Minor cleanup (#3379)

**What problem is this PR intended to solve?**

Some cleanup and refactoring that was originally in #3378 but is
generally valuable even if that PR doesn't land, so I split it out.

ext/nokogiri/xml_xpath_context.c

@@ -132,12 +132,7 @@ rb_xml_xpath_context_register_ns(VALUE rb_context, VALUE prefix, VALUE uri)
 {
   xmlXPathContextPtr c_context;
 
-  TypedData_Get_Struct(
-    rb_context,
-    xmlXPathContext,
-    &xml_xpath_context_type,
-    c_context
-  );
+  TypedData_Get_Struct(rb_context, xmlXPathContext, &xml_xpath_context_type, c_context);
 
   xmlXPathRegisterNs(c_context,
                      (const xmlChar *)StringValueCStr(prefix),
@@ -160,12 +155,7 @@ rb_xml_xpath_context_register_variable(VALUE rb_context, VALUE name, VALUE value
   xmlXPathContextPtr c_context;
   xmlXPathObjectPtr xmlValue;
 
-  TypedData_Get_Struct(
-    rb_context,
-    xmlXPathContext,
-    &xml_xpath_context_type,
-    c_context
-  );
+  TypedData_Get_Struct(rb_context, xmlXPathContext, &xml_xpath_context_type, c_context);
 
   xmlValue = xmlXPathNewCString(StringValueCStr(value));
 
@@ -428,34 +418,29 @@ rb_xml_xpath_context_evaluate(int argc, VALUE *argv, VALUE rb_context)
 static VALUE
 rb_xml_xpath_context_new(VALUE klass, VALUE rb_node)
 {
-  xmlNodePtr node;
+  xmlNodePtr c_node;
   xmlXPathContextPtr c_context;
   VALUE rb_context;
 
-  Noko_Node_Get_Struct(rb_node, xmlNode, node);
+  Noko_Node_Get_Struct(rb_node, xmlNode, c_node);
 
 #if LIBXML_VERSION < 21000
   /* deprecated in 40483d0 */
   xmlXPathInit();
 #endif
 
-  c_context = xmlXPathNewContext(node->doc);
-  c_context->node = node;
+  c_context = xmlXPathNewContext(c_node->doc);
+  c_context->node = c_node;
 
   xmlXPathRegisterNs(c_context, NOKOGIRI_PREFIX, NOKOGIRI_URI);
   xmlXPathRegisterNs(c_context, NOKOGIRI_BUILTIN_PREFIX, NOKOGIRI_BUILTIN_URI);
-  xmlXPathRegisterFuncNS(
-    c_context,
-    (const xmlChar *)"css-class",
-    NOKOGIRI_BUILTIN_URI,
-    xpath_builtin_css_class
-  );
-  xmlXPathRegisterFuncNS(
-    c_context,
-    (const xmlChar *)"local-name-is",
-    NOKOGIRI_BUILTIN_URI,
-    xpath_builtin_local_name_is
-  );
+
+  xmlXPathRegisterFuncNS(c_context,
+                         (const xmlChar *)"css-class", NOKOGIRI_BUILTIN_URI,
+                         xpath_builtin_css_class);
+  xmlXPathRegisterFuncNS(c_context,
+                         (const xmlChar *)"local-name-is", NOKOGIRI_BUILTIN_URI,
+                         xpath_builtin_local_name_is);
 
   rb_context = TypedData_Wrap_Struct(
                  klass,

lib/nokogiri/xml/searchable.rb

@@ -207,35 +207,26 @@ def >(selector) # rubocop:disable Naming/BinaryOperatorParameterName
 
       private
 
-      def css_internal(node, rules, handler, ns)
-        xpath_internal(node, css_rules_to_xpath(rules, ns), handler, ns, nil)
-      end
-
-      def xpath_internal(node, paths, handler, ns, binds)
-        document = node.document
-        return NodeSet.new(document) unless document
-
-        if paths.length == 1
-          return xpath_impl(node, paths.first, handler, ns, binds)
+      def extract_params(params) # :nodoc:
+        handler = params.find do |param|
+          ![Hash, String, Symbol].include?(param.class)
         end
+        params -= [handler] if handler
 
-        NodeSet.new(document) do |combined|
-          paths.each do |path|
-            xpath_impl(node, path, handler, ns, binds).each { |set| combined << set }
-          end
+        hashes = []
+        while Hash === params.last || params.last.nil?
+          hashes << params.pop
+          break if params.empty?
         end
-      end
+        ns, binds = hashes.reverse
 
-      def xpath_impl(node, path, handler, ns, binds)
-        ctx = XPathContext.new(node)
-        ctx.register_namespaces(ns)
-        path = path.gsub("xmlns:", " :") unless Nokogiri.uses_libxml?
+        ns ||= document.root&.namespaces || {}
 
-        binds&.each do |key, value|
-          ctx.register_variable(key.to_s, value)
-        end
+        [params, handler, ns, binds]
+      end
 
-        ctx.evaluate(path, handler)
+      def css_internal(node, rules, handler, ns)
+        xpath_internal(node, css_rules_to_xpath(rules, ns), handler, ns, nil)
       end
 
       def css_rules_to_xpath(rules, ns)
@@ -254,22 +245,29 @@ def xpath_query_from_css_rule(rule, ns)
         end.join(" | ")
       end
 
-      def extract_params(params) # :nodoc:
-        handler = params.find do |param|
-          ![Hash, String, Symbol].include?(param.class)
+      def xpath_internal(node, paths, handler, ns, binds)
+        document = node.document
+        return NodeSet.new(document) unless document
+
+        if paths.length == 1
+          return xpath_impl(node, paths.first, handler, ns, binds)
         end
-        params -= [handler] if handler
 
-        hashes = []
-        while Hash === params.last || params.last.nil?
-          hashes << params.pop
-          break if params.empty?
+        NodeSet.new(document) do |combined|
+          paths.each do |path|
+            xpath_impl(node, path, handler, ns, binds).each { |set| combined << set }
+          end
         end
-        ns, binds = hashes.reverse
+      end
 
-        ns ||= document.root&.namespaces || {}
+      def xpath_impl(node, path, handler, ns, binds)
+        ctx = XPathContext.new(node)
+        ctx.register_namespaces(ns)
+        ctx.register_variables(binds)
 
-        [params, handler, ns, binds]
+        path = path.gsub("xmlns:", " :") unless Nokogiri.uses_libxml?
+
+        ctx.evaluate(path, handler)
       end
     end
   end

lib/nokogiri/xml/xpath_context.rb

@@ -6,9 +6,20 @@ class XPathContext
       ###
       # Register namespaces in +namespaces+
       def register_namespaces(namespaces)
-        namespaces.each do |k, v|
-          k = k.to_s.gsub(/.*:/, "") # strip off 'xmlns:' or 'xml:'
-          register_ns(k, v)
+        namespaces.each do |key, value|
+          key = key.to_s.gsub(/.*:/, "") # strip off 'xmlns:' or 'xml:'
+
+          register_ns(key, value)
+        end
+      end
+
+      def register_variables(binds)
+        return if binds.nil?
+
+        binds.each do |key, value|
+          key = key.to_s
+
+          register_variable(key, value)
         end
       end
     end