wit/bindgen: add WIT generation for each WIT interface (Go package)

Currently disabled.

Author: ydnar

wit/bindgen/generator.go

@@ -83,8 +83,9 @@ type typeUse struct {
 }
 
 type generator struct {
-	opts options
-	res  *wit.Resolve
+	opts  options
+	res   *wit.Resolve
+	world *wit.World // optional, can be nil
 
 	// versioned is set to true if there are multiple versions of a WIT package in res,
 	// which affects the generated Go package paths.
@@ -152,9 +153,25 @@ func newGenerator(res *wit.Resolve, opts ...Option) (*generator, error) {
 		g.opts.cmPackage = cmPackage
 	}
 	g.res = res
+	for _, g.world = range res.Worlds {
+		if g.world.Match(g.opts.world) {
+			break
+		}
+		// otherwise chose the last world
+	}
 	return g, nil
 }
 
+// TODO: factor this out
+func findWorld(r *wit.Resolve, pattern string) *wit.World {
+	for _, w := range r.Worlds {
+		if w.Match(pattern) {
+			return w
+		}
+	}
+	return nil
+}
+
 func (g *generator) generate() ([]*gen.Package, error) {
 	g.detectVersionedPackages()
 	err := g.defineWorlds()
@@ -205,8 +222,8 @@ func (g *generator) define(dir wit.Direction, v wit.Node) (defined bool) {
 // WIT interfaces and/or worlds into a single Go package.
 func (g *generator) defineWorlds() error {
 	g.opts.logger.Infof("Generating Go for %d world(s)\n", len(g.res.Worlds))
-	for i, w := range g.res.Worlds {
-		if w.Match(g.opts.world) || (g.opts.world == "" && i == len(g.res.Worlds)-1) {
+	for _, w := range g.res.Worlds {
+		if w == g.world || g.world == nil {
 			err := g.defineWorld(w)
 			if err != nil {
 				return err
@@ -299,8 +316,13 @@ func (g *generator) defineInterface(w *wit.World, dir wit.Direction, i *wit.Inte
 	if err != nil {
 		return err
 	}
-	file := g.fileFor(i)
 
+	// Write WIT file for this interface
+	// Disabled until we write metadata .wasm file
+	// witFile := g.witFileFor(i)
+	// witFile.WriteString(g.res.WIT(wit.Filter(g.world, i), ""))
+
+	file := g.fileFor(i)
 	{
 		var b strings.Builder
 		stringio.Write(&b, "Package ", pkg.Name, " represents the ", dir.String(), " ", i.WITKind(), " \"", g.moduleNames[i], "\".\n")