Abstract out the context cancel logic for reuse (#7)

Author: tommyo

evaluate.go

@@ -3,12 +3,13 @@ package typescript
 import (
 	"context"
 	"fmt"
-	"github.com/clarkmcc/go-typescript/packages"
-	_ "github.com/clarkmcc/go-typescript/versions/v4.7.2"
-	"github.com/dop251/goja"
 	"io"
 	"io/ioutil"
 	"strings"
+
+	"github.com/clarkmcc/go-typescript/packages"
+	_ "github.com/clarkmcc/go-typescript/versions/v4.7.2"
+	"github.com/dop251/goja"
 )
 
 type EvaluateOptionFunc func(cfg *EvaluateConfig)
@@ -102,22 +103,8 @@ func EvaluateCtx(ctx context.Context, src io.Reader, opts ...EvaluateOptionFunc)
 	for _, fn := range opts {
 		fn(cfg)
 	}
-	done := make(chan struct{})
-	started := make(chan struct{})
+	done := startInterruptable(ctx, cfg.Runtime)
 	defer close(done)
-	go func() {
-		// Inform the parent go-routine that we've started, this prevents a race condition where the
-		// runtime would beat the context cancellation in unit tests even though the context started
-		// out in a 'cancelled' state.
-		close(started)
-		select {
-		case <-ctx.Done():
-			cfg.Runtime.Interrupt("context halt")
-		case <-done:
-			return
-		}
-	}()
-	<-started
 	if cfg.HasEvaluateBefore() {
 		for _, s := range cfg.EvaluateBefore {
 			b, err := ioutil.ReadAll(s)
@@ -130,6 +117,7 @@ func EvaluateCtx(ctx context.Context, src io.Reader, opts ...EvaluateOptionFunc)
 			}
 		}
 	}
+
 	b, err := ioutil.ReadAll(src)
 	if err != nil {
 		return nil, fmt.Errorf("reading src: %w", err)
@@ -149,9 +137,7 @@ func EvaluateCtx(ctx context.Context, src io.Reader, opts ...EvaluateOptionFunc)
 			WithRuntime(cfg.Runtime),
 			WithPreventCancellation(),
 		}
-		for _, opt := range cfg.TranspileOptions {
-			opts = append(opts, opt)
-		}
+		opts = append(opts, cfg.TranspileOptions...)
 		for _, h := range cfg.ScriptPreTranspileHooks {
 			script, err = h(script)
 			if err != nil {

interrupt.go

@@ -0,0 +1,26 @@
+package typescript
+
+import (
+	"context"
+
+	"github.com/dop251/goja"
+)
+
+func startInterruptable(ctx context.Context, vm *goja.Runtime) chan struct{} {
+	done := make(chan struct{})
+	started := make(chan struct{})
+	go func() {
+		// Inform the parent go-routine that we've started, this prevents a race condition where the
+		// runtime would beat the context cancellation in unit tests even though the context started
+		// out in a 'cancelled' state.
+		close(started)
+		select {
+		case <-ctx.Done():
+			vm.Interrupt("context halt")
+		case <-done:
+			return
+		}
+	}()
+	<-started
+	return done
+}

transpiler.go

@@ -30,22 +30,8 @@ func TranspileCtx(ctx context.Context, script io.Reader, opts ...TranspileOption
 	}
 	// Handle context cancellation
 	if !cfg.PreventCancellation {
-		done := make(chan struct{})
-		started := make(chan struct{})
+		done := startInterruptable(ctx, cfg.Runtime)
 		defer close(done)
-		go func() {
-			// Inform the parent go-routine that we've started, this prevents a race condition where the
-			// runtime would beat the context cancellation in unit tests even though the context started
-			// out in a 'cancelled' state.
-			close(started)
-			select {
-			case <-ctx.Done():
-				cfg.Runtime.Interrupt("halt")
-			case <-done:
-				return
-			}
-		}()
-		<-started
 	}
 	err := cfg.Initialize()
 	if err != nil {