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//
// Copyright 2018-2025 Cristian Maglie. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//
package semver
import "sort"
// Dependency represents a dependency, it must provide methods to return Name and Constraints
type Dependency interface {
GetName() string
GetConstraint() Constraint
}
// Release represents a release, it must provide methods to return Name, Version and Dependencies
type Release[D Dependency] interface {
GetName() string
GetVersion() *Version
GetDependencies() []D
}
// Releases is a list of Release of the same package (all releases with
// the same Name but different Version)
type Releases[R Release[D], D Dependency] []R
// FilterBy return a subset of the Releases matching the provided Constraint
func (set Releases[R, D]) FilterBy(c Constraint) Releases[R, D] {
var res Releases[R, D]
for _, r := range set {
if c.Match(r.GetVersion()) {
res = append(res, r)
}
}
return res
}
// SortDescent sort the Releases in this set in descending order (the lastest
// release is the first)
func (set Releases[R, D]) SortDescent() {
sort.Slice(set, func(i, j int) bool {
return set[i].GetVersion().GreaterThan(set[j].GetVersion())
})
}
// Resolver is a container with references to all Releases to consider for
// dependency resolution
type Resolver[R Release[D], D Dependency] struct {
releases map[string]Releases[R, D]
// resolver state
solution map[string]R
depsToProcess []D
problematicDeps map[dependencyHash]int
}
// NewResolver creates a new archive
func NewResolver[R Release[D], D Dependency]() *Resolver[R, D] {
return &Resolver[R, D]{
releases: map[string]Releases[R, D]{},
}
}
// AddRelease adds a release to this archive
func (ar *Resolver[R, D]) AddRelease(rel R) {
relName := rel.GetName()
ar.releases[relName] = append(ar.releases[relName], rel)
}
// AddReleases adds all the releases to this archive
func (ar *Resolver[R, D]) AddReleases(rels ...R) {
for _, rel := range rels {
relName := rel.GetName()
ar.releases[relName] = append(ar.releases[relName], rel)
}
}
// Resolve will try to depp-resolve dependencies from the Release passed as
// arguent using a backtracking algorithm. This function is NOT thread-safe.
func (ar *Resolver[R, D]) Resolve(release R) Releases[R, D] {
// Initial empty state of the resolver
ar.solution = map[string]R{}
ar.depsToProcess = []D{}
ar.problematicDeps = map[dependencyHash]int{}
// Check if the release is in the archive
if len(ar.releases[release.GetName()].FilterBy(&Equals{Version: release.GetVersion()})) == 0 {
return nil
}
// Add the requested release to the solution and proceed
// with the dependencies resolution
ar.solution[release.GetName()] = release
ar.depsToProcess = append(ar.depsToProcess, release.GetDependencies()...)
return ar.resolve()
}
type dependencyHash string
func hashDependency[D Dependency](dep D) dependencyHash {
return dependencyHash(dep.GetName() + "/" + dep.GetConstraint().String())
}
func (ar *Resolver[R, D]) resolve() Releases[R, D] {
debug("deps to process: %s", ar.depsToProcess)
if len(ar.depsToProcess) == 0 {
debug("All dependencies have been resolved.")
var res Releases[R, D]
for _, v := range ar.solution {
res = append(res, v)
}
return res
}
// Pick the first dependency in the deps to process
dep := ar.depsToProcess[0]
depName := dep.GetName()
debug("Considering next dep: %s", depName)
// If a release is already picked in the solution check if it match the dep
if existingRelease, has := ar.solution[depName]; has {
if dep.GetConstraint().Match(existingRelease.GetVersion()) {
debug("%s already in solution and matching", existingRelease)
oldDepsToProcess := ar.depsToProcess
ar.depsToProcess = ar.depsToProcess[1:]
if res := ar.resolve(); res != nil {
return res
}
ar.depsToProcess = oldDepsToProcess
return nil
}
debug("%s already in solution do not match... rollingback", existingRelease)
return nil
}
// Otherwise start backtracking the dependency
releases := ar.releases[depName].FilterBy(dep.GetConstraint())
// Consider the latest versions first
releases.SortDescent()
debug("releases matching criteria: %s", releases)
backtracking_loop:
for _, release := range releases {
releaseDeps := release.GetDependencies()
debug("try with %s %s", release, releaseDeps)
for _, releaseDep := range releaseDeps {
if _, ok := ar.releases[releaseDep.GetName()]; !ok {
debug("%s did not work, becuase his dependency %s does not exists", release, releaseDep.GetName())
continue backtracking_loop
}
}
ar.solution[depName] = release
oldDepsToProcess := ar.depsToProcess
ar.depsToProcess = append(ar.depsToProcess[1:], releaseDeps...)
// bubble up problematics deps so they are processed first
sort.Slice(ar.depsToProcess, func(i, j int) bool {
ci := hashDependency(ar.depsToProcess[i])
cj := hashDependency(ar.depsToProcess[j])
return ar.problematicDeps[ci] > ar.problematicDeps[cj]
})
if res := ar.resolve(); res != nil {
return res
}
ar.depsToProcess = oldDepsToProcess
debug("%s did not work...", release)
delete(ar.solution, depName)
}
ar.problematicDeps[hashDependency(dep)]++
return nil
}
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