Add include-package option

Plugins/SwiftPackageListPlugin/SwiftPackageListPlugin.Configuration.swift

@@ -21,6 +21,7 @@ extension SwiftPackageListPlugin.Configuration {
         let outputType: OutputType?
         let packageOrder: PackageOrder?
         let requiresLicense: Bool? // swiftlint:disable:this discouraged_optional_boolean
+        let includePackages: [String]? // swiftlint:disable:this discouraged_optional_collection
         let ignorePackages: [String]? // swiftlint:disable:this discouraged_optional_collection
         let customPackagesFilePaths: [String]? // swiftlint:disable:this discouraged_optional_collection
     }

Plugins/SwiftPackageListPlugin/SwiftPackageListPlugin.swift

@@ -26,6 +26,10 @@ struct SwiftPackageListPlugin: Plugin {
             return ["--ignore-package", identity]
         } ?? []
 
+        let includePackageArguments: [String] = targetConfiguration?.includePackages?.flatMap { identity in
+            return ["--include-package", identity]
+        } ?? []
+
         let customPackagesFilePathArguments: [String] = targetConfiguration?.customPackagesFilePaths?.flatMap { filePath in
             return ["--custom-packages-file-path", filePath]
         } ?? []

README.md

@@ -61,6 +61,7 @@ In addition to that you can specify the following options:
 | --package-order \<package-order\>                             | The order in which the packages will be listed. (values: source, name-ascending, name-descending, identity-ascending, identity-descending; default: source) |
 | --requires-license                                            | Will skip the packages without a license-file.                                                                                                              |
 | --ignore-package \<package-identity\>                         | Will skip a package with the specified identity. (This option may be repeated multiple times)                                                               |
+| --include-package \<package-identity\>                        | Will include a package with the specified identity. Use when there are fewer to include than to ignore. (This option may be repeated multiple times)        |
 | --version                                                     | Show the version.                                                                                                                                           |
 | -h, --help                                                    | Show help information.                                                                                                                                      |
 

Sources/swift-package-list/SwiftPackageList+OutputOptions.swift

@@ -38,6 +38,16 @@ extension SwiftPackageList {
             )
         )
         var ignoredPackageIdentities: [String] = []
+
+        @Option(
+            name: .customLong("include-package"),
+            help: ArgumentHelp(
+                "Will include a package with the specified identity. Use when there are fewer to include than to ignore. " +
+                "(This option may be repeated multiple times)",
+                valueName: "package-identity"
+            )
+        )
+        var includedPackageIdentities: [String] = []
     }
 }
 
@@ -61,6 +71,9 @@ extension SwiftPackageList.OutputOptions {
 extension SwiftPackageList.OutputOptions {
     func filter(package: Package) -> Bool {
         if requiresLicense && !package.hasLicense { return false }
+        if !includedPackageIdentities.isEmpty {
+            return includedPackageIdentities.contains(package.identity) && !ignoredPackageIdentities.contains(package.identity)
+        }
         return !ignoredPackageIdentities.contains(package.identity)
     }