/* Copyright (c) 2006-2007 Apple Inc.
 * Please see the LICENSE file for copyright and distribution information. */

#include "ruby_libxml.h"
#include "ruby_xml_reader.h"

/*
 * Document-class: LibXML::XML::Reader
 *
 * The XML::Reader class provides a simpler, alternative way of parsing an XML
 * document in contrast to XML::Parser or XML::SaxParser.  A XML::Reader instance
 * acts like a cursor going forward in a document stream, stopping at each node
 * it encounters.  To advance to the next node, simply cadd XML::Reader#read.
 *
 * The XML::Reader API closely matches the DOM Core specification and supports
 * namespaces, xml:base, entity handling and DTDs.
 *
 * To summarize, XML::Reader provides a far simpler API to use versus XML::SaxParser
 * and is more memory efficient than using XML::Parser to create a DOM tree.
 *
 * Example:
 *
 *  parser = XML::Reader.string("<foo><bar>1</bar><bar>2</bar><bar>3</bar></foo>")
 *  reader.read
 *  assert_equal('foo', reader.name)
 *  assert_equal(nil, reader.value)
 *
 *  3.times do |i|
 *    reader.read
 *    assert_equal(XML::Reader::TYPE_ELEMENT, reader.node_type)
 *    assert_equal('bar', reader.name)
 *    reader.read
 *    assert_equal(XML::Reader::TYPE_TEXT, reader.node_type)
 *    assert_equal((i + 1).to_s, reader.value)
 *    reader.read
 *    assert_equal(XML::Reader::TYPE_END_ELEMENT, reader.node_type)
 *  end
 *
 * You can also parse documents (see XML::Reader.document), 
 * strings (see XML::Parser.string) and io objects (see
 * XML::Parser.io).
 *
 * For a more in depth tutorial, albeit in C, see http://xmlsoft.org/xmlreader.html.*/


  /* NOTE - We need to wrap the readers document to support Reader.read.node.find('/').
     To do this we need to use xmlTextReaderCurrentDoc which means we have to free the
     document ourselves. Annoying... */

VALUE cXMLReader;

static ID BASE_URI_SYMBOL;
static ID ENCODING_SYMBOL;
static ID IO_ATTR;
static ID OPTIONS_SYMBOL;

static void rxml_reader_free(xmlTextReaderPtr xreader)
{
  xmlFreeTextReader(xreader);
}

static void rxml_reader_mark(xmlTextReaderPtr xreader)
{
  xmlDocPtr xdoc = xmlTextReaderCurrentDoc(xreader);

  if (xdoc && xdoc->_private)
    rb_gc_mark((VALUE) xdoc->_private);
}

static VALUE rxml_reader_wrap(xmlTextReaderPtr xreader)
{
  return Data_Wrap_Struct(cXMLReader, NULL, rxml_reader_free, xreader);
}


static xmlTextReaderPtr rxml_text_reader_get(VALUE obj)
{
  xmlTextReaderPtr xreader;
  Data_Get_Struct(obj, xmlTextReader, xreader);
  return xreader;
}

/*
 * call-seq:
 *    XML::Reader.document(doc) -> XML::Reader
 *
 * Create an new reader for the specified document.
 */
VALUE rxml_reader_document(VALUE klass, VALUE doc)
{
  xmlDocPtr xdoc;
  xmlTextReaderPtr xreader;

  Data_Get_Struct(doc, xmlDoc, xdoc);

  xreader = xmlReaderWalker(xdoc);

  if (xreader == NULL)
    rxml_raise(&xmlLastError);

  return rxml_reader_wrap(xreader);
}

/* call-seq:
 *    XML::Reader.file(path) -> XML::Reader
 *    XML::Reader.file(path, :encoding => XML::Encoding::UTF_8,
 *                           :options => XML::Parser::Options::NOENT) -> XML::Parser
 *
 * Creates a new reader by parsing the specified file or uri.
 *
 * You may provide an optional hash table to control how the
 * parsing is performed.  Valid options are:
 *
 *  encoding - The document encoding, defaults to nil. Valid values
 *             are the encoding constants defined on XML::Encoding.
 *  options - Controls the execution of the parser, defaults to 0.
 *            Valid values are the constants defined on
 *            XML::Parser::Options.  Mutliple options can be combined
 *            by using Bitwise OR (|). 
 */
static VALUE rxml_reader_file(int argc, VALUE *argv, VALUE klass)
{
  xmlTextReaderPtr xreader;
  VALUE path;
  VALUE options;

  const char *xencoding = NULL;
  int xoptions = 0;

  rb_scan_args(argc, argv, "11", &path, &options);
  Check_Type(path, T_STRING);

  if (!NIL_P(options))
  {
    VALUE encoding = Qnil;
    VALUE parserOptions = Qnil;

    Check_Type(options, T_HASH);

    encoding = rb_hash_aref(options, BASE_URI_SYMBOL);
    xencoding = NIL_P(encoding) ? NULL : xmlGetCharEncodingName(NUM2INT(encoding));

    parserOptions = rb_hash_aref(options, OPTIONS_SYMBOL);
    xoptions = NIL_P(parserOptions) ? 0 : NUM2INT(parserOptions);
  }

  xreader = xmlReaderForFile(StringValueCStr(path), xencoding, xoptions);

  if (xreader == NULL)
    rxml_raise(&xmlLastError);

  return rxml_reader_wrap(xreader);
}

/* call-seq:
 *    XML::Reader.io(io) -> XML::Reader
 *    XML::Reader.io(io, :encoding => XML::Encoding::UTF_8,
 *                       :options => XML::Parser::Options::NOENT) -> XML::Parser
 *
 * Creates a new reader by parsing the specified io object.
 *
 * You may provide an optional hash table to control how the
 * parsing is performed.  Valid options are:
 *
 *  base_uri - The base url for the parsed document.
 *  encoding - The document encoding, defaults to nil. Valid values
 *             are the encoding constants defined on XML::Encoding.
 *  options - Controls the execution of the parser, defaults to 0.
 *            Valid values are the constants defined on
 *            XML::Parser::Options.  Mutliple options can be combined
 *            by using Bitwise OR (|). 
 */
static VALUE rxml_reader_io(int argc, VALUE *argv, VALUE klass)
{
  xmlTextReaderPtr xreader;
  VALUE result;
  VALUE io;
  VALUE options;
  char *xbaseurl = NULL;
  const char *xencoding = NULL;
  int xoptions = 0;

  rb_scan_args(argc, argv, "11", &io, &options);

  if (!NIL_P(options))
  {
    VALUE baseurl = Qnil;
    VALUE encoding = Qnil;
    VALUE parserOptions = Qnil;

    Check_Type(options, T_HASH);

    baseurl = rb_hash_aref(options, BASE_URI_SYMBOL);
    xbaseurl = NIL_P(baseurl) ? NULL : StringValueCStr(baseurl);

    encoding = rb_hash_aref(options, ENCODING_SYMBOL);
    xencoding = NIL_P(encoding) ? NULL : xmlGetCharEncodingName(NUM2INT(encoding));

    parserOptions = rb_hash_aref(options, OPTIONS_SYMBOL);
    xoptions = NIL_P(parserOptions) ? 0 : NUM2INT(parserOptions);
  }
  
  xreader = xmlReaderForIO((xmlInputReadCallback) rxml_read_callback, NULL,
                           (void *) io, 
                           xbaseurl, xencoding, xoptions);

  if (xreader == NULL)
    rxml_raise(&xmlLastError);

  result = rxml_reader_wrap(xreader);

  /* Attach io object to parser so it won't get freed.*/
  rb_ivar_set(result, IO_ATTR, io);

  return result;
}

/* call-seq:
 *    XML::Reader.string(io) -> XML::Reader
 *    XML::Reader.string(io, :encoding => XML::Encoding::UTF_8,
 *                           :options => XML::Parser::Options::NOENT) -> XML::Parser
 *
 * Creates a new reader by parsing the specified string.
 *
 * You may provide an optional hash table to control how the
 * parsing is performed.  Valid options are:
 *
 *  base_uri - The base url for the parsed document.
 *  encoding - The document encoding, defaults to nil. Valid values
 *             are the encoding constants defined on XML::Encoding.
 *  options - Controls the execution of the parser, defaults to 0.
 *            Valid values are the constants defined on
 *            XML::Parser::Options.  Mutliple options can be combined
 *            by using Bitwise OR (|).
 */
static VALUE rxml_reader_string(int argc, VALUE *argv, VALUE klass)
{
  xmlTextReaderPtr xreader;
  VALUE string;
  VALUE options;
  char *xbaseurl = NULL;
  const char *xencoding = NULL;
  int xoptions = 0;

  rb_scan_args(argc, argv, "11", &string, &options);
  Check_Type(string, T_STRING);

  if (!NIL_P(options))
  {
    VALUE baseurl = Qnil;
    VALUE encoding = Qnil;
    VALUE parserOptions = Qnil;

    Check_Type(options, T_HASH);

    baseurl = rb_hash_aref(options, BASE_URI_SYMBOL);
    xbaseurl = NIL_P(baseurl) ? NULL : StringValueCStr(baseurl);

    encoding = rb_hash_aref(options, ENCODING_SYMBOL);
    xencoding = NIL_P(encoding) ? NULL : xmlGetCharEncodingName(NUM2INT(encoding));
      
    parserOptions = rb_hash_aref(options, OPTIONS_SYMBOL);
    xoptions = NIL_P(parserOptions) ? 0 : NUM2INT(parserOptions);
  }
  
  xreader = xmlReaderForMemory(StringValueCStr(string), RSTRING_LEN(string), 
                               xbaseurl, xencoding, xoptions);

  if (xreader == NULL)
    rxml_raise(&xmlLastError);

  return rxml_reader_wrap(xreader);
}

/*
 * call-seq:
 *    reader.close -> code
 *
 * This method releases any resources allocated by the current instance
 * changes the state to Closed and close any underlying input.
 */
static VALUE rxml_reader_close(VALUE self)
{
  xmlTextReaderPtr xreader = rxml_text_reader_get(self);
  return INT2FIX(xmlTextReaderClose(xreader));
}

/*
 * call-seq:
 *   reader.move_to_attribute(val) -> code
 *
 * Move the position of the current instance to the attribute with the
 * specified index (if +val+ is an integer) or name (if +val+ is a string)
 * relative to the containing element.
 */
static VALUE rxml_reader_move_to_attr(VALUE self, VALUE val)
{
  xmlTextReaderPtr xreader;
  int ret;

  xreader = rxml_text_reader_get(self);

  if (TYPE(val) == T_FIXNUM)
  {
    ret = xmlTextReaderMoveToAttributeNo(xreader, FIX2INT(val));
  }
  else
  {
    ret = xmlTextReaderMoveToAttribute(xreader,
        (const xmlChar *) StringValueCStr(val));
  }

  return INT2FIX(ret);
}

/*
 * call-seq:
 *    reader.move_to_first_attribute -> code
 *
 * Move the position of the current instance to the first attribute associated
 * with the current node.
 */
static VALUE rxml_reader_move_to_first_attr(VALUE self)
{
  xmlTextReaderPtr xreader = rxml_text_reader_get(self);
  return INT2FIX(xmlTextReaderMoveToFirstAttribute(xreader));
}

/*
 * call-seq:
 *    reader.move_to_next_attribute -> code
 *
 * Move the position of the current instance to the next attribute associated
 * with the current node.
 */
static VALUE rxml_reader_move_to_next_attr(VALUE self)
{
  xmlTextReaderPtr xreader = rxml_text_reader_get(self);
  return INT2FIX(xmlTextReaderMoveToNextAttribute(xreader));
}

/*
 * call-seq:
 *    reader.move_to_element -> code
 *
 * Move the position of the current instance to the node that contains the
 * current attribute node.
 */
static VALUE rxml_reader_move_to_element(VALUE self)
{
  xmlTextReaderPtr xreader = rxml_text_reader_get(self);
  return INT2FIX(xmlTextReaderMoveToElement(xreader));
}

/*
 * call-seq:
 *    reader.next -> code
 *
 * Skip to the node following the current one in document order while avoiding
 * the subtree if any.
 */
static VALUE rxml_reader_next(VALUE self)
{
  xmlTextReaderPtr xreader = rxml_text_reader_get(self);
  return INT2FIX(xmlTextReaderNext(xreader));
}

/*
 * call-seq:
 *    reader.next_sibling -> code
 *
 * Skip to the node following the current one in document order while avoiding
 * the subtree if any. Currently implemented only for Readers built on a
 * document.
 */
static VALUE rxml_reader_next_sibling(VALUE self)
{
  xmlTextReaderPtr xreader = rxml_text_reader_get(self);
  return INT2FIX(xmlTextReaderNextSibling(xreader));
}

/*
 * call-seq:
 *    reader.node -> XML::Node
 *
 * Returns the reader's current node.  It will return
 * nil if Reader#read has not yet been called.
 * WARNING - Using this method is dangerous because the
 * the node may be destroyed on the next #read.
 */
static VALUE rxml_reader_node(VALUE self)
{
  xmlTextReaderPtr xreader = rxml_text_reader_get(self);
  xmlNodePtr xnode = xmlTextReaderCurrentNode(xreader);
  return xnode ? rxml_node_wrap(xnode) : Qnil;
}

/*
 * call-seq:
 *    reader.node_type -> type
 *
 * Get the node type of the current node. Reference:
 * http://dotgnu.org/pnetlib-doc/System/Xml/XmlNodeType.html
 */
static VALUE rxml_reader_node_type(VALUE self)
{
  xmlTextReaderPtr xreader = rxml_text_reader_get(self);
  return INT2FIX(xmlTextReaderNodeType(xreader));
}

/*
 * call-seq:
 *    reader.normalization -> value
 *
 * The value indicating whether to normalize white space and attribute values.
 * Since attribute value and end of line normalizations are a MUST in the XML
 * specification only the value true is accepted. The broken bahaviour of
 * accepting out of range character entities like &#0; is of course not
 * supported either.
 *
 * Return 1 or -1 in case of error.
 */
static VALUE rxml_reader_normalization(VALUE self)
{
  xmlTextReaderPtr xreader = rxml_text_reader_get(self);
  return INT2FIX(xmlTextReaderNormalization(xreader));
}

/*
 * call-seq:
 *    reader.read -> nil|true|false
 *
 * Causes the reader to move to the next node in the stream, exposing its properties.
 *
 * Returns true if a node was successfully read or false if there are no more
 * nodes to read.  On errors, an exception is raised.*/
static VALUE rxml_reader_read(VALUE self)
{
  xmlTextReaderPtr xreader = rxml_text_reader_get(self);
  int result = xmlTextReaderRead(xreader);
  switch(result)
  {
    case -1:
      rxml_raise(&xmlLastError);
      return Qnil;
      break;
    case 0:
      return Qfalse;
    case 1:
      return Qtrue;
    default:
      rb_raise(rb_eRuntimeError,
               "xmlTextReaderRead did not return -1, 0 or 1.  Return value was: %d", result);
  }
}

/*
 * call-seq:
 *    reader.read_attribute_value -> code
 *
 * Parse an attribute value into one or more Text and EntityReference nodes.
 *
 * Return 1 in case of success, 0 if the reader was not positionned on an
 * attribute node or all the attribute values have been read, or -1 in case of
 * error.
 */
static VALUE rxml_reader_read_attr_value(VALUE self)
{
  xmlTextReaderPtr xreader = rxml_text_reader_get(self);
  return INT2FIX(xmlTextReaderReadAttributeValue(xreader));
}

/*
 * call-seq:
 *    reader.read_inner_xml -> data
 *
 * Read the contents of the current node, including child nodes and markup.
 *
 * Return a string containing the XML content, or nil if the current node is
 * neither an element nor attribute, or has no child nodes.
 */
static VALUE rxml_reader_read_inner_xml(VALUE self)
{
  VALUE result = Qnil;
  xmlTextReaderPtr xReader = rxml_text_reader_get(self);

  xmlChar *xml = xmlTextReaderReadInnerXml(xReader);

  if (xml)
  {
    const xmlChar *xencoding = xmlTextReaderConstEncoding(xReader);
    result = rxml_new_cstr((const char*) xml, xencoding);
    xmlFree(xml);
  }

  return result;
}

/*
 * call-seq:
 *    reader.read_outer_xml -> data
 *
 * Read the contents of the current node, including child nodes and markup.
 *
 * Return a string containing the XML content, or nil if the current node is
 * neither an element nor attribute, or has no child nodes.
 */
static VALUE rxml_reader_read_outer_xml(VALUE self)
{
  VALUE result = Qnil;
  xmlTextReaderPtr xReader = rxml_text_reader_get(self);

  xmlChar *xml = xmlTextReaderReadOuterXml(xReader);

  if (xml)
  {
    const xmlChar *xencoding = xmlTextReaderConstEncoding(xReader);
    result = rxml_new_cstr((const char*) xml, xencoding);
    xmlFree(xml);
  }

  return result;
}

/*
 * call-seq:
 *    reader.read_state -> state
 *
 * Get the read state of the reader.
 */
static VALUE rxml_reader_read_state(VALUE self)
{
  xmlTextReaderPtr xreader = rxml_text_reader_get(self);
  return INT2FIX(xmlTextReaderReadState(xreader));
}

/*
 * call-seq:
 *    reader.read_string -> string
 *
 * Read the contents of an element or a text node as a string.
 *
 * Return a string containing the contents of the Element or Text node, or nil
 * if the reader is positioned on any other type of node.
 */
static VALUE rxml_reader_read_string(VALUE self)
{
  VALUE result = Qnil;
  xmlTextReaderPtr xReader = rxml_text_reader_get(self);

  xmlChar *xml = xmlTextReaderReadString(xReader);

  if (xml)
  {
    const xmlChar *xencoding = xmlTextReaderConstEncoding(xReader);
    result = rxml_new_cstr((const char*) xml, xencoding);
    xmlFree(xml);
  }

  return result;
}

/*
 * call-seq:
 *    reader.relax_ng_validate(rng) -> boolean
 *
 * Use RelaxNG to validate the document as it is processed. Activation is only
 * possible before the first read. If +rng+ is nil, the RelaxNG validation is
 * desactivated.
 *
 * Return true in case the RelaxNG validation could be (des)activated and false in
 * case of error.
 */
static VALUE rxml_reader_relax_ng_validate(VALUE self, VALUE rng)
{
  xmlTextReaderPtr xreader = rxml_text_reader_get(self);
  xmlRelaxNGPtr xrelax;
  int status;
  Data_Get_Struct(rng, xmlRelaxNG, xrelax);
  
  status = xmlTextReaderRelaxNGSetSchema(xreader, xrelax);
  return (status == 0 ? Qtrue : Qfalse);
}

#if LIBXML_VERSION >= 20620
/*
 * call-seq:
 *    reader.schema_validate(schema) -> boolean
 *
 * Use W3C XSD schema to validate the document as it is processed. Activation
 * is only possible before the first read. If +schema+ is nil, then XML Schema
 * validation is deactivated.
 *
 * Return false if if the schema's validation could be (de)activated and true
 * otherwise.
 */
static VALUE
rxml_reader_schema_validate(VALUE self, VALUE xsd)
{
  xmlTextReaderPtr xreader = rxml_text_reader_get(self);
  xmlSchemaPtr xschema;
  int status;

  Data_Get_Struct(xsd, xmlSchema, xschema);
  status = xmlTextReaderSetSchema(xreader, xschema);
  return (status == 0 ? Qtrue : Qfalse);
}
#endif

/*
 * call-seq:
 *    reader.name -> name
 *
 * Return the qualified name of the node.
 */
static VALUE rxml_reader_name(VALUE self)
{
  xmlTextReaderPtr xReader = rxml_text_reader_get(self);
  const xmlChar *result = xmlTextReaderConstName(xReader);
  const xmlChar *xencoding = xmlTextReaderConstEncoding(xReader);

  return (result == NULL ? Qnil : rxml_new_cstr(result, xencoding));
}

/*
 * call-seq:
 *    reader.local_name -> name
 *
 * Return the local name of the node.
 */
static VALUE rxml_reader_local_name(VALUE self)
{
  xmlTextReaderPtr xReader = rxml_text_reader_get(self);
  const xmlChar *result = xmlTextReaderConstLocalName(xReader);
  const xmlChar *xencoding = xmlTextReaderConstEncoding(xReader);

  return (result == NULL ? Qnil : rxml_new_cstr(result, xencoding));
}

/*
 * call-seq:
 *    reader.attribute_count -> count
 *
 * Provide the number of attributes of the current node.
 */
static VALUE rxml_reader_attr_count(VALUE self)
{
  xmlTextReaderPtr xreader = rxml_text_reader_get(self);
  return INT2FIX(xmlTextReaderAttributeCount(xreader));
}

/*
 * call-seq:
 *    reader.encoding -> XML::Encoding::UTF_8
 *
 * Returns the encoding of the document being read.  Note you
 * first have to read data from the reader for encoding
 * to return a value
 *
 *   reader = XML::Reader.file(XML_FILE)
 *   assert_nil(reader.encoding)
 *   reader.read
 *   assert_equal(XML::Encoding::UTF_8, reader.encoding)
 *
 * In addition, libxml always appears to return nil for the encoding
 * when parsing strings.
 */
static VALUE rxml_reader_encoding(VALUE self)
{
  xmlTextReaderPtr xreader = rxml_text_reader_get(self);
  const xmlChar *xencoding = xmlTextReaderConstEncoding(xreader);
  if (xencoding)
    return INT2NUM(xmlParseCharEncoding(xencoding));
  else
    return INT2NUM(XML_CHAR_ENCODING_NONE);
}

/*
 * call-seq:
 *    reader.base_uri -> URI
 *
 * Determine the base URI of the node.
 */
static VALUE rxml_reader_base_uri(VALUE self)
{
  xmlTextReaderPtr xReader = rxml_text_reader_get(self);
  const xmlChar *result = xmlTextReaderConstBaseUri(xReader);
  const xmlChar *xencoding = xmlTextReaderConstEncoding(xReader);

  return (result == NULL ? Qnil : rxml_new_cstr(result, xencoding));
}

/*
 * call-seq:
 *    reader.namespace_uri -> URI
 *
 * Determine the namespace URI of the node.
 */
static VALUE rxml_reader_namespace_uri(VALUE self)
{
  xmlTextReaderPtr xReader = rxml_text_reader_get(self);
  const xmlChar *result = xmlTextReaderConstNamespaceUri(xReader);
  const xmlChar *xencoding = xmlTextReaderConstEncoding(xReader);

  return (result == NULL ? Qnil : rxml_new_cstr(result, xencoding));
}

/*
 * call-seq:
 *    reader.value -> text
 *
 * Provide the text value of the node if present.
 */
static VALUE rxml_reader_value(VALUE self)
{
  xmlTextReaderPtr xReader = rxml_text_reader_get(self);
  const xmlChar *result = xmlTextReaderConstValue(xReader);
  const xmlChar *xencoding = xmlTextReaderConstEncoding(xReader);

  return (result == NULL ? Qnil : rxml_new_cstr(result, xencoding));
}

/*
 * call-seq:
 *    reader.prefix -> prefix
 *
 * Get a shorthand reference to the namespace associated with the node.
 */
static VALUE rxml_reader_prefix(VALUE self)
{
  xmlTextReaderPtr xReader = rxml_text_reader_get(self);
  const xmlChar *result = xmlTextReaderConstPrefix(xReader);
  const xmlChar *xencoding = xmlTextReaderConstEncoding(xReader);

  return (result == NULL ? Qnil : rxml_new_cstr(result, xencoding));
}

/*
 * call-seq:
 *    reader.depth -> depth
 *
 * Get the depth of the node in the tree.
 */
static VALUE rxml_reader_depth(VALUE self)
{
  xmlTextReaderPtr xreader = rxml_text_reader_get(self);
  return INT2FIX(xmlTextReaderDepth(xreader));
}

/*
 * call-seq:
 *    reader.quote_char -> char
 *
 * Get the quotation mark character used to enclose the value of an attribute,
 * as an integer value (and -1 in case of error).
 */
static VALUE rxml_reader_quote_char(VALUE self)
{
  xmlTextReaderPtr xreader = rxml_text_reader_get(self);
  return INT2FIX(xmlTextReaderQuoteChar(xreader));
}

/*
 * call-seq:
 *    reader.standalone -> code
 *
 * Determine the standalone status of the document being read.
 *
 * Return 1 if the document was declared to be standalone, 0 if it was
 * declared to be not standalone, or -1 if the document did not specify its
 * standalone status or in case of error.
 */
static VALUE rxml_reader_standalone(VALUE self)
{
  xmlTextReaderPtr xreader = rxml_text_reader_get(self);
  return INT2FIX(xmlTextReaderStandalone(xreader));
}

/*
 * call-seq:
 *    reader.xml_lang -> value
 *
 * Get the xml:lang scope within which the node resides.
 */
static VALUE rxml_reader_xml_lang(VALUE self)
{
  xmlTextReaderPtr xReader = rxml_text_reader_get(self);
  const xmlChar *result = xmlTextReaderConstXmlLang(xReader);
  const xmlChar *xencoding = xmlTextReaderConstEncoding(xReader);

  return (result == NULL ? Qnil : rxml_new_cstr(result, xencoding));
}

/*
 * call-seq:
 *    reader.xml_version -> version
 *
 * Determine the XML version of the document being read.
 */
static VALUE rxml_reader_xml_version(VALUE self)
{
  xmlTextReaderPtr xReader = rxml_text_reader_get(self);
  const xmlChar *result = xmlTextReaderConstXmlVersion(xReader);
  const xmlChar *xencoding = xmlTextReaderConstEncoding(xReader);

  return (result == NULL ? Qnil : rxml_new_cstr(result, xencoding));
}

/*
 * call-seq:
 *    reader.has_attributes? -> bool
 *
 * Get whether the node has attributes.
 */
static VALUE rxml_reader_has_attributes(VALUE self)
{
  xmlTextReaderPtr xreader = rxml_text_reader_get(self);
  return xmlTextReaderHasAttributes(xreader) ? Qtrue : Qfalse;
}

/*
 * call-seq:
 *    reader.has_value? -> bool
 *
 * Get whether the node can have a text value.
 */
static VALUE rxml_reader_has_value(VALUE self)
{
  xmlTextReaderPtr xreader = rxml_text_reader_get(self);
  return xmlTextReaderHasValue(xreader) ? Qtrue : Qfalse;
}

/*
 * call-seq:
 *    reader[key] -> value
 *
 * Provide the value of the attribute with the specified index (if +key+ is an
 * integer) or with the specified name (if +key+ is a string) relative to the
 * containing element, as a string.
 */
static VALUE rxml_reader_attribute(VALUE self, VALUE key)
{
  VALUE result = Qnil;
  xmlChar *xattr;
  xmlTextReaderPtr xReader = rxml_text_reader_get(self);
  const xmlChar *xencoding = xmlTextReaderConstEncoding(xReader);

  if (TYPE(key) == T_FIXNUM)
  {
    xattr = xmlTextReaderGetAttributeNo(xReader, FIX2INT(key));
  }
  else
  {
    xattr = xmlTextReaderGetAttribute(xReader, (const xmlChar *) StringValueCStr(key));
  }

  if (xattr)
  {
    result = rxml_new_cstr(xattr, xencoding);
    xmlFree(xattr);
  }
  return result;
}

/*
 * call-seq:
 *    reader.lookup_namespace(prefix) -> value
 *
 * Resolve a namespace prefix in the scope of the current element.
 * To return the default namespace, specify nil as +prefix+.
 */
static VALUE rxml_reader_lookup_namespace(VALUE self, VALUE prefix)
{
  VALUE result = Qnil;
  xmlTextReaderPtr xReader = rxml_text_reader_get(self);
  const xmlChar *xnamespace = xmlTextReaderLookupNamespace(xReader, (const xmlChar *) StringValueCStr(prefix));
  const xmlChar *xencoding = xmlTextReaderConstEncoding(xReader);

  if (xnamespace)
  {
    result = rxml_new_cstr((const char*)xnamespace, (const char*)xencoding);
    xmlFree((void *)xnamespace);
  }
  return result;
}

/*
 * call-seq:
 *    reader.expand -> node
 *
 * Returns the current node and its full subtree. Note the returned node
 * is valid ONLY until the next read call.  
 */
static VALUE rxml_reader_expand(VALUE self)
{
  xmlTextReaderPtr xreader = rxml_text_reader_get(self);
  xmlNodePtr xnode = NULL;

  /* At this point we need to wrap the reader's document as explained above. */
  xmlDocPtr xdoc = xmlTextReaderCurrentDoc(xreader);

  if (!xdoc)
    rb_raise(rb_eRuntimeError, "The reader does not have a document.  Did you forget to call read?");

  rxml_document_wrap(xdoc);

  /* And now hook in a mark function */
  RDATA(self)->dmark = (RUBY_DATA_FUNC)rxml_reader_mark;

  xnode = xmlTextReaderExpand(xreader);
  
  if (!xnode)
  {
    return Qnil;
  }
  else
  {
    return rxml_node_wrap(xnode);
  }
}

#if LIBXML_VERSION >= 20618
/*
 * call-seq:
 *    reader.byte_consumed -> value
 *
 * This method provides the current index of the parser used by the reader,
 * relative to the start of the current entity.
 */
static VALUE
rxml_reader_byte_consumed(VALUE self)
{
  xmlTextReaderPtr xreader = rxml_text_reader_get(self);
  return INT2NUM(xmlTextReaderByteConsumed(xreader));
}
#endif

#if LIBXML_VERSION >= 20617
/*
 * call-seq:
 *    reader.column_number -> number
 *
 * Provide the column number of the current parsing point.
 */
static VALUE
rxml_reader_column_number(VALUE self)
{
  xmlTextReaderPtr xreader = rxml_text_reader_get(self);
  return INT2NUM(xmlTextReaderGetParserColumnNumber(xreader));
}

/*
 * call-seq:
 *    reader.line_number -> number
 *
 * Provide the line number of the current parsing point.
 */
static VALUE
rxml_reader_line_number(VALUE self)
{
  xmlTextReaderPtr xreader = rxml_text_reader_get(self);
  return INT2NUM(xmlTextReaderGetParserLineNumber(xreader));
}
#endif

/*
 * call-seq:
 *    reader.default? -> bool
 *
 * Return whether an Attribute node was generated from the default value
 * defined in the DTD or schema.
 */
static VALUE rxml_reader_default(VALUE self)
{
  xmlTextReaderPtr xreader = rxml_text_reader_get(self);
  return xmlTextReaderIsDefault(xreader) ? Qtrue : Qfalse;
}

/*
 * call-seq:
 *    reader.namespace_declaration? -> bool
 *
 * Determine whether the current node is a namespace declaration rather than a
 * regular attribute.
 */
static VALUE rxml_reader_namespace_declaration(VALUE self)
{
  xmlTextReaderPtr xreader = rxml_text_reader_get(self);
  return xmlTextReaderIsNamespaceDecl(xreader) ? Qtrue : Qfalse;
}

/*
 * call-seq:
 *    reader.empty_element? -> bool
 *
 * Check if the current node is empty.
 */
static VALUE rxml_reader_empty_element(VALUE self)
{
  xmlTextReaderPtr xreader = rxml_text_reader_get(self);
  return xmlTextReaderIsEmptyElement(xreader) ? Qtrue : Qfalse;
}

/*
 * call-seq:
 *    reader.valid? -> bool
 *
 * Retrieve the validity status from the parser context.
 */
static VALUE rxml_reader_valid(VALUE self)
{
  xmlTextReaderPtr xreader = rxml_text_reader_get(self);
  return xmlTextReaderIsValid(xreader) ? Qtrue : Qfalse;
}

void rxml_init_reader(void)
{
  BASE_URI_SYMBOL = ID2SYM(rb_intern("base_uri"));
  ENCODING_SYMBOL = ID2SYM(rb_intern("encoding"));
  IO_ATTR = rb_intern("@io");
  OPTIONS_SYMBOL = ID2SYM(rb_intern("options"));

  cXMLReader = rb_define_class_under(mXML, "Reader", rb_cObject);

  rb_define_singleton_method(cXMLReader, "document", rxml_reader_document, 1);
  rb_define_singleton_method(cXMLReader, "file", rxml_reader_file, -1);
  rb_define_singleton_method(cXMLReader, "io", rxml_reader_io, -1);
  rb_define_singleton_method(cXMLReader, "string", rxml_reader_string, -1);

  rb_define_method(cXMLReader, "[]", rxml_reader_attribute, 1);
  rb_define_method(cXMLReader, "attribute_count", rxml_reader_attr_count, 0);
  rb_define_method(cXMLReader, "base_uri", rxml_reader_base_uri, 0);
#if LIBXML_VERSION >= 20618
  rb_define_method(cXMLReader, "byte_consumed", rxml_reader_byte_consumed, 0);
#endif
  rb_define_method(cXMLReader, "close", rxml_reader_close, 0);
#if LIBXML_VERSION >= 20617
  rb_define_method(cXMLReader, "column_number", rxml_reader_column_number, 0);
#endif
  rb_define_method(cXMLReader, "depth", rxml_reader_depth, 0);
  rb_define_method(cXMLReader, "encoding", rxml_reader_encoding, 0);
  rb_define_method(cXMLReader, "expand", rxml_reader_expand, 0);
  rb_define_method(cXMLReader, "has_attributes?", rxml_reader_has_attributes, 0);
  rb_define_method(cXMLReader, "has_value?", rxml_reader_has_value, 0);
#if LIBXML_VERSION >= 20617
  rb_define_method(cXMLReader, "line_number", rxml_reader_line_number, 0);
#endif
  rb_define_method(cXMLReader, "local_name", rxml_reader_local_name, 0);
  rb_define_method(cXMLReader, "lookup_namespace",       rxml_reader_lookup_namespace, 1);
  rb_define_method(cXMLReader, "move_to_attribute", rxml_reader_move_to_attr, 1);
  rb_define_method(cXMLReader, "move_to_first_attribute",       rxml_reader_move_to_first_attr, 0);
  rb_define_method(cXMLReader, "move_to_next_attribute",       rxml_reader_move_to_next_attr, 0);
  rb_define_method(cXMLReader, "move_to_element", rxml_reader_move_to_element,       0);
  rb_define_method(cXMLReader, "name", rxml_reader_name, 0);
  rb_define_method(cXMLReader, "namespace_uri", rxml_reader_namespace_uri, 0);
  rb_define_method(cXMLReader, "next", rxml_reader_next, 0);
  rb_define_method(cXMLReader, "next_sibling", rxml_reader_next_sibling, 0);
  rb_define_method(cXMLReader, "node", rxml_reader_node, 0);
  rb_define_method(cXMLReader, "node_type", rxml_reader_node_type, 0);
  rb_define_method(cXMLReader, "normalization", rxml_reader_normalization, 0);
  rb_define_method(cXMLReader, "prefix", rxml_reader_prefix, 0);
  rb_define_method(cXMLReader, "quote_char", rxml_reader_quote_char, 0);
  rb_define_method(cXMLReader, "read", rxml_reader_read, 0);
  rb_define_method(cXMLReader, "read_attribute_value", rxml_reader_read_attr_value, 0);
  rb_define_method(cXMLReader, "read_inner_xml", rxml_reader_read_inner_xml, 0);
  rb_define_method(cXMLReader, "read_outer_xml", rxml_reader_read_outer_xml, 0);
  rb_define_method(cXMLReader, "read_state", rxml_reader_read_state, 0);
  rb_define_method(cXMLReader, "read_string", rxml_reader_read_string, 0);
  rb_define_method(cXMLReader, "relax_ng_validate",       rxml_reader_relax_ng_validate, 1);
  rb_define_method(cXMLReader, "standalone", rxml_reader_standalone, 0);
#if LIBXML_VERSION >= 20620
  rb_define_method(cXMLReader, "schema_validate", rxml_reader_schema_validate, 1);
#endif
  rb_define_method(cXMLReader, "value", rxml_reader_value, 0);
  rb_define_method(cXMLReader, "xml_lang", rxml_reader_xml_lang, 0);
  rb_define_method(cXMLReader, "xml_version", rxml_reader_xml_version, 0);
  rb_define_method(cXMLReader, "default?", rxml_reader_default, 0);
  rb_define_method(cXMLReader, "empty_element?", rxml_reader_empty_element, 0);
  rb_define_method(cXMLReader, "namespace_declaration?", rxml_reader_namespace_declaration, 0);
  rb_define_method(cXMLReader, "valid?", rxml_reader_valid, 0);

  /* Constants */
  rb_define_const(cXMLReader, "LOADDTD", INT2FIX(XML_PARSER_LOADDTD));
  rb_define_const(cXMLReader, "DEFAULTATTRS", INT2FIX(XML_PARSER_DEFAULTATTRS));
  rb_define_const(cXMLReader, "VALIDATE", INT2FIX(XML_PARSER_VALIDATE));
  rb_define_const(cXMLReader, "SUBST_ENTITIES", INT2FIX(XML_PARSER_SUBST_ENTITIES));

  rb_define_const(cXMLReader, "SEVERITY_VALIDITY_WARNING", INT2FIX(XML_PARSER_SEVERITY_VALIDITY_WARNING));
  rb_define_const(cXMLReader, "SEVERITY_VALIDITY_ERROR", INT2FIX(XML_PARSER_SEVERITY_VALIDITY_ERROR));
  rb_define_const(cXMLReader, "SEVERITY_WARNING", INT2FIX(XML_PARSER_SEVERITY_WARNING));
  rb_define_const(cXMLReader, "SEVERITY_ERROR", INT2FIX(XML_PARSER_SEVERITY_ERROR));

  rb_define_const(cXMLReader, "TYPE_NONE", INT2FIX(XML_READER_TYPE_NONE));
  rb_define_const(cXMLReader, "TYPE_ELEMENT", INT2FIX(XML_READER_TYPE_ELEMENT));
  rb_define_const(cXMLReader, "TYPE_ATTRIBUTE", INT2FIX(XML_READER_TYPE_ATTRIBUTE));
  rb_define_const(cXMLReader, "TYPE_TEXT", INT2FIX(XML_READER_TYPE_TEXT));
  rb_define_const(cXMLReader, "TYPE_CDATA", INT2FIX(XML_READER_TYPE_CDATA));
  rb_define_const(cXMLReader, "TYPE_ENTITY_REFERENCE", INT2FIX(XML_READER_TYPE_ENTITY_REFERENCE));
  rb_define_const(cXMLReader, "TYPE_ENTITY", INT2FIX(XML_READER_TYPE_ENTITY));
  rb_define_const(cXMLReader, "TYPE_PROCESSING_INSTRUCTION", INT2FIX(XML_READER_TYPE_PROCESSING_INSTRUCTION));
  rb_define_const(cXMLReader, "TYPE_COMMENT", INT2FIX(XML_READER_TYPE_COMMENT));
  rb_define_const(cXMLReader, "TYPE_DOCUMENT",       INT2FIX(XML_READER_TYPE_DOCUMENT));
  rb_define_const(cXMLReader, "TYPE_DOCUMENT_TYPE", INT2FIX(XML_READER_TYPE_DOCUMENT_TYPE));
  rb_define_const(cXMLReader, "TYPE_DOCUMENT_FRAGMENT", INT2FIX(XML_READER_TYPE_DOCUMENT_FRAGMENT));
  rb_define_const(cXMLReader, "TYPE_NOTATION",       INT2FIX(XML_READER_TYPE_NOTATION));
  rb_define_const(cXMLReader, "TYPE_WHITESPACE", INT2FIX(XML_READER_TYPE_WHITESPACE));
  rb_define_const(cXMLReader, "TYPE_SIGNIFICANT_WHITESPACE", INT2FIX(XML_READER_TYPE_SIGNIFICANT_WHITESPACE));
  rb_define_const(cXMLReader, "TYPE_END_ELEMENT", INT2FIX(XML_READER_TYPE_END_ELEMENT));
  rb_define_const(cXMLReader, "TYPE_END_ENTITY", INT2FIX(XML_READER_TYPE_END_ENTITY));
  rb_define_const(cXMLReader, "TYPE_XML_DECLARATION", INT2FIX(XML_READER_TYPE_XML_DECLARATION));

  /* Read states */
  rb_define_const(cXMLReader, "MODE_INITIAL", INT2FIX(XML_TEXTREADER_MODE_INITIAL));
  rb_define_const(cXMLReader, "MODE_INTERACTIVE", INT2FIX(XML_TEXTREADER_MODE_INTERACTIVE));
  rb_define_const(cXMLReader, "MODE_ERROR", INT2FIX(XML_TEXTREADER_MODE_ERROR));
  rb_define_const(cXMLReader, "MODE_EOF", INT2FIX(XML_TEXTREADER_MODE_EOF));
  rb_define_const(cXMLReader, "MODE_CLOSED",       INT2FIX(XML_TEXTREADER_MODE_CLOSED));
  rb_define_const(cXMLReader, "MODE_READING", INT2FIX(XML_TEXTREADER_MODE_READING));
}