Add global XPath functions handler

ext/java/nokogiri/XmlXpathContext.java

@@ -1,6 +1,5 @@
 package nokogiri;
 
-import java.util.Set;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
@@ -104,7 +103,7 @@ public class XmlXpathContext extends RubyObject
   {
     String query = rbQuery.convertToString().asJavaString();
 
-    if (!handler.isNil() && !isContainsPrefix(query)) {
+    if (!isContainsPrefix(query)) {
       //
       //  The user has passed in a handler, but isn't using the `nokogiri:` prefix as
       //  instructed in JRuby land, so let's try to be clever and rewrite the query, inserting
@@ -113,17 +112,14 @@ public class XmlXpathContext extends RubyObject
       StringBuilder namespacedQuery = new StringBuilder();
       int jchar = 0;
 
-      // Find the methods on the handler object
-      Set<String> methodNames = handler.getMetaClass().getMethods().keySet();
-
       // Find the function calls in the xpath query
       Matcher xpathFunctionCalls = XPathFunctionCaptureRE.matcher(query);
 
       while (xpathFunctionCalls.find()) {
         namespacedQuery.append(query.subSequence(jchar, xpathFunctionCalls.start()));
         jchar = xpathFunctionCalls.start();
 
-        if (methodNames.contains(xpathFunctionCalls.group())) {
+        if (handler.respondsTo(xpathFunctionCalls.group())) {
           namespacedQuery.append(NokogiriNamespaceContext.NOKOGIRI_PREFIX);
           namespacedQuery.append(":");
         }
@@ -132,7 +128,7 @@ public class XmlXpathContext extends RubyObject
         jchar = xpathFunctionCalls.end();
       }
 
-      if (jchar < query.length() - 1) {
+      if (jchar < query.length()) {
         namespacedQuery.append(query.subSequence(jchar, query.length()));
       }
       query = namespacedQuery.toString();

lib/nokogiri/xml.rb

@@ -67,6 +67,7 @@ def fragment(string, options = ParseOptions::DEFAULT_XML, &block)
 require_relative "xml/syntax_error"
 require_relative "xml/xpath"
 require_relative "xml/xpath_context"
+require_relative "xml/xpath_functions"
 require_relative "xml/builder"
 require_relative "xml/reader"
 require_relative "xml/notation"

lib/nokogiri/xml/searchable.rb

@@ -253,6 +253,7 @@ def extract_params(params) # :nodoc:
           ![Hash, String, Symbol].include?(param.class)
         end
         params -= [handler] if handler
+        handler = XPathFunctions.wrap(handler)
 
         hashes = []
         while Hash === params.last || params.last.nil?

lib/nokogiri/xml/xpath_functions.rb

@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+require "delegate"
+
+module Nokogiri
+  module XML
+    class XPathFunctions < SimpleDelegator
+      class << self
+        def wrap(handler)
+          if handler.nil?
+            @wrap_nil ||= new(Object.new)
+          else
+            new(handler)
+          end
+        end
+      end
+    end
+  end
+end

nokogiri.gemspec

@@ -309,6 +309,7 @@ Gem::Specification.new do |spec|
     "lib/nokogiri/xml/xpath.rb",
     "lib/nokogiri/xml/xpath/syntax_error.rb",
     "lib/nokogiri/xml/xpath_context.rb",
+    "lib/nokogiri/xml/xpath_functions.rb",
     "lib/nokogiri/xslt.rb",
     "lib/nokogiri/xslt/stylesheet.rb",
     "lib/xsd/xmlparser/nokogiri.rb",

test/xml/test_xpath.rb

@@ -166,6 +166,40 @@ def test_search_with_xpath_query_using_namespaced_custom_function
         end
       end
 
+      def test_search_with_xpath_query_uses_global_custom_selectors_with_arguments
+        XPathFunctions.include(Module.new do
+          def our_filter(*args)
+            my_filter(*args)
+          end
+        end)
+
+        set = if Nokogiri.uses_libxml?
+          @xml.search('//employee/address[our_filter(., "domestic", "Yes")]', @handler)
+        else
+          @xml.search('//employee/address[nokogiri:our_filter(., "domestic", "Yes")]', @handler)
+        end
+        refute_empty(set)
+        set.each do |node|
+          assert_equal("Yes", node["domestic"])
+        end
+      end
+
+      def test_search_with_xpath_query_uses_global_custom_selectors_with_arguments_without_namespace
+        skip("Testing fallback behavior in JRuby") unless Nokogiri.jruby?
+
+        XPathFunctions.include(Module.new do
+          def our_filter(*args)
+            my_filter(*args)
+          end
+        end)
+
+        set = @xml.search('//employee/address[our_filter(., "domestic", "Yes")]', @handler)
+        refute_empty(set)
+        set.each do |node|
+          assert_equal("Yes", node["domestic"])
+        end
+      end
+
       def test_pass_self_to_function
         set = if Nokogiri.uses_libxml?
           @xml.xpath('//employee/address[my_filter(., "domestic", "Yes")]', @handler)