page_util_flow(3tcl) Parser generator tools page_util_flow(3tcl)______________________________________________________________________________NAMEpage_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...
_________________________________________________________________DESCRIPTION
This package provides a single utility command for easy dataflow based
manipulation of arbitrary data structures, especially abstract syntax
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 speci‐
fied 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 vari‐
able 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 acces‐
sible 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>
page 1.0 page_util_flow(3tcl)
