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