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Old 06-16-2008
A virtual appliance primer
Mon, 16 Jun 2008 20:00:00 GMT
Virtual machines are virtually taking over the world. By itself a virtual machine is just a container that describes various resources such as memory, disk space, processor, and network card, and allocates them from a physical machine. As with a physical machine, it's the software bits (the operating system and applications) that make a virtual machine usable. When you mix a virtual machine with real software you get a virtual appliance. Some complete Linux distributions as well as specialized apps are available as virtual appliances. Thanks to the ease in packaging one, there's no shortage of virtual appliances around, if you know where to look.


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LEARN ABOUT DEBIAN

me_intro

grammar::me_intro(3tcl) 				   Grammar operations and usage 				   grammar::me_intro(3tcl)

__________________________________________________________________________________________________________________________________________________

NAME

       grammar::me_intro - Introduction to virtual machines for parsing token streams

DESCRIPTION

       This  document is an introduction to and overview of the basic facilities for the parsing and/or matching of token streams. One possibility
       often used for the token domain are characters.

       The packages themselves all provide variants of one virtual machine, called a match engine (short ME), which has all the facilities  needed
       for  the  matching  and	parsing of a stream, and which are either controlled directly, or are customized with a match program. The virtual
       machine is basically a pushdown automaton, with additional elements for backtracking and/or handling of semantic data and  construction	of
       abstract syntax trees (AST).

       Because	of  the high degree of similarity in the actual implementations of the aforementioned virtual machine and the data structures they
       receive and generate these common parts are specified in a separate document which will be referenced by  the  documentation  for  packages
       actually implementing it.

       The relevant documents are:

       grammar::me_vm
	      Virtual machine specification.

       grammar::me_ast
	      Specification of various representations used for abstract syntax trees.

       grammar::me::util
	      Utility commands.

       grammar::me::tcl
	      Singleton  ME  virtual  machine implementation tied to Tcl for control flow and stacks. Hardwired for pull operation. Uninteruptible
	      during processing.

       grammar::me::cpu
	      Object-based ME virtual machine implementation with explicit control flow, and stacks, using bytecodes. Suspend/Resumable. Push/pull
	      operation.

       grammar::me::cpu::core
	      Core functionality for state manipulation and stepping used in the bytecode based implementation of ME virtual machines.

BUGS, IDEAS, FEEDBACK
       This  document,	and  the package it describes, will undoubtedly contain bugs and other problems.  Please report such in the category gram-
       mar_me of the Tcllib SF Trackers [http://sourceforge.net/tracker/?group_id=12883].  Please also report any ideas for enhancements  you  may
       have for either package and/or documentation.

KEYWORDS

       CFG,  CFL, LL(k), PEG, TPDL, context-free grammar, context-free languages, expression, grammar, matching, parsing, parsing expression gram-
       mar, push down automaton, recursive descent, top-down parsing languages, transducer, virtual machine

CATEGORY

       Grammars and finite automata

COPYRIGHT

       Copyright (c) 2005 Andreas Kupries <andreas_kupries@users.sourceforge.net>

grammar_me								0.1						   grammar::me_intro(3tcl)