youtubebeat/vendor/github.com/antchfx/xpath/xpath.go

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2018-11-18 15:32:28 +01:00
package xpath
import (
"errors"
)
// NodeType represents a type of XPath node.
type NodeType int
const (
// RootNode is a root node of the XML document or node tree.
RootNode NodeType = iota
// ElementNode is an element, such as <element>.
ElementNode
// AttributeNode is an attribute, such as id='123'.
AttributeNode
// TextNode is the text content of a node.
TextNode
// CommentNode is a comment node, such as <!-- my comment -->
CommentNode
// allNode is any types of node, used by xpath package only to predicate match.
allNode
)
// NodeNavigator provides cursor model for navigating XML data.
type NodeNavigator interface {
// NodeType returns the XPathNodeType of the current node.
NodeType() NodeType
// LocalName gets the Name of the current node.
LocalName() string
// Prefix returns namespace prefix associated with the current node.
Prefix() string
// Value gets the value of current node.
Value() string
// Copy does a deep copy of the NodeNavigator and all its components.
Copy() NodeNavigator
// MoveToRoot moves the NodeNavigator to the root node of the current node.
MoveToRoot()
// MoveToParent moves the NodeNavigator to the parent node of the current node.
MoveToParent() bool
// MoveToNextAttribute moves the NodeNavigator to the next attribute on current node.
MoveToNextAttribute() bool
// MoveToChild moves the NodeNavigator to the first child node of the current node.
MoveToChild() bool
// MoveToFirst moves the NodeNavigator to the first sibling node of the current node.
MoveToFirst() bool
// MoveToNext moves the NodeNavigator to the next sibling node of the current node.
MoveToNext() bool
// MoveToPrevious moves the NodeNavigator to the previous sibling node of the current node.
MoveToPrevious() bool
// MoveTo moves the NodeNavigator to the same position as the specified NodeNavigator.
MoveTo(NodeNavigator) bool
}
// NodeIterator holds all matched Node object.
type NodeIterator struct {
node NodeNavigator
query query
}
// Current returns current node which matched.
func (t *NodeIterator) Current() NodeNavigator {
return t.node
}
// MoveNext moves Navigator to the next match node.
func (t *NodeIterator) MoveNext() bool {
n := t.query.Select(t)
if n != nil {
if !t.node.MoveTo(n) {
t.node = n.Copy()
}
return true
}
return false
}
// Select selects a node set using the specified XPath expression.
// This method is deprecated, recommend using Expr.Select() method instead.
func Select(root NodeNavigator, expr string) *NodeIterator {
exp, err := Compile(expr)
if err != nil {
panic(err)
}
return exp.Select(root)
}
// Expr is an XPath expression for query.
type Expr struct {
s string
q query
}
type iteratorFunc func() NodeNavigator
func (f iteratorFunc) Current() NodeNavigator {
return f()
}
// Evaluate returns the result of the expression.
// The result type of the expression is one of the follow: bool,float64,string,NodeIterator).
func (expr *Expr) Evaluate(root NodeNavigator) interface{} {
val := expr.q.Evaluate(iteratorFunc(func() NodeNavigator { return root }))
switch val.(type) {
case query:
return &NodeIterator{query: expr.q.Clone(), node: root}
}
return val
}
// Select selects a node set using the specified XPath expression.
func (expr *Expr) Select(root NodeNavigator) *NodeIterator {
return &NodeIterator{query: expr.q.Clone(), node: root}
}
// String returns XPath expression string.
func (expr *Expr) String() string {
return expr.s
}
// Compile compiles an XPath expression string.
func Compile(expr string) (*Expr, error) {
if expr == "" {
return nil, errors.New("expr expression is nil")
}
qy, err := build(expr)
if err != nil {
return nil, err
}
return &Expr{s: expr, q: qy}, nil
}
// MustCompile compiles an XPath expression string and ignored error.
func MustCompile(expr string) *Expr {
exp, err := Compile(expr)
if err != nil {
return nil
}
return exp
}