feat: generate same dev and prod code, fixes #700 (#1027)

Author: a-h

.version

@@ -1 +1 @@
-0.2.808
+0.2.810

benchmarks/templ/template_templ.go

@@ -7,6 +7,7 @@ import (
 	"log/slog"
 	"net/http"
 	"net/url"
+	"os"
 	"path"
 	"path/filepath"
 	"regexp"
@@ -54,6 +55,7 @@ type Generate struct {
 
 type GenerationEvent struct {
 	Event       fsnotify.Event
+	Updated     bool
 	GoUpdated   bool
 	TextUpdated bool
 }
@@ -114,7 +116,7 @@ func (cmd Generate) Run(ctx context.Context) (err error) {
 
 	// If we're processing a single file, don't bother setting up the channels/multithreaing.
 	if cmd.Args.FileName != "" {
-		_, _, err = fseh.HandleEvent(ctx, fsnotify.Event{
+		_, err = fseh.HandleEvent(ctx, fsnotify.Event{
 			Name: cmd.Args.FileName,
 			Op:   fsnotify.Create,
 		})
@@ -219,15 +221,16 @@ func (cmd Generate) Run(ctx context.Context) (err error) {
 				cmd.Log.Debug("Processing file", slog.String("file", event.Name))
 				defer eventsWG.Done()
 				defer func() { <-sem }()
-				goUpdated, textUpdated, err := fseh.HandleEvent(ctx, event)
+				r, err := fseh.HandleEvent(ctx, event)
 				if err != nil {
 					errs <- err
 				}
-				if goUpdated || textUpdated {
+				if r.GoUpdated || r.TextUpdated {
 					postGeneration <- &GenerationEvent{
 						Event:       event,
-						GoUpdated:   goUpdated,
-						TextUpdated: textUpdated,
+						Updated:     r.Updated,
+						GoUpdated:   r.GoUpdated,
+						TextUpdated: r.TextUpdated,
 					}
 				}
 			}(event)
@@ -273,6 +276,9 @@ func (cmd Generate) Run(ctx context.Context) (err error) {
 				postGenerationEventsWG.Add(1)
 				if cmd.Args.Command != "" && goUpdated {
 					cmd.Log.Debug("Executing command", slog.String("command", cmd.Args.Command))
+					if cmd.Args.Watch {
+						os.Setenv("TEMPL_DEV_MODE", "true")
+					}
 					if _, err := run.Run(ctx, cmd.Args.Path, cmd.Args.Command); err != nil {
 						cmd.Log.Error("Error executing command", slog.Any("error", err))
 					}

cmd/templ/generatecmd/cmd.go

@@ -57,18 +57,17 @@ func NewFSEventHandler(
 		fileNameToLastModTimeMutex: &sync.Mutex{},
 		fileNameToError:            make(map[string]struct{}),
 		fileNameToErrorMutex:       &sync.Mutex{},
+		fileNameToOutput:           make(map[string]generator.GeneratorOutput),
+		fileNameToOutputMutex:      &sync.Mutex{},
+		devMode:                    devMode,
 		hashes:                     make(map[string][sha256.Size]byte),
 		hashesMutex:                &sync.Mutex{},
 		genOpts:                    genOpts,
 		genSourceMapVis:            genSourceMapVis,
-		DevMode:                    devMode,
 		keepOrphanedFiles:          keepOrphanedFiles,
 		writer:                     fileWriter,
 		lazy:                       lazy,
 	}
-	if devMode {
-		fseh.genOpts = append(fseh.genOpts, generator.WithExtractStrings())
-	}
 	return fseh
 }
 
@@ -80,71 +79,84 @@ type FSEventHandler struct {
 	fileNameToLastModTimeMutex *sync.Mutex
 	fileNameToError            map[string]struct{}
 	fileNameToErrorMutex       *sync.Mutex
+	fileNameToOutput           map[string]generator.GeneratorOutput
+	fileNameToOutputMutex      *sync.Mutex
+	devMode                    bool
 	hashes                     map[string][sha256.Size]byte
 	hashesMutex                *sync.Mutex
 	genOpts                    []generator.GenerateOpt
 	genSourceMapVis            bool
-	DevMode                    bool
 	Errors                     []error
 	keepOrphanedFiles          bool
 	writer                     func(string, []byte) error
 	lazy                       bool
 }
 
-func (h *FSEventHandler) HandleEvent(ctx context.Context, event fsnotify.Event) (goUpdated, textUpdated bool, err error) {
+type GenerateResult struct {
+	// Updated indicates that the file was updated.
+	Updated bool
+	// GoUpdated indicates that Go expressions were updated.
+	GoUpdated bool
+	// TextUpdated indicates that text literals were updated.
+	TextUpdated bool
+}
+
+func (h *FSEventHandler) HandleEvent(ctx context.Context, event fsnotify.Event) (result GenerateResult, err error) {
 	// Handle _templ.go files.
 	if !event.Has(fsnotify.Remove) && strings.HasSuffix(event.Name, "_templ.go") {
 		_, err = os.Stat(strings.TrimSuffix(event.Name, "_templ.go") + ".templ")
 		if !os.IsNotExist(err) {
-			return false, false, err
+			return GenerateResult{}, err
 		}
 		// File is orphaned.
 		if h.keepOrphanedFiles {
-			return false, false, nil
+			return GenerateResult{}, nil
 		}
 		h.Log.Debug("Deleting orphaned Go file", slog.String("file", event.Name))
 		if err = os.Remove(event.Name); err != nil {
 			h.Log.Warn("Failed to remove orphaned file", slog.Any("error", err))
 		}
-		return true, false, nil
+		return GenerateResult{Updated: true, GoUpdated: true, TextUpdated: false}, nil
 	}
 	// Handle _templ.txt files.
 	if !event.Has(fsnotify.Remove) && strings.HasSuffix(event.Name, "_templ.txt") {
-		if h.DevMode {
-			// Don't delete the file if we're in dev mode, but mark that text was updated.
-			return false, true, nil
+		if h.devMode {
+			// Don't delete the file in dev mode, ignore changes to it, since the .templ file
+			// must have been updated in order to trigger a change in the _templ.txt file.
+			return GenerateResult{Updated: false, GoUpdated: false, TextUpdated: false}, nil
 		}
 		h.Log.Debug("Deleting watch mode file", slog.String("file", event.Name))
 		if err = os.Remove(event.Name); err != nil {
 			h.Log.Warn("Failed to remove watch mode text file", slog.Any("error", err))
-			return false, false, nil
+			return GenerateResult{}, nil
 		}
-		return false, false, nil
+		return GenerateResult{}, nil
 	}
 
 	// Handle .templ files.
 	if !strings.HasSuffix(event.Name, ".templ") {
-		return false, false, nil
+		return GenerateResult{}, nil
 	}
 
 	// If the file hasn't been updated since the last time we processed it, ignore it.
 	lastModTime, updatedModTime := h.UpsertLastModTime(event.Name)
 	if !updatedModTime {
 		h.Log.Debug("Skipping file because it wasn't updated", slog.String("file", event.Name))
-		return false, false, nil
+		return GenerateResult{}, nil
 	}
 	// If the go file is newer than the templ file, skip generation, because it's up-to-date.
 	if h.lazy && goFileIsUpToDate(event.Name, lastModTime) {
 		h.Log.Debug("Skipping file because the Go file is up-to-date", slog.String("file", event.Name))
-		return false, false, nil
+		return GenerateResult{}, nil
 	}
 
 	// Start a processor.
 	start := time.Now()
-	goUpdated, textUpdated, diag, err := h.generate(ctx, event.Name)
+	var diag []parser.Diagnostic
+	result, diag, err = h.generate(ctx, event.Name)
 	if err != nil {
 		h.SetError(event.Name, true)
-		return goUpdated, textUpdated, fmt.Errorf("failed to generate code for %q: %w", event.Name, err)
+		return result, fmt.Errorf("failed to generate code for %q: %w", event.Name, err)
 	}
 	if len(diag) > 0 {
 		for _, d := range diag {
@@ -153,14 +165,14 @@ func (h *FSEventHandler) HandleEvent(ctx context.Context, event fsnotify.Event)
 				slog.String("to", fmt.Sprintf("%d:%d", d.Range.To.Line, d.Range.To.Col)),
 			)
 		}
-		return
+		return result, nil
 	}
 	if errorCleared, errorCount := h.SetError(event.Name, false); errorCleared {
 		h.Log.Info("Error cleared", slog.String("file", event.Name), slog.Int("errors", errorCount))
 	}
 	h.Log.Debug("Generated code", slog.String("file", event.Name), slog.Duration("in", time.Since(start)))
 
-	return goUpdated, textUpdated, nil
+	return result, nil
 }
 
 func goFileIsUpToDate(templFileName string, templFileLastMod time.Time) (upToDate bool) {
@@ -212,68 +224,78 @@ func (h *FSEventHandler) UpsertHash(fileName string, hash [sha256.Size]byte) (up
 
 // generate Go code for a single template.
 // If a basePath is provided, the filename included in error messages is relative to it.
-func (h *FSEventHandler) generate(ctx context.Context, fileName string) (goUpdated, textUpdated bool, diagnostics []parser.Diagnostic, err error) {
+func (h *FSEventHandler) generate(ctx context.Context, fileName string) (result GenerateResult, diagnostics []parser.Diagnostic, err error) {
 	t, err := parser.Parse(fileName)
 	if err != nil {
-		return false, false, nil, fmt.Errorf("%s parsing error: %w", fileName, err)
+		return GenerateResult{}, nil, fmt.Errorf("%s parsing error: %w", fileName, err)
 	}
 	targetFileName := strings.TrimSuffix(fileName, ".templ") + "_templ.go"
 
 	// Only use relative filenames to the basepath for filenames in runtime error messages.
 	absFilePath, err := filepath.Abs(fileName)
 	if err != nil {
-		return false, false, nil, fmt.Errorf("failed to get absolute path for %q: %w", fileName, err)
+		return GenerateResult{}, nil, fmt.Errorf("failed to get absolute path for %q: %w", fileName, err)
 	}
 	relFilePath, err := filepath.Rel(h.dir, absFilePath)
 	if err != nil {
-		return false, false, nil, fmt.Errorf("failed to get relative path for %q: %w", fileName, err)
+		return GenerateResult{}, nil, fmt.Errorf("failed to get relative path for %q: %w", fileName, err)
 	}
 	// Convert Windows file paths to Unix-style for consistency.
 	relFilePath = filepath.ToSlash(relFilePath)
 
 	var b bytes.Buffer
-	sourceMap, literals, err := generator.Generate(t, &b, append(h.genOpts, generator.WithFileName(relFilePath))...)
+	generatorOutput, err := generator.Generate(t, &b, append(h.genOpts, generator.WithFileName(relFilePath))...)
 	if err != nil {
-		return false, false, nil, fmt.Errorf("%s generation error: %w", fileName, err)
+		return GenerateResult{}, nil, fmt.Errorf("%s generation error: %w", fileName, err)
 	}
 
 	formattedGoCode, err := format.Source(b.Bytes())
 	if err != nil {
-		err = remapErrorList(err, sourceMap, fileName)
-		return false, false, nil, fmt.Errorf("% source formatting error %w", fileName, err)
+		err = remapErrorList(err, generatorOutput.SourceMap, fileName)
+		return GenerateResult{}, nil, fmt.Errorf("%s source formatting error %w", fileName, err)
 	}
 
 	// Hash output, and write out the file if the goCodeHash has changed.
 	goCodeHash := sha256.Sum256(formattedGoCode)
 	if h.UpsertHash(targetFileName, goCodeHash) {
-		goUpdated = true
+		result.Updated = true
 		if err = h.writer(targetFileName, formattedGoCode); err != nil {
-			return false, false, nil, fmt.Errorf("failed to write target file %q: %w", targetFileName, err)
+			return result, nil, fmt.Errorf("failed to write target file %q: %w", targetFileName, err)
 		}
 	}
 
 	// Add the txt file if it has changed.
-	if len(literals) > 0 {
+	if h.devMode {
 		txtFileName := strings.TrimSuffix(fileName, ".templ") + "_templ.txt"
-		txtHash := sha256.Sum256([]byte(literals))
+		joined := strings.Join(generatorOutput.Literals, "\n")
+		txtHash := sha256.Sum256([]byte(joined))
 		if h.UpsertHash(txtFileName, txtHash) {
-			textUpdated = true
-			if err = os.WriteFile(txtFileName, []byte(literals), 0o644); err != nil {
-				return false, false, nil, fmt.Errorf("failed to write string literal file %q: %w", txtFileName, err)
+			result.TextUpdated = true
+			if err = os.WriteFile(txtFileName, []byte(joined), 0o644); err != nil {
+				return result, nil, fmt.Errorf("failed to write string literal file %q: %w", txtFileName, err)
+			}
+
+			// Check whether the change would require a recompilation to take effect.
+			h.fileNameToOutputMutex.Lock()
+			defer h.fileNameToOutputMutex.Unlock()
+			previous := h.fileNameToOutput[fileName]
+			if generator.HasChanged(previous, generatorOutput) {
+				result.GoUpdated = true
 			}
+			h.fileNameToOutput[fileName] = generatorOutput
 		}
 	}
 
 	parsedDiagnostics, err := parser.Diagnose(t)
 	if err != nil {
-		return goUpdated, textUpdated, nil, fmt.Errorf("%s diagnostics error: %w", fileName, err)
+		return result, nil, fmt.Errorf("%s diagnostics error: %w", fileName, err)
 	}
 
 	if h.genSourceMapVis {
-		err = generateSourceMapVisualisation(ctx, fileName, targetFileName, sourceMap)
+		err = generateSourceMapVisualisation(ctx, fileName, targetFileName, generatorOutput.SourceMap)
 	}
 
-	return goUpdated, textUpdated, parsedDiagnostics, err
+	return result, parsedDiagnostics, err
 }
 
 // Takes an error from the formatter and attempts to convert the positions reported in the target file to their positions

cmd/templ/generatecmd/eventhandler.go

@@ -52,7 +52,7 @@ func ignoreExited(err error) error {
 	return err
 }
 
-func Run(ctx context.Context, workingDir, input string) (cmd *exec.Cmd, err error) {
+func Run(ctx context.Context, workingDir string, input string) (cmd *exec.Cmd, err error) {
 	m.Lock()
 	defer m.Unlock()
 	cmd, ok := running[input]

cmd/templ/generatecmd/run/run_unix.go

@@ -37,7 +37,7 @@ func Stop(cmd *exec.Cmd) (err error) {
 	return kill.Run()
 }
 
-func Run(ctx context.Context, workingDir, input string) (cmd *exec.Cmd, err error) {
+func Run(ctx context.Context, workingDir string, input string) (cmd *exec.Cmd, err error) {
 	m.Lock()
 	defer m.Unlock()
 	cmd, ok := running[input]