feat: observer pattern for statistics

internal/executer/executer.go

@@ -3,47 +3,37 @@ package executer
 import (
 	"fmt"
 	"log/slog"
-	"time"
 
 	"git.maximhutz.com/max/lambda/internal/config"
+	"git.maximhutz.com/max/lambda/pkg/emitter"
 	"git.maximhutz.com/max/lambda/pkg/lambda"
 )
 
 type Executor struct {
 	Config *config.Config
+	emitter.Emitter[*lambda.Expression]
 }
 
 func New(config *config.Config) *Executor {
 	return &Executor{Config: config}
 }
 
-func (e Executor) Run(expr *lambda.Expression) (*Results, error) {
-	results := &Results{}
-
-	if e.Config.Profile != "" {
-		profiler := Profiler{File: e.Config.Profile}
-		if err := profiler.Start(); err != nil {
-			return nil, err
-		}
-		defer profiler.End()
-	}
-
-	start := time.Now()
+func (e Executor) Run(expr *lambda.Expression) {
+	e.Emit("start", expr)
 
 	if e.Config.Explanation {
 		fmt.Println(lambda.Stringify(*expr))
 	}
 
 	for lambda.ReduceOnce(expr) {
+		e.Emit("step", expr)
 		if e.Config.Verbose {
 			slog.Info("reduction", "tree", lambda.Stringify(*expr))
 		}
 		if e.Config.Explanation {
 			fmt.Println("    =", lambda.Stringify(*expr))
 		}
-		results.StepsTaken++
 	}
 
-	results.TimeElapsed = uint64(time.Since(start).Milliseconds())
-	return results, nil
+	e.Emit("end", expr)
 }