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diff --git a/src/scaladoc/scala/tools/nsc/doc/doclet/Generator.scala b/src/scaladoc/scala/tools/nsc/doc/doclet/Generator.scala
new file mode 100644
index 0000000000..42b56aa927
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+++ b/src/scaladoc/scala/tools/nsc/doc/doclet/Generator.scala
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+package scala.tools.nsc.doc
+package doclet
+
+import scala.collection._
+
+/** Custom Scaladoc generators must implement the `Generator` class. A custom generator can be selected in Scaladoc
+  * using the `-doc-generator` command line option.
+  * The `Generator` class does not provide data about the documented code. A number of data provider traits can be used
+  * to configure what data is actually available to the generator:
+  *  - A `Universer` provides a `Universe` data structure representing the interfaces and comments of the documented
+  *    program.
+  *  - An `Indexer` provides precalculated indexing information about a universe.
+  * To implement this class only requires defining method `generateImpl`. */
+abstract class Generator {
+
+  /** A series of tests that must be true before generation can be done. This is used by data provider traits to
+    * confirm that they have been correctly initialised before allowing generation to proceed. */
+  protected val checks: mutable.Set[()=>Boolean] =
+    mutable.Set.empty[()=>Boolean]
+
+  /** Outputs documentation (as a side effect). */
+  def generate(): Unit = {
+    assert(checks forall { check => check() })
+    generateImpl()
+  }
+
+  /** Outputs documentation (as a side effect). This method is called only if all `checks` are true. */
+  protected def generateImpl(): Unit
+
+}