digraph

Overview ¶

Copyright 2019 The Go Authors. All rights reserved. Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.

The digraph command performs queries over unlabelled directed graphs represented in text form. It is intended to integrate nicely with typical UNIX command pipelines.

Usage:

your-application | digraph [command]

The supported commands are:

nodes
	the set of all nodes
degree
	the in-degree and out-degree of each node
transpose
	the reverse of the input edges
preds <node> ...
	the set of immediate predecessors of the specified nodes
succs <node> ...
	the set of immediate successors of the specified nodes
forward <node> ...
	the set of nodes transitively reachable from the specified nodes
reverse <node> ...
	the set of nodes that transitively reach the specified nodes
somepath <node> <node>
	the list of nodes on some arbitrary path from the first node to the second
allpaths <node> <node>
	the set of nodes on all paths from the first node to the second
sccs
	all strongly connected components (one per line)
scc <node>
	the set of nodes strongly connected to the specified one
focus <node>
	the subgraph containing all directed paths that pass through the specified node
to dot
	print the graph in Graphviz dot format (other formats may be supported in the future)

Input format:

Each line contains zero or more words. Words are separated by unquoted whitespace; words may contain Go-style double-quoted portions, allowing spaces and other characters to be expressed.

Each word declares a node, and if there are more than one, an edge from the first to each subsequent one. The graph is provided on the standard input.

For instance, the following (acyclic) graph specifies a partial order among the subtasks of getting dressed:

$ cat clothes.txt
socks shoes
"boxer shorts" pants
pants belt shoes
shirt tie sweater
sweater jacket
hat

The line "shirt tie sweater" indicates the two edges shirt -> tie and shirt -> sweater, not shirt -> tie -> sweater.

Example usage:

Show which clothes (see above) must be donned before a jacket:

$ digraph reverse jacket

Many tools can be persuaded to produce output in digraph format, as in the following examples.

Using an import graph produced by go list, show a path that indicates why the gopls application depends on the cmp package:

$ go list -f '{{.ImportPath}} {{join .Imports " "}}' -deps golang.org/x/tools/gopls |
	digraph somepath golang.org/x/tools/gopls github.com/google/go-cmp/cmp

Show which packages in x/tools depend, perhaps indirectly, on the callgraph package:

$ go list -f '{{.ImportPath}} {{join .Imports " "}}' -deps golang.org/x/tools/... |
	digraph reverse golang.org/x/tools/go/callgraph

Visualize the package dependency graph of the current package:

$ go list -f '{{.ImportPath}} {{join .Imports " "}}' -deps |
	digraph to dot | dot -Tpng -o x.png

Using a module graph produced by go mod, show all dependencies of the current module:

$ go mod graph | digraph forward $(go list -m)