125 lines
2.6 KiB
Go
125 lines
2.6 KiB
Go
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package main
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import (
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"errors"
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"math"
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"strconv"
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"gonum.org/v1/gonum/graph"
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"gonum.org/v1/gonum/graph/encoding"
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"gonum.org/v1/gonum/graph/simple"
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"gonum.org/v1/gonum/graph/topo"
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)
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type projectNetwork struct {
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*simple.DirectedGraph
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}
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func newProjectNetwork() *projectNetwork {
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return &projectNetwork{DirectedGraph: simple.NewDirectedGraph()}
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}
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func (g *projectNetwork) NewNode() graph.Node {
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return &activity{Node: g.DirectedGraph.NewNode()}
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}
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func (g *projectNetwork) calculateTimes() error {
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sorted, err := topo.Sort(g)
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if err != nil {
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return err
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}
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toposort := make([]*activity, len(sorted))
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for i := range sorted {
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toposort[i] = sorted[i].(*activity)
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}
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g.forwardPass(toposort)
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g.backwardPass(toposort)
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return nil
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}
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func (g *projectNetwork) forwardPass(toposort []*activity) {
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for _, a := range toposort {
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g.setEarlyTimes(a)
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}
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}
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func (g *projectNetwork) backwardPass(toposort []*activity) {
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n := len(toposort)
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end := toposort[n-1]
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end.lateFinish = end.earlyFinish
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end.lateStart = end.lateFinish - end.duration
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for i := n - 2; i >= 0; i-- {
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a := toposort[i]
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g.setLateTimes(a)
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}
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}
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func (g *projectNetwork) setEarlyTimes(a *activity) {
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es := 0.0
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predecessors := g.To(a.ID())
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for predecessors.Next() {
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p := predecessors.Node().(*activity)
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es = math.Max(es, p.earlyFinish)
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}
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a.earlyStart = es
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a.earlyFinish = a.earlyStart + a.duration
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}
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func (g *projectNetwork) setLateTimes(a *activity) {
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lf := math.Inf(1)
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successors := g.From(a.ID())
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for successors.Next() {
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s := successors.Node().(*activity)
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lf = math.Min(lf, s.lateStart)
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}
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a.lateFinish = lf
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a.lateStart = a.lateFinish - a.duration
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a.slack = a.lateFinish - a.earlyFinish
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}
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type activity struct {
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graph.Node
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dotID string
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duration float64
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earlyStart float64
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earlyFinish float64
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lateStart float64
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lateFinish float64
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slack float64
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}
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func (a *activity) Attributes() []encoding.Attribute {
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return []encoding.Attribute{
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{"DUR", strconv.FormatFloat(a.duration, 'g', -1, 64)},
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{"ES", strconv.FormatFloat(a.earlyStart, 'g', -1, 64)},
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{"EF", strconv.FormatFloat(a.earlyStart, 'g', -1, 64)},
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{"LS", strconv.FormatFloat(a.lateStart, 'g', -1, 64)},
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{"LF", strconv.FormatFloat(a.lateFinish, 'g', -1, 64)},
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{"SLACK", strconv.FormatFloat(a.slack, 'g', -1, 64)},
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}
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}
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func (a *activity) SetAttribute(attr encoding.Attribute) error {
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var err error
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switch attr.Key {
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case "DUR":
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a.duration, err = strconv.ParseFloat(attr.Value, 64)
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default:
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err = errors.New("can't set attribute " + attr.Key)
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}
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return err
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}
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func (a *activity) DOTID() string {
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return a.dotID
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}
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func (a *activity) SetDOTID(id string) {
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a.dotID = id
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}
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