printer: support void elements

printer/nodes.go

@@ -1200,10 +1200,12 @@ func (p *printer) stmtList(list []ast.Stmt, nindent int, nextIsRBrace bool) {
 
 	var (
 		forceNextNewline = false
-		tagOneLine       = make([]bool, 1, 16)
+		tagOneLine       = make([]bool, 1, 32)
 	)
 
-	for j, s := range list {
+	openTagIndent, endTagUnindent, oneline := p.tagIndent(list)
+
+	for _, s := range list {
 		// ignore empty statements (was issue 3466)
 		if _, isEmpty := s.(*ast.EmptyStmt); !isEmpty {
 			// nindent == 0 only for lists of switch/select case clauses;
@@ -1214,21 +1216,30 @@ func (p *printer) stmtList(list []ast.Stmt, nindent int, nextIsRBrace bool) {
 				p.linebreak(p.lineFor(s.Pos()), 1, ignore, i == 0 || nindent == 0 || p.linesFrom(line) > 0)
 			}
 
-			if _, ok := s.(*ast.EndTagStmt); ok {
+			if v, ok := s.(*ast.EndTagStmt); ok {
+				if _, ok := endTagUnindent[v]; ok {
+					p.print(unindent)
+				}
 				forceNextNewline = !tagOneLine[len(tagOneLine)-1]
 				tagOneLine = tagOneLine[:len(tagOneLine)-1]
-				p.print(unindent)
 				if forceNextNewline && p.commentBefore(p.posFor(s.Pos())) {
 					p.linebreak(p.lineFor(s.Pos()), 0, ignore, false)
 				}
-			} else if _, ok := s.(*ast.OpenTagStmt); ok {
+			} else if v, ok := s.(*ast.OpenTagStmt); ok {
 				forceNextNewline = false
-				// TODO(mateusz834): void elements
-				tagOneLine = append(tagOneLine, p.oneLineTag(list[j:]))
+				_, ok := oneline[v]
+				tagOneLine = append(tagOneLine, ok)
 			}
 
 			p.recordLine(&line)
 			p.stmt(s, nextIsRBrace && i == len(list)-1)
+
+			if v, ok := s.(*ast.OpenTagStmt); ok {
+				if _, ok := openTagIndent[v]; ok {
+					p.print(indent)
+				}
+			}
+
 			// labeled statements put labels on a separate line, but here
 			// we only care about the start line of the actual statement
 			// without label - correct line for each label

printer/testdata/tgo/void_elements.formatted

@@ -0,0 +1,63 @@
+package templates
+
+func test() {
+	<div>
+		<br>
+		_ = 3
+	</div>
+}
+
+func test() {
+	<div>
+		<br>
+		<br>
+		_ = 3
+	</div>
+}
+
+func test() {
+	<div>
+		<span>
+		_ = 3
+	</div>
+}
+
+func test() {
+	<div>
+		<span>
+			_ = 3
+		</span>
+	</div>
+}
+
+func test() {
+	<div>
+	<div>
+		_ = 3
+	</div>
+}
+
+func test() {
+	<div>
+		_ = 3
+	</div>
+	</div>
+}
+
+func test() {
+	<div>
+	<div>
+		<div>
+			_ = 3
+		</div>
+	</div>
+}
+
+func test() {
+	<div>
+		<div>
+			_ = 3
+		</div>
+	</div>
+	</div>
+}

printer/testdata/tgo/void_elements.tgo

@@ -0,0 +1,63 @@
+package templates
+
+func test() {
+	<div>
+	<br>
+	_ = 3
+	</div>
+}
+
+func test() {
+	<div>
+	<br>
+	<br>
+	_ = 3
+	</div>
+}
+
+func test() {
+	<div>
+	<span>
+	_ = 3
+	</div>
+}
+
+func test() {
+	<div>
+	<span>
+	_ = 3
+	</span>
+	</div>
+}
+
+func test() {
+	<div>
+	<div>
+	_ = 3
+	</div>
+}
+
+func test() {
+	<div>
+	_ = 3
+	</div>
+	</div>
+}
+
+func test() {
+	<div>
+	<div>
+	<div>
+	_ = 3
+	</div>
+	</div>
+}
+
+func test() {
+	<div>
+	<div>
+	_ = 3
+	</div>
+	</div>
+	</div>
+}

printer/tgo.go

@@ -78,9 +78,6 @@ func (p *printer) opentag(b *ast.OpenTagStmt) {
 	p.tagEndLine = p.lineFor(b.ClosePos)
 	p.print(token.GTR)
 	p.inStartTag = false
-
-	// TODO(nmateusz834): void elements
-	p.print(indent)
 }
 
 func (p *printer) endtag(b *ast.EndTagStmt) {
@@ -142,24 +139,34 @@ func (p *printer) templateLiteralExpr(x *ast.TemplateLiteralExpr) {
 	}
 }
 
-func (p *printer) oneLineTag(list []ast.Stmt) bool {
-	deep := 0
-	startPos := token.NoPos
+func (p *printer) tagIndent(list []ast.Stmt) (indent map[*ast.OpenTagStmt]struct{}, unindent map[*ast.EndTagStmt]struct{}, oneline map[*ast.OpenTagStmt]struct{}) {
+	indent = make(map[*ast.OpenTagStmt]struct{})
+	unindent = make(map[*ast.EndTagStmt]struct{})
+	oneline = make(map[*ast.OpenTagStmt]struct{})
+
+	deep := make([]int, 0, 32)
 	for i, v := range list {
-		if _, ok := v.(*ast.OpenTagStmt); ok {
-			// TODO(mateusz834): void elements
-			deep++
-			startPos = v.Pos()
-		}
-		if _, ok := v.(*ast.EndTagStmt); ok {
-			if deep--; deep == 0 {
-				return p.lineFor(startPos) == p.lineFor(v.End()) &&
-					!p.willHaveNewLine(list[0].(*ast.OpenTagStmt), list[1:i])
+		switch v := v.(type) {
+		case *ast.OpenTagStmt:
+			deep = append(deep, i)
+		case *ast.EndTagStmt:
+			for len(deep) != 0 {
+				openTagIndex := deep[len(deep)-1]
+				openTag := list[openTagIndex].(*ast.OpenTagStmt)
+				deep = deep[:len(deep)-1]
+				if openTag.Name.Name == v.Name.Name {
+					indent[openTag] = struct{}{}
+					unindent[v] = struct{}{}
+					if p.lineFor(openTag.Pos()) == p.lineFor(v.End()) && !p.willHaveNewLine(openTag, list[openTagIndex+1:i]) {
+						oneline[openTag] = struct{}{}
+					}
+					break
+				}
 			}
 		}
 	}
 
-	panic("unreachable")
+	return
 }
 
 func (p *printer) willHaveNewLine(o *ast.OpenTagStmt, list []ast.Stmt) bool {