92 lines
1.9 KiB
Go
92 lines
1.9 KiB
Go
package engine
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import (
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"fmt"
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"sort"
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"github.com/MDietermann/ArduinoArchSetup/internal/module"
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)
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// TopoSort returns module IDs in a valid dependency order.
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// Ties are broken alphabetically for deterministic output.
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// Returns an error on unknown deps or cycles.
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func TopoSort(metas []module.Meta) ([]string, error) {
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known := make(map[string]bool, len(metas))
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for _, m := range metas {
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known[m.ID] = true
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}
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for _, m := range metas {
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for _, d := range m.Deps {
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if !known[d] {
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return nil, fmt.Errorf("module %q depends on unknown %q", m.ID, d)
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}
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}
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}
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// Kahn's algorithm with alphabetical tie-breaking.
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indeg := make(map[string]int, len(metas))
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children := make(map[string][]string, len(metas))
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for _, m := range metas {
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if _, ok := indeg[m.ID]; !ok {
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indeg[m.ID] = 0
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}
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for _, d := range m.Deps {
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indeg[m.ID]++
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children[d] = append(children[d], m.ID)
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}
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}
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var ready []string
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for id, d := range indeg {
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if d == 0 {
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ready = append(ready, id)
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}
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}
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sort.Strings(ready)
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var order []string
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for len(ready) > 0 {
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next := ready[0]
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ready = ready[1:]
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order = append(order, next)
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kids := append([]string(nil), children[next]...)
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sort.Strings(kids)
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for _, c := range kids {
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indeg[c]--
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if indeg[c] == 0 {
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ready = append(ready, c)
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sort.Strings(ready)
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}
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}
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}
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if len(order) != len(metas) {
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return nil, fmt.Errorf("dependency cycle detected among modules")
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}
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return order, nil
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}
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// Descendants returns the set of module IDs transitively downstream of root.
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// Root itself is NOT included.
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func Descendants(metas []module.Meta, root string) map[string]bool {
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children := make(map[string][]string)
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for _, m := range metas {
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for _, d := range m.Deps {
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children[d] = append(children[d], m.ID)
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}
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}
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out := make(map[string]bool)
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var walk func(string)
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walk = func(id string) {
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for _, c := range children[id] {
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if out[c] {
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continue
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}
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out[c] = true
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walk(c)
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}
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}
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walk(root)
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return out
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}
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