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v/compiler/depgraph.v

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// Copyright (c) 2019 Alexander Medvednikov. All rights reserved.
// Use of this source code is governed by an MIT license
// that can be found in the LICENSE file.
// Directed acyclic graph
// this implementation is specifically suited to ordering dependencies
module main
struct DepGraphNode {
mut:
name string
deps []string
last_cycle string
}
struct DepGraph {
pub:
mut:
acyclic bool
nodes []DepGraphNode
}
struct DepSet {
mut:
items []string
}
pub fn(dset mut DepSet) add(item string) {
dset.items << item
}
pub fn(dset &DepSet) diff(otherset DepSet) DepSet {
mut diff := DepSet{}
for item in dset.items {
if !item in otherset.items {
diff.items << item
}
}
return diff
}
pub fn(dset &DepSet) size() int {
return dset.items.len
}
pub fn new_dep_graph() &DepGraph {
return &DepGraph{
acyclic: true
}
}
pub fn(graph mut DepGraph) add(mod string, deps []string) {
graph.nodes << DepGraphNode{
name: mod,
deps: deps
}
}
pub fn(graph &DepGraph) resolve() &DepGraph {
mut node_names := map[string]DepGraphNode
mut node_deps := map[string]DepSet
for _, node in graph.nodes {
node_names[node.name] = node
mut dep_set := DepSet{}
for _, dep in node.deps {
dep_set.add(dep)
}
node_deps[node.name] = dep_set
}
mut resolved := new_dep_graph()
for node_deps.size != 0 {
mut ready_set := DepSet{}
for name, deps in node_deps {
if deps.size() == 0 {
ready_set.add(name)
}
}
if ready_set.size() == 0 {
mut g := new_dep_graph()
g.acyclic = false
ndk := node_deps.keys()
for name, _ in node_deps {
mut node := node_names[name]
if name == ndk[node_deps.size-1] {
node.last_cycle = node_deps[name].items[node_deps[name].items.len-1]
}
g.nodes << node
}
return g
}
for name in ready_set.items {
node_deps.delete(name)
resolved.nodes << node_names[name]
}
for name, deps in node_deps {
node_deps[name] = deps.diff(ready_set)
}
}
return resolved
}
pub fn(graph &DepGraph) last_node() DepGraphNode {
return graph.nodes[graph.nodes.len-1]
}
pub fn(graph &DepGraph) last_cycle() string {
return graph.last_node().last_cycle
}
pub fn(graph &DepGraph) display() {
for i:=0; i<graph.nodes.len; i++ {
node := graph.nodes[i]
for dep in node.deps {
mut out := ' * $node.name -> $dep'
if !graph.acyclic && i == graph.nodes.len-1 && dep == node.last_cycle {
out += ' <-- last cycle'
}
println(out)
}
}
}