Experiment: else ifs in serializer code (#116)

Use scalameta to transform lists of mutually exclusive ifs into else ifs, to potentially save a miniscule amount of performance.

Also, restructure metaprogramming transformations to make them easier to chain together.

project/Generator.scala

@@ -12,8 +12,8 @@ object Generator {
       println(s"  Processing ${inputFile.getName}")
       val inputStr = IO.read(inputFile)
       val outputFile = outputDir / inputFile.name
-      // Apply transformations: 1, 2
-      val outputStr = ProtoTransformer2.transform(ProtoTransformer1.transform(inputStr))
+      // Apply transformations
+      val outputStr = ProtoTransformer.transform(inputStr)
       IO.write(outputFile, outputStr)
       outputFile
     }

project/ProtoTransformer.scala

@@ -0,0 +1,23 @@
+import scala.meta._
+
+object ProtoTransformer {
+  val transformations: Seq[Transformer] = Seq(
+    Transform1.transformer,
+    Transform2.transformer,
+    Transform3.transformer,
+  )
+
+  def transform(input: String): String = {
+    val tree = input.parse[Source].get
+
+    val transformer = new Transformer {
+      override def apply(tree: Tree): Tree = {
+        transformations.foldLeft(tree) { (t, transformer) =>
+          transformer(t)
+        }
+      }
+    }
+
+    transformer(tree).syntax
+  }
+}

project/Transform1.scala

@@ -0,0 +1,80 @@
+import scala.meta._
+
+/**
+ * Source code transformer that for oneof protos:
+ *  - Unifies naming of is[S/P/O/G]Something methods to isSomething
+ *  - Removes with[S/P/O/G]Something methods
+ *  - Unifies naming of [S/P/O/G]Something classes to Something
+ *  - Unifies naming of [s/p/o/g]Something fields to something
+ *  - Adds base traits (RdfTerm, RdfTermCompanion)
+ *
+ * All this must be done before ProtoTransformer2 is executed.
+ */
+object Transform1 {
+  val isMethodNamePattern = "^is[SPOG](Iri|Bnode|Literal|TripleTerm|DefaultGraph)$".r
+  val withMethodNamePattern = "^with[SPOG](Iri|Bnode|Literal|TripleTerm|DefaultGraph)$".r
+  val classNamePattern = "^[SPOG](Iri|Bnode|Literal|TripleTerm|DefaultGraph)".r
+  val fieldNamePattern = "^[spog](Iri|Bnode|Literal|TripleTerm|DefaultGraph)".r
+  val traitNamePattern = "^(Subject|Predicate|Object|Graph)$".r
+
+  val transformer = new Transformer {
+    override def apply(tree: Tree): Tree = tree match {
+      // Transform method and class names in references
+      case Term.Name(name) => name match {
+        case isMethodNamePattern(t) => Term.Name(f"is$t")
+        case classNamePattern(t) => Term.Name(t)
+        case fieldNamePattern(t) => Term.Name(f"${t.head.toLower}${t.tail}")
+        case _ => super.apply(tree)
+      }
+
+      // Transform class names in definitions
+      case Type.Name(classNamePattern(t)) => Type.Name(t)
+
+      // Remove with[S/P/O/G]Something methods
+      case Template.After_4_4_0(_, _, _, stats, _) => tree.asInstanceOf[Template].copy(
+        stats = stats.flatMap { stat => stat match {
+          case Defn.Def.After_4_7_3(_, Term.Name(withMethodNamePattern(t)), _, _, _) => None
+          case t => Some(apply(t).asInstanceOf[Stat])
+        }}
+      )
+
+      // Transform traits for RDF terms
+      case Defn.Trait.After_4_6_0(_, Type.Name(traitNamePattern(name)), _, _, templ) =>
+        val adapterName = if (name == "Graph") "GraphTerm" else s"SpoTerm"
+        tree.asInstanceOf[Defn.Trait].copy(
+          templ = apply(templ.copy(
+            inits = templ.inits :+ Init.After_4_6_0(
+              Type.Select(q"eu.ostrzyciel.jelly.core.proto_adapters", Type.Name(adapterName)),
+              Name.Anonymous(), Nil
+            )
+          )).asInstanceOf[Template]
+        )
+
+      // Transform companion objects for RDF terms
+      case Defn.Object(_, Term.Name(traitNamePattern(name)), templ) =>
+        val adapterName = if (name == "Graph") "GraphTermCompanion" else s"SpoTermCompanion"
+        val lastMethod = if (name == "Graph")
+          q"val makeDefaultGraph: DefaultGraph = DefaultGraph(RdfDefaultGraph.defaultInstance)"
+        else q"def makeTripleTerm(t: eu.ostrzyciel.jelly.core.proto.v1.RdfTriple): TripleTerm = TripleTerm(t)"
+        tree.asInstanceOf[Defn.Object].copy(
+          templ = apply(templ.copy(
+            inits = templ.inits :+ Init.After_4_6_0(
+              Type.Apply(
+                Type.Select(q"eu.ostrzyciel.jelly.core.proto_adapters", Type.Name(adapterName)),
+                Type.ArgClause(Type.Name(name) :: Nil)
+              ),
+              Name.Anonymous(), Nil
+            ),
+            stats = templ.stats ++ Seq(
+              q"val makeEmpty: Empty.type = Empty",
+              q"def makeIri(iri: eu.ostrzyciel.jelly.core.proto.v1.RdfIri): Iri = Iri(iri)",
+              q"def makeBnode(bnode: String): Bnode = Bnode(bnode)",
+              q"def makeLiteral(literal: eu.ostrzyciel.jelly.core.proto.v1.RdfLiteral): Literal = Literal(literal)"
+            ) ++ Seq(lastMethod),
+          )).asInstanceOf[Template]
+        )
+
+      case node => super.apply(node)
+    }
+  }
+}