[experiment] currentCtx should return the context for the last ran unit

Author: tanishiking

mtags/src/main/scala-3/scala/meta/internal/pc/MetalsDriver.scala

@@ -17,19 +17,40 @@ class MetalsDriver(
     override val settings: List[String]
 ) extends InteractiveDriver(settings):
 
+  private val contextCache: TrieMap[URI, Context] = TrieMap.empty
+  private var lastCompiledURI: Option[URI] = None
+
   private def alreadyCompiled(uri: URI, content: Array[Char]): Boolean =
     compilationUnits.get(uri) match
       case Some(unit) if ju.Arrays.equals(unit.source.content(), content) =>
         true
       case _ => false
 
+  override def currentCtx: Context =
+    (for
+      uri <-
+        // lastCompiledURI is initialized as null (!?), it might be a bug in scala3
+        if lastCompiledURI != null then lastCompiledURI
+        else None
+      ctx <- contextCache.get(uri)
+    yield ctx) match
+      case Some(ctx) => ctx
+      case None => super.currentCtx
+
   override def run(uri: URI, source: SourceFile): List[Diagnostic] =
+    lastCompiledURI = Some(uri)
     if alreadyCompiled(uri, source.content) then Nil
-    else super.run(uri, source)
+    else
+      val diags = super.run(uri, source)
+      contextCache.put(uri, currentCtx)
+      diags
 
   override def run(uri: URI, sourceCode: String): List[Diagnostic] =
-    val contentHash = MD5.compute(sourceCode)
+    lastCompiledURI = Some(uri)
     if alreadyCompiled(uri, sourceCode.toCharArray()) then Nil
-    else super.run(uri, sourceCode)
+    else
+      val diags = super.run(uri, sourceCode)
+      contextCache.put(uri, currentCtx)
+      diags
 
 end MetalsDriver