// That's all we need when looking for well-known params.
		firstIdentifier := n.(*parse.FieldNode).Ident[0]
		out.Insert(firstIdentifier)
	case parse.NodeIf:
		out.Merge(getParams(n.(*parse.IfNode).Pipe))
	case parse.NodeWith:
		out.Merge(getParams(n.(*parse.WithNode).Pipe))
	case parse.NodeRange:
		out.Merge(getParams(n.(*parse.RangeNode).Pipe))
	case parse.NodeAction:

		panic("unknown branch type")
	}
}

// IfNode represents an {{if}} action and its commands.
type IfNode struct {
	BranchNode
}

func (t *Tree) newIf(pos Pos, line int, pipe *PipeNode, list, elseList *ListNode) *IfNode {
	return &IfNode{BranchNode{tr: t, NodeType: NodeIf, Pos: pos, Line: line, Pipe: pipe, List: list, ElseList: elseList}}
}

func (i *IfNode) Copy() Node {

func IsEmptyTree(n Node) bool {
	switch n := n.(type) {
	case nil:
		return true
	case *ActionNode:
	case *CommentNode:
		return true
	case *IfNode:
	case *ListNode:
		for _, node := range n.Nodes {
			if !IsEmptyTree(node) {
				return false
			}
		}
		return true
	case *RangeNode:
	case *TemplateNode:
	case *TextNode:

	case *parse.CommentNode:
		return c
	case *parse.ContinueNode:
		c.n = n
		e.rangeContext.continues = append(e.rangeContext.breaks, c)
		return context{state: stateDead}
	case *parse.IfNode:
		return e.escapeBranch(c, &n.BranchNode, "if")
	case *parse.ListNode:
		return e.escapeList(c, n)
	case *parse.RangeNode:
		return e.escapeBranch(c, &n.BranchNode, "range")
	case *parse.TemplateNode:

		if len(node.Pipe.Decl) == 0 {
			s.printValue(node, val)
		}
	case *parse.BreakNode:
		panic(walkBreak)
	case *parse.CommentNode:
	case *parse.ContinueNode:
		panic(walkContinue)
	case *parse.IfNode:
		s.walkIfOrWith(parse.NodeIf, dot, node.Pipe, node.List, node.ElseList)
	case *parse.ListNode:
		for _, node := range node.Nodes {
			s.walk(dot, node)
		}
	case *parse.RangeNode:
		s.walkRange(dot, node)

		{"(*IdentifierNode).Copy", Method, 0},
		{"(*IdentifierNode).SetPos", Method, 1},
		{"(*IdentifierNode).SetTree", Method, 4},
		{"(*IdentifierNode).String", Method, 0},
		{"(*IfNode).Copy", Method, 0},
		{"(*IfNode).String", Method, 0},
		{"(*ListNode).Copy", Method, 0},
		{"(*ListNode).CopyList", Method, 0},
		{"(*ListNode).String", Method, 0},
		{"(*NilNode).Copy", Method, 1},

	if v := unsafe.Sizeof(si); v != 128 {
		t.Fatalf("sizeof: got %d, want 128", v)
	}

	ofSigno := 0
	ofErrno := 4
	ofCode := 8
	if strings.HasPrefix(runtime.GOARCH, "mips") {
		// These two fields are swapped on MIPS platforms.
		ofErrno, ofCode = ofCode, ofErrno
	}
	ofPid := 12
	if host64bit {
		ofPid = 16
	}
	ofUid := ofPid + 4
	ofStatus := ofPid + 8

	offsets := []struct {

func lfnodeValidate(node *lfnode) {
	if base, _, _ := findObject(uintptr(unsafe.Pointer(node)), 0, 0); base != 0 {
		throw("lfstack node allocated from the heap")
	}
	if lfstackUnpack(lfstackPack(node, ^uintptr(0))) != node {
		printlock()
		println("runtime: bad lfnode address", hex(uintptr(unsafe.Pointer(node))))
		throw("bad lfnode address")
	}
}

func lfstackPack(node *lfnode, cnt uintptr) uint64 {

	return (*LFNode)(unsafe.Pointer(node))
}

func toMyNode(node *LFNode) *MyNode {
	return (*MyNode)(unsafe.Pointer(node))
}

var global any

func TestLFStack(t *testing.T) {
	stack := new(uint64)
	global = stack // force heap allocation

	// Check the stack is initially empty.
	if LFStackPop(stack) != nil {
		t.Fatalf("stack is not empty")
	}

	// Push one element.

		valid := true
		switch mode := finfo.flags & fMode; mode {
		case 0:
			finfo.flags |= fElement
		case fAttr, fCDATA, fCharData, fInnerXML, fComment, fAny, fAny | fAttr:
			if f.Name == xmlName || tag != "" && mode != fAttr {
				valid = false
			}
		default:
			// This will also catch multiple modes in a single field.
			valid = false
		}
		if finfo.flags&fMode == fAny {
			finfo.flags |= fElement
		}