plugins: Introduce generated, static core plugin registry (#54118)

* Refactor towards template/codegen framework

* Add templates for plugin gen

* Add Go codegen for plugins; overhaul framework, too

* Add new codegen output; assorted framework fixes

* Regenerate after merge

* Remove accidental commit file, update templates

* Export the pfs.Tree loader from plugin types

* Print details from cuetsy errors

* Generate loaders for all plugins and list in registry

* Use pfs_gen.go over lineage_gen.go

* Un-un-ignore main file

* Introduce simple List static registry for plugins

* Last tweaks to codegen

* remove unused tvars

* Ensure loop-local instances for both vars

* Generate pfs parsing in-place in registry

* Stop generating pfs_gen.go

* Move Tree into pfs, rename subdir

* Change package name to match dir

* Ignore gocyclo on HTTPServer.getNavTree

pkg/framework/coremodel/registry/provide.go

@@ -54,6 +54,6 @@ func provideBase(lib *thema.Library) *Base {
 //
 // The returned slice is sorted lexicographically by coremodel name. It should
 // not be modified.
-func (s *Base) All() []coremodel.Interface {
-	return s.all
+func (b *Base) All() []coremodel.Interface {
+	return b.all
 }

pkg/framework/coremodel/registry/registry_gen.go

@@ -1,7 +1,8 @@
 // This file is autogenerated. DO NOT EDIT.
 //
 // Generated by pkg/framework/coremodel/gen.go
-// Run "make gen-cue" from repository root to regenerate.
+//
+// Run `make gen-cue` from repository root to regenerate.
 
 package registry
 
@@ -37,14 +38,14 @@ var (
 
 // Dashboard returns the dashboard coremodel. The return value is guaranteed to
 // implement coremodel.Interface.
-func (s *Base) Dashboard() *dashboard.Coremodel {
-	return s.dashboard
+func (b *Base) Dashboard() *dashboard.Coremodel {
+	return b.dashboard
 }
 
 // Pluginmeta returns the pluginmeta coremodel. The return value is guaranteed to
 // implement coremodel.Interface.
-func (s *Base) Pluginmeta() *pluginmeta.Coremodel {
-	return s.pluginmeta
+func (b *Base) Pluginmeta() *pluginmeta.Coremodel {
+	return b.pluginmeta
 }
 
 func doProvideBase(lib thema.Library) *Base {

pkg/framework/coremodel/slot.go

@@ -42,6 +42,22 @@ func (s Slot) ForPluginType(plugintype string) (may, must bool) {
 	return
 }
 
+// IsGroup indicates whether the slot specifies a group lineage - one in which
+// each top-level key represents a distinct schema for objects that are expected
+// to exist in the wild, but objects corresponding to the root of the schema are not
+// expected to exist.
+func (s Slot) IsGroup() bool {
+	// TODO rely on first-class Thema properties for this, one they exist - https://github.com/grafana/thema/issues/62
+	switch s.name {
+	case "Panel", "DSOptions":
+		return true
+	case "Query":
+		return false
+	default:
+		panic("unreachable - unknown slot name " + s.name)
+	}
+}
+
 func AllSlots() map[string]*Slot {
 	fw := CUEFramework()
 	slots := make(map[string]*Slot)