Ubuntu Manpage: page_util_peg - page PEG transformation utilities

NAME

       page_util_peg - page PEG transformation utilities

SYNOPSIS

       package require page::util::peg  ?0.1?

       package require snit

       ::page::util::peg::symbolNodeOf tree node

       ::page::util::peg::symbolOf tree node

       ::page::util::peg::updateUndefinedDueRemoval tree

       ::page::util::peg::flatten treequery tree

       ::page::util::peg::getWarnings tree

       ::page::util::peg::printWarnings msg

       ::page::util::peg::peOf tree eroot

       ::page::util::peg::printTclExpr pe

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DESCRIPTION

       This  package  provides  a  few  common  operations to PEG transformations.  They assume a
       Normalized PE Grammar Tree as  input,  see  the  package  page::util::norm::peg,  possibly
       augmented  with  attributes  coming  from  transformations  not  in conflict with the base
       definition.

API

::page::util::peg::symbolNodeOf tree node
Given an arbitrary expression node in the AST tree it determines the node (itself
or an ancestor) containing the name of the nonterminal symbol the node belongs to,
and returns its id. The result is either the root of the tree (for the start
expression), or a definition node.

::page::util::peg::symbolOf tree node
As ::page::util::peg::symbolNodeOf, but returns the symbol name instead of the
node.

::page::util::peg::updateUndefinedDueRemoval tree
The removal of nodes in the AST tree can cause symbols to lose one or more users.
A used by B and C,
B is reachable,
C is not,
so A now loses the node in the expression for C calling it,
or rather, not calling it anymore.

This command updates the cross-references and which nonterminals are now undefined.

::page::util::peg::flatten treequery tree
This commands flattens nested sequence and choice operators in the AST tree, re-
using the treeql object treequery to run the query determining which nodes to cut.

::page::util::peg::getWarnings tree
This command looks at the attributes of the AST tree for problems with the grammar
and issues warnings. They do not prevent us from writing the grammar, but still
represent problems with it the user should be made aware of.

The result of the command is a dictionary mapping nonterminal names to their
associated warnings.

::page::util::peg::printWarnings msg
The argument of the command is a dictionary mapping nonterminal names to their
associated warnings, as generated by, for example, the command
::page::util::peg::getWarnings.

The warnings contained therein are formatted and then printed via the log command
page_info. This means that this command can be used only from within a plugin
managed by the package page::pluginmgr.

::page::util::peg::peOf tree eroot
This command converts the parsing expression starting at the node eroot in the AST
tree into a nested list. The exact syntax of this list specified by the package
grammar::peg.

::page::util::peg::printTclExpr pe
This command converts the parsing expression contained in the nested list pe into a
Tcl string which can be placed into a Tcl script. See the package grammar::peg for
the exact syntax of pe.

BUGS, IDEAS, FEEDBACK

       This document, will undoubtedly contain bugs and other problems.  Please  report  such  in
       the        category        page        of        the        Tcllib       SF       Trackers
       [http://sourceforge.net/tracker/?group_id=12883].   Please  also  report  any  ideas   for
       enhancements you may have.

KEYWORDS

       PEG, page, parser generator, parsing expression grammar, text processing, transformation

COPYRIGHT

       Copyright (c) 2007 Andreas Kupries <andreas_kupries@users.sourceforge.net>