From 82c33cfa314bba17eb284ddc6a58dc20e7930577 Mon Sep 17 00:00:00 2001
From: Adrian Hesketh <adrianhesketh@hushmail.com>
Date: Sun, 6 Jun 2021 15:08:33 +0100
Subject: [PATCH] generate void elements, instead of <br></br>, fixes #12

---
 .gitignore                            |   2 +-
 generator/generator.go                | 162 +++++++++++++++++---------
 generator/test-void/render_test.go    |  22 ++++
 generator/test-void/template.templ    |   8 ++
 generator/test-void/template_templ.go |  38 ++++++
 types.go                              |   4 +-
 6 files changed, 175 insertions(+), 61 deletions(-)
 create mode 100644 generator/test-void/render_test.go
 create mode 100644 generator/test-void/template.templ
 create mode 100644 generator/test-void/template_templ.go

diff --git a/.gitignore b/.gitignore
index fbba37a10..805cc1002 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,5 @@
 cmd/example/*.go
 dist
 cmd/templ/templ
-cmd/lspcmd/*log.txt
+cmd/templ/lspcmd/*log.txt
 .DS_Store
diff --git a/generator/generator.go b/generator/generator.go
index ccd3b4d77..76c0a83e3 100644
--- a/generator/generator.go
+++ b/generator/generator.go
@@ -393,9 +393,47 @@ func (g *generator) writeErrorHandler(indentLevel int) (err error) {
 }
 
 func (g *generator) writeElement(indentLevel int, n templ.Element) error {
-	var r templ.Range
-	var err error
-	// Attributes.
+	if n.IsVoidElement() {
+		return g.writeVoidElement(indentLevel, n)
+	}
+	return g.writeStandardElement(indentLevel, n)
+}
+
+func (g *generator) writeVoidElement(indentLevel int, n templ.Element) (err error) {
+	if len(n.Children) > 0 {
+		return fmt.Errorf("writeVoidElement: void element %q must not have child elements", n.Name)
+	}
+	if len(n.Attributes) == 0 {
+		// <div/>
+		if _, err = g.w.WriteIndent(indentLevel, fmt.Sprintf(`_, err = io.WriteString(w, "<%s/>")`+"\n", html.EscapeString(n.Name))); err != nil {
+			return err
+		}
+		if err = g.writeErrorHandler(indentLevel); err != nil {
+			return err
+		}
+	} else {
+		// <div
+		if _, err = g.w.WriteIndent(indentLevel, fmt.Sprintf(`_, err = io.WriteString(w, "<%s")`+"\n", html.EscapeString(n.Name))); err != nil {
+			return err
+		}
+		if err = g.writeErrorHandler(indentLevel); err != nil {
+			return err
+		}
+		if err = g.writeElementAttributes(indentLevel, n); err != nil {
+			return err
+		}
+		// />
+		if _, err = g.w.WriteIndent(indentLevel, `_, err = io.WriteString(w, "/>")`+"\n"); err != nil {
+			return err
+		}
+		if err = g.writeErrorHandler(indentLevel); err != nil {
+			return err
+		}
+	}
+	return err
+}
+
+func (g *generator) writeStandardElement(indentLevel int, n templ.Element) (err error) {
 	if len(n.Attributes) == 0 {
 		// <div>
 		if _, err = g.w.WriteIndent(indentLevel, fmt.Sprintf(`_, err = io.WriteString(w, "<%s>")`+"\n", html.EscapeString(n.Name))); err != nil {
@@ -412,60 +450,8 @@ func (g *generator) writeElement(indentLevel int, n templ.Element) error {
 		if err = g.writeErrorHandler(indentLevel); err != nil {
 			return err
 		}
-		for i := 0; i < len(n.Attributes); i++ {
-			switch attr := n.Attributes[i].(type) {
-			case templ.ConstantAttribute:
-				name := html.EscapeString(attr.Name)
-				value := html.EscapeString(attr.Value)
-				if _, err = g.w.WriteIndent(indentLevel, fmt.Sprintf(`_, err = io.WriteString(w, " %s=\"%s\"")`+"\n", name, value)); err != nil {
-					return err
-				}
-				if err = g.writeErrorHandler(indentLevel); err != nil {
-					return err
-				}
-			case templ.ExpressionAttribute:
-				name := html.EscapeString(attr.Name)
-				// Name
-				if _, err = g.w.WriteIndent(indentLevel, fmt.Sprintf(`_, err = io.WriteString(w, " %s=")`+"\n", name)); err != nil {
-					return err
-				}
-				if err = g.writeErrorHandler(indentLevel); err != nil {
-					return err
-				}
-				// Value.
-				// Open quote.
-				if _, err = g.w.WriteIndent(indentLevel, `_, err = io.WriteString(w, "\"")`+"\n"); err != nil {
-					return err
-				}
-				if err = g.writeErrorHandler(indentLevel); err != nil {
-					return err
-				}
-				// io.WriteString(w, templ.EscapeString(
-				if _, err = g.w.WriteIndent(indentLevel, "_, err = io.WriteString(w, templ.EscapeString("); err != nil {
-					return err
-				}
-				// p.Name()
-				if r, err = g.w.Write(attr.Expression.Value); err != nil {
-					return err
-				}
-				g.sourceMap.Add(attr.Expression, r)
-				// ))
-				if _, err = g.w.Write("))\n"); err != nil {
-					return err
-				}
-				if err = g.writeErrorHandler(indentLevel); err != nil {
-					return err
-				}
-				// Close quote.
-				if _, err = g.w.WriteIndent(indentLevel, `_, err = io.WriteString(w, "\"")`+"\n"); err != nil {
-					return err
-				}
-				if err = g.writeErrorHandler(indentLevel); err != nil {
-					return err
-				}
-			default:
-				return fmt.Errorf("unknown attribute type %s", reflect.TypeOf(n.Attributes[i]))
-			}
+		if err = g.writeElementAttributes(indentLevel, n); err != nil {
+			return err
 		}
 		// >
 		if _, err = g.w.WriteIndent(indentLevel, `_, err = io.WriteString(w, ">")`+"\n"); err != nil {
@@ -484,7 +470,67 @@ func (g *generator) writeElement(indentLevel int, n templ.Element) error {
 	if err = g.writeErrorHandler(indentLevel); err != nil {
 		return err
 	}
-	return nil
+	return err
+}
+
+func (g *generator) writeElementAttributes(indentLevel int, n templ.Element) (err error) {
+	var r templ.Range
+	for i := 0; i < len(n.Attributes); i++ {
+		switch attr := n.Attributes[i].(type) {
+		case templ.ConstantAttribute:
+			name := html.EscapeString(attr.Name)
+			value := html.EscapeString(attr.Value)
+			if _, err = g.w.WriteIndent(indentLevel, fmt.Sprintf(`_, err = io.WriteString(w, " %s=\"%s\"")`+"\n", name, value)); err != nil {
+				return err
+			}
+			if err = g.writeErrorHandler(indentLevel); err != nil {
+				return err
+			}
+		case templ.ExpressionAttribute:
+			name := html.EscapeString(attr.Name)
+			// Name
+			if _, err = g.w.WriteIndent(indentLevel, fmt.Sprintf(`_, err = io.WriteString(w, " %s=")`+"\n", name)); err != nil {
+				return err
+			}
+			if err = g.writeErrorHandler(indentLevel); err != nil {
+				return err
+			}
+			// Value.
+			// Open quote.
+			if _, err = g.w.WriteIndent(indentLevel, `_, err = io.WriteString(w, "\"")`+"\n"); err != nil {
+				return err
+			}
+			if err = g.writeErrorHandler(indentLevel); err != nil {
+				return err
+			}
+			// io.WriteString(w, templ.EscapeString(
+			if _, err = g.w.WriteIndent(indentLevel, "_, err = io.WriteString(w, templ.EscapeString("); err != nil {
+				return err
+			}
+			// p.Name()
+			if r, err = g.w.Write(attr.Expression.Value); err != nil {
+				return err
+			}
+			g.sourceMap.Add(attr.Expression, r)
+			// ))
+			if _, err = g.w.Write("))\n"); err != nil {
+				return err
+			}
+			if err = g.writeErrorHandler(indentLevel); err != nil {
+				return err
+			}
+			// Close quote.
+			if _, err = g.w.WriteIndent(indentLevel, `_, err = io.WriteString(w, "\"")`+"\n"); err != nil {
+				return err
+			}
+			if err = g.writeErrorHandler(indentLevel); err != nil {
+				return err
+			}
+		default:
+			return fmt.Errorf("unknown attribute type %s", reflect.TypeOf(n.Attributes[i]))
+		}
+	}
+	return err
 }
 
 func (g *generator) writeStringExpression(indentLevel int, e templ.Expression) error {
diff --git a/generator/test-void/render_test.go b/generator/test-void/render_test.go
new file mode 100644
index 000000000..5b0350ff7
--- /dev/null
+++ b/generator/test-void/render_test.go
@@ -0,0 +1,22 @@
+package testvoid
+
+import (
+	"context"
+	"strings"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+)
+
+const expected = `<br/><img src="https://example.com/image.png"/><br/><br/>`
+
+func TestRender(t *testing.T) {
+	w := new(strings.Builder)
+	err := render().Render(context.Background(), w)
+	if err != nil {
+		t.Errorf("failed to render: %v", err)
+	}
+	if diff := cmp.Diff(expected, w.String()); diff != "" {
+		t.Error(diff)
+	}
+}
diff --git a/generator/test-void/template.templ b/generator/test-void/template.templ
new file mode 100644
index 000000000..35a255a1b
--- /dev/null
+++ b/generator/test-void/template.templ
@@ -0,0 +1,8 @@
+{% package testvoid %}
+
+{% templ render() %}
+	<br/>
+	<img src="https://example.com/image.png"/>
+	<br/><br/>
+{% endtempl %}
+
diff --git a/generator/test-void/template_templ.go b/generator/test-void/template_templ.go
new file mode 100644
index 000000000..cf90e3712
--- /dev/null
+++ b/generator/test-void/template_templ.go
@@ -0,0 +1,38 @@
+// Code generated by templ DO NOT EDIT.
+
+package testvoid
+
+import "github.com/a-h/templ"
+import "context"
+import "io"
+
+func render() templ.Component {
+	return templ.ComponentFunc(func(ctx context.Context, w io.Writer) (err error) {
+		_, err = io.WriteString(w, "<br/>")
+		if err != nil {
+			return err
+		}
+		_, err = io.WriteString(w, "<img")
+		if err != nil {
+			return err
+		}
+		_, err = io.WriteString(w, " src=\"https://example.com/image.png\"")
+		if err != nil {
+			return err
+		}
+		_, err = io.WriteString(w, "/>")
+		if err != nil {
+			return err
+		}
+		_, err = io.WriteString(w, "<br/>")
+		if err != nil {
+			return err
+		}
+		_, err = io.WriteString(w, "<br/>")
+		if err != nil {
+			return err
+		}
+		return err
+	})
+}
+
diff --git a/types.go b/types.go
index 52e845706..1491e22fb 100644
--- a/types.go
+++ b/types.go
@@ -248,7 +248,7 @@ var voidElements = map[string]struct{}{
 	"area": {}, "base": {}, "br": {}, "col": {}, "command": {}, "embed": {}, "hr": {}, "img": {}, "input": {}, "keygen": {}, "link": {}, "meta": {}, "param": {}, "source": {}, "track": {}, "wbr": {}}
 
 // https://www.w3.org/TR/2011/WD-html-markup-20110113/syntax.html#void-element
-func (e Element) isVoidElement() bool {
+func (e Element) IsVoidElement() bool {
 	_, ok := voidElements[e.Name]
 	return ok
 }
@@ -328,7 +328,7 @@ func (e Element) Write(w io.Writer, indent int) error {
 		}
 		return nil
 	}
-	if e.isVoidElement() {
+	if e.IsVoidElement() {
 		if _, err := w.Write([]byte("/>")); err != nil {
 			return err
 		}