Fix chained predicates on ancestor axis

query.go

@@ -201,6 +201,8 @@ func (a *ancestorQuery) Select(t iterator) NodeNavigator {
 func (a *ancestorQuery) Evaluate(t iterator) interface{} {
 	a.Input.Evaluate(t)
 	a.iterator = nil
+	// Reset the table when re-evaluating to ensure clean state
+	a.table = nil
 	return a
 }
 
@@ -829,6 +831,8 @@ func (f *filterQuery) Select(t iterator) NodeNavigator {
 
 func (f *filterQuery) Evaluate(t iterator) interface{} {
 	f.Input.Evaluate(t)
+	// Reset the position map when re-evaluating to ensure clean state
+	f.positmap = nil
 	return f
 }
 

xpath_axes_test.go

@@ -65,6 +65,28 @@ func Test_ancestor_predicate(t *testing.T) {
 	test_xpath_elements(t, doc, `//span/ancestor::section[2]`, 4, 9)
 }
 
+func Test_ancestor_predicate_chain(t *testing.T) {
+	doc := createElement(0, "",
+		createElement(1, "html",
+			createElementAttr(2, "body", map[string]string{"itemscope": "", "itemtype": "Article"},
+				createElement(3, "section",
+					createElementAttr(4, "span", map[string]string{"itemprop": "author"}),
+					createElementAttr(5, "div", map[string]string{"itemscope": "", "itemtype": "Comment"},
+						createElementAttr(6, "span", map[string]string{"itemprop": "author"}),
+						createElement(7, "div",
+							createElementAttr(8, "span", map[string]string{"itemprop": "author"}),
+						),
+					),
+				),
+			),
+		),
+	)
+
+	// Find elements marked as "author" property whose closest "itemscope" ancestor is of "Comment" type.
+	// This should find "span" elements on lines 6 and 8, but not line 4 since that one is under "Article".
+	test_xpath_elements(t, doc, `//*[@itemprop="author"][ancestor::*[@itemscope][1][@itemtype="Comment"]]`, 6, 8)
+}
+
 func Test_ancestor_or_self(t *testing.T) {
 	// Expected the value is [2, 3, 8, 13], but got [3, 2, 8, 13]
 	test_xpath_elements(t, employee_example, `//employee/ancestor-or-self::*`, 3, 2, 8, 13)

xpath_test.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"fmt"
 	"math"
+	"reflect"
 	"sort"
 	"strings"
 	"testing"
@@ -41,10 +42,14 @@ func (t testQuery) Properties() queryProp {
 
 func test_xpath_elements(t *testing.T, root *TNode, expr string, expected ...int) {
 	result := selectNodes(root, expr)
-	assertEqual(t, len(expected), len(result))
 
-	for i := 0; i < len(expected); i++ {
-		assertEqual(t, expected[i], result[i].lines)
+	var gotLines []int
+	for i := 0; i < len(result); i++ {
+		gotLines = append(gotLines, result[i].lines)
+	}
+
+	if !reflect.DeepEqual(gotLines, expected) {
+		t.Fatalf("expected lines %+v, got %+v", expected, gotLines)
 	}
 }
 
@@ -587,6 +592,14 @@ func (n *TNode) getAttribute(key string) string {
 	return ""
 }
 
+func createElementAttr(line int, name string, attrs map[string]string, children ...*TNode) *TNode {
+	el := createElement(line, name, children...)
+	for k, v := range attrs {
+		el.addAttribute(k, v)
+	}
+	return el
+}
+
 func createElement(line int, name string, children ...*TNode) *TNode {
 	nodeType := ElementNode
 	if name == "" {