Initial lexer and interfaces

1 files changed, 113 insertions, 0 deletions

diff --git a/json/nav.go b/json/nav.go
new file mode 100644
index 0000000..c366966
--- /dev/null
+++ b/json/nav.go
@@ -0,0 +1,113 @@
+package json
+
+import (
+	"fmt"
+
+	base "src.userspace.com.au/query"
+)
+
+// NodeNavigator implements the Nav interface for navigating JSON nodes.
+type NodeNavigator struct {
+	root, cur *Node
+}
+
+func (a *NodeNavigator) Current() *Node {
+	return a.cur
+}
+
+func (a *NodeNavigator) NodeType() base.NodeType {
+	switch a.cur.Type {
+	case TextNode:
+		return base.TextNode
+	case DocumentNode:
+		return base.DocumentNode
+	case ElementNode:
+		return base.ElementNode
+	default:
+		panic(fmt.Sprintf("unknown node type %v", a.cur.Type))
+	}
+}
+
+func (a *NodeNavigator) LocalName() string {
+	return a.cur.Data
+
+}
+
+func (a *NodeNavigator) Prefix() string {
+	return ""
+}
+
+func (a *NodeNavigator) Value() string {
+	switch a.cur.Type {
+	case ElementNode:
+		return a.cur.InnerText()
+	case TextNode:
+		return a.cur.Data
+	}
+	return ""
+}
+
+func (a *NodeNavigator) Copy() base.Nav {
+	n := *a
+	return &n
+}
+
+func (a *NodeNavigator) MoveToRoot() {
+	a.cur = a.root
+}
+
+func (a *NodeNavigator) MoveToParent() bool {
+	if n := a.cur.Parent; n != nil {
+		a.cur = n
+		return true
+	}
+	return false
+}
+
+func (x *NodeNavigator) MoveToNextAttribute() bool {
+	return false
+}
+
+func (a *NodeNavigator) MoveToChild() bool {
+	if n := a.cur.FirstChild; n != nil {
+		a.cur = n
+		return true
+	}
+	return false
+}
+
+func (a *NodeNavigator) MoveToFirst() bool {
+	for n := a.cur.PrevSibling; n != nil; n = n.PrevSibling {
+		a.cur = n
+	}
+	return true
+}
+
+func (a *NodeNavigator) String() string {
+	return a.Value()
+}
+
+func (a *NodeNavigator) MoveToNext() bool {
+	if n := a.cur.NextSibling; n != nil {
+		a.cur = n
+		return true
+	}
+	return false
+}
+
+func (a *NodeNavigator) MoveToPrevious() bool {
+	if n := a.cur.PrevSibling; n != nil {
+		a.cur = n
+		return true
+	}
+	return false
+}
+
+func (a *NodeNavigator) MoveTo(other base.Nav) bool {
+	node, ok := other.(*NodeNavigator)
+	if !ok || node.root != a.root {
+		return false
+	}
+	a.cur = node.cur
+	return true
+}