goquery/traversal.go

package goquery

import (
	"code.google.com/p/cascadia"
	"exp/html"
)

// Find() gets the descendants of each element in the current set of matched
// elements, filtered by a selector. It returns a new Selection object
// containing these matched elements.
func (this *Selection) Find(selector string) *Selection {
	return pushStack(this, findWithContext(selector, this.Nodes...))
}

// FindSelection() gets the descendants of each element in the current
// Selection, filtered by a Selection. It returns a new Selection object
// containing these matched elements.
func (this *Selection) FindSelection(sel *Selection) *Selection {
	if sel == nil {
		return pushStack(this, nil)
	}

	// Filter the specified Selection to only the current nodes that
	// contain one of the Selection.
	return sel.FilterFunction(func(i int, s *Selection) bool {
		return sliceContains(this.Nodes, s.Nodes[0])
	})
}

// FindNodes() gets the descendants of each element in the current
// Selection, filtered by some nodes. It returns a new Selection object
// containing these matched elements.
func (this *Selection) FindNodes(nodes ...*html.Node) *Selection {
	var matches []*html.Node

	for _, n := range nodes {
		if sliceContains(this.Nodes, n) {
			matches = appendWithoutDuplicates(matches, []*html.Node{n})
		}
	}
	return pushStack(this, matches)
}

// Contents() gets the children of each element in the Selection,
// including text and comment nodes. It returns a new Selection object
// containing these elements.
func (this *Selection) Contents() *Selection {
	return pushStack(this, getSelectionChildren(this, false))
}

// ContentsFiltered() gets the children of each element in the Selection,
// filtered by the specified selector. It returns a new Selection
// object containing these elements. Since selectors only act on Element nodes,
// this function is an alias to ChildrenFiltered() unless the selector is empty,
// in which case it is an alias to Contents().
func (this *Selection) ContentsFiltered(selector string) *Selection {
	if selector != "" {
		return this.ChildrenFiltered(selector)
	}
	return this.Contents()
}

// Children() gets the child elements of each element in the Selection.
// It returns a new Selection object containing these elements.
func (this *Selection) Children() *Selection {
	return pushStack(this, getSelectionChildren(this, true))
}

// ChildrenFiltered() gets the child elements of each element in the Selection,
// filtered by the specified selector. It returns a new
// Selection object containing these elements.
func (this *Selection) ChildrenFiltered(selector string) *Selection {
	// Get the Children() unfiltered
	nodes := getSelectionChildren(this, true)
	// Create a temporary Selection to filter using winnow
	sel := &Selection{nodes, this.document, nil}
	// Filter based on selector
	nodes = winnow(sel, selector, true)
	// Push on the stack and return the "real" Selection
	return pushStack(this, nodes)
}

// Parent() gets the parent of each element in the Selection. It returns a 
// new Selection object containing the matched elements.
func (this *Selection) Parent() *Selection {
	return pushStack(this, getParentNodes(this.Nodes))
}

// ParentFiltered() gets the parent of each element in the Selection filtered by a
// selector. It returns a new Selection object containing the matched elements.
func (this *Selection) ParentFiltered(selector string) *Selection {
	// Get the Parent() unfiltered
	nodes := getParentNodes(this.Nodes)
	// Create a temporary Selection to filter using winnow
	sel := &Selection{nodes, this.document, nil}
	// Filter based on selector
	nodes = winnow(sel, selector, true)
	return pushStack(this, nodes)
}

// Parents() gets the ancestors of each element in the current Selection. It
// returns a new Selection object with the matched elements.
func (this *Selection) Parents() *Selection {
	return pushStack(this, getParentsNodes(this.Nodes, nil))
}

// ParentsFiltered() gets the ancestors of each element in the current
// Selection. It returns a new Selection object with the matched elements.
func (this *Selection) ParentsFiltered(selector string) *Selection {
	// Get the Parents() unfiltered
	nodes := getParentsNodes(this.Nodes, nil)
	// Create a temporary Selection to filter using winnow
	sel := &Selection{nodes, this.document, nil}
	// Filter based on selector
	nodes = winnow(sel, selector, true)
	return pushStack(this, nodes)
}

// Internal implementation to get all parent nodes, stopping at the specified 
// node (or nil if no stop).
func getParentsNodes(nodes []*html.Node, stopNode *html.Node) []*html.Node {
	return mapNodes(nodes, func(i int, n *html.Node, stop *html.Node) (result []*html.Node) {
		for p := n.Parent; p != nil; p = p.Parent {
			if p == stopNode {
				break
			}
			if p.Type == html.ElementNode {
				result = append(result, p)
			}
		}
		return
	}, stopNode)
}

// Internal implementation of parent nodes that return a raw slice of Nodes.
func getParentNodes(nodes []*html.Node) []*html.Node {
	return mapNodes(nodes, func(i int, n *html.Node, _ *html.Node) []*html.Node {
		if n.Parent != nil && n.Parent.Type == html.ElementNode {
			return []*html.Node{n.Parent}
		}
		return nil
	}, nil)
}

// Internal map function used by many traversing methods. Takes the source nodes
// to iterate on, the mapping function that returns an array of nodes, and a
// stop node used for the *Until methods. Returns an array of nodes mapped by
// calling the callback function once for each node in the source nodes.
func mapNodes(nodes []*html.Node, f func(int, *html.Node, *html.Node) []*html.Node, stopNode *html.Node) (result []*html.Node) {

	for i, n := range nodes {
		if vals := f(i, n, stopNode); len(vals) > 0 {
			result = appendWithoutDuplicates(result, vals)
		}
	}

	return
}

// Private internal implementation of the Find() methods
func findWithContext(selector string, nodes ...*html.Node) []*html.Node {
	var matches []*html.Node

	// TODO : Refactor to use mapNodes?
	sel := cascadia.MustCompile(selector)
	// Match the selector on each node
	for _, n := range nodes {
		// Go down one level, becausejQuery's Find() selects only within descendants
		for _, c := range n.Child {
			if c.Type == html.ElementNode {
				matches = appendWithoutDuplicates(matches, sel.MatchAll(c))
			}
		}
	}
	return matches
}

// Return the child nodes of each node in the Selection object, without
// duplicates.
func getSelectionChildren(s *Selection, elemOnly bool) (result []*html.Node) {
	for _, n := range s.Nodes {
		result = appendWithoutDuplicates(result, getChildren(n, elemOnly))
	}
	return
}

// Return the immediate children of the node, filtered on element nodes only
// if requested. The result is necessarily a slice of unique nodes.
func getChildren(n *html.Node, elemOnly bool) (result []*html.Node) {
	if n != nil {
		for _, c := range n.Child {
			if c.Type == html.ElementNode || !elemOnly {
				result = append(result, c)
			}
		}
	}
	return
}