use and explicitly removed when no longer needed. On some systems (POSIX), this function also creates a file with that name, to avoid security risks. (Someone else might create the file with wrong permissions in the time between getting the name and creating the file.) You still have to open the file to use it and to remove it (even if you do not use it).
      Returns:
      String filename to use