


grammar::me_intro(nGrammar operations and usagrammar::me_intro(n)


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

DESCRIPTION
       This document is an introduction to and overview of the  basic  facili-
       ties  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  con-
       trolled  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  syn-
              tax trees.

       grammar::me::util
              Utility commands.

       grammar::me::tcl
              Singleton ME virtual machine implementation tied to Tcl for con-
              trol flow and stacks. Hardwired for pull operation.  Uninterupt-
              ible 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.






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grammar::me_intro(nGrammar operations and usagrammar::me_intro(n)


BUGS, IDEAS, FEEDBACK
       This document, and the package it describes, will  undoubtedly  contain
       bugs and other problems.  Please report such in the category grammar_me
       of       the       Tcllib       SF       Trackers       [http://source-
       forge.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  lan-
       guages,  expression,  grammar,  matching,  parsing,  parsing expression
       grammar, push down automaton, recursive descent, top-down parsing  lan-
       guages, transducer, virtual machine

CATEGORY
       Grammars and finite automata

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







































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