Allow custom directives to be added to sbt setting

core/src/main/scala/com/lightbend/paradox/markdown/Writer.scala

@@ -30,11 +30,11 @@ class Writer(serializer: Writer.Context => ToHtmlSerializer) {
   def this(
     linkRenderer:        Writer.Context => LinkRenderer                = Writer.defaultLinks,
     verbatimSerializers: Map[String, VerbatimSerializer]               = Writer.defaultVerbatims,
-    serializerPlugins:   Writer.Context => Seq[ToHtmlSerializerPlugin] = Writer.defaultPlugins) =
+    serializerPlugins:   Seq[Writer.Context => ToHtmlSerializerPlugin] = Writer.defaultPlugins(Writer.defaultDirectives)) =
     this((context: Writer.Context) => new ToHtmlSerializer(
       linkRenderer(context),
       verbatimSerializers.asJava,
-      serializerPlugins(context).asJava))
+      serializerPlugins.map(p => p(context)).asJava))
 
   /**
    * Write main content.
@@ -108,28 +108,28 @@ object Writer {
     Map(VerbatimSerializer.DEFAULT -> PrettifyVerbatimSerializer)
   }
 
-  def defaultPlugins(context: Context): Seq[ToHtmlSerializerPlugin] = Seq(
-    new ClassyLinkSerializer,
-    new AnchorLinkSerializer,
-    new DirectiveSerializer(defaultDirectives(context))
+  def defaultPlugins(directives: Seq[Context => Directive]): Seq[Context => ToHtmlSerializerPlugin] = Seq(
+    context => new ClassyLinkSerializer,
+    context => new AnchorLinkSerializer,
+    context => new DirectiveSerializer(directives.map(d => d(context)))
   )
 
-  def defaultDirectives(context: Context): Seq[Directive] = Seq(
-    RefDirective(context.location.tree.label, context.paths, context.pageMappings),
-    ExtRefDirective(context.location.tree.label, context.properties),
-    ScaladocDirective(context.location.tree.label, context.properties),
-    JavadocDirective(context.location.tree.label, context.properties),
-    GitHubDirective(context.location.tree.label, context.properties),
-    SnipDirective(context.location.tree.label, context.properties),
-    FiddleDirective(context.location.tree.label),
-    TocDirective(context.location),
-    VarDirective(context.properties),
-    VarsDirective(context.properties),
-    CalloutDirective("note", "Note"),
-    CalloutDirective("warning", "Warning"),
-    WrapDirective("div"),
-    InlineWrapDirective("span"),
-    InlineGroupDirective(context.groups.values.flatten.map(_.toLowerCase).toSeq)
+  def defaultDirectives: Seq[Context => Directive] = Seq(
+    context => RefDirective(context.location.tree.label, context.paths, context.pageMappings),
+    context => ExtRefDirective(context.location.tree.label, context.properties),
+    context => ScaladocDirective(context.location.tree.label, context.properties),
+    context => JavadocDirective(context.location.tree.label, context.properties),
+    context => GitHubDirective(context.location.tree.label, context.properties),
+    context => SnipDirective(context.location.tree.label, context.properties),
+    context => FiddleDirective(context.location.tree.label),
+    context => TocDirective(context.location),
+    context => VarDirective(context.properties),
+    context => VarsDirective(context.properties),
+    context => CalloutDirective("note", "Note"),
+    context => CalloutDirective("warning", "Warning"),
+    context => WrapDirective("div"),
+    context => InlineWrapDirective("span"),
+    context => InlineGroupDirective(context.groups.values.flatten.map(_.toLowerCase).toSeq)
   )
 
   class DefaultLinkRenderer(context: Context) extends LinkRenderer {

plugin/src/main/scala/com/lightbend/paradox/sbt/ParadoxKeys.scala

@@ -18,6 +18,7 @@ package com.lightbend.paradox.sbt
 
 import sbt._
 import com.lightbend.paradox.ParadoxProcessor
+import com.lightbend.paradox.markdown.{ Directive, Writer }
 import com.lightbend.paradox.template.PageTemplate
 
 trait ParadoxKeys {
@@ -28,6 +29,7 @@ trait ParadoxKeys {
   val paradoxNavigationIncludeHeaders = settingKey[Boolean]("Whether to include headers in the navigation.")
   val paradoxLeadingBreadcrumbs = settingKey[List[(String, String)]]("Any leading breadcrumbs (label -> url)")
   val paradoxOrganization = settingKey[String]("Paradox dependency organization (for theme dependencies).")
+  val paradoxDirectives = taskKey[Seq[Writer.Context => Directive]]("Enabled paradox directives.")
   val paradoxProcessor = taskKey[ParadoxProcessor]("ParadoxProcessor to use when generating the site.")
   val paradoxProperties = taskKey[Map[String, String]]("Property map passed to paradox.")
   val paradoxSourceSuffix = settingKey[String]("Source file suffix for markdown files [default = \".md\"].")

plugin/src/main/scala/com/lightbend/paradox/sbt/ParadoxPlugin.scala

@@ -20,6 +20,7 @@ import sbt._
 import sbt.Keys._
 
 import com.lightbend.paradox.ParadoxProcessor
+import com.lightbend.paradox.markdown.Writer
 import com.lightbend.paradox.template.PageTemplate
 import com.typesafe.sbt.web.Import.{ Assets, WebKeys }
 import com.typesafe.sbt.web.SbtWeb
@@ -45,6 +46,7 @@ object ParadoxPlugin extends AutoPlugin {
     paradoxNavigationDepth := 2,
     paradoxNavigationExpandDepth := None,
     paradoxNavigationIncludeHeaders := false,
+    paradoxDirectives := Writer.defaultDirectives,
     paradoxProperties := Map.empty,
     paradoxTheme := Some(builtinParadoxTheme("generic")),
     paradoxDefaultTemplateName := "page",
@@ -54,7 +56,7 @@ object ParadoxPlugin extends AutoPlugin {
   )
 
   def paradoxSettings(config: Configuration): Seq[Setting[_]] = paradoxGlobalSettings ++ inConfig(config)(Seq(
-    paradoxProcessor := new ParadoxProcessor,
+    paradoxProcessor := new ParadoxProcessor(writer = new Writer(serializerPlugins = Writer.defaultPlugins(paradoxDirectives.value))),
 
     sourceDirectory := {
       if (config.name != Compile.name)

plugin/src/sbt-test/paradox/custom-directive/build.sbt

@@ -0,0 +1,9 @@
+lazy val docs = project
+  .in(file("."))
+  .enablePlugins(ParadoxPlugin)
+  .settings(
+    name := "Paradox Directives Test",
+    paradoxTheme := None,
+    paradoxDirectives += CustomDirective,
+    paradoxProperties += "custom.content" -> "directive"
+  )

plugin/src/sbt-test/paradox/custom-directive/expected/test.html

@@ -0,0 +1 @@
+directive

plugin/src/sbt-test/paradox/custom-directive/project/CustomDirective.scala

@@ -0,0 +1,13 @@
+import com.lightbend.paradox.markdown.{ Directive, LeafBlockDirective, Writer }
+import org.pegdown.Printer
+import org.pegdown.ast.{ DirectiveNode, Visitor }
+
+object CustomDirective extends (Writer.Context => CustomDirective) {
+  def apply(context: Writer.Context): CustomDirective = CustomDirective(context.properties)
+}
+
+case class CustomDirective(properties: Map[String, String]) extends LeafBlockDirective("custom") {
+  def render(node: DirectiveNode, visitor: Visitor, printer: Printer): Unit = {
+    printer.println.print(properties.getOrElse("custom.content", ""))
+  }
+}

plugin/src/sbt-test/paradox/custom-directive/project/plugins.sbt

@@ -0,0 +1 @@
+addSbtPlugin("com.lightbend.paradox" % "sbt-paradox" % sys.props("project.version"))

plugin/src/sbt-test/paradox/custom-directive/src/main/paradox/_template/page.st

@@ -0,0 +1 @@
+$page.content$

plugin/src/sbt-test/paradox/custom-directive/src/main/paradox/test.md

@@ -0,0 +1 @@
+@@custom

plugin/src/sbt-test/paradox/custom-directive/test

@@ -0,0 +1,3 @@
+> paradox
+
+$ must-mirror target/paradox/site/main/test.html expected/test.html