Add maxTransitiveDepth config (#24)

* Add feature to ignoreTransitive dependencies

* rename to maxTransitiveDepth

* Use consistent naming

* Set reasonable default for maxTransitiveDependency and add to README

README.md

@@ -32,6 +32,9 @@ libyear {
 
   // alternatively:
   validator = singleArtifactMustNotBeOlderThan(2.days)
+
+  // optional: limit the depth of the dependency traversal, default is 0 = only the root level, null = no limit
+  maxTransitiveDepth = 5
 }
 ```
 
@@ -45,6 +48,7 @@ libyear {
   configurations = ['compileClasspath']
   failOnError = true
   validator = allArtifactsCombinedMustNotBeOlderThan(days(5))
+  maxTransitiveDepth = 5
 }
 ```
 

libyear-gradle-plugin/src/main/kotlin/com/libyear/LibYearExtension.kt

@@ -20,6 +20,8 @@ open class LibYearExtension {
 
   var validator: DependencyValidatorSpec = defaultValidator
 
+  var maxTransitiveDepth: Int? = 0
+
   var configurations: List<String> = defaultConfigurations
 
   // DSL for build script authors

libyear-gradle-plugin/src/main/kotlin/com/libyear/LibYearPlugin.kt

@@ -59,7 +59,7 @@ class LibYearPlugin : Plugin<Project> {
     val ageOracle = createOracle(project, extension)
     val validator = createValidator(project, extension)
     val visitor = ValidatingVisitor(project.logger, ageOracle, validator, ValidationConfig(failOnError = extension.failOnError))
-    DependencyTraversal.visit(resolvableDependencies.resolutionResult.root, visitor)
+    DependencyTraversal.visit(resolvableDependencies.resolutionResult.root, visitor, extension.maxTransitiveDepth)
     maybeReportFailure(project.logger, validator)
   }
 

libyear-gradle-plugin/src/main/kotlin/com/libyear/LibYearReportTask.kt

@@ -15,7 +15,7 @@ open class LibYearReportTask : DefaultTask() {
       .forEach {
         val ageOracle = createOracle(project, extension)
         val visitor = ReportingVisitor(project.logger, ageOracle)
-        DependencyTraversal.visit(it.incoming.resolutionResult.root, visitor)
+        DependencyTraversal.visit(it.incoming.resolutionResult.root, visitor, extension.maxTransitiveDepth)
         visitor.print()
       }
   }

libyear-gradle-plugin/src/main/kotlin/com/libyear/traversal/DependencyTraversal.kt

@@ -6,12 +6,13 @@ import org.gradle.api.artifacts.result.ResolvedComponentResult
 import org.gradle.api.artifacts.result.ResolvedDependencyResult
 
 class DependencyTraversal private constructor(
-  private val visitor: DependencyVisitor
+  private val visitor: DependencyVisitor,
+  private val maxTransitiveDepth: Int?
 ) {
 
   private val seen = mutableSetOf<ComponentIdentifier>()
 
-  private fun visit(component: ComponentResult) {
+  private fun visit(component: ComponentResult, depth: Int = 0) {
     if (!seen.add(component.id)) return
 
     visitor.visitComponentResult(component)
@@ -23,12 +24,15 @@ class DependencyTraversal private constructor(
       if (!visitor.canContinue()) return
 
       if (dependency is ResolvedDependencyResult) {
+        if (maxTransitiveDepth != null && depth > maxTransitiveDepth) {
+          continue
+        }
         nextComponents.add(dependency.selected)
       }
     }
 
     for (nextComponent in nextComponents) {
-      visit(nextComponent)
+      visit(nextComponent, depth + 1)
       if (!visitor.canContinue()) break
     }
   }
@@ -37,7 +41,8 @@ class DependencyTraversal private constructor(
 
     fun visit(
       root: ResolvedComponentResult,
-      visitor: DependencyVisitor
-    ): Unit = DependencyTraversal(visitor).visit(root)
+      visitor: DependencyVisitor,
+      maxTransitiveDepth: Int? = null
+    ): Unit = DependencyTraversal(visitor, maxTransitiveDepth).visit(root, depth = 0)
   }
 }