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Source file src/text/template/parse/node.go

Documentation: text/template/parse

  // Copyright 2011 The Go Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style
  // license that can be found in the LICENSE file.
  
  // Parse nodes.
  
  package parse
  
  import (
  	"bytes"
  	"fmt"
  	"strconv"
  	"strings"
  )
  
  var textFormat = "%s" // Changed to "%q" in tests for better error messages.
  
  // A Node is an element in the parse tree. The interface is trivial.
  // The interface contains an unexported method so that only
  // types local to this package can satisfy it.
  type Node interface {
  	Type() NodeType
  	String() string
  	// Copy does a deep copy of the Node and all its components.
  	// To avoid type assertions, some XxxNodes also have specialized
  	// CopyXxx methods that return *XxxNode.
  	Copy() Node
  	Position() Pos // byte position of start of node in full original input string
  	// tree returns the containing *Tree.
  	// It is unexported so all implementations of Node are in this package.
  	tree() *Tree
  }
  
  // NodeType identifies the type of a parse tree node.
  type NodeType int
  
  // Pos represents a byte position in the original input text from which
  // this template was parsed.
  type Pos int
  
  func (p Pos) Position() Pos {
  	return p
  }
  
  // Type returns itself and provides an easy default implementation
  // for embedding in a Node. Embedded in all non-trivial Nodes.
  func (t NodeType) Type() NodeType {
  	return t
  }
  
  const (
  	NodeText       NodeType = iota // Plain text.
  	NodeAction                     // A non-control action such as a field evaluation.
  	NodeBool                       // A boolean constant.
  	NodeChain                      // A sequence of field accesses.
  	NodeCommand                    // An element of a pipeline.
  	NodeDot                        // The cursor, dot.
  	nodeElse                       // An else action. Not added to tree.
  	nodeEnd                        // An end action. Not added to tree.
  	NodeField                      // A field or method name.
  	NodeIdentifier                 // An identifier; always a function name.
  	NodeIf                         // An if action.
  	NodeList                       // A list of Nodes.
  	NodeNil                        // An untyped nil constant.
  	NodeNumber                     // A numerical constant.
  	NodePipe                       // A pipeline of commands.
  	NodeRange                      // A range action.
  	NodeString                     // A string constant.
  	NodeTemplate                   // A template invocation action.
  	NodeVariable                   // A $ variable.
  	NodeWith                       // A with action.
  )
  
  // Nodes.
  
  // ListNode holds a sequence of nodes.
  type ListNode struct {
  	NodeType
  	Pos
  	tr    *Tree
  	Nodes []Node // The element nodes in lexical order.
  }
  
  func (t *Tree) newList(pos Pos) *ListNode {
  	return &ListNode{tr: t, NodeType: NodeList, Pos: pos}
  }
  
  func (l *ListNode) append(n Node) {
  	l.Nodes = append(l.Nodes, n)
  }
  
  func (l *ListNode) tree() *Tree {
  	return l.tr
  }
  
  func (l *ListNode) String() string {
  	b := new(bytes.Buffer)
  	for _, n := range l.Nodes {
  		fmt.Fprint(b, n)
  	}
  	return b.String()
  }
  
  func (l *ListNode) CopyList() *ListNode {
  	if l == nil {
  		return l
  	}
  	n := l.tr.newList(l.Pos)
  	for _, elem := range l.Nodes {
  		n.append(elem.Copy())
  	}
  	return n
  }
  
  func (l *ListNode) Copy() Node {
  	return l.CopyList()
  }
  
  // TextNode holds plain text.
  type TextNode struct {
  	NodeType
  	Pos
  	tr   *Tree
  	Text []byte // The text; may span newlines.
  }
  
  func (t *Tree) newText(pos Pos, text string) *TextNode {
  	return &TextNode{tr: t, NodeType: NodeText, Pos: pos, Text: []byte(text)}
  }
  
  func (t *TextNode) String() string {
  	return fmt.Sprintf(textFormat, t.Text)
  }
  
  func (t *TextNode) tree() *Tree {
  	return t.tr
  }
  
  func (t *TextNode) Copy() Node {
  	return &TextNode{tr: t.tr, NodeType: NodeText, Pos: t.Pos, Text: append([]byte{}, t.Text...)}
  }
  
  // PipeNode holds a pipeline with optional declaration
  type PipeNode struct {
  	NodeType
  	Pos
  	tr   *Tree
  	Line int             // The line number in the input. Deprecated: Kept for compatibility.
  	Decl []*VariableNode // Variable declarations in lexical order.
  	Cmds []*CommandNode  // The commands in lexical order.
  }
  
  func (t *Tree) newPipeline(pos Pos, line int, decl []*VariableNode) *PipeNode {
  	return &PipeNode{tr: t, NodeType: NodePipe, Pos: pos, Line: line, Decl: decl}
  }
  
  func (p *PipeNode) append(command *CommandNode) {
  	p.Cmds = append(p.Cmds, command)
  }
  
  func (p *PipeNode) String() string {
  	s := ""
  	if len(p.Decl) > 0 {
  		for i, v := range p.Decl {
  			if i > 0 {
  				s += ", "
  			}
  			s += v.String()
  		}
  		s += " := "
  	}
  	for i, c := range p.Cmds {
  		if i > 0 {
  			s += " | "
  		}
  		s += c.String()
  	}
  	return s
  }
  
  func (p *PipeNode) tree() *Tree {
  	return p.tr
  }
  
  func (p *PipeNode) CopyPipe() *PipeNode {
  	if p == nil {
  		return p
  	}
  	var decl []*VariableNode
  	for _, d := range p.Decl {
  		decl = append(decl, d.Copy().(*VariableNode))
  	}
  	n := p.tr.newPipeline(p.Pos, p.Line, decl)
  	for _, c := range p.Cmds {
  		n.append(c.Copy().(*CommandNode))
  	}
  	return n
  }
  
  func (p *PipeNode) Copy() Node {
  	return p.CopyPipe()
  }
  
  // ActionNode holds an action (something bounded by delimiters).
  // Control actions have their own nodes; ActionNode represents simple
  // ones such as field evaluations and parenthesized pipelines.
  type ActionNode struct {
  	NodeType
  	Pos
  	tr   *Tree
  	Line int       // The line number in the input. Deprecated: Kept for compatibility.
  	Pipe *PipeNode // The pipeline in the action.
  }
  
  func (t *Tree) newAction(pos Pos, line int, pipe *PipeNode) *ActionNode {
  	return &ActionNode{tr: t, NodeType: NodeAction, Pos: pos, Line: line, Pipe: pipe}
  }
  
  func (a *ActionNode) String() string {
  	return fmt.Sprintf("{{%s}}", a.Pipe)
  
  }
  
  func (a *ActionNode) tree() *Tree {
  	return a.tr
  }
  
  func (a *ActionNode) Copy() Node {
  	return a.tr.newAction(a.Pos, a.Line, a.Pipe.CopyPipe())
  
  }
  
  // CommandNode holds a command (a pipeline inside an evaluating action).
  type CommandNode struct {
  	NodeType
  	Pos
  	tr   *Tree
  	Args []Node // Arguments in lexical order: Identifier, field, or constant.
  }
  
  func (t *Tree) newCommand(pos Pos) *CommandNode {
  	return &CommandNode{tr: t, NodeType: NodeCommand, Pos: pos}
  }
  
  func (c *CommandNode) append(arg Node) {
  	c.Args = append(c.Args, arg)
  }
  
  func (c *CommandNode) String() string {
  	s := ""
  	for i, arg := range c.Args {
  		if i > 0 {
  			s += " "
  		}
  		if arg, ok := arg.(*PipeNode); ok {
  			s += "(" + arg.String() + ")"
  			continue
  		}
  		s += arg.String()
  	}
  	return s
  }
  
  func (c *CommandNode) tree() *Tree {
  	return c.tr
  }
  
  func (c *CommandNode) Copy() Node {
  	if c == nil {
  		return c
  	}
  	n := c.tr.newCommand(c.Pos)
  	for _, c := range c.Args {
  		n.append(c.Copy())
  	}
  	return n
  }
  
  // IdentifierNode holds an identifier.
  type IdentifierNode struct {
  	NodeType
  	Pos
  	tr    *Tree
  	Ident string // The identifier's name.
  }
  
  // NewIdentifier returns a new IdentifierNode with the given identifier name.
  func NewIdentifier(ident string) *IdentifierNode {
  	return &IdentifierNode{NodeType: NodeIdentifier, Ident: ident}
  }
  
  // SetPos sets the position. NewIdentifier is a public method so we can't modify its signature.
  // Chained for convenience.
  // TODO: fix one day?
  func (i *IdentifierNode) SetPos(pos Pos) *IdentifierNode {
  	i.Pos = pos
  	return i
  }
  
  // SetTree sets the parent tree for the node. NewIdentifier is a public method so we can't modify its signature.
  // Chained for convenience.
  // TODO: fix one day?
  func (i *IdentifierNode) SetTree(t *Tree) *IdentifierNode {
  	i.tr = t
  	return i
  }
  
  func (i *IdentifierNode) String() string {
  	return i.Ident
  }
  
  func (i *IdentifierNode) tree() *Tree {
  	return i.tr
  }
  
  func (i *IdentifierNode) Copy() Node {
  	return NewIdentifier(i.Ident).SetTree(i.tr).SetPos(i.Pos)
  }
  
  // VariableNode holds a list of variable names, possibly with chained field
  // accesses. The dollar sign is part of the (first) name.
  type VariableNode struct {
  	NodeType
  	Pos
  	tr    *Tree
  	Ident []string // Variable name and fields in lexical order.
  }
  
  func (t *Tree) newVariable(pos Pos, ident string) *VariableNode {
  	return &VariableNode{tr: t, NodeType: NodeVariable, Pos: pos, Ident: strings.Split(ident, ".")}
  }
  
  func (v *VariableNode) String() string {
  	s := ""
  	for i, id := range v.Ident {
  		if i > 0 {
  			s += "."
  		}
  		s += id
  	}
  	return s
  }
  
  func (v *VariableNode) tree() *Tree {
  	return v.tr
  }
  
  func (v *VariableNode) Copy() Node {
  	return &VariableNode{tr: v.tr, NodeType: NodeVariable, Pos: v.Pos, Ident: append([]string{}, v.Ident...)}
  }
  
  // DotNode holds the special identifier '.'.
  type DotNode struct {
  	NodeType
  	Pos
  	tr *Tree
  }
  
  func (t *Tree) newDot(pos Pos) *DotNode {
  	return &DotNode{tr: t, NodeType: NodeDot, Pos: pos}
  }
  
  func (d *DotNode) Type() NodeType {
  	// Override method on embedded NodeType for API compatibility.
  	// TODO: Not really a problem; could change API without effect but
  	// api tool complains.
  	return NodeDot
  }
  
  func (d *DotNode) String() string {
  	return "."
  }
  
  func (d *DotNode) tree() *Tree {
  	return d.tr
  }
  
  func (d *DotNode) Copy() Node {
  	return d.tr.newDot(d.Pos)
  }
  
  // NilNode holds the special identifier 'nil' representing an untyped nil constant.
  type NilNode struct {
  	NodeType
  	Pos
  	tr *Tree
  }
  
  func (t *Tree) newNil(pos Pos) *NilNode {
  	return &NilNode{tr: t, NodeType: NodeNil, Pos: pos}
  }
  
  func (n *NilNode) Type() NodeType {
  	// Override method on embedded NodeType for API compatibility.
  	// TODO: Not really a problem; could change API without effect but
  	// api tool complains.
  	return NodeNil
  }
  
  func (n *NilNode) String() string {
  	return "nil"
  }
  
  func (n *NilNode) tree() *Tree {
  	return n.tr
  }
  
  func (n *NilNode) Copy() Node {
  	return n.tr.newNil(n.Pos)
  }
  
  // FieldNode holds a field (identifier starting with '.').
  // The names may be chained ('.x.y').
  // The period is dropped from each ident.
  type FieldNode struct {
  	NodeType
  	Pos
  	tr    *Tree
  	Ident []string // The identifiers in lexical order.
  }
  
  func (t *Tree) newField(pos Pos, ident string) *FieldNode {
  	return &FieldNode{tr: t, NodeType: NodeField, Pos: pos, Ident: strings.Split(ident[1:], ".")} // [1:] to drop leading period
  }
  
  func (f *FieldNode) String() string {
  	s := ""
  	for _, id := range f.Ident {
  		s += "." + id
  	}
  	return s
  }
  
  func (f *FieldNode) tree() *Tree {
  	return f.tr
  }
  
  func (f *FieldNode) Copy() Node {
  	return &FieldNode{tr: f.tr, NodeType: NodeField, Pos: f.Pos, Ident: append([]string{}, f.Ident...)}
  }
  
  // ChainNode holds a term followed by a chain of field accesses (identifier starting with '.').
  // The names may be chained ('.x.y').
  // The periods are dropped from each ident.
  type ChainNode struct {
  	NodeType
  	Pos
  	tr    *Tree
  	Node  Node
  	Field []string // The identifiers in lexical order.
  }
  
  func (t *Tree) newChain(pos Pos, node Node) *ChainNode {
  	return &ChainNode{tr: t, NodeType: NodeChain, Pos: pos, Node: node}
  }
  
  // Add adds the named field (which should start with a period) to the end of the chain.
  func (c *ChainNode) Add(field string) {
  	if len(field) == 0 || field[0] != '.' {
  		panic("no dot in field")
  	}
  	field = field[1:] // Remove leading dot.
  	if field == "" {
  		panic("empty field")
  	}
  	c.Field = append(c.Field, field)
  }
  
  func (c *ChainNode) String() string {
  	s := c.Node.String()
  	if _, ok := c.Node.(*PipeNode); ok {
  		s = "(" + s + ")"
  	}
  	for _, field := range c.Field {
  		s += "." + field
  	}
  	return s
  }
  
  func (c *ChainNode) tree() *Tree {
  	return c.tr
  }
  
  func (c *ChainNode) Copy() Node {
  	return &ChainNode{tr: c.tr, NodeType: NodeChain, Pos: c.Pos, Node: c.Node, Field: append([]string{}, c.Field...)}
  }
  
  // BoolNode holds a boolean constant.
  type BoolNode struct {
  	NodeType
  	Pos
  	tr   *Tree
  	True bool // The value of the boolean constant.
  }
  
  func (t *Tree) newBool(pos Pos, true bool) *BoolNode {
  	return &BoolNode{tr: t, NodeType: NodeBool, Pos: pos, True: true}
  }
  
  func (b *BoolNode) String() string {
  	if b.True {
  		return "true"
  	}
  	return "false"
  }
  
  func (b *BoolNode) tree() *Tree {
  	return b.tr
  }
  
  func (b *BoolNode) Copy() Node {
  	return b.tr.newBool(b.Pos, b.True)
  }
  
  // NumberNode holds a number: signed or unsigned integer, float, or complex.
  // The value is parsed and stored under all the types that can represent the value.
  // This simulates in a small amount of code the behavior of Go's ideal constants.
  type NumberNode struct {
  	NodeType
  	Pos
  	tr         *Tree
  	IsInt      bool       // Number has an integral value.
  	IsUint     bool       // Number has an unsigned integral value.
  	IsFloat    bool       // Number has a floating-point value.
  	IsComplex  bool       // Number is complex.
  	Int64      int64      // The signed integer value.
  	Uint64     uint64     // The unsigned integer value.
  	Float64    float64    // The floating-point value.
  	Complex128 complex128 // The complex value.
  	Text       string     // The original textual representation from the input.
  }
  
  func (t *Tree) newNumber(pos Pos, text string, typ itemType) (*NumberNode, error) {
  	n := &NumberNode{tr: t, NodeType: NodeNumber, Pos: pos, Text: text}
  	switch typ {
  	case itemCharConstant:
  		rune, _, tail, err := strconv.UnquoteChar(text[1:], text[0])
  		if err != nil {
  			return nil, err
  		}
  		if tail != "'" {
  			return nil, fmt.Errorf("malformed character constant: %s", text)
  		}
  		n.Int64 = int64(rune)
  		n.IsInt = true
  		n.Uint64 = uint64(rune)
  		n.IsUint = true
  		n.Float64 = float64(rune) // odd but those are the rules.
  		n.IsFloat = true
  		return n, nil
  	case itemComplex:
  		// fmt.Sscan can parse the pair, so let it do the work.
  		if _, err := fmt.Sscan(text, &n.Complex128); err != nil {
  			return nil, err
  		}
  		n.IsComplex = true
  		n.simplifyComplex()
  		return n, nil
  	}
  	// Imaginary constants can only be complex unless they are zero.
  	if len(text) > 0 && text[len(text)-1] == 'i' {
  		f, err := strconv.ParseFloat(text[:len(text)-1], 64)
  		if err == nil {
  			n.IsComplex = true
  			n.Complex128 = complex(0, f)
  			n.simplifyComplex()
  			return n, nil
  		}
  	}
  	// Do integer test first so we get 0x123 etc.
  	u, err := strconv.ParseUint(text, 0, 64) // will fail for -0; fixed below.
  	if err == nil {
  		n.IsUint = true
  		n.Uint64 = u
  	}
  	i, err := strconv.ParseInt(text, 0, 64)
  	if err == nil {
  		n.IsInt = true
  		n.Int64 = i
  		if i == 0 {
  			n.IsUint = true // in case of -0.
  			n.Uint64 = u
  		}
  	}
  	// If an integer extraction succeeded, promote the float.
  	if n.IsInt {
  		n.IsFloat = true
  		n.Float64 = float64(n.Int64)
  	} else if n.IsUint {
  		n.IsFloat = true
  		n.Float64 = float64(n.Uint64)
  	} else {
  		f, err := strconv.ParseFloat(text, 64)
  		if err == nil {
  			// If we parsed it as a float but it looks like an integer,
  			// it's a huge number too large to fit in an int. Reject it.
  			if !strings.ContainsAny(text, ".eE") {
  				return nil, fmt.Errorf("integer overflow: %q", text)
  			}
  			n.IsFloat = true
  			n.Float64 = f
  			// If a floating-point extraction succeeded, extract the int if needed.
  			if !n.IsInt && float64(int64(f)) == f {
  				n.IsInt = true
  				n.Int64 = int64(f)
  			}
  			if !n.IsUint && float64(uint64(f)) == f {
  				n.IsUint = true
  				n.Uint64 = uint64(f)
  			}
  		}
  	}
  	if !n.IsInt && !n.IsUint && !n.IsFloat {
  		return nil, fmt.Errorf("illegal number syntax: %q", text)
  	}
  	return n, nil
  }
  
  // simplifyComplex pulls out any other types that are represented by the complex number.
  // These all require that the imaginary part be zero.
  func (n *NumberNode) simplifyComplex() {
  	n.IsFloat = imag(n.Complex128) == 0
  	if n.IsFloat {
  		n.Float64 = real(n.Complex128)
  		n.IsInt = float64(int64(n.Float64)) == n.Float64
  		if n.IsInt {
  			n.Int64 = int64(n.Float64)
  		}
  		n.IsUint = float64(uint64(n.Float64)) == n.Float64
  		if n.IsUint {
  			n.Uint64 = uint64(n.Float64)
  		}
  	}
  }
  
  func (n *NumberNode) String() string {
  	return n.Text
  }
  
  func (n *NumberNode) tree() *Tree {
  	return n.tr
  }
  
  func (n *NumberNode) Copy() Node {
  	nn := new(NumberNode)
  	*nn = *n // Easy, fast, correct.
  	return nn
  }
  
  // StringNode holds a string constant. The value has been "unquoted".
  type StringNode struct {
  	NodeType
  	Pos
  	tr     *Tree
  	Quoted string // The original text of the string, with quotes.
  	Text   string // The string, after quote processing.
  }
  
  func (t *Tree) newString(pos Pos, orig, text string) *StringNode {
  	return &StringNode{tr: t, NodeType: NodeString, Pos: pos, Quoted: orig, Text: text}
  }
  
  func (s *StringNode) String() string {
  	return s.Quoted
  }
  
  func (s *StringNode) tree() *Tree {
  	return s.tr
  }
  
  func (s *StringNode) Copy() Node {
  	return s.tr.newString(s.Pos, s.Quoted, s.Text)
  }
  
  // endNode represents an {{end}} action.
  // It does not appear in the final parse tree.
  type endNode struct {
  	NodeType
  	Pos
  	tr *Tree
  }
  
  func (t *Tree) newEnd(pos Pos) *endNode {
  	return &endNode{tr: t, NodeType: nodeEnd, Pos: pos}
  }
  
  func (e *endNode) String() string {
  	return "{{end}}"
  }
  
  func (e *endNode) tree() *Tree {
  	return e.tr
  }
  
  func (e *endNode) Copy() Node {
  	return e.tr.newEnd(e.Pos)
  }
  
  // elseNode represents an {{else}} action. Does not appear in the final tree.
  type elseNode struct {
  	NodeType
  	Pos
  	tr   *Tree
  	Line int // The line number in the input. Deprecated: Kept for compatibility.
  }
  
  func (t *Tree) newElse(pos Pos, line int) *elseNode {
  	return &elseNode{tr: t, NodeType: nodeElse, Pos: pos, Line: line}
  }
  
  func (e *elseNode) Type() NodeType {
  	return nodeElse
  }
  
  func (e *elseNode) String() string {
  	return "{{else}}"
  }
  
  func (e *elseNode) tree() *Tree {
  	return e.tr
  }
  
  func (e *elseNode) Copy() Node {
  	return e.tr.newElse(e.Pos, e.Line)
  }
  
  // BranchNode is the common representation of if, range, and with.
  type BranchNode struct {
  	NodeType
  	Pos
  	tr       *Tree
  	Line     int       // The line number in the input. Deprecated: Kept for compatibility.
  	Pipe     *PipeNode // The pipeline to be evaluated.
  	List     *ListNode // What to execute if the value is non-empty.
  	ElseList *ListNode // What to execute if the value is empty (nil if absent).
  }
  
  func (b *BranchNode) String() string {
  	name := ""
  	switch b.NodeType {
  	case NodeIf:
  		name = "if"
  	case NodeRange:
  		name = "range"
  	case NodeWith:
  		name = "with"
  	default:
  		panic("unknown branch type")
  	}
  	if b.ElseList != nil {
  		return fmt.Sprintf("{{%s %s}}%s{{else}}%s{{end}}", name, b.Pipe, b.List, b.ElseList)
  	}
  	return fmt.Sprintf("{{%s %s}}%s{{end}}", name, b.Pipe, b.List)
  }
  
  func (b *BranchNode) tree() *Tree {
  	return b.tr
  }
  
  func (b *BranchNode) Copy() Node {
  	switch b.NodeType {
  	case NodeIf:
  		return b.tr.newIf(b.Pos, b.Line, b.Pipe, b.List, b.ElseList)
  	case NodeRange:
  		return b.tr.newRange(b.Pos, b.Line, b.Pipe, b.List, b.ElseList)
  	case NodeWith:
  		return b.tr.newWith(b.Pos, b.Line, b.Pipe, b.List, b.ElseList)
  	default:
  		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 {
  	return i.tr.newIf(i.Pos, i.Line, i.Pipe.CopyPipe(), i.List.CopyList(), i.ElseList.CopyList())
  }
  
  // RangeNode represents a {{range}} action and its commands.
  type RangeNode struct {
  	BranchNode
  }
  
  func (t *Tree) newRange(pos Pos, line int, pipe *PipeNode, list, elseList *ListNode) *RangeNode {
  	return &RangeNode{BranchNode{tr: t, NodeType: NodeRange, Pos: pos, Line: line, Pipe: pipe, List: list, ElseList: elseList}}
  }
  
  func (r *RangeNode) Copy() Node {
  	return r.tr.newRange(r.Pos, r.Line, r.Pipe.CopyPipe(), r.List.CopyList(), r.ElseList.CopyList())
  }
  
  // WithNode represents a {{with}} action and its commands.
  type WithNode struct {
  	BranchNode
  }
  
  func (t *Tree) newWith(pos Pos, line int, pipe *PipeNode, list, elseList *ListNode) *WithNode {
  	return &WithNode{BranchNode{tr: t, NodeType: NodeWith, Pos: pos, Line: line, Pipe: pipe, List: list, ElseList: elseList}}
  }
  
  func (w *WithNode) Copy() Node {
  	return w.tr.newWith(w.Pos, w.Line, w.Pipe.CopyPipe(), w.List.CopyList(), w.ElseList.CopyList())
  }
  
  // TemplateNode represents a {{template}} action.
  type TemplateNode struct {
  	NodeType
  	Pos
  	tr   *Tree
  	Line int       // The line number in the input. Deprecated: Kept for compatibility.
  	Name string    // The name of the template (unquoted).
  	Pipe *PipeNode // The command to evaluate as dot for the template.
  }
  
  func (t *Tree) newTemplate(pos Pos, line int, name string, pipe *PipeNode) *TemplateNode {
  	return &TemplateNode{tr: t, NodeType: NodeTemplate, Pos: pos, Line: line, Name: name, Pipe: pipe}
  }
  
  func (t *TemplateNode) String() string {
  	if t.Pipe == nil {
  		return fmt.Sprintf("{{template %q}}", t.Name)
  	}
  	return fmt.Sprintf("{{template %q %s}}", t.Name, t.Pipe)
  }
  
  func (t *TemplateNode) tree() *Tree {
  	return t.tr
  }
  
  func (t *TemplateNode) Copy() Node {
  	return t.tr.newTemplate(t.Pos, t.Line, t.Name, t.Pipe.CopyPipe())
  }
  

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