switch glide to govendor (#43)

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>

vendor/github.com/aymerick/raymond/ast/node.go

@@ -0,0 +1,785 @@
+// Package ast provides structures to represent a handlebars Abstract Syntax Tree, and a Visitor interface to visit that tree.
+package ast
+
+import (
+	"fmt"
+	"strconv"
+)
+
+// References:
+//   - https://github.com/wycats/handlebars.js/blob/master/lib/handlebars/compiler/ast.js
+//   - https://github.com/wycats/handlebars.js/blob/master/docs/compiler-api.md
+//   - https://github.com/golang/go/blob/master/src/text/template/parse/node.go
+
+// Node is an element in the AST.
+type Node interface {
+	// node type
+	Type() NodeType
+
+	// location of node in original input string
+	Location() Loc
+
+	// string representation, used for debugging
+	String() string
+
+	// accepts visitor
+	Accept(Visitor) interface{}
+}
+
+// Visitor is the interface to visit an AST.
+type Visitor interface {
+	VisitProgram(*Program) interface{}
+
+	// statements
+	VisitMustache(*MustacheStatement) interface{}
+	VisitBlock(*BlockStatement) interface{}
+	VisitPartial(*PartialStatement) interface{}
+	VisitContent(*ContentStatement) interface{}
+	VisitComment(*CommentStatement) interface{}
+
+	// expressions
+	VisitExpression(*Expression) interface{}
+	VisitSubExpression(*SubExpression) interface{}
+	VisitPath(*PathExpression) interface{}
+
+	// literals
+	VisitString(*StringLiteral) interface{}
+	VisitBoolean(*BooleanLiteral) interface{}
+	VisitNumber(*NumberLiteral) interface{}
+
+	// miscellaneous
+	VisitHash(*Hash) interface{}
+	VisitHashPair(*HashPair) interface{}
+}
+
+// NodeType represents an AST Node type.
+type NodeType int
+
+// Type returns itself, and permits struct includers to satisfy that part of Node interface.
+func (t NodeType) Type() NodeType {
+	return t
+}
+
+const (
+	// NodeProgram is the program node
+	NodeProgram NodeType = iota
+
+	// NodeMustache is the mustache statement node
+	NodeMustache
+
+	// NodeBlock is the block statement node
+	NodeBlock
+
+	// NodePartial is the partial statement node
+	NodePartial
+
+	// NodeContent is the content statement node
+	NodeContent
+
+	// NodeComment is the comment statement node
+	NodeComment
+
+	// NodeExpression is the expression node
+	NodeExpression
+
+	// NodeSubExpression is the subexpression node
+	NodeSubExpression
+
+	// NodePath is the expression path node
+	NodePath
+
+	// NodeBoolean is the literal boolean node
+	NodeBoolean
+
+	// NodeNumber is the literal number node
+	NodeNumber
+
+	// NodeString is the literal string node
+	NodeString
+
+	// NodeHash is the hash node
+	NodeHash
+
+	// NodeHashPair is the hash pair node
+	NodeHashPair
+)
+
+// Loc represents the position of a parsed node in source file.
+type Loc struct {
+	Pos  int // Byte position
+	Line int // Line number
+}
+
+// Location returns itself, and permits struct includers to satisfy that part of Node interface.
+func (l Loc) Location() Loc {
+	return l
+}
+
+// Strip describes node whitespace management.
+type Strip struct {
+	Open  bool
+	Close bool
+
+	OpenStandalone   bool
+	CloseStandalone  bool
+	InlineStandalone bool
+}
+
+// NewStrip instanciates a Strip for given open and close mustaches.
+func NewStrip(openStr, closeStr string) *Strip {
+	return &Strip{
+		Open:  (len(openStr) > 2) && openStr[2] == '~',
+		Close: (len(closeStr) > 2) && closeStr[len(closeStr)-3] == '~',
+	}
+}
+
+// NewStripForStr instanciates a Strip for given tag.
+func NewStripForStr(str string) *Strip {
+	return &Strip{
+		Open:  (len(str) > 2) && str[2] == '~',
+		Close: (len(str) > 2) && str[len(str)-3] == '~',
+	}
+}
+
+// String returns a string representation of receiver that can be used for debugging.
+func (s *Strip) String() string {
+	return fmt.Sprintf("Open: %t, Close: %t, OpenStandalone: %t, CloseStandalone: %t, InlineStandalone: %t", s.Open, s.Close, s.OpenStandalone, s.CloseStandalone, s.InlineStandalone)
+}
+
+//
+// Program
+//
+
+// Program represents a program node.
+type Program struct {
+	NodeType
+	Loc
+
+	Body        []Node // [ Statement ... ]
+	BlockParams []string
+	Chained     bool
+
+	// whitespace management
+	Strip *Strip
+}
+
+// NewProgram instanciates a new program node.
+func NewProgram(pos int, line int) *Program {
+	return &Program{
+		NodeType: NodeProgram,
+		Loc:      Loc{pos, line},
+	}
+}
+
+// String returns a string representation of receiver that can be used for debugging.
+func (node *Program) String() string {
+	return fmt.Sprintf("Program{Pos: %d}", node.Loc.Pos)
+}
+
+// Accept is the receiver entry point for visitors.
+func (node *Program) Accept(visitor Visitor) interface{} {
+	return visitor.VisitProgram(node)
+}
+
+// AddStatement adds given statement to program.
+func (node *Program) AddStatement(statement Node) {
+	node.Body = append(node.Body, statement)
+}
+
+//
+// Mustache Statement
+//
+
+// MustacheStatement represents a mustache node.
+type MustacheStatement struct {
+	NodeType
+	Loc
+
+	Unescaped  bool
+	Expression *Expression
+
+	// whitespace management
+	Strip *Strip
+}
+
+// NewMustacheStatement instanciates a new mustache node.
+func NewMustacheStatement(pos int, line int, unescaped bool) *MustacheStatement {
+	return &MustacheStatement{
+		NodeType:  NodeMustache,
+		Loc:       Loc{pos, line},
+		Unescaped: unescaped,
+	}
+}
+
+// String returns a string representation of receiver that can be used for debugging.
+func (node *MustacheStatement) String() string {
+	return fmt.Sprintf("Mustache{Pos: %d}", node.Loc.Pos)
+}
+
+// Accept is the receiver entry point for visitors.
+func (node *MustacheStatement) Accept(visitor Visitor) interface{} {
+	return visitor.VisitMustache(node)
+}
+
+//
+// Block Statement
+//
+
+// BlockStatement represents a block node.
+type BlockStatement struct {
+	NodeType
+	Loc
+
+	Expression *Expression
+
+	Program *Program
+	Inverse *Program
+
+	// whitespace management
+	OpenStrip    *Strip
+	InverseStrip *Strip
+	CloseStrip   *Strip
+}
+
+// NewBlockStatement instanciates a new block node.
+func NewBlockStatement(pos int, line int) *BlockStatement {
+	return &BlockStatement{
+		NodeType: NodeBlock,
+		Loc:      Loc{pos, line},
+	}
+}
+
+// String returns a string representation of receiver that can be used for debugging.
+func (node *BlockStatement) String() string {
+	return fmt.Sprintf("Block{Pos: %d}", node.Loc.Pos)
+}
+
+// Accept is the receiver entry point for visitors.
+func (node *BlockStatement) Accept(visitor Visitor) interface{} {
+	return visitor.VisitBlock(node)
+}
+
+//
+// Partial Statement
+//
+
+// PartialStatement represents a partial node.
+type PartialStatement struct {
+	NodeType
+	Loc
+
+	Name   Node   // PathExpression | SubExpression
+	Params []Node // [ Expression ... ]
+	Hash   *Hash
+
+	// whitespace management
+	Strip  *Strip
+	Indent string
+}
+
+// NewPartialStatement instanciates a new partial node.
+func NewPartialStatement(pos int, line int) *PartialStatement {
+	return &PartialStatement{
+		NodeType: NodePartial,
+		Loc:      Loc{pos, line},
+	}
+}
+
+// String returns a string representation of receiver that can be used for debugging.
+func (node *PartialStatement) String() string {
+	return fmt.Sprintf("Partial{Name:%s, Pos:%d}", node.Name, node.Loc.Pos)
+}
+
+// Accept is the receiver entry point for visitors.
+func (node *PartialStatement) Accept(visitor Visitor) interface{} {
+	return visitor.VisitPartial(node)
+}
+
+//
+// Content Statement
+//
+
+// ContentStatement represents a content node.
+type ContentStatement struct {
+	NodeType
+	Loc
+
+	Value    string
+	Original string
+
+	// whitespace management
+	RightStripped bool
+	LeftStripped  bool
+}
+
+// NewContentStatement instanciates a new content node.
+func NewContentStatement(pos int, line int, val string) *ContentStatement {
+	return &ContentStatement{
+		NodeType: NodeContent,
+		Loc:      Loc{pos, line},
+
+		Value:    val,
+		Original: val,
+	}
+}
+
+// String returns a string representation of receiver that can be used for debugging.
+func (node *ContentStatement) String() string {
+	return fmt.Sprintf("Content{Value:'%s', Pos:%d}", node.Value, node.Loc.Pos)
+}
+
+// Accept is the receiver entry point for visitors.
+func (node *ContentStatement) Accept(visitor Visitor) interface{} {
+	return visitor.VisitContent(node)
+}
+
+//
+// Comment Statement
+//
+
+// CommentStatement represents a comment node.
+type CommentStatement struct {
+	NodeType
+	Loc
+
+	Value string
+
+	// whitespace management
+	Strip *Strip
+}
+
+// NewCommentStatement instanciates a new comment node.
+func NewCommentStatement(pos int, line int, val string) *CommentStatement {
+	return &CommentStatement{
+		NodeType: NodeComment,
+		Loc:      Loc{pos, line},
+
+		Value: val,
+	}
+}
+
+// String returns a string representation of receiver that can be used for debugging.
+func (node *CommentStatement) String() string {
+	return fmt.Sprintf("Comment{Value:'%s', Pos:%d}", node.Value, node.Loc.Pos)
+}
+
+// Accept is the receiver entry point for visitors.
+func (node *CommentStatement) Accept(visitor Visitor) interface{} {
+	return visitor.VisitComment(node)
+}
+
+//
+// Expression
+//
+
+// Expression represents an expression node.
+type Expression struct {
+	NodeType
+	Loc
+
+	Path   Node   // PathExpression | StringLiteral | BooleanLiteral | NumberLiteral
+	Params []Node // [ Expression ... ]
+	Hash   *Hash
+}
+
+// NewExpression instanciates a new expression node.
+func NewExpression(pos int, line int) *Expression {
+	return &Expression{
+		NodeType: NodeExpression,
+		Loc:      Loc{pos, line},
+	}
+}
+
+// String returns a string representation of receiver that can be used for debugging.
+func (node *Expression) String() string {
+	return fmt.Sprintf("Expr{Path:%s, Pos:%d}", node.Path, node.Loc.Pos)
+}
+
+// Accept is the receiver entry point for visitors.
+func (node *Expression) Accept(visitor Visitor) interface{} {
+	return visitor.VisitExpression(node)
+}
+
+// HelperName returns helper name, or an empty string if this expression can't be a helper.
+func (node *Expression) HelperName() string {
+	path, ok := node.Path.(*PathExpression)
+	if !ok {
+		return ""
+	}
+
+	if path.Data || (len(path.Parts) != 1) || (path.Depth > 0) || path.Scoped {
+		return ""
+	}
+
+	return path.Parts[0]
+}
+
+// FieldPath returns path expression representing a field path, or nil if this is not a field path.
+func (node *Expression) FieldPath() *PathExpression {
+	path, ok := node.Path.(*PathExpression)
+	if !ok {
+		return nil
+	}
+
+	return path
+}
+
+// LiteralStr returns the string representation of literal value, with a boolean set to false if this is not a literal.
+func (node *Expression) LiteralStr() (string, bool) {
+	return LiteralStr(node.Path)
+}
+
+// Canonical returns the canonical form of expression node as a string.
+func (node *Expression) Canonical() string {
+	if str, ok := HelperNameStr(node.Path); ok {
+		return str
+	}
+
+	return ""
+}
+
+// HelperNameStr returns the string representation of a helper name, with a boolean set to false if this is not a valid helper name.
+//
+// helperName : path | dataName | STRING | NUMBER | BOOLEAN | UNDEFINED | NULL
+func HelperNameStr(node Node) (string, bool) {
+	// PathExpression
+	if str, ok := PathExpressionStr(node); ok {
+		return str, ok
+	}
+
+	// Literal
+	if str, ok := LiteralStr(node); ok {
+		return str, ok
+	}
+
+	return "", false
+}
+
+// PathExpressionStr returns the string representation of path expression value, with a boolean set to false if this is not a path expression.
+func PathExpressionStr(node Node) (string, bool) {
+	if path, ok := node.(*PathExpression); ok {
+		result := path.Original
+
+		// "[foo bar]"" => "foo bar"
+		if (len(result) >= 2) && (result[0] == '[') && (result[len(result)-1] == ']') {
+			result = result[1 : len(result)-1]
+		}
+
+		return result, true
+	}
+
+	return "", false
+}
+
+// LiteralStr returns the string representation of literal value, with a boolean set to false if this is not a literal.
+func LiteralStr(node Node) (string, bool) {
+	if lit, ok := node.(*StringLiteral); ok {
+		return lit.Value, true
+	}
+
+	if lit, ok := node.(*BooleanLiteral); ok {
+		return lit.Canonical(), true
+	}
+
+	if lit, ok := node.(*NumberLiteral); ok {
+		return lit.Canonical(), true
+	}
+
+	return "", false
+}
+
+//
+// SubExpression
+//
+
+// SubExpression represents a subexpression node.
+type SubExpression struct {
+	NodeType
+	Loc
+
+	Expression *Expression
+}
+
+// NewSubExpression instanciates a new subexpression node.
+func NewSubExpression(pos int, line int) *SubExpression {
+	return &SubExpression{
+		NodeType: NodeSubExpression,
+		Loc:      Loc{pos, line},
+	}
+}
+
+// String returns a string representation of receiver that can be used for debugging.
+func (node *SubExpression) String() string {
+	return fmt.Sprintf("Sexp{Path:%s, Pos:%d}", node.Expression.Path, node.Loc.Pos)
+}
+
+// Accept is the receiver entry point for visitors.
+func (node *SubExpression) Accept(visitor Visitor) interface{} {
+	return visitor.VisitSubExpression(node)
+}
+
+//
+// Path Expression
+//
+
+// PathExpression represents a path expression node.
+type PathExpression struct {
+	NodeType
+	Loc
+
+	Original string
+	Depth    int
+	Parts    []string
+	Data     bool
+	Scoped   bool
+}
+
+// NewPathExpression instanciates a new path expression node.
+func NewPathExpression(pos int, line int, data bool) *PathExpression {
+	result := &PathExpression{
+		NodeType: NodePath,
+		Loc:      Loc{pos, line},
+
+		Data: data,
+	}
+
+	if data {
+		result.Original = "@"
+	}
+
+	return result
+}
+
+// String returns a string representation of receiver that can be used for debugging.
+func (node *PathExpression) String() string {
+	return fmt.Sprintf("Path{Original:'%s', Pos:%d}", node.Original, node.Loc.Pos)
+}
+
+// Accept is the receiver entry point for visitors.
+func (node *PathExpression) Accept(visitor Visitor) interface{} {
+	return visitor.VisitPath(node)
+}
+
+// Part adds path part.
+func (node *PathExpression) Part(part string) {
+	node.Original += part
+
+	switch part {
+	case "..":
+		node.Depth++
+		node.Scoped = true
+	case ".", "this":
+		node.Scoped = true
+	default:
+		node.Parts = append(node.Parts, part)
+	}
+}
+
+// Sep adds path separator.
+func (node *PathExpression) Sep(separator string) {
+	node.Original += separator
+}
+
+// IsDataRoot returns true if path expression is @root.
+func (node *PathExpression) IsDataRoot() bool {
+	return node.Data && (node.Parts[0] == "root")
+}
+
+//
+// String Literal
+//
+
+// StringLiteral represents a string node.
+type StringLiteral struct {
+	NodeType
+	Loc
+
+	Value string
+}
+
+// NewStringLiteral instanciates a new string node.
+func NewStringLiteral(pos int, line int, val string) *StringLiteral {
+	return &StringLiteral{
+		NodeType: NodeString,
+		Loc:      Loc{pos, line},
+
+		Value: val,
+	}
+}
+
+// String returns a string representation of receiver that can be used for debugging.
+func (node *StringLiteral) String() string {
+	return fmt.Sprintf("String{Value:'%s', Pos:%d}", node.Value, node.Loc.Pos)
+}
+
+// Accept is the receiver entry point for visitors.
+func (node *StringLiteral) Accept(visitor Visitor) interface{} {
+	return visitor.VisitString(node)
+}
+
+//
+// Boolean Literal
+//
+
+// BooleanLiteral represents a boolean node.
+type BooleanLiteral struct {
+	NodeType
+	Loc
+
+	Value    bool
+	Original string
+}
+
+// NewBooleanLiteral instanciates a new boolean node.
+func NewBooleanLiteral(pos int, line int, val bool, original string) *BooleanLiteral {
+	return &BooleanLiteral{
+		NodeType: NodeBoolean,
+		Loc:      Loc{pos, line},
+
+		Value:    val,
+		Original: original,
+	}
+}
+
+// String returns a string representation of receiver that can be used for debugging.
+func (node *BooleanLiteral) String() string {
+	return fmt.Sprintf("Boolean{Value:%s, Pos:%d}", node.Canonical(), node.Loc.Pos)
+}
+
+// Accept is the receiver entry point for visitors.
+func (node *BooleanLiteral) Accept(visitor Visitor) interface{} {
+	return visitor.VisitBoolean(node)
+}
+
+// Canonical returns the canonical form of boolean node as a string (ie. "true" | "false").
+func (node *BooleanLiteral) Canonical() string {
+	if node.Value {
+		return "true"
+	}
+
+	return "false"
+}
+
+//
+// Number Literal
+//
+
+// NumberLiteral represents a number node.
+type NumberLiteral struct {
+	NodeType
+	Loc
+
+	Value    float64
+	IsInt    bool
+	Original string
+}
+
+// NewNumberLiteral instanciates a new number node.
+func NewNumberLiteral(pos int, line int, val float64, isInt bool, original string) *NumberLiteral {
+	return &NumberLiteral{
+		NodeType: NodeNumber,
+		Loc:      Loc{pos, line},
+
+		Value:    val,
+		IsInt:    isInt,
+		Original: original,
+	}
+}
+
+// String returns a string representation of receiver that can be used for debugging.
+func (node *NumberLiteral) String() string {
+	return fmt.Sprintf("Number{Value:%s, Pos:%d}", node.Canonical(), node.Loc.Pos)
+}
+
+// Accept is the receiver entry point for visitors.
+func (node *NumberLiteral) Accept(visitor Visitor) interface{} {
+	return visitor.VisitNumber(node)
+}
+
+// Canonical returns the canonical form of number node as a string (eg: "12", "-1.51").
+func (node *NumberLiteral) Canonical() string {
+	prec := -1
+	if node.IsInt {
+		prec = 0
+	}
+	return strconv.FormatFloat(node.Value, 'f', prec, 64)
+}
+
+// Number returns an integer or a float.
+func (node *NumberLiteral) Number() interface{} {
+	if node.IsInt {
+		return int(node.Value)
+	}
+
+	return node.Value
+}
+
+//
+// Hash
+//
+
+// Hash represents a hash node.
+type Hash struct {
+	NodeType
+	Loc
+
+	Pairs []*HashPair
+}
+
+// NewHash instanciates a new hash node.
+func NewHash(pos int, line int) *Hash {
+	return &Hash{
+		NodeType: NodeHash,
+		Loc:      Loc{pos, line},
+	}
+}
+
+// String returns a string representation of receiver that can be used for debugging.
+func (node *Hash) String() string {
+	result := fmt.Sprintf("Hash{[%d", node.Loc.Pos)
+
+	for i, p := range node.Pairs {
+		if i > 0 {
+			result += ", "
+		}
+		result += p.String()
+	}
+
+	return result + fmt.Sprintf("], Pos:%d}", node.Loc.Pos)
+}
+
+// Accept is the receiver entry point for visitors.
+func (node *Hash) Accept(visitor Visitor) interface{} {
+	return visitor.VisitHash(node)
+}
+
+//
+// HashPair
+//
+
+// HashPair represents a hash pair node.
+type HashPair struct {
+	NodeType
+	Loc
+
+	Key string
+	Val Node // Expression
+}
+
+// NewHashPair instanciates a new hash pair node.
+func NewHashPair(pos int, line int) *HashPair {
+	return &HashPair{
+		NodeType: NodeHashPair,
+		Loc:      Loc{pos, line},
+	}
+}
+
+// String returns a string representation of receiver that can be used for debugging.
+func (node *HashPair) String() string {
+	return node.Key + "=" + node.Val.String()
+}
+
+// Accept is the receiver entry point for visitors.
+func (node *HashPair) Accept(visitor Visitor) interface{} {
+	return visitor.VisitHashPair(node)
+}

vendor/github.com/aymerick/raymond/ast/print.go

@@ -0,0 +1,279 @@
+package ast
+
+import (
+	"fmt"
+	"strings"
+)
+
+// printVisitor implements the Visitor interface to print a AST.
+type printVisitor struct {
+	buf   string
+	depth int
+
+	original bool
+	inBlock  bool
+}
+
+func newPrintVisitor() *printVisitor {
+	return &printVisitor{}
+}
+
+// Print returns a string representation of given AST, that can be used for debugging purpose.
+func Print(node Node) string {
+	visitor := newPrintVisitor()
+	node.Accept(visitor)
+	return visitor.output()
+}
+
+func (v *printVisitor) output() string {
+	return v.buf
+}
+
+func (v *printVisitor) indent() {
+	for i := 0; i < v.depth; {
+		v.buf += "  "
+		i++
+	}
+}
+
+func (v *printVisitor) str(val string) {
+	v.buf += val
+}
+
+func (v *printVisitor) nl() {
+	v.str("\n")
+}
+
+func (v *printVisitor) line(val string) {
+	v.indent()
+	v.str(val)
+	v.nl()
+}
+
+//
+// Visitor interface
+//
+
+// Statements
+
+// VisitProgram implements corresponding Visitor interface method
+func (v *printVisitor) VisitProgram(node *Program) interface{} {
+	if len(node.BlockParams) > 0 {
+		v.line("BLOCK PARAMS: [ " + strings.Join(node.BlockParams, " ") + " ]")
+	}
+
+	for _, n := range node.Body {
+		n.Accept(v)
+	}
+
+	return nil
+}
+
+// VisitMustache implements corresponding Visitor interface method
+func (v *printVisitor) VisitMustache(node *MustacheStatement) interface{} {
+	v.indent()
+	v.str("{{ ")
+
+	node.Expression.Accept(v)
+
+	v.str(" }}")
+	v.nl()
+
+	return nil
+}
+
+// VisitBlock implements corresponding Visitor interface method
+func (v *printVisitor) VisitBlock(node *BlockStatement) interface{} {
+	v.inBlock = true
+
+	v.line("BLOCK:")
+	v.depth++
+
+	node.Expression.Accept(v)
+
+	if node.Program != nil {
+		v.line("PROGRAM:")
+		v.depth++
+		node.Program.Accept(v)
+		v.depth--
+	}
+
+	if node.Inverse != nil {
+		// if node.Program != nil {
+		// 	v.depth++
+		// }
+
+		v.line("{{^}}")
+		v.depth++
+		node.Inverse.Accept(v)
+		v.depth--
+
+		// if node.Program != nil {
+		// 	v.depth--
+		// }
+	}
+
+	v.inBlock = false
+
+	return nil
+}
+
+// VisitPartial implements corresponding Visitor interface method
+func (v *printVisitor) VisitPartial(node *PartialStatement) interface{} {
+	v.indent()
+	v.str("{{> PARTIAL:")
+
+	v.original = true
+	node.Name.Accept(v)
+	v.original = false
+
+	if len(node.Params) > 0 {
+		v.str(" ")
+		node.Params[0].Accept(v)
+	}
+
+	// hash
+	if node.Hash != nil {
+		v.str(" ")
+		node.Hash.Accept(v)
+	}
+
+	v.str(" }}")
+	v.nl()
+
+	return nil
+}
+
+// VisitContent implements corresponding Visitor interface method
+func (v *printVisitor) VisitContent(node *ContentStatement) interface{} {
+	v.line("CONTENT[ '" + node.Value + "' ]")
+
+	return nil
+}
+
+// VisitComment implements corresponding Visitor interface method
+func (v *printVisitor) VisitComment(node *CommentStatement) interface{} {
+	v.line("{{! '" + node.Value + "' }}")
+
+	return nil
+}
+
+// Expressions
+
+// VisitExpression implements corresponding Visitor interface method
+func (v *printVisitor) VisitExpression(node *Expression) interface{} {
+	if v.inBlock {
+		v.indent()
+	}
+
+	// path
+	node.Path.Accept(v)
+
+	// params
+	v.str(" [")
+	for i, n := range node.Params {
+		if i > 0 {
+			v.str(", ")
+		}
+		n.Accept(v)
+	}
+	v.str("]")
+
+	// hash
+	if node.Hash != nil {
+		v.str(" ")
+		node.Hash.Accept(v)
+	}
+
+	if v.inBlock {
+		v.nl()
+	}
+
+	return nil
+}
+
+// VisitSubExpression implements corresponding Visitor interface method
+func (v *printVisitor) VisitSubExpression(node *SubExpression) interface{} {
+	node.Expression.Accept(v)
+
+	return nil
+}
+
+// VisitPath implements corresponding Visitor interface method
+func (v *printVisitor) VisitPath(node *PathExpression) interface{} {
+	if v.original {
+		v.str(node.Original)
+	} else {
+		path := strings.Join(node.Parts, "/")
+
+		result := ""
+		if node.Data {
+			result += "@"
+		}
+
+		v.str(result + "PATH:" + path)
+	}
+
+	return nil
+}
+
+// Literals
+
+// VisitString implements corresponding Visitor interface method
+func (v *printVisitor) VisitString(node *StringLiteral) interface{} {
+	if v.original {
+		v.str(node.Value)
+	} else {
+		v.str("\"" + node.Value + "\"")
+	}
+
+	return nil
+}
+
+// VisitBoolean implements corresponding Visitor interface method
+func (v *printVisitor) VisitBoolean(node *BooleanLiteral) interface{} {
+	if v.original {
+		v.str(node.Original)
+	} else {
+		v.str(fmt.Sprintf("BOOLEAN{%s}", node.Canonical()))
+	}
+
+	return nil
+}
+
+// VisitNumber implements corresponding Visitor interface method
+func (v *printVisitor) VisitNumber(node *NumberLiteral) interface{} {
+	if v.original {
+		v.str(node.Original)
+	} else {
+		v.str(fmt.Sprintf("NUMBER{%s}", node.Canonical()))
+	}
+
+	return nil
+}
+
+// Miscellaneous
+
+// VisitHash implements corresponding Visitor interface method
+func (v *printVisitor) VisitHash(node *Hash) interface{} {
+	v.str("HASH{")
+
+	for i, p := range node.Pairs {
+		if i > 0 {
+			v.str(", ")
+		}
+		p.Accept(v)
+	}
+
+	v.str("}")
+
+	return nil
+}
+
+// VisitHashPair implements corresponding Visitor interface method
+func (v *printVisitor) VisitHashPair(node *HashPair) interface{} {
+	v.str(node.Key + "=")
+	node.Val.Accept(v)
+
+	return nil
+}