fix: sourcemap not handling multiline expressions (e.g. import statem…

…ents) properly

cmd/templ/lspcmd/httpdebug/handler.go

@@ -1,6 +1,7 @@
 package httpdebug
 
 import (
+	"encoding/json"
 	"io"
 	"net/http"
 	"net/url"
@@ -21,6 +22,17 @@ func NewHandler(s *proxy.Server) http.Handler {
 		}
 		io.WriteString(w, c.String())
 	})
+	m.HandleFunc("/sourcemap", func(w http.ResponseWriter, r *http.Request) {
+		uri := r.URL.Query().Get("uri")
+		sm, ok := s.SourceMapCache.Get(uri)
+		if !ok {
+			Error(w, "uri not found", http.StatusNotFound)
+			return
+		}
+		enc := json.NewEncoder(w)
+		enc.SetIndent("", "  ")
+		enc.Encode(sm.SourceLinesToTarget)
+	})
 	m.HandleFunc("/go", func(w http.ResponseWriter, r *http.Request) {
 		uri := r.URL.Query().Get("uri")
 		c, ok := s.GoSource[uri]
@@ -66,6 +78,10 @@ func getMapURL(uri string) templ.SafeURL {
 	return withQuery("/", uri)
 }
 
+func getSourceMapURL(uri string) templ.SafeURL {
+	return withQuery("/sourcemap", uri)
+}
+
 func getTemplURL(uri string) templ.SafeURL {
 	return withQuery("/templ", uri)
 }

cmd/templ/lspcmd/httpdebug/list.templ

@@ -7,11 +7,13 @@ templ list(uris []string) {
 			<th></th>
 			<th></th>
 			<th></th>
+			<th></th>
 		</tr>
 		for _, uri := range uris {
 			<tr>
 				<td>{ uri }</td>
 				<td><a href={ getMapURL(uri) }>Mapping</a></td>
+				<td><a href={ getSourceMapURL(uri) }>Source Map</a></td>
 				<td><a href={ getTemplURL(uri) }>Templ</a></td>
 				<td><a href={ getGoURL(uri) }>Go</a></td>
 			</tr>

cmd/templ/lspcmd/proxy/client.go

@@ -58,12 +58,12 @@ func (p Client) PublishDiagnostics(ctx context.Context, params *lsp.PublishDiagn
 	// Rewrite the positions.
 	for i := 0; i < len(params.Diagnostics); i++ {
 		item := params.Diagnostics[i]
-		start, _, ok := sourceMap.SourcePositionFromTarget(item.Range.Start.Line, item.Range.Start.Character)
+		start, ok := sourceMap.SourcePositionFromTarget(item.Range.Start.Line, item.Range.Start.Character)
 		if ok {
 			item.Range.Start.Line = start.Line
 			item.Range.Start.Character = start.Col
 		}
-		end, _, ok := sourceMap.SourcePositionFromTarget(item.Range.End.Line, item.Range.End.Character)
+		end, ok := sourceMap.SourcePositionFromTarget(item.Range.End.Line, item.Range.End.Character)
 		if ok {
 			item.Range.End.Line = end.Line
 			item.Range.End.Line = end.Col

cmd/templ/lspcmd/proxy/server.go

@@ -5,9 +5,9 @@ import (
 	"fmt"
 	"strings"
 
+	lsp "github.com/a-h/protocol"
 	"github.com/a-h/templ/generator"
 	"github.com/a-h/templ/parser/v2"
-	lsp "github.com/a-h/protocol"
 	"go.lsp.dev/uri"
 	"go.uber.org/zap"
 )
@@ -64,7 +64,7 @@ func (p *Server) updatePosition(templURI lsp.DocumentURI, current lsp.Position)
 		return
 	}
 	// Map from the source position to target Go position.
-	to, _, ok := sourceMap.TargetPositionFromSource(current.Line, current.Character)
+	to, ok := sourceMap.TargetPositionFromSource(current.Line, current.Character)
 	if ok {
 		log.Info("updatePosition: found", zap.String("fromTempl", fmt.Sprintf("%d:%d", current.Line, current.Character)),
 			zap.String("toGo", fmt.Sprintf("%d:%d", to.Line, to.Col)))
@@ -83,12 +83,12 @@ func (p *Server) convertTemplRangeToGoRange(templURI lsp.DocumentURI, input lsp.
 		return
 	}
 	// Map from the source position to target Go position.
-	start, _, ok := sourceMap.TargetPositionFromSource(input.Start.Line, input.Start.Character)
+	start, ok := sourceMap.TargetPositionFromSource(input.Start.Line, input.Start.Character)
 	if ok {
 		output.Start.Line = start.Line
 		output.Start.Character = start.Col
 	}
-	end, _, ok := sourceMap.TargetPositionFromSource(input.End.Line, input.End.Character)
+	end, ok := sourceMap.TargetPositionFromSource(input.End.Line, input.End.Character)
 	if ok {
 		output.End.Line = end.Line
 		output.End.Character = end.Col
@@ -103,12 +103,12 @@ func (p *Server) convertGoRangeToTemplRange(templURI lsp.DocumentURI, input lsp.
 		return
 	}
 	// Map from the source position to target Go position.
-	start, _, ok := sourceMap.SourcePositionFromTarget(input.Start.Line, input.Start.Character)
+	start, ok := sourceMap.SourcePositionFromTarget(input.Start.Line, input.Start.Character)
 	if ok {
 		output.Start.Line = start.Line
 		output.Start.Character = start.Col
 	}
-	end, _, ok := sourceMap.SourcePositionFromTarget(input.End.Line, input.End.Character)
+	end, ok := sourceMap.SourcePositionFromTarget(input.End.Line, input.End.Character)
 	if ok {
 		output.End.Line = end.Line
 		output.End.Character = end.Col

cmd/templ/visualize/sourcemapvisualisation.templ

@@ -6,6 +6,8 @@ css row() {
 
 css column() {
 	flex: 50%;
+	overflow-y: scroll;
+	max-height: 100vh;
 }
 
 css code() {

cmd/templ/visualize/types.go

@@ -28,9 +28,9 @@ func (tl templLines) Render(ctx context.Context, w io.Writer) error {
 	for lineIndex, line := range templLines {
 		w.Write([]byte("<span>" + strconv.Itoa(lineIndex) + "&nbsp;</span>\n"))
 		for colIndex, c := range line {
-			if _, m, ok := tl.sourceMap.TargetPositionFromSource(uint32(lineIndex), uint32(colIndex)); ok {
-				sourceID := fmt.Sprintf("src_%d_%d_%d", m.Source.Range.From.Index, m.Source.Range.From.Line, m.Source.Range.From.Col)
-				targetID := fmt.Sprintf("tgt_%d_%d_%d", m.Target.From.Index, m.Target.From.Index, m.Target.From.Col)
+			if tgt, ok := tl.sourceMap.TargetPositionFromSource(uint32(lineIndex), uint32(colIndex)); ok {
+				sourceID := fmt.Sprintf("src_%d_%d", lineIndex, colIndex)
+				targetID := fmt.Sprintf("tgt_%d_%d", tgt.Line, tgt.Col)
 				if err := mappedCharacter(string(c), sourceID, targetID).Render(ctx, w); err != nil {
 					return err
 				}
@@ -58,9 +58,9 @@ func (gl goLines) Render(ctx context.Context, w io.Writer) error {
 	for lineIndex, line := range templLines {
 		w.Write([]byte("<span>" + strconv.Itoa(lineIndex) + "&nbsp;</span>\n"))
 		for colIndex, c := range line {
-			if _, m, ok := gl.sourceMap.SourcePositionFromTarget(uint32(lineIndex), uint32(colIndex)); ok {
-				sourceID := fmt.Sprintf("src_%d_%d_%d", m.Source.Range.From.Index, m.Source.Range.From.Line, m.Source.Range.From.Col)
-				targetID := fmt.Sprintf("tgt_%d_%d_%d", m.Target.From.Index, m.Target.From.Index, m.Target.From.Col)
+			if src, ok := gl.sourceMap.SourcePositionFromTarget(uint32(lineIndex), uint32(colIndex)); ok {
+				sourceID := fmt.Sprintf("src_%d_%d", src.Line, src.Col)
+				targetID := fmt.Sprintf("tgt_%d_%d", lineIndex, colIndex)
 				if err := mappedCharacter(string(c), sourceID, targetID).Render(ctx, w); err != nil {
 					return err
 				}

generator/generator_test.go

@@ -23,17 +23,15 @@ func TestGeneratorSourceMap(t *testing.T) {
 	if err != nil {
 		t.Fatalf("failed to write Go expression: %v", err)
 	}
-	if len(g.sourceMap.Items) != 1 {
-		t.Fatalf("expected that writing an expression adds to the source map, ubut got %d items", len(g.sourceMap.Items))
+	// The from value is (16, 1, 0) because the generator prefixes the
+	// expression with a "// GoExpression" comment.
+	expected := parser.NewPositionFromValues(16, 1, 0)
+
+	actual, ok := g.sourceMap.TargetPositionFromSource(0, 0)
+	if !ok {
+		t.Errorf("failed to get matching target")
 	}
-	expectedTarget := parser.NewRange(
-		// The from value is (16, 1, 0) because the generator prefixes the
-		// expression with a "// GoExpression" comment.
-		parser.NewPositionFromValues(16, 1, 0),
-		parser.NewPositionFromValues(int64(16+len(exp.Expression.Value)), 2, 5),
-	)
-	actual := g.sourceMap.Items[0].Target
-	if diff := cmp.Diff(expectedTarget, actual); diff != "" {
+	if diff := cmp.Diff(expected, actual); diff != "" {
 		t.Errorf("unexpected target:\n%v", diff)
 	}
 }