H4CK3R 5/hacker05/05_HACK_05.ISO/programacao/freewrap/TCLLIBsampleApp.exe/sample/tcllib/tcllib1.0/struct/graph.tcl

Text File | 2001-08-17 | 35.7 KB | 1,541 lines

# graph.tcl --
#
#    Implementation of a graph data structure for Tcl.
#
# Copyright (c) 2000 by Andreas Kupries
#
# See the file "license.terms" for information on usage and redistribution
# of this file, and for a DISCLAIMER OF ALL WARRANTIES.
#
# RCS: @(#) $Id: graph.tcl,v 1.3 2001/06/22 15:29:18 andreas_kupries Exp $

namespace eval ::struct {}

namespace eval ::struct::graph {
    # Data storage in the graph module
    # -------------------------------
    #
    # There's a lot of bits to keep track of for each graph:
    #    nodes
    #    node values
    #    node relationships (arcs)
    #   arc values
    #
    # It would quickly become unwieldy to try to keep these in arrays or lists
    # within the graph namespace itself.  Instead, each graph structure will
    # get its own namespace.  Each namespace contains:
    #    node:$node    array mapping keys to values for the node $node
    #    arc:$arc    array mapping keys to values for the arc $arc
    #    inArcs        array mapping nodes to the list of incoming arcs
    #    outArcs        array mapping nodes to the list of outgoing arcs
    #    arcNodes    array mapping arcs to the two nodes (start & end)

    # counter is used to give a unique name for unnamed graph
    variable counter 0

    # commands is the list of subcommands recognized by the graph
    variable commands [list    \
        "arc"        \
        "arcs"        \
        "destroy"        \
        "node"        \
        "nodes"        \
        "swap"        \
        "walk"        \
        ]

    variable arcCommands [list    \
        "delete"    \
        "exists"    \
        "get"    \
        "insert"    \
        "set"    \
        "source"    \
        "target"    \
        "unset"    \
        ]

    variable nodeCommands [list    \
        "degree"    \
        "delete"    \
        "exists"    \
        "get"    \
        "insert"    \
        "opposite"    \
        "set"    \
        "unset"    \
        ]

    # Only export one command, the one used to instantiate a new graph
    namespace export graph
}

# ::struct::graph::graph --
#
#    Create a new graph with a given name; if no name is given, use
#    graphX, where X is a number.
#
# Arguments:
#    name    name of the graph; if null, generate one.
#
# Results:
#    name    name of the graph created

proc ::struct::graph::graph {{name ""}} {
    variable counter

    if { [llength [info level 0]] == 1 } {
    incr counter
    set name "graph${counter}"
    }

    if { ![string equal [info commands ::$name] ""] } {
    error "command \"$name\" already exists, unable to create graph"
    }

    # Set up the namespace
    namespace eval ::struct::graph::graph$name {

    # Set up the map from nodes to the arcs coming to them
    variable  inArcs
    array set inArcs {}

    # Set up the map from nodes to the arcs going out from them
    variable  outArcs
    array set outArcs {}

    # Set up the map from arcs to the nodes they touch.
    variable  arcNodes
    array set arcNodes {}

    # Set up a value for use in creating unique node names
    variable nextUnusedNode
    set nextUnusedNode 1

    # Set up a value for use in creating unique arc names
    variable nextUnusedArc
    set nextUnusedArc 1
    }

    # Create the command to manipulate the graph
    interp alias {} ::$name {} ::struct::graph::GraphProc $name

    return $name
}

##########################
# Private functions follow

# ::struct::graph::GraphProc --
#
#    Command that processes all graph object commands.
#
# Arguments:
#    name    name of the graph object to manipulate.
#    args    command name and args for the command
#
# Results:
#    Varies based on command to perform

proc ::struct::graph::GraphProc {name {cmd ""} args} {
    # Do minimal args checks here
    if { [llength [info level 0]] == 2 } {
    error "wrong # args: should be \"$name option ?arg arg ...?\""
    }

    # Split the args into command and args components
    if { [llength [info commands ::struct::graph::_$cmd]] == 0 } {
    variable commands
    set optlist [join $commands ", "]
    set optlist [linsert $optlist "end-1" "or"]
    error "bad option \"$cmd\": must be $optlist"
    }
    eval [list ::struct::graph::_$cmd $name] $args
}

# ::struct::graph::_arc --
#
#    Dispatches the invocation of arc methods to the proper handler
#    procedure.
#
# Arguments:
#    name    name of the graph.
#    cmd    arc command to invoke
#    args    arguments to propagate to the handler for the arc command
#
# Results:
#    As of the invoked handler.

proc ::struct::graph::_arc {name cmd args} {

    # Split the args into command and args components
    if { [llength [info commands ::struct::graph::__arc_$cmd]] == 0 } {
    variable arcCommands
    set optlist [join $arcCommands ", "]
    set optlist [linsert $optlist "end-1" "or"]
    error "bad option \"$cmd\": must be $optlist"
    }

    eval [list ::struct::graph::__arc_$cmd $name] $args
}

# ::struct::graph::__arc_delete --
#
#    Remove an arc from a graph, including all of its values.
#
# Arguments:
#    name    name of the graph.
#    args    list of arcs to delete.
#
# Results:
#    None.

proc ::struct::graph::__arc_delete {name args} {

    foreach arc $args {
    if { ![__arc_exists $name $arc] } {
        error "arc \"$arc\" does not exist in graph \"$name\""
    }
    }

    upvar ::struct::graph::graph${name}::inArcs   inArcs
    upvar ::struct::graph::graph${name}::outArcs  outArcs
    upvar ::struct::graph::graph${name}::arcNodes arcNodes

    foreach arc $args {
    foreach {source target} $arcNodes($arc) break ; # lassign

    unset arcNodes($arc)
    # FRINK: nocheck
    unset ::struct::graph::graph${name}::arc$arc

    # Remove arc from the arc lists of source and target nodes.

    set index            [lsearch -exact $outArcs($source) $arc]
    set outArcs($source) [lreplace       $outArcs($source) $index $index]

    set index            [lsearch -exact $inArcs($target)  $arc]
    set inArcs($target)  [lreplace       $inArcs($target)  $index $index]
    }

    return
}

# ::struct::graph::__arc_exists --
#
#    Test for existance of a given arc in a graph.
#
# Arguments:
#    name    name of the graph.
#    arc    arc to look for.
#
# Results:
#    1 if the arc exists, 0 else.

proc ::struct::graph::__arc_exists {name arc} {
    return [info exists ::struct::graph::graph${name}::arcNodes($arc)]
}

# ::struct::graph::__arc_get --
#
#    Get a keyed value from an arc in a graph.
#
# Arguments:
#    name    name of the graph.
#    arc    arc to query.
#    flag    -key; anything else is an error
#    key    key to lookup; defaults to data
#
# Results:
#    value    value associated with the key given.

proc ::struct::graph::__arc_get {name arc {flag -key} {key data}} {
    if { ![__arc_exists $name $arc] } {
    error "arc \"$arc\" does not exist in graph \"$name\""
    }

    upvar ::struct::graph::graph${name}::arc${arc} data

    if { ![info exists data($key)] } {
    error "invalid key \"$key\" for arc \"$arc\""
    }

    return $data($key)
}

# ::struct::graph::__arc_insert --
#
#    Add an arc to a graph.
#
# Arguments:
#    name        name of the graph.
#    source        source node of the new arc
#    target        target node of the new arc
#    args        arc to insert; must be unique.  If none is given,
#            the routine will generate a unique node name.
#
# Results:
#    arc        The name of the new arc.

proc ::struct::graph::__arc_insert {name source target args} {

    if { [llength $args] == 0 } {
    # No arc name was given; generate a unique one
    set arc [__generateUniqueArcName $name]
    } else {
    set arc [lindex $args 0]
    }

    if { [__arc_exists $name $arc] } {
    error "arc \"$arc\" already exists in graph \"$name\""
    }

    if { ![__node_exists $name $source] } {
    error "source node \"$source\" does not exist in graph \"$name\""
    }

    if { ![__node_exists $name $target] } {
    error "target node \"$target\" does not exist in graph \"$name\""
    }

    upvar ::struct::graph::graph${name}::inArcs    inArcs
    upvar ::struct::graph::graph${name}::outArcs   outArcs
    upvar ::struct::graph::graph${name}::arcNodes  arcNodes
    upvar ::struct::graph::graph${name}::arc${arc} data

    # Set up the new arc
    set data(data)       ""
    set arcNodes($arc) [list $source $target]

    # Add this arc to the arc lists of its source resp. target nodes.
    lappend outArcs($source) $arc
    lappend inArcs($target)  $arc

    return $arc
}

# ::struct::graph::__arc_set --
#
#    Set or get a value for an arc in a graph.
#
# Arguments:
#    name    name of the graph.
#    arc    arc to modify or query.
#    args    ?-key key? ?value?
#
# Results:
#    val    value associated with the given key of the given arc

proc ::struct::graph::__arc_set {name arc args} {
    if { ![__arc_exists $name $arc] } {
    error "arc \"$arc\" does not exist in graph \"$name\""
    }

    upvar ::struct::graph::graph${name}::arc$arc data

    if { [llength $args] > 3 } {
    error "wrong # args: should be \"$name arc set $arc ?-key key?\
        ?value?\""
    }

    set key "data"
    set haveValue 0
    if { [llength $args] > 1 } {
    foreach {flag key} $args break
    if { ![string match "${flag}*" "-key"] } {
        error "invalid option \"$flag\": should be key"
    }
    if { [llength $args] == 3 } {
        set haveValue 1
        set value [lindex $args end]
    }
    } elseif { [llength $args] == 1 } {
    set haveValue 1
    set value [lindex $args end]
    }

    if { $haveValue } {
    # Setting a value
    return [set data($key) $value]
    } else {
    # Getting a value
    if { ![info exists data($key)] } {
        error "invalid key \"$key\" for arc \"$arc\""
    }
    return $data($key)
    }
}

# ::struct::graph::__arc_source --
#
#    Return the node at the beginning of the specified arc.
#
# Arguments:
#    name    name of the graph object.
#    arc    arc to look up.
#
# Results:
#    node    name of the node.

proc ::struct::graph::__arc_source {name arc} {
    if { ![__arc_exists $name $arc] } {
    error "arc \"$arc\" does not exist in graph \"$name\""
    }

    upvar ::struct::graph::graph${name}::arcNodes arcNodes
    return [lindex $arcNodes($arc) 0]
}

# ::struct::graph::__arc_target --
#
#    Return the node at the end of the specified arc.
#
# Arguments:
#    name    name of the graph object.
#    arc    arc to look up.
#
# Results:
#    node    name of the node.

proc ::struct::graph::__arc_target {name arc} {
    if { ![__arc_exists $name $arc] } {
    error "arc \"$arc\" does not exist in graph \"$name\""
    }

    upvar ::struct::graph::graph${name}::arcNodes arcNodes
    return [lindex $arcNodes($arc) 1]
}

# ::struct::graph::__arc_unset --
#
#    Remove a keyed value from a arc.
#
# Arguments:
#    name    name of the graph.
#    arc    arc to modify.
#    args    additional args: ?-key key?
#
# Results:
#    None.

proc ::struct::graph::__arc_unset {name arc {flag -key} {key data}} {
    if { ![__arc_exists $name $arc] } {
    error "arc \"$arc\" does not exist in graph \"$name\""
    }

    if { ![string match "${flag}*" "-key"] } {
    error "invalid option \"$flag\": should be \"$name unset\
        $arc ?-key key?\""
    }

    upvar ::struct::graph::graph${name}::arc${arc} data
    if { [info exists data($key)] } {
    unset data($key)
    }
    return
}

# ::struct::graph::_arcs --
#
#    Return a list of all arcs in a graph satisfying some
#    node based restriction.
#
# Arguments:
#    name    name of the graph.
#
# Results:
#    arcs    list of arcs

proc ::struct::graph::_arcs {name args} {

    if {[llength $args] == 0} {
    # No restriction, deliver all.

    upvar ::struct::graph::graph${name}::arcNodes arcNodes
    return [array names arcNodes]
    }

    # Get mode and node list

    set cond [lindex $args 0]
    set args [lrange $args 1 end]

    # Validate that the cond is good.
    switch -glob -- $cond {
    "-in" {
        set cond "in"
    }
    "-out" {
        set cond "out"
    }
    "-adj" {
        set cond "adj"
    }
    "-inner" {
        set cond "inner"
    }
    "-embedding" {
        set cond "embedding"
    }
    default {
        error "invalid restriction \"$cond\": should be -in, -out,\
            -adj, -inner or -embedding"
    }
    }

    # Validate that there are nodes to use in the restriction.
    # otherwise what's the point?
    if {[llength $args] == 0} {
    set usage "$name arcs ?-in|-out|-adj|-inner|-embedding node node...?"
    error "no nodes specified: should be \"$usage\""
    }

    # Make sure that the specified nodes exist!
    foreach node $args {
    if { ![__node_exists $name $node] } {
        error "node \"$node\" does not exist in graph \"$name\""
    }
    }

    # Now we are able to go to work
    upvar ::struct::graph::graph${name}::inArcs   inArcs
    upvar ::struct::graph::graph${name}::outArcs  outArcs
    upvar ::struct::graph::graph${name}::arcNodes arcNodes

    set       arcs [list]
    array set coll  {}

    switch -exact -- $cond {
    in {
        # Result is all arcs going to at least one node
        # in the list of arguments.

        foreach node $args {
        foreach e $inArcs($node) {
            if {[info exists coll($e)]} {continue}
            lappend arcs    $e
            set     coll($e) .
        }
        }
    }
    out {
        # Result is all arcs coming from at least one node
        # in the list of arguments.

        foreach node $args {
        foreach e $outArcs($node) {
            if {[info exists coll($e)]} {continue}
            lappend arcs    $e
            set     coll($e) .
        }
        }
    }
    adj {
        # Result is all arcs coming from or going to at
        # least one node in the list of arguments.

        foreach node $args {
        foreach e $inArcs($node) {
            if {[info exists coll($e)]} {continue}
            lappend arcs    $e
            set     coll($e) .
        }
        foreach e $outArcs($node) {
            if {[info exists coll($e)]} {continue}
            lappend arcs    $e
            set     coll($e) .
        }
        }
    }
    inner {
        # Result is all arcs running between nodes in the list.

        array set group {}
        foreach node $args {
        set group($node) .
        }

        foreach node $args {
        foreach e $inArcs($node) {
            set n [lindex $arcNodes($e) 0]
            if {![info exists group($n)]} {continue}
            if { [info exists coll($e)]}  {continue}
            lappend arcs    $e
            set     coll($e) .
        }
        foreach e $outArcs($node) {
            set n [lindex $arcNodes($e) 1]
            if {![info exists group($n)]} {continue}
            if { [info exists coll($e)]}  {continue}
            lappend arcs    $e
            set     coll($e) .
        }
        }
    }
    embedding {
        # Result is all arcs from -adj minus the arcs from -inner.
        # IOW all arcs goint from a node in the list to a node
        # which is *not* in the list

        array set group {}
        foreach node $args {
        set group($node) .
        }

        foreach node $args {
        foreach e $inArcs($node) {
            set n [lindex $arcNodes($e) 0]
            if {[info exists group($n)]} {continue}
            if {[info exists coll($e)]}  {continue}
            lappend arcs    $e
            set     coll($e) .
        }
        foreach e $outArcs($node) {
            set n [lindex $arcNodes($e) 1]
            if {[info exists group($n)]} {continue}
            if {[info exists coll($e)]}  {continue}
            lappend arcs    $e
            set     coll($e) .
        }
        }
    }
    default {error "Can't happen, panic"}
    }

    return $arcs
}

# ::struct::graph::_destroy --
#
#    Destroy a graph, including its associated command and data storage.
#
# Arguments:
#    name    name of the graph.
#
# Results:
#    None.

proc ::struct::graph::_destroy {name} {
    namespace delete ::struct::graph::graph$name
    interp alias {} ::$name {}
}

# ::struct::graph::__generateUniqueArcName --
#
#    Generate a unique arc name for the given graph.
#
# Arguments:
#    name    name of the graph.
#
# Results:
#    arc    name of a arc guaranteed to not exist in the graph.

proc ::struct::graph::__generateUniqueArcName {name} {
    upvar ::struct::graph::graph${name}::nextUnusedArc nextUnusedArc
    while {[__arc_exists $name "arc${nextUnusedArc}"]} {
    incr nextUnusedArc
    }
    return "arc${nextUnusedArc}"
}

# ::struct::graph::__generateUniqueNodeName --
#
#    Generate a unique node name for the given graph.
#
# Arguments:
#    name    name of the graph.
#
# Results:
#    node    name of a node guaranteed to not exist in the graph.

proc ::struct::graph::__generateUniqueNodeName {name} {
    upvar ::struct::graph::graph${name}::nextUnusedNode nextUnusedNode
    while {[__node_exists $name "node${nextUnusedNode}"]} {
    incr nextUnusedNode
    }
    return "node${nextUnusedNode}"
}

# ::struct::graph::_node --
#
#    Dispatches the invocation of node methods to the proper handler
#    procedure.
#
# Arguments:
#    name    name of the graph.
#    cmd    node command to invoke
#    args    arguments to propagate to the handler for the node command
#
# Results:
#    As of the the invoked handler.

proc ::struct::graph::_node {name cmd args} {

    # Split the args into command and args components
    if { [llength [info commands ::struct::graph::__node_$cmd]] == 0 } {
    variable nodeCommands
    set optlist [join $nodeCommands ", "]
    set optlist [linsert $optlist "end-1" "or"]
    error "bad option \"$cmd\": must be $optlist"
    }

    eval [list ::struct::graph::__node_$cmd $name] $args
}

# ::struct::graph::__node_degree --
#
#    Return the number of arcs adjacent to the specified node.
#    If one of the restrictions -in or -out is given only
#    incoming resp. outgoing arcs are counted.
#
# Arguments:
#    name    name of the graph.
#    args    option, followed by the node.
#
# Results:
#    None.

proc ::struct::graph::__node_degree {name args} {

    if {([llength $args] < 1) || ([llength $args] > 2)} {
    error "wrong # args: should be \"$name node degree ?-in|-out| node\""
    }

    switch -exact -- [llength $args] {
    1 {
        set opt {}
        set node [lindex $args 0]
    }
    2 {
        set opt  [lindex $args 0]
        set node [lindex $args 1]
    }
    default {
        error "Wrong # arguments given to 'degree'"
    }
    }

    # Validate the option.

    switch -exact -- $opt {
    {}   -
    -in  -
    -out {}
    default {
        error "invalid option \"$opt\": should be -in or -out"
    }
    }

    # Validate the node

    if { ![__node_exists $name $node] } {
    error "node \"$node\" does not exist in graph \"$name\""
    }

    upvar ::struct::graph::graph${name}::inArcs   inArcs
    upvar ::struct::graph::graph${name}::outArcs  outArcs

    switch -exact -- $opt {
    -in  {
        set result [llength $inArcs($node)]
    }
    -out {
        set result [llength $outArcs($node)]
    }
    {} {
        set result [expr {[llength $inArcs($node)] \
            + [llength $outArcs($node)]}]

        # loops count twice, don't do <set> arithmetics, i.e. no union!
        if {0} {
        array set coll  {}
        set result [llength $inArcs($node)]

        foreach e $inArcs($node) {
            set coll($e) .
        }
        foreach e $outArcs($node) {
            if {[info exists coll($e)]} {continue}
            incr result
            set     coll($e) .
        }
        }
    }
    default {error "Can't happen, panic"}
    }

    return $result
}

# ::struct::graph::__node_delete --
#
#    Remove a node from a graph, including all of its values.
#    Additionally removes the arcs connected to this node.
#
# Arguments:
#    name    name of the graph.
#    args    list of the nodes to delete.
#
# Results:
#    None.

proc ::struct::graph::__node_delete {name args} {

    foreach node $args {
    if { ![__node_exists $name $node] } {
        error "node \"$node\" does not exist in graph \"$name\""
    }
    }

    upvar ::struct::graph::graph${name}::inArcs  inArcs
    upvar ::struct::graph::graph${name}::outArcs outArcs

    foreach node $args {
    # Remove all the arcs connected to this node
    foreach e $inArcs($node) {
        __arc_delete $name $e
    }
    foreach e $outArcs($node) {
        # Check existence to avoid problems with
        # loops (they are in and out arcs! at
        # the same time and thus already deleted)
        if { [__arc_exists $name $e] } {
        __arc_delete $name $e
        }
    }

    unset inArcs($node)
    unset outArcs($node)
    # FRINK: nocheck
    unset ::struct::graph::graph${name}::node$node
    }

    return
}

# ::struct::graph::__node_exists --
#
#    Test for existance of a given node in a graph.
#
# Arguments:
#    name    name of the graph.
#    node    node to look for.
#
# Results:
#    1 if the node exists, 0 else.

proc ::struct::graph::__node_exists {name node} {
    return [info exists ::struct::graph::graph${name}::inArcs($node)]
}

# ::struct::graph::__node_get --
#
#    Get a keyed value from a node in a graph.
#
# Arguments:
#    name    name of the graph.
#    node    node to query.
#    flag    -key; anything else is an error
#    key    key to lookup; defaults to data
#
# Results:
#    value    value associated with the key given.

proc ::struct::graph::__node_get {name node {flag -key} {key data}} {
    if { ![__node_exists $name $node] } {
    error "node \"$node\" does not exist in graph \"$name\""
    }

    upvar ::struct::graph::graph${name}::node${node} data

    if { ![info exists data($key)] } {
    error "invalid key \"$key\" for node \"$node\""
    }

    return $data($key)
}

# ::struct::graph::__node_insert --
#
#    Add a node to a graph.
#
# Arguments:
#    name        name of the graph.
#    args        node to insert; must be unique.  If none is given,
#            the routine will generate a unique node name.
#
# Results:
#    node        The namee of the new node.

proc ::struct::graph::__node_insert {name args} {

    if { [llength $args] == 0 } {
    # No node name was given; generate a unique one
    set node [__generateUniqueNodeName $name]
    } else {
    set node [lindex $args 0]
    }

    if { [__node_exists $name $node] } {
    error "node \"$node\" already exists in graph \"$name\""
    }

    upvar ::struct::graph::graph${name}::inArcs      inArcs
    upvar ::struct::graph::graph${name}::outArcs     outArcs
    upvar ::struct::graph::graph${name}::node${node} data

    # Set up the new node
    set inArcs($node)  [list]
    set outArcs($node) [list]
    set data(data) ""

    return $node
}

# ::struct::graph::__node_opposite --
#
#    Retrieve node opposite to the specified one, along the arc.
#
# Arguments:
#    name        name of the graph.
#    node        node to look up.
#    arc        arc to look up.
#
# Results:
#    nodex    Node opposite to <node,arc>

proc ::struct::graph::__node_opposite {name node arc} {
    if {![__node_exists $name $node] } {
    error "node \"$node\" does not exist in graph \"$name\""
    }

    if {![__arc_exists $name $arc] } {
    error "arc \"$arc\" does not exist in graph \"$name\""
    }

    upvar ::struct::graph::graph${name}::arcNodes arcNodes

    # Node must be connected to at least one end of the arc.

    if {[string equal $node [lindex $arcNodes($arc) 0]]} {
    set result [lindex $arcNodes($arc) 1]
    } elseif {[string equal $node [lindex $arcNodes($arc) 1]]} {
    set result [lindex $arcNodes($arc) 0]
    } else {
    error "node \"$node\" and arc \"$arc\" are not connected\
        in graph \"$name\""
    }

    return $result
}

# ::struct::graph::__node_set --
#
#    Set or get a value for a node in a graph.
#
# Arguments:
#    name    name of the graph.
#    node    node to modify or query.
#    args    ?-key key? ?value?
#
# Results:
#    val    value associated with the given key of the given node

proc ::struct::graph::__node_set {name node args} {
    if { ![__node_exists $name $node] } {
    error "node \"$node\" does not exist in graph \"$name\""
    }
    upvar ::struct::graph::graph${name}::node$node data

    if { [llength $args] > 3 } {
    error "wrong # args: should be \"$name node set $node ?-key key?\
        ?value?\""
    }

    set key "data"
    set haveValue 0
    if { [llength $args] > 1 } {
    foreach {flag key} $args break
    if { ![string match "${flag}*" "-key"] } {
        error "invalid option \"$flag\": should be key"
    }
    if { [llength $args] == 3 } {
        set haveValue 1
        set value [lindex $args end]
    }
    } elseif { [llength $args] == 1 } {
    set haveValue 1
    set value [lindex $args end]
    }

    if { $haveValue } {
    # Setting a value
    return [set data($key) $value]
    } else {
    # Getting a value
    if { ![info exists data($key)] } {
        error "invalid key \"$key\" for node \"$node\""
    }
    return $data($key)
    }
}

# ::struct::graph::__node_unset --
#
#    Remove a keyed value from a node.
#
# Arguments:
#    name    name of the graph.
#    node    node to modify.
#    args    additional args: ?-key key?
#
# Results:
#    None.

proc ::struct::graph::__node_unset {name node {flag -key} {key data}} {
    if { ![__node_exists $name $node] } {
    error "node \"$node\" does not exist in graph \"$name\""
    }

    if { ![string match "${flag}*" "-key"] } {
    error "invalid option \"$flag\": should be \"$name unset\
        $node ?-key key?\""
    }

    upvar ::struct::graph::graph${name}::node${node} data
    if { [info exists data($key)] } {
    unset data($key)
    }
    return
}

# ::struct::graph::_nodes --
#
#    Return a list of all nodes in a graph satisfying some restriction.
#
# Arguments:
#    name    name of the graph.
#    args    list of options and nodes specifying the restriction.
#
# Results:
#    nodes    list of nodes

proc ::struct::graph::_nodes {name args} {

    if {[llength $args] == 0} {
    # No restriction, deliver all.

    upvar ::struct::graph::graph${name}::inArcs inArcs
    return [array names inArcs]
    }

    # Get mode and node list

    set cond [lindex $args 0]
    set args [lrange $args 1 end]

    # Validate that the cond is good.
    switch -glob -- $cond {
    "-in" {
        set cond "in"
    }
    "-out" {
        set cond "out"
    }
    "-adj" {
        set cond "adj"
    }
    "-inner" {
        set cond "inner"
    }
    "-embedding" {
        set cond "embedding"
    }
    default {
        error "invalid restriction \"$cond\": should be -in, -out,\
            -adj, -inner or -embedding"
    }
    }

    # Validate that there are nodes to use in the restriction.
    # otherwise what's the point?
    if {[llength $args] == 0} {
    set usage "$name nodes ?-in|-out|-adj|-inner|-embedding node node...?"
    error "no nodes specified: should be \"$usage\""
    }

    # Make sure that the specified nodes exist!
    foreach node $args {
    if { ![__node_exists $name $node] } {
        error "node \"$node\" does not exist in graph \"$name\""
    }
    }

    # Now we are able to go to work
    upvar ::struct::graph::graph${name}::inArcs   inArcs
    upvar ::struct::graph::graph${name}::outArcs  outArcs
    upvar ::struct::graph::graph${name}::arcNodes arcNodes

    set       nodes [list]
    array set coll  {}

    switch -exact -- $cond {
    in {
        # Result is all nodes with at least one arc going to
        # at least one node in the list of arguments.

        foreach node $args {
        foreach e $inArcs($node) {
            set n [lindex $arcNodes($e) 0]
            if {[info exists coll($n)]} {continue}
            lappend nodes    $n
            set     coll($n) .
        }
        }
    }
    out {
        # Result is all nodes with at least one arc coming from
        # at least one node in the list of arguments.

        foreach node $args {
        foreach e $outArcs($node) {
            set n [lindex $arcNodes($e) 1]
            if {[info exists coll($n)]} {continue}
            lappend nodes    $n
            set     coll($n) .
        }
        }
    }
    adj {
        # Result is all nodes with at least one arc coming from
        # or going to at least one node in the list of arguments.

        foreach node $args {
        foreach e $inArcs($node) {
            set n [lindex $arcNodes($e) 0]
            if {[info exists coll($n)]} {continue}
            lappend nodes    $n
            set     coll($n) .
        }
        foreach e $outArcs($node) {
            set n [lindex $arcNodes($e) 1]
            if {[info exists coll($n)]} {continue}
            lappend nodes    $n
            set     coll($n) .
        }
        }
    }
    inner {
        # Result is all nodes from the list! with at least one arc
        # coming from or going to at least one node in the list of
        # arguments.

        array set group {}
        foreach node $args {
        set group($node) .
        }

        foreach node $args {
        foreach e $inArcs($node) {
            set n [lindex $arcNodes($e) 0]
            if {![info exists group($n)]} {continue}
            if { [info exists coll($n)]}  {continue}
            lappend nodes    $n
            set     coll($n) .
        }
        foreach e $outArcs($node) {
            set n [lindex $arcNodes($e) 1]
            if {![info exists group($n)]} {continue}
            if { [info exists coll($n)]}  {continue}
            lappend nodes    $n
            set     coll($n) .
        }
        }
    }
    embedding {
        # Result is all nodes with at least one arc coming from
        # or going to at least one node in the list of arguments,
        # but not in the list itself!

        array set group {}
        foreach node $args {
        set group($node) .
        }

        foreach node $args {
        foreach e $inArcs($node) {
            set n [lindex $arcNodes($e) 0]
            if {[info exists group($n)]} {continue}
            if {[info exists coll($n)]}  {continue}
            lappend nodes    $n
            set     coll($n) .
        }
        foreach e $outArcs($node) {
            set n [lindex $arcNodes($e) 1]
            if {[info exists group($n)]} {continue}
            if {[info exists coll($n)]}  {continue}
            lappend nodes    $n
            set     coll($n) .
        }
        }
    }
    default {error "Can't happen, panic"}
    }

    return $nodes
}

# ::struct::graph::_swap --
#
#    Swap two nodes in a graph.
#
# Arguments:
#    name    name of the graph.
#    node1    first node to swap.
#    node2    second node to swap.
#
# Results:
#    None.

proc ::struct::graph::_swap {name node1 node2} {
    # Can only swap two real nodes
    if { ![__node_exists $name $node1] } {
    error "node \"$node1\" does not exist in graph \"$name\""
    }
    if { ![__node_exists $name $node2] } {
    error "node \"$node2\" does not exist in graph \"$name\""
    }

    # Can't swap a node with itself
    if { [string equal $node1 $node2] } {
    error "cannot swap node \"$node1\" with itself"
    }

    # Swapping nodes means swapping their labels, values and arcs
    upvar ::struct::graph::graph${name}::outArcs      outArcs
    upvar ::struct::graph::graph${name}::inArcs       inArcs
    upvar ::struct::graph::graph${name}::arcNodes     arcNodes
    upvar ::struct::graph::graph${name}::node${node1} node1Vals
    upvar ::struct::graph::graph${name}::node${node2} node2Vals

    # Redirect arcs to the new nodes.

    foreach e $inArcs($node1) {
    set arcNodes($e) [lreplace $arcNodes($e) end end $node2]
    }
    foreach e $inArcs($node2) {
    set arcNodes($e) [lreplace $arcNodes($e) end end $node1]
    }
    foreach e $outArcs($node1) {
    set arcNodes($e) [lreplace $arcNodes($e) 0 0 $node2]
    }
    foreach e $outArcs($node2) {
    set arcNodes($e) [lreplace $arcNodes($e) 0 0 $node1]
    }

    # Swap arc lists

    set tmp            $inArcs($node1)
    set inArcs($node1) $inArcs($node2)
    set inArcs($node2) $tmp

    set tmp             $outArcs($node1)
    set outArcs($node1) $outArcs($node2)
    set outArcs($node2) $tmp

    # Swap the values
    set   value1        [array get node1Vals]
    unset node1Vals
    array set node1Vals [array get node2Vals]
    unset node2Vals
    array set node2Vals $value1

    return
}

# ::struct::graph::_walk --
#
#    Walk a graph using a pre-order depth or breadth first
#    search. Pre-order DFS is the default.  At each node that is visited,
#    a command will be called with the name of the graph and the node.
#
# Arguments:
#    name    name of the graph.
#    node    node at which to start.
#    args    additional args: ?-order pre|post|both? ?-type {bfs|dfs}?
#        -command cmd
#
# Results:
#    None.

proc ::struct::graph::_walk {name node args} {
    set usage "$name walk $node ?-dir forward|backward?\
        ?-order pre|post|both? ?-type {bfs|dfs}? -command cmd"

    if {[llength $args] > 8 || [llength $args] < 2} {
    error "wrong # args: should be \"$usage\""
    }

    if { ![__node_exists $name $node] } {
    error "node \"$node\" does not exist in graph \"$name\""
    }

    # Set defaults
    set type  dfs
    set order pre
    set cmd   ""
    set dir   forward

    # Process specified options
    for {set i 0} {$i < [llength $args]} {incr i} {
    set flag [lindex $args $i]
    incr i
    if { $i >= [llength $args] } {
        error "value for \"$flag\" missing: should be \"$usage\""
    }
    switch -glob -- $flag {
        "-type" {
        set type [string tolower [lindex $args $i]]
        }
        "-order" {
        set order [string tolower [lindex $args $i]]
        }
        "-command" {
        set cmd [lindex $args $i]
        }
        "-dir" {
        set dir [string tolower [lindex $args $i]]
        }
        default {
        error "unknown option \"$flag\": should be \"$usage\""
        }
    }
    }

    # Make sure we have a command to run, otherwise what's the point?
    if { [string equal $cmd ""] } {
    error "no command specified: should be \"$usage\""
    }

    # Validate that the given type is good
    switch -glob -- $type {
    "dfs" {
        set type "dfs"
    }
    "bfs" {
        set type "bfs"
    }
    default {
        error "invalid search type \"$type\": should be dfs, or bfs"
    }
    }

    # Validate that the given order is good
    switch -glob -- $order {
    "both" {
        set order both
    }
    "pre" {
        set order pre
    }
    "post" {
        set order post
    }
    default {
        error "invalid search order \"$order\": should be both,\
            pre or post"
    }
    }

    # Validate that the given direction is good
    switch -glob -- $dir {
    "forward" {
        set dir -out
    }
    "backward" {
        set dir -in
    }
    default {
        error "invalid search direction \"$dir\": should be\
            forward or backward"
    }
    }

    # Do the walk

    set st [list ]
    lappend st $node
    array set visited {}

    if { [string equal $type "dfs"] } {
    if { [string equal $order "pre"] } {
        # Pre-order Depth-first search

        while { [llength $st] > 0 } {
        set node [lindex   $st end]
        set st   [lreplace $st end end]

        # Evaluate the command at this node
        set cmdcpy $cmd
        lappend cmdcpy enter $name $node
        uplevel 2 $cmdcpy

        set visited($node) .

        # Add this node's neighbours (according to direction)
        #  Have to add them in reverse order
        #  so that they will be popped left-to-right

        set next [_nodes $name $dir $node]
        set len  [llength $next]

        for {set i [expr {$len - 1}]} {$i >= 0} {incr i -1} {
            set nextnode [lindex $next $i]
            if {[info exists visited($nextnode)]} {
            # Skip nodes already visited
            continue
            }
            lappend st $nextnode
        }
        }
    } elseif { [string equal $order "post"] } {
        # Post-order Depth-first search

        while { [llength $st] > 0 } {
        set node [lindex $st end]

        if {[info exists visited($node)]} {
            # Second time we are here, pop it,
            # then evaluate the command.

            set st [lreplace $st end end]

            # Evaluate the command at this node
            set cmdcpy $cmd
            lappend cmdcpy leave $name $node
            uplevel 2 $cmdcpy
        } else {
            # First visit. Remember it.
            set visited($node) .

            # Add this node's neighbours.
            set next [_nodes $name $dir $node]
            set len  [llength $next]

            for {set i [expr {$len - 1}]} {$i >= 0} {incr i -1} {
            set nextnode [lindex $next $i]
            if {[info exists visited($nextnode)]} {
                # Skip nodes already visited
                continue
            }
            lappend st $nextnode
            }
        }
        }
    } else {
        # Both-order Depth-first search

        while { [llength $st] > 0 } {
        set node [lindex $st end]

        if {[info exists visited($node)]} {
            # Second time we are here, pop it,
            # then evaluate the command.

            set st [lreplace $st end end]

            # Evaluate the command at this node
            set cmdcpy $cmd
            lappend cmdcpy leave $name $node
            uplevel 2 $cmdcpy
        } else {
            # First visit. Remember it.
            set visited($node) .

            # Evaluate the command at this node
            set cmdcpy $cmd
            lappend cmdcpy enter $name $node
            uplevel 2 $cmdcpy

            # Add this node's neighbours.
            set next [_nodes $name $dir $node]
            set len  [llength $next]

            for {set i [expr {$len - 1}]} {$i >= 0} {incr i -1} {
            set nextnode [lindex $next $i]
            if {[info exists visited($nextnode)]} {
                # Skip nodes already visited
                continue
            }
            lappend st $nextnode
            }
        }
        }
    }

    } else {
    if { [string equal $order "pre"] } {
        # Pre-order Breadth first search
        while { [llength $st] > 0 } {
        set node [lindex $st 0]
        set st   [lreplace $st 0 0]
        # Evaluate the command at this node
        set cmdcpy $cmd
        lappend cmdcpy enter $name $node
        uplevel 2 $cmdcpy

        set visited($node) .

        # Add this node's neighbours.
        foreach child [_nodes $name $dir $node] {
            if {[info exists visited($child)]} {
            # Skip nodes already visited
            continue
            }
            lappend st $child
        }
        }
    } else {
        # Post-order Breadth first search
        # Both-order Breadth first search
        # Haven't found anything in Knuth
        # and unable to define something
        # consistent for myself. Leave it
        # out.

        error "unable to do a ${order}-order breadth first walk"
    }
    }
    return
}

# ::struct::graph::Union --
#
#    Return a list which is the union of the elements
#    in the specified lists.
#
# Arguments:
#    args    list of lists representing sets.
#
# Results:
#    set    list representing the union of the argument lists.

proc ::struct::graph::Union {args} {
    switch -- [llength $args] {
    0 {
        return {}
    }
    1 {
        return [lindex $args 0]
    }
    default {
        foreach set $args {
        foreach e $set {
            set tmp($e) .
        }
        }
        return [array names tmp]
    }
    }
}