Add "--project", "-p" option for resolving subprojects explicitly

Fixes #4.

Also resolves #3 by excluding the local maven repo.

app/src/main/kotlin/org/nixos/gradle2nix/GradleRunner.kt

@@ -13,24 +13,18 @@ fun connect(config: Config): ProjectConnection =
         .forProjectDirectory(config.projectDir)
         .connect()
 
+@Suppress("UnstableApiUsage")
 fun ProjectConnection.getBuildModel(config: Config, path: String): DefaultBuild {
-    val arguments = mutableListOf(
-        "--init-script=$shareDir/init.gradle",
-        "-Dorg.nixos.gradle2nix.configurations='${config.configurations.joinToString(",")}'"
-    )
-
-    if (path.isNotEmpty()) {
-        arguments += "--project-dir=$path"
-    }
-
-    return model(Build::class.java)
-        .withArguments(arguments)
-        .apply {
-            if (!config.quiet) {
-                setStandardOutput(System.err)
-                setStandardError(System.err)
-            }
+    return model(Build::class.java).apply {
+        addArguments("--init-script=$shareDir/init.gradle")
+        if (path.isNotEmpty()) addArguments("--project-dir=$path")
+        addJvmArguments(
+            "-Dorg.nixos.gradle2nix.configurations='${config.configurations.joinToString(",")}'",
+            "-Dorg.nixos.gradle2nix.subprojects='${config.subprojects.joinToString(",")}'"
+        )
+        if (!config.quiet) {
+            setStandardOutput(System.err)
+            setStandardError(System.err)
         }
-        .get()
-        .let { DefaultBuild(it) }
+    }.get().let { DefaultBuild(it) }
 }

app/src/main/kotlin/org/nixos/gradle2nix/Main.kt

@@ -23,6 +23,7 @@ data class Config(
     val configurations: List<String>,
     val projectDir: File,
     val includes: List<File>,
+    val subprojects: List<String>,
     val buildSrc: Boolean,
     val quiet: Boolean
 ) {
@@ -55,6 +56,19 @@ class Main : CliktCommand(
             }
         }
 
+    private val subprojects: List<String> by option("--project", "-p",
+        metavar = "PATH",
+        help = "Only resolve these subproject paths, e.g. ':', or ':sub:project' (default: all projects)")
+        .multiple()
+        .validate { paths ->
+            val failures = paths.filterNot { it.startsWith(":") }
+            if (failures.isNotEmpty()) {
+                val message = failures.joinToString("\n    ")
+                fail("Subproject paths must be absolute:\n$message\n" +
+                    "Paths are in the form ':parent:child'.")
+            }
+        }
+
     private val outDir: File? by option("--out-dir", "-o",
         metavar = "DIR",
         help = "Path to write generated files (default: PROJECT-DIR)")
@@ -82,7 +96,7 @@ class Main : CliktCommand(
     }
 
     override fun run() {
-        val config = Config(gradleVersion, configurations, projectDir, includes, buildSrc, quiet)
+        val config = Config(gradleVersion, configurations, projectDir, includes, subprojects, buildSrc, quiet)
         val (log, _, _) = Logger(verbose = !config.quiet)
 
         val paths = resolveProjects(config).map { p ->