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bin/gems/nokogiri-1.18.3-x86_64-linux-gnu/ext/nokogiri/xml_namespace.c

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+#include <nokogiri.h>
+
+/*
+ *  The lifecycle of a Namespace node is more complicated than other Nodes, for two reasons:
+ *
+ *  1. the underlying C structure has a different layout than all the other node structs, with the
+ *     `_private` member where we store a pointer to Ruby object data not being in first position.
+ *  2. xmlNs structures returned in an xmlNodeset from an XPath query are copies of the document's
+ *     namespaces, and so do not share the same memory lifecycle as everything else in a document.
+ *
+ *  As a result of 1, you may see special handling of XML_NAMESPACE_DECL node types throughout the
+ *  Nokogiri C code, though I intend to wrap up that logic in ruby_object_{get,set} functions
+ *  shortly.
+ *
+ *  As a result of 2, you will see we have special handling in this file and in xml_node_set.c to
+ *  carefully manage the memory lifecycle of xmlNs structs to match the Ruby object's GC
+ *  lifecycle. In xml_node_set.c we have local versions of xmlXPathNodeSetDel() and
+ *  xmlXPathFreeNodeSet() that avoid freeing xmlNs structs in the node set. In this file, we decide
+ *  whether or not to call dealloc_namespace() depending on whether the xmlNs struct appears to be
+ *  in an xmlNodeSet (and thus the result of an XPath query) or not.
+ *
+ *  Yes, this is madness.
+ */
+
+VALUE cNokogiriXmlNamespace ;
+
+static void
+_xml_namespace_dealloc(void *ptr)
+{
+  /*
+   * this deallocator is only used for namespace nodes that are part of an xpath
+   * node set. see noko_xml_namespace_wrap().
+   */
+  xmlNsPtr ns = ptr;
+
+  if (ns->href) {
+    xmlFree(DISCARD_CONST_QUAL_XMLCHAR(ns->href));
+  }
+  if (ns->prefix) {
+    xmlFree(DISCARD_CONST_QUAL_XMLCHAR(ns->prefix));
+  }
+  xmlFree(ns);
+}
+
+static void
+_xml_namespace_update_references(void *ptr)
+{
+  xmlNsPtr ns = ptr;
+  if (ns->_private) {
+    ns->_private = (void *)rb_gc_location((VALUE)ns->_private);
+  }
+}
+
+static const rb_data_type_t xml_ns_type_with_free = {
+  .wrap_struct_name = "xmlNs (with free)",
+  .function = {
+    .dfree = _xml_namespace_dealloc,
+    .dcompact = _xml_namespace_update_references,
+  },
+  .flags = RUBY_TYPED_FREE_IMMEDIATELY | RUBY_TYPED_WB_PROTECTED,
+};
+
+static const rb_data_type_t xml_ns_type_without_free = {
+  .wrap_struct_name = "xmlNs (without free)",
+  .function = {
+    .dcompact = _xml_namespace_update_references,
+  },
+  .flags = RUBY_TYPED_FREE_IMMEDIATELY | RUBY_TYPED_WB_PROTECTED,
+};
+
+/*
+ *  :call-seq:
+ *    prefix() → String or nil
+ *
+ *  Return the prefix for this Namespace, or +nil+ if there is no prefix (e.g., default namespace).
+ *
+ *  *Example*
+ *
+ *    doc = Nokogiri::XML.parse(<<~XML)
+ *      <?xml version="1.0"?>
+ *      <root xmlns="http://nokogiri.org/ns/default" xmlns:noko="http://nokogiri.org/ns/noko">
+ *        <child1 foo="abc" noko:bar="def"/>
+ *        <noko:child2 foo="qwe" noko:bar="rty"/>
+ *      </root>
+ *    XML
+ *
+ *    doc.root.elements.first.namespace.prefix
+ *    # => nil
+ *
+ *    doc.root.elements.last.namespace.prefix
+ *    # => "noko"
+ */
+static VALUE
+prefix(VALUE self)
+{
+  xmlNsPtr ns;
+
+  Noko_Namespace_Get_Struct(self, xmlNs, ns);
+  if (!ns->prefix) { return Qnil; }
+
+  return NOKOGIRI_STR_NEW2(ns->prefix);
+}
+
+/*
+ *  :call-seq:
+ *    href() → String
+ *
+ *  Returns the URI reference for this Namespace.
+ *
+ *  *Example*
+ *
+ *    doc = Nokogiri::XML.parse(<<~XML)
+ *      <?xml version="1.0"?>
+ *      <root xmlns="http://nokogiri.org/ns/default" xmlns:noko="http://nokogiri.org/ns/noko">
+ *        <child1 foo="abc" noko:bar="def"/>
+ *        <noko:child2 foo="qwe" noko:bar="rty"/>
+ *      </root>
+ *    XML
+ *
+ *    doc.root.elements.first.namespace.href
+ *    # => "http://nokogiri.org/ns/default"
+ *
+ *    doc.root.elements.last.namespace.href
+ *    # => "http://nokogiri.org/ns/noko"
+ */
+static VALUE
+href(VALUE self)
+{
+  xmlNsPtr ns;
+
+  Noko_Namespace_Get_Struct(self, xmlNs, ns);
+  if (!ns->href) { return Qnil; }
+
+  return NOKOGIRI_STR_NEW2(ns->href);
+}
+
+VALUE
+noko_xml_namespace_wrap(xmlNsPtr c_namespace, xmlDocPtr c_document)
+{
+  VALUE rb_namespace;
+
+  if (c_namespace->_private) {
+    return (VALUE)c_namespace->_private;
+  }
+
+  if (c_document) {
+    rb_namespace = TypedData_Wrap_Struct(cNokogiriXmlNamespace,
+                                         &xml_ns_type_without_free,
+                                         c_namespace);
+
+    if (DOC_RUBY_OBJECT_TEST(c_document)) {
+      rb_iv_set(rb_namespace, "@document", DOC_RUBY_OBJECT(c_document));
+      rb_ary_push(DOC_NODE_CACHE(c_document), rb_namespace);
+    }
+  } else {
+    rb_namespace = TypedData_Wrap_Struct(cNokogiriXmlNamespace,
+                                         &xml_ns_type_with_free,
+                                         c_namespace);
+  }
+
+  c_namespace->_private = (void *)rb_namespace;
+
+  return rb_namespace;
+}
+
+VALUE
+noko_xml_namespace_wrap_xpath_copy(xmlNsPtr c_namespace)
+{
+  return noko_xml_namespace_wrap(c_namespace, NULL);
+}
+
+void
+noko_init_xml_namespace(void)
+{
+  cNokogiriXmlNamespace = rb_define_class_under(mNokogiriXml, "Namespace", rb_cObject);
+
+  rb_undef_alloc_func(cNokogiriXmlNamespace);
+
+  rb_define_method(cNokogiriXmlNamespace, "prefix", prefix, 0);
+  rb_define_method(cNokogiriXmlNamespace, "href", href, 0);
+}