page_util_flow(n)					      Parser generator tools						 page_util_flow(n)

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NAME

       page_util_flow - page dataflow/treewalker utility

SYNOPSIS

       package require page::util::flow  ?0.1?

       package require snit

       ::page::util::flow start flowvar nodevar script

       flow visit node

       flow visitl nodelist

       flow visita node...

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DESCRIPTION

       This  package provides a single utility command for easy dataflow based manipulation of arbitrary data structures, especially abstract syn-
       tax trees.

API

       ::page::util::flow start flowvar nodevar script
	      This command contains the core logic to drive the walking of an arbitrary data structure which can partitioned into separate  parts.
	      Examples of such structures are trees and graphs.

	      The  command makes no assumptions at all about the API of the structure to be walked, except that that its parts, here called nodes,
	      are identified by strings. These strings are taken as is, from the arguments, and the body, and handed back  to  the  body,  without
	      modification.

	      Access to the actual data structure, and all decisions regarding which nodes to visit in what order are delegated to the body of the
	      loop, i.e. the script.

	      The body is invoked first for the nodes in the start-set specified via start), and from then on for the nodes the body has requested
	      to  be  visited. The command stops when the set of nodes to visit becomes empty. Note that a node can be visited more than once. The
	      body has complete control about this.

	      The body is invoked in the context of the caller. The variable named by nodevar will be set to the current node,	and  the  variable
	      named  by  flowvar will be set to the command of the flow object through which the body can request the nodes to visit next. The API
	      provided by this object is described in the next section, FLOW API.

	      Note that the command makes no promises regarding the order in which nodes are visited, excpt that the nodes requested to be visited
	      by the current iteration will be visited afterward, in some order.

FLOW API

       This section describes the API provided by the flow object made accessible to the body script of ::page::util::flow.

       flow visit node
	      Invoking this method requests that the node n is visited after the current iteration.

       flow visitl nodelist
	      Invoking this method requests that all the nodes found in the list nodelist are visited after the current iteration.

       flow visita node...
	      This is the variadic arguments form of the method visitl, see above.

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

       dataflow, graph walking, page, parser generator, text processing, tree walking

CATEGORY

       Page Parser Generator

COPYRIGHT

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

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