add new methods:QueryAll(), Query(), QuerySelectorAll(), QuerySelector()

Author: zhengchun

README.md

@@ -46,6 +46,8 @@ doc, err := jsonquery.Parse(f)
 list := jsonquery.Find(doc, "store/book/*/author")
 // or equal to
 list := jsonquery.Find(doc, "//author")
+// or by QueryAll()
+nodes, err := jsonquery.QueryAll(doc, "//a")
 ```
 
 #### Find the third book.
@@ -72,7 +74,7 @@ list := jsonquery.Find(doc, "//book/*[isbn]")
 list := jsonquery.Find(doc, "//book/*[price<10]")
 ```
 
-Quick Tutorial
+Examples
 ===
 
 ```go
@@ -96,7 +98,10 @@ func main() {
 		  }
 		]
 	}`
-	doc, _ := jsonquery.Parse(strings.NewReader(s))
+	doc, err := jsonquery.Parse(strings.NewReader(s))
+	if err != nil {
+		panic(err)
+	}
 	name := jsonquery.FindOne(doc, "name")
 	fmt.Printf("name: %s\n", name.InnerText())
 	var a []string
@@ -160,7 +165,7 @@ The above JSON document will be convert to similar to XML document by the *JSONQ
 
 Notes: `element` is empty element that have no any name.
 
-List of supported XPath query packages
+List of XPath query packages
 ===
 |Name |Description |
 |--------------------------|----------------|

query.go

@@ -13,33 +13,61 @@ func CreateXPathNavigator(top *Node) *NodeNavigator {
 	return &NodeNavigator{cur: top, root: top}
 }
 
-// Find searches the Node that matches by the specified XPath expr.
+// Find is like QueryAll but will panics if `expr` cannot be parsed.
 func Find(top *Node, expr string) []*Node {
-	exp, err := xpath.Compile(expr)
+	nodes, err := QueryAll(top, expr)
 	if err != nil {
 		panic(err)
 	}
-	t := exp.Select(CreateXPathNavigator(top))
-	var elems []*Node
-	for t.MoveNext() {
-		elems = append(elems, (t.Current().(*NodeNavigator)).cur)
+	return nodes
+}
+
+// FindOne is like Query but will panics if `expr` cannot be parsed.
+func FindOne(top *Node, expr string) *Node {
+	node, err := Query(top, expr)
+	if err != nil {
+		panic(err)
 	}
-	return elems
+	return node
+}
+
+// QueryAll searches the Node that matches by the specified XPath expr.
+// Return an error if the expression `expr` cannot be parsed.
+func QueryAll(top *Node, expr string) ([]*Node, error) {
+	exp, err := xpath.Compile(expr)
+	if err != nil {
+		return nil, err
+	}
+	return QuerySelectorAll(top, exp), nil
 }
 
-// FindOne searches the Node that matches by the specified XPath expr,
+// Query searches the Node that matches by the specified XPath expr,
 // and returns first element of matched.
-func FindOne(top *Node, expr string) *Node {
+func Query(top *Node, expr string) (*Node, error) {
 	exp, err := xpath.Compile(expr)
 	if err != nil {
-		panic(err)
+		return nil, err
 	}
-	t := exp.Select(CreateXPathNavigator(top))
-	var elem *Node
+	return QuerySelector(top, exp), nil
+}
+
+// QuerySelectorAll searches all of the Node that matches the specified XPath selectors.
+func QuerySelectorAll(top *Node, selector *xpath.Expr) []*Node {
+	t := selector.Select(CreateXPathNavigator(top))
+	var elems []*Node
+	for t.MoveNext() {
+		elems = append(elems, (t.Current().(*NodeNavigator)).cur)
+	}
+	return elems
+}
+
+// QuerySelector returns the first matched XML Node by the specified XPath selector.
+func QuerySelector(top *Node, selector *xpath.Expr) *Node {
+	t := selector.Select(CreateXPathNavigator(top))
 	if t.MoveNext() {
-		elem = (t.Current().(*NodeNavigator)).cur
+		return (t.Current().(*NodeNavigator)).cur
 	}
-	return elem
+	return nil
 }
 
 // NodeNavigator is for navigating JSON document.