33 lines
1.9 KiB
Factor
33 lines
1.9 KiB
Factor
IN: graphs
|
|
USING: help.markup help.syntax kernel assocs hashtables ;
|
|
|
|
ARTICLE: "graphs" "Directed graph utilities"
|
|
"Words for treating associative mappings as directed graphs can be found in the " { $vocab-link "graphs" } " vocabulary. A directed graph is represented as an assoc mapping each vertex to a set of edges entering that vertex, where the set is itself an assoc, with equal keys and values."
|
|
$nl
|
|
"To create a new graph, just create an assoc, for example by calling " { $link <hashtable> } ". To add vertices and edges to a graph:"
|
|
{ $subsections add-vertex }
|
|
"To remove vertices from the graph:"
|
|
{ $subsections remove-vertex }
|
|
"Since graphs are represented as assocs, they can be cleared out by calling " { $link clear-assoc } "."
|
|
$nl
|
|
"You can perform queries on the graph:"
|
|
{ $subsections closure }
|
|
"Directed graphs are used to maintain cross-referencing information for " { $link "definitions" } "." ;
|
|
|
|
ABOUT: "graphs"
|
|
|
|
HELP: add-vertex
|
|
{ $values { "vertex" object } { "edges" "a sequence" } { "graph" "an assoc mapping vertices to sequences of edges" } }
|
|
{ $description "Adds a vertex to a directed graph, with " { $snippet "edges" } " as the outward edges from the vertex." }
|
|
{ $side-effects "graph" } ;
|
|
|
|
HELP: remove-vertex
|
|
{ $values { "vertex" object } { "edges" "a sequence" } { "graph" "an assoc mapping vertices to sequences of edges" } }
|
|
{ $description "Removes a vertex from a graph, using the given edges sequence." }
|
|
{ $notes "The " { $snippet "edges" } " sequence must equal the value passed to " { $link add-vertex } ", otherwise some vertices of the graph may continue to refer to the removed vertex." }
|
|
{ $side-effects "graph" } ;
|
|
|
|
HELP: closure
|
|
{ $values { "obj" object } { "quot" "a a quotation with stack effect " { $snippet "( obj -- assoc )" } } { "assoc" "a new assoc" } }
|
|
{ $description "Outputs a set of all vertices reachable from " { $snippet "vertex" } " via edges given by the quotation. The set always includes " { $snippet "vertex" } "." } ;
|