/// <summary>
        /// Resolve a package closure
        /// </summary>
        public IEnumerable <PackageIdentity> Resolve(PackageResolverContext context, CancellationToken token)
        {
            var stopWatch = new Stopwatch();

            token.ThrowIfCancellationRequested();

            if (context == null)
            {
                throw new ArgumentNullException(nameof(context));
            }

            // validation
            foreach (var requiredId in context.RequiredPackageIds)
            {
                if (!context.AvailablePackages.Any(p => StringComparer.OrdinalIgnoreCase.Equals(p.Id, requiredId)))
                {
                    throw new NuGetResolverInputException(String.Format(CultureInfo.CurrentCulture, Strings.MissingDependencyInfo, requiredId));
                }
            }

            // convert the available packages into ResolverPackages
            var resolverPackages = new List <ResolverPackage>();

            // pre-process the available packages to remove any packages that can't possibly form part of a solution
            var availablePackages = RemoveImpossiblePackages(context.AvailablePackages, context.RequiredPackageIds);

            foreach (var package in availablePackages)
            {
                IEnumerable <PackageDependency> dependencies = null;

                // clear out the dependencies if the behavior is set to ignore
                if (context.DependencyBehavior == DependencyBehavior.Ignore)
                {
                    dependencies = Enumerable.Empty <PackageDependency>();
                }
                else
                {
                    dependencies = package.Dependencies ?? Enumerable.Empty <PackageDependency>();
                }

                resolverPackages.Add(new ResolverPackage(package.Id, package.Version, dependencies, package.Listed, false));
            }

            // Sort the packages to make this process as deterministic as possible
            resolverPackages.Sort(PackageIdentityComparer.Default);

            // Keep track of the ids we have added
            var groupsAdded = new HashSet <string>(StringComparer.OrdinalIgnoreCase);
            var grouped     = new List <List <ResolverPackage> >();

            // group the packages by id
            foreach (var group in resolverPackages.GroupBy(e => e.Id, StringComparer.OrdinalIgnoreCase))
            {
                groupsAdded.Add(group.Key);

                var curSet = group.ToList();

                // add an absent package for non-targets
                // being absent allows the resolver to throw it out if it is not needed
                if (!context.RequiredPackageIds.Contains(group.Key, StringComparer.OrdinalIgnoreCase))
                {
                    curSet.Add(new ResolverPackage(id: group.Key, version: null, dependencies: null, listed: true, absent: true));
                }

                grouped.Add(curSet);
            }

            // find all needed dependencies
            var dependencyIds = resolverPackages.Where(e => e.Dependencies != null)
                                .SelectMany(e => e.Dependencies.Select(d => d.Id).Distinct(StringComparer.OrdinalIgnoreCase));

            foreach (string depId in dependencyIds)
            {
                // packages which are unavailable need to be added as absent packages
                // ex: if A -> B  and B is not found anywhere in the source repositories we add B as absent
                if (!groupsAdded.Contains(depId))
                {
                    groupsAdded.Add(depId);
                    grouped.Add(new List <ResolverPackage>()
                    {
                        new ResolverPackage(id: depId, version: null, dependencies: null, listed: true, absent: true)
                    });
                }
            }

            token.ThrowIfCancellationRequested();

            // keep track of the best partial solution
            var bestSolution = Enumerable.Empty <ResolverPackage>();

            Action <IEnumerable <ResolverPackage> > diagnosticOutput = (partialSolution) =>
            {
                // store each solution as they pass through.
                // the combination solver verifies that the last one returned is the best
                bestSolution = partialSolution;
            };

            // Run solver
            var comparer = new ResolverComparer(context.DependencyBehavior, context.PreferredVersions, context.TargetIds);

            var sortedGroups = ResolverInputSort.TreeFlatten(grouped, context);

            var solution = CombinationSolver <ResolverPackage> .FindSolution(
                groupedItems : sortedGroups,
                itemSorter : comparer,
                shouldRejectPairFunc : ResolverUtility.ShouldRejectPackagePair,
                diagnosticOutput : diagnosticOutput);

            // check if a solution was found
            if (solution != null)
            {
                var nonAbsentCandidates = solution.Where(c => !c.Absent);

                if (nonAbsentCandidates.Any())
                {
                    // topologically sort non absent packages
                    var sortedSolution = ResolverUtility.TopologicalSort(nonAbsentCandidates);

                    // Find circular dependency for topologically sorted non absent packages since it will help maintain cache of
                    // already processed packages
                    var circularReferences = ResolverUtility.FindFirstCircularDependency(sortedSolution);

                    if (circularReferences.Any())
                    {
                        // the resolver is able to handle circular dependencies, however we should throw here to keep these from happening
                        throw new NuGetResolverConstraintException(
                                  String.Format(CultureInfo.CurrentCulture, Strings.CircularDependencyDetected,
                                                String.Join(" => ", circularReferences.Select(package => $"{package.Id} {package.Version.ToNormalizedString()}"))));
                    }

                    // solution found!
                    stopWatch.Stop();
                    context.Log.LogMinimal(
                        string.Format(Strings.ResolverTotalTime, DatetimeUtility.ToReadableTimeFormat(stopWatch.Elapsed)));
                    return(sortedSolution.ToArray());
                }
            }

            // no solution was found, throw an error with a diagnostic message
            var message = ResolverUtility.GetDiagnosticMessage(bestSolution, context.AvailablePackages, context.PackagesConfig, context.TargetIds, context.PackageSources);

            throw new NuGetResolverConstraintException(message);
        }
Exemple #2
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        public IEnumerable <PackageIdentity> Resolve(IEnumerable <PackageIdentity> targets, IEnumerable <PackageDependencyInfo> availablePackages, IEnumerable <PackageReference> installedPackages, CancellationToken token)
        {
            if (installedPackages != null)
            {
                _installedPackages = new HashSet <PackageIdentity>(installedPackages.Select(e => e.PackageIdentity), PackageIdentity.Comparer);
            }

            // find the list of new packages to add
            _newPackageIds = new HashSet <string>(targets.Select(e => e.Id).Except(_installedPackages.Select(e => e.Id), StringComparer.OrdinalIgnoreCase), StringComparer.OrdinalIgnoreCase);


            // validation
            foreach (var target in targets)
            {
                if (!availablePackages.Any(p => StringComparer.OrdinalIgnoreCase.Equals(p.Id, target.Id)))
                {
                    throw new NuGetResolverInputException(String.Format(CultureInfo.CurrentUICulture, Strings.MissingDependencyInfo, target.Id));
                }
            }

            // validation
            foreach (var installed in _installedPackages)
            {
                if (!availablePackages.Any(p => StringComparer.OrdinalIgnoreCase.Equals(p.Id, installed.Id)))
                {
                    throw new NuGetResolverInputException(String.Format(CultureInfo.CurrentUICulture, Strings.MissingDependencyInfo, installed.Id));
                }
            }

            // TODO: this will be removed later when the interface changes
            foreach (var installed in _installedPackages)
            {
                if (!targets.Any(p => StringComparer.OrdinalIgnoreCase.Equals(p.Id, installed.Id)))
                {
                    throw new NuGetResolverInputException("Installed packages should be passed as targets");
                }
            }

            // Solve
            var solver = new CombinationSolver <ResolverPackage>();

            var comparer = new ResolverComparer(_dependencyBehavior, _installedPackages, _newPackageIds);

            List <List <ResolverPackage> > grouped = new List <List <ResolverPackage> >();

            var packageComparer = PackageIdentity.Comparer;

            List <ResolverPackage> resolverPackages = new List <ResolverPackage>();

            // convert the available packages into ResolverPackages
            foreach (var package in availablePackages)
            {
                IEnumerable <PackageDependency> dependencies = null;

                // clear out the dependencies if the behavior is set to ignore
                if (_dependencyBehavior == DependencyBehavior.Ignore)
                {
                    dependencies = Enumerable.Empty <PackageDependency>();
                }
                else
                {
                    dependencies = package.Dependencies;
                }

                resolverPackages.Add(new ResolverPackage(package.Id, package.Version, dependencies));
            }

            // Sort the packages to make this process as deterministic as possible
            resolverPackages.Sort(PackageIdentityComparer.Default);

            // Keep track of the ids we have added
            HashSet <string> groupsAdded = new HashSet <string>(StringComparer.OrdinalIgnoreCase);

            // group the packages by id
            foreach (var group in resolverPackages.GroupBy(e => e.Id, StringComparer.OrdinalIgnoreCase))
            {
                groupsAdded.Add(group.Key);

                List <ResolverPackage> curSet = group.ToList();

                // add an absent package for non-targets
                // being absent allows the resolver to throw it out if it is not needed
                if (!targets.Any(e => StringComparer.OrdinalIgnoreCase.Equals(e.Id, group.Key)))
                {
                    curSet.Add(new ResolverPackage(group.Key, null, null, true));
                }

                grouped.Add(curSet);
            }

            // find all needed dependencies
            var dependencyIds = resolverPackages.Where(e => e.Dependencies != null).SelectMany(e => e.Dependencies.Select(d => d.Id).Distinct(StringComparer.OrdinalIgnoreCase));

            foreach (string depId in dependencyIds)
            {
                // packages which are unavailable need to be added as absent packages
                // ex: if A -> B  and B is not found anywhere in the source repositories we add B as absent
                if (!groupsAdded.Contains(depId))
                {
                    grouped.Add(new List <ResolverPackage>()
                    {
                        new ResolverPackage(depId, null, null, true)
                    });
                }
            }

            var solution = solver.FindSolution(grouped, comparer, ShouldRejectPackagePair);

            if (solution != null)
            {
                var nonAbsentCandidates = solution.Where(c => !c.Absent);

                if (nonAbsentCandidates.Any())
                {
                    var sortedSolution = TopologicalSort(nonAbsentCandidates);

                    return(sortedSolution.ToArray());
                }
            }

            // no solution found
            throw new NuGetResolverConstraintException(Strings.NoSolution);
        }