tree

type Adapter interface {
	// Returns the type of the node
	GetNodeType(interface{}) NodeType
	// Returns the parent node of the given node
	GetParent(interface{}) interface{}
	// Returns the position of the node within the document. This is
	// used to order nodes within nodesets
	NodePos(interface{}) int
	// The input is a pointer to an element node. The call should build
	// the namespace of the nodes, and return an array of namespace
	// objects (of type NtNs)
	GetNamespaces(interface{}) []interface{}

	// GetElementName should return the name of the element
	GetElementName(interface{}) xml.Name

	// The input is an attribute. This must return the attribute token
	GetAttrTok(interface{}) xml.Attr
	// The input in a namespace object. This must return a namespace attribute
	GetNamespaceTok(interface{}) xml.Attr
	// The input is an element. It should return an element token
	GetElemTok(interface{}) xml.StartElement
	// The input is a processing instruction. It should return a ProcInst token
	GetProcInstTok(interface{}) xml.ProcInst
	// The input is chardata. It should return a chardata token
	GetCharDataTok(interface{}) xml.CharData
	// The input is a comment. It should return a comment token
	GetCommentTok(interface{}) xml.Comment

	// If the node is an element, iterate attributes of element and call
	// the func with the attribute, and a pointer to the attribute node
	ForEachAttr(interface{}, func(xml.Attr, interface{}))
	// If the node is an element, iterate direct children of the node,
	// and call func with a pointer to each child
	ForEachChild(interface{}, func(interface{}))

	// NewNodeSet must return a new nodeset implementation containing the given nodes
	NewNodeSet([]interface{}) NodeSet
	// StringValue must return the string value of the node
	StringValue(interface{}) string
}

type Bool bool

type Ctx struct {
	NodeSet
	Pos  int
	Size int
}

type Fn func(a Adapter, c Ctx, args ...Result) (Result, error)

type IsBool interface {
	Bool() Bool
}

type IsNum interface {
	Num() Num
}

type LastArgOpt int

type NodeSet interface {
	GetNodes() []interface{}
	String() string
	Bool() Bool
	Num() Num
	Sort()
	Unique()
}

type NodeType int

type Num float64

type Result interface {
	fmt.Stringer
}

type String string

type Wrap struct {
	Fn Fn
	//NArgs represents the number of arguments to the XPath function.  -1 represents a single optional argument
	NArgs      int
	LastArgOpt LastArgOpt
}