/
cyclic_detector.go
93 lines (82 loc) · 1.92 KB
/
cyclic_detector.go
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package internal
import (
"strings"
)
type CyclicDependencyError struct {
cyclicPath []string
}
func (e *CyclicDependencyError) Error() string {
return "detect cyclic dependency '" + strings.Join(e.cyclicPath, "' -> '") + "'"
}
type walkState struct {
stack []string
marked map[string]struct{}
}
func (ws *walkState) visit(name string) error {
ws.stack = append(ws.stack, name)
if _, ok := ws.marked[name]; ok {
for i, x := range ws.stack {
if x == name {
return &CyclicDependencyError{cyclicPath: ws.stack[i:]}
}
}
panic("unreachable")
}
ws.marked[name] = struct{}{}
return nil
}
func (ws *walkState) leave() {
last := ws.stack[len(ws.stack)-1]
ws.stack = ws.stack[:len(ws.stack)-1]
delete(ws.marked, last)
}
type cyclicDetector struct {
dependencies map[string][]string
visited map[string]struct{}
}
func (cd *cyclicDetector) detect() error {
for name, _ := range cd.dependencies {
if _, ok := cd.visited[name]; ok {
continue
}
ws := &walkState{
marked: make(map[string]struct{}),
}
if err := cd.walk(name, ws); err != nil {
return err
}
}
return nil
}
func (cd *cyclicDetector) walk(name string, state *walkState) error {
if err := state.visit(name); err != nil {
return err
}
if _, ok := cd.visited[name]; ok {
return nil
}
for _, dependency := range cd.dependencies[name] {
if err := cd.walk(dependency, state); err != nil {
return err
}
}
state.leave()
cd.visited[name] = struct{}{}
return nil
}
func DetectCyclicDependency(funcs []FuncType) error {
dependencies := make(map[string][]string, len(funcs))
for _, fn := range funcs {
name := fn.ReturnTypes[0].SimpleName()
deps := make([]string, 0, len(fn.ArgumentTypes))
for _, dep := range fn.ArgumentTypes {
deps = append(deps, dep.SimpleName())
}
dependencies[name] = deps
}
cd := &cyclicDetector{
dependencies: dependencies,
visited: make(map[string]struct{}),
}
return cd.detect()
}