1 // Copyright 2019 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 /* 6 The digraph command performs queries over unlabelled directed graphs 7 represented in text form. It is intended to integrate nicely with 8 typical UNIX command pipelines. 9 10 Usage: 11 12 your-application | digraph [command] 13 14 The supported commands are: 15 16 nodes 17 the set of all nodes 18 degree 19 the in-degree and out-degree of each node 20 transpose 21 the reverse of the input edges 22 preds <node> ... 23 the set of immediate predecessors of the specified nodes 24 succs <node> ... 25 the set of immediate successors of the specified nodes 26 forward <node> ... 27 the set of nodes transitively reachable from the specified nodes 28 reverse <node> ... 29 the set of nodes that transitively reach the specified nodes 30 somepath <node> <node> 31 the list of nodes on some arbitrary path from the first node to the second 32 allpaths <node> <node> 33 the set of nodes on all paths from the first node to the second 34 sccs 35 all strongly connected components (one per line) 36 scc <node> 37 the set of nodes strongly connected to the specified one 38 focus <node> 39 the subgraph containing all directed paths that pass through the specified node 40 to dot 41 print the graph in Graphviz dot format (other formats may be supported in the future) 42 43 Input format: 44 45 Each line contains zero or more words. Words are separated by unquoted 46 whitespace; words may contain Go-style double-quoted portions, allowing spaces 47 and other characters to be expressed. 48 49 Each word declares a node, and if there are more than one, an edge from the 50 first to each subsequent one. The graph is provided on the standard input. 51 52 For instance, the following (acyclic) graph specifies a partial order among the 53 subtasks of getting dressed: 54 55 $ cat clothes.txt 56 socks shoes 57 "boxer shorts" pants 58 pants belt shoes 59 shirt tie sweater 60 sweater jacket 61 hat 62 63 The line "shirt tie sweater" indicates the two edges shirt -> tie and 64 shirt -> sweater, not shirt -> tie -> sweater. 65 66 Example usage: 67 68 Show which clothes (see above) must be donned before a jacket: 69 70 $ digraph reverse jacket 71 72 Many tools can be persuaded to produce output in digraph format, 73 as in the following examples. 74 75 Using an import graph produced by go list, show a path that indicates 76 why the gopls application depends on the cmp package: 77 78 $ go list -f '{{.ImportPath}} {{join .Imports " "}}' -deps golang.org/x/tools/gopls | 79 digraph somepath golang.org/x/tools/gopls github.com/google/go-cmp/cmp 80 81 Show which packages in x/tools depend, perhaps indirectly, on the callgraph package: 82 83 $ go list -f '{{.ImportPath}} {{join .Imports " "}}' -deps golang.org/x/tools/... | 84 digraph reverse golang.org/x/tools/go/callgraph 85 86 Visualize the package dependency graph of the current package: 87 88 $ go list -f '{{.ImportPath}} {{join .Imports " "}}' -deps | 89 digraph to dot | dot -Tpng -o x.png 90 91 Using a module graph produced by go mod, show all dependencies of the current module: 92 93 $ go mod graph | digraph forward $(go list -m) 94 */ 95 package main 96