Provided by: tcllib_1.19-dfsg-2_all 
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 grammar_me of the Tcllib Trackers [http://core.tcl.tk/tcllib/reportlist].
Please also report any ideas for enhancements you may have for either package and/or documentation.
When proposing code changes, please provide unified diffs, i.e the output of diff -u.
Note further that attachments are strongly preferred over inlined patches. Attachments can be made by
going to the Edit form of the ticket immediately after its creation, and then using the left-most button
in the secondary navigation bar.
KEYWORDS
CFG, CFL, LL(k), PEG, TPDL, context-free grammar, context-free languages, expression, grammar, matching,
parsing, parsing expression grammar, 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>