class Nokogiri::XML::Reader - nokogiri-1.10.3 Documentation

# class Nokogiri::XML::Reader

The Reader parser allows you to effectively pull parse an XML document. Once instantiated, call #each to iterate over each node. Note that you may only iterate over the document once!

Nokogiri::XML::Reader parses an XML document similar to the way a cursor would move. The Reader is given an XML document, and yields nodes to an each block.

Here is an example of usage:

    reader = Nokogiri::XML::Reader(<<-eoxml)
      <x xmlns:tenderlove='http://tenderlovemaking.com/'>
        <tenderlove:foo awesome='true'>snuggles!</tenderlove:foo>
      </x>
    eoxml

    reader.each do |node|

      # node is an instance of Nokogiri::XML::Reader
      puts node.name

    end

Note that #each can only be called once!! Once the cursor moves through the entire document, you must parse the document again. So make sure that you capture any information you need during the first iteration.

The Reader parser is good for when you need the speed of a SAX parser, but do not want to write a Document handler.

### Constants

TYPE_ATTRIBUTE

  Attribute node type

TYPE_CDATA

  CDATA node type

TYPE_COMMENT

  Comment node type

TYPE_DOCUMENT

  Document node type

TYPE_DOCUMENT_FRAGMENT

  Document Fragment node type

TYPE_DOCUMENT_TYPE

  Document Type node type

TYPE_ELEMENT

  Element node type

TYPE_END_ELEMENT

  Element end node type

TYPE_END_ENTITY

  Entity end node type

TYPE_ENTITY

  Entity node type

TYPE_ENTITY_REFERENCE

  Entity Reference node type

TYPE_NONE
TYPE_NOTATION

  Notation node type

TYPE_PROCESSING_INSTRUCTION

  PI node type

TYPE_SIGNIFICANT_WHITESPACE

  Significant Whitespace node type

TYPE_TEXT

  Text node type

TYPE_WHITESPACE

  Whitespace node type

TYPE_XML_DECLARATION

  XML Declaration node type

### Attributes

encoding[R]

The encoding for the document

errors[RW]

A list of errors encountered while parsing

source[R]

The XML source

### Public Class Methods

from_io(io, url = nil, encoding = nil, options = 0) click to toggle source

Create a new reader that parses `io`

    static VALUE from_io(int argc, VALUE *argv, VALUE klass)
    {
      VALUE rb_io, rb_url, encoding, rb_options;
      xmlTextReaderPtr reader;
      const char * c_url      = NULL;
      const char * c_encoding = NULL;
      int c_options           = 0;
      VALUE rb_reader, args[3];

      rb_scan_args(argc, argv, "13", &rb_io, &rb_url, &encoding, &rb_options);

      if (!RTEST(rb_io)) rb_raise(rb_eArgError, "io cannot be nil");
      if (RTEST(rb_url)) c_url = StringValueCStr(rb_url);
      if (RTEST(encoding)) c_encoding = StringValueCStr(encoding);
      if (RTEST(rb_options)) c_options = (int)NUM2INT(rb_options);

      reader = xmlReaderForIO(
          (xmlInputReadCallback)io_read_callback,
          (xmlInputCloseCallback)io_close_callback,
          (void *)rb_io,
          c_url,
          c_encoding,
          c_options
      );

      if(reader == NULL) {
        xmlFreeTextReader(reader);
        rb_raise(rb_eRuntimeError, "couldn't create a parser");
      }

      rb_reader = Data_Wrap_Struct(klass, NULL, dealloc, reader);
      args[0] = rb_io;
      args[1] = rb_url;
      args[2] = encoding;
      rb_obj_call_init(rb_reader, 3, args);

      return rb_reader;
    }

from_memory(string, url = nil, encoding = nil, options = 0) click to toggle source

Create a new reader that parses `string`

    static VALUE from_memory(int argc, VALUE *argv, VALUE klass)
    {
      VALUE rb_buffer, rb_url, encoding, rb_options;
      xmlTextReaderPtr reader;
      const char * c_url      = NULL;
      const char * c_encoding = NULL;
      int c_options           = 0;
      VALUE rb_reader, args[3];

      rb_scan_args(argc, argv, "13", &rb_buffer, &rb_url, &encoding, &rb_options);

      if (!RTEST(rb_buffer)) rb_raise(rb_eArgError, "string cannot be nil");
      if (RTEST(rb_url)) c_url = StringValueCStr(rb_url);
      if (RTEST(encoding)) c_encoding = StringValueCStr(encoding);
      if (RTEST(rb_options)) c_options = (int)NUM2INT(rb_options);

      reader = xmlReaderForMemory(
          StringValuePtr(rb_buffer),
          (int)RSTRING_LEN(rb_buffer),
          c_url,
          c_encoding,
          c_options
      );

      if(reader == NULL) {
        xmlFreeTextReader(reader);
        rb_raise(rb_eRuntimeError, "couldn't create a parser");
      }

      rb_reader = Data_Wrap_Struct(klass, NULL, dealloc, reader);
      args[0] = rb_buffer;
      args[1] = rb_url;
      args[2] = encoding;
      rb_obj_call_init(rb_reader, 3, args);

      return rb_reader;
    }

### Public Instance Methods

attribute(name) click to toggle source

Get the value of attribute named `name`

    static VALUE reader_attribute(VALUE self, VALUE name)
    {
      xmlTextReaderPtr reader;
      xmlChar *value ;
      VALUE rb_value;

      Data_Get_Struct(self, xmlTextReader, reader);

      if(NIL_P(name)) return Qnil;
      name = StringValue(name) ;

      value = xmlTextReaderGetAttribute(reader, (xmlChar*)StringValueCStr(name));
      if(value == NULL) return Qnil;

      rb_value = NOKOGIRI_STR_NEW2(value);
      xmlFree(value);
      return rb_value;
    }

attribute_at(index) click to toggle source

Get the value of attribute at `index`

    static VALUE attribute_at(VALUE self, VALUE index)
    {
      xmlTextReaderPtr reader;
      xmlChar *value;
      VALUE rb_value;

      Data_Get_Struct(self, xmlTextReader, reader);

      if(NIL_P(index)) return Qnil;
      index = rb_Integer(index);

      value = xmlTextReaderGetAttributeNo(
          reader,
          (int)NUM2INT(index)
      );
      if(value == NULL) return Qnil;

      rb_value = NOKOGIRI_STR_NEW2(value);
      xmlFree(value);
      return rb_value;
    }

attribute_count click to toggle source

Get the number of attributes for the current node

    static VALUE attribute_count(VALUE self)
    {
      xmlTextReaderPtr reader;
      int count;

      Data_Get_Struct(self, xmlTextReader, reader);
      count = xmlTextReaderAttributeCount(reader);
      if(count == -1) return Qnil;

      return INT2NUM((long)count);
    }

attribute_nodes() click to toggle source

Get a list of attributes for the current node

    # File lib/nokogiri/xml/reader.rb, line 97
    def attribute_nodes
      nodes = attr_nodes
      nodes.each { |v| v.instance_variable_set(:@_r, self) }
      nodes
    end

attributes() click to toggle source

Get a list of attributes for the current node.

    # File lib/nokogiri/xml/reader.rb, line 89
    def attributes
      Hash[attribute_nodes.map { |node|
        [node.name, node.to_s]
      }].merge(namespaces || {})
    end

attributes? click to toggle source

Does this node have attributes?

    static VALUE attributes_eh(VALUE self)
    {
      xmlTextReaderPtr reader;
      int eh;

      Data_Get_Struct(self, xmlTextReader, reader);
      eh = has_attributes(reader);
      if(eh == 0) return Qfalse;
      if(eh == 1) return Qtrue;

      return Qnil;
    }

base_uri click to toggle source

Get the xml:base of the node

    static VALUE base_uri(VALUE self)
    {
      xmlTextReaderPtr reader;
      const char * base_uri;

      Data_Get_Struct(self, xmlTextReader, reader);
      base_uri = (const char *)xmlTextReaderBaseUri(reader);
      if (base_uri == NULL) return Qnil;

      return NOKOGIRI_STR_NEW2(base_uri);
    }

default? click to toggle source

Was an attribute generated from the default value in the DTD or schema?

    static VALUE default_eh(VALUE self)
    {
      xmlTextReaderPtr reader;
      int eh;

      Data_Get_Struct(self, xmlTextReader, reader);
      eh = xmlTextReaderIsDefault(reader);
      if(eh == 0) return Qfalse;
      if(eh == 1) return Qtrue;

      return Qnil;
    }

depth click to toggle source

Get the depth of the node

    static VALUE depth(VALUE self)
    {
      xmlTextReaderPtr reader;
      int depth;

      Data_Get_Struct(self, xmlTextReader, reader);
      depth = xmlTextReaderDepth(reader);
      if(depth == -1) return Qnil;

      return INT2NUM((long)depth);
    }

each() { |cursor| ... } click to toggle source

Move the cursor through the document yielding the cursor to the block

    # File lib/nokogiri/xml/reader.rb, line 105
    def each
      while cursor = self.read
        yield cursor
      end
    end

empty_element? # → true or false click to toggle source

Returns true if the current node is empty, otherwise false.

    static VALUE empty_element_p(VALUE self)
    {
      xmlTextReaderPtr reader;

      Data_Get_Struct(self, xmlTextReader, reader);

      if(xmlTextReaderIsEmptyElement(reader))
        return Qtrue;

      return Qfalse;
    }

Also aliased as: self_closing?
inner_xml click to toggle source

Read the contents of the current node, including child nodes and markup. Returns a utf-8 encoded string.

    static VALUE inner_xml(VALUE self)
    {
      xmlTextReaderPtr reader;
      xmlChar* value;
      VALUE str;

      Data_Get_Struct(self, xmlTextReader, reader);

      value = xmlTextReaderReadInnerXml(reader);

      str = Qnil;
      if(value) {
        str = NOKOGIRI_STR_NEW2((char*)value);
        xmlFree(value);
      }

      return str;
    }

lang click to toggle source

Get the xml:lang scope within which the node resides.

    static VALUE lang(VALUE self)
    {
      xmlTextReaderPtr reader;
      const char *lang;

      Data_Get_Struct(self, xmlTextReader, reader);
      lang = (const char *)xmlTextReaderConstXmlLang(reader);
      if(lang == NULL) return Qnil;

      return NOKOGIRI_STR_NEW2(lang);
    }

local_name click to toggle source

Get the local name of the node

    static VALUE local_name(VALUE self)
    {
      xmlTextReaderPtr reader;
      const char *name;

      Data_Get_Struct(self, xmlTextReader, reader);
      name = (const char *)xmlTextReaderConstLocalName(reader);
      if(name == NULL) return Qnil;

      return NOKOGIRI_STR_NEW2(name);
    }

name click to toggle source

Get the name of the node. Returns a utf-8 encoded string.

    static VALUE name(VALUE self)
    {
      xmlTextReaderPtr reader;
      const char *name;

      Data_Get_Struct(self, xmlTextReader, reader);
      name = (const char *)xmlTextReaderConstName(reader);
      if(name == NULL) return Qnil;

      return NOKOGIRI_STR_NEW2(name);
    }

namespace_uri click to toggle source

Get the URI defining the namespace associated with the node

    static VALUE namespace_uri(VALUE self)
    {
      xmlTextReaderPtr reader;
      const char *uri;

      Data_Get_Struct(self, xmlTextReader, reader);
      uri = (const char *)xmlTextReaderConstNamespaceUri(reader);
      if(uri == NULL) return Qnil;

      return NOKOGIRI_STR_NEW2(uri);
    }

namespaces click to toggle source

Get a hash of namespaces for this Node

    static VALUE namespaces(VALUE self)
    {
      xmlTextReaderPtr reader;
      xmlNodePtr ptr;
      VALUE attr ;

      Data_Get_Struct(self, xmlTextReader, reader);

      attr = rb_hash_new() ;

      if (! has_attributes(reader))
        return attr ;

      ptr = xmlTextReaderExpand(reader);
      if(ptr == NULL) return Qnil;

      Nokogiri_xml_node_namespaces(ptr, attr);

      return attr ;
    }

node_type click to toggle source

Get the type of readers current node

    static VALUE node_type(VALUE self)
    {
      xmlTextReaderPtr reader;
      Data_Get_Struct(self, xmlTextReader, reader);
      return INT2NUM((long)xmlTextReaderNodeType(reader));
    }

outer_xml click to toggle source

Read the current node and its contents, including child nodes and markup. Returns a utf-8 encoded string.

    static VALUE outer_xml(VALUE self)
    {
      xmlTextReaderPtr reader;
      xmlChar *value;
      VALUE str = Qnil;

      Data_Get_Struct(self, xmlTextReader, reader);

      value = xmlTextReaderReadOuterXml(reader);

      if(value) {
        str = NOKOGIRI_STR_NEW2((char*)value);
        xmlFree(value);
      }
      return str;
    }

prefix click to toggle source

Get the shorthand reference to the namespace associated with the node.

    static VALUE prefix(VALUE self)
    {
      xmlTextReaderPtr reader;
      const char *prefix;

      Data_Get_Struct(self, xmlTextReader, reader);
      prefix = (const char *)xmlTextReaderConstPrefix(reader);
      if(prefix == NULL) return Qnil;

      return NOKOGIRI_STR_NEW2(prefix);
    }

read click to toggle source

Move the Reader forward through the XML document.

    static VALUE read_more(VALUE self)
    {
      xmlTextReaderPtr reader;
      xmlErrorPtr error;
      VALUE error_list;
      int ret;

      Data_Get_Struct(self, xmlTextReader, reader);

      error_list = rb_funcall(self, rb_intern("errors"), 0);

      xmlSetStructuredErrorFunc((void *)error_list, Nokogiri_error_array_pusher);
      ret = xmlTextReaderRead(reader);
      xmlSetStructuredErrorFunc(NULL, NULL);

      if(ret == 1) return self;
      if(ret == 0) return Qnil;

      error = xmlGetLastError();
      if(error)
        rb_exc_raise(Nokogiri_wrap_xml_syntax_error(error));
      else
        rb_raise(rb_eRuntimeError, "Error pulling: %d", ret);

      return Qnil;
    }

self_closing?()
Alias for: empty_element?
state click to toggle source

Get the state of the reader

    static VALUE state(VALUE self)
    {
      xmlTextReaderPtr reader;
      Data_Get_Struct(self, xmlTextReader, reader);
      return INT2NUM((long)xmlTextReaderReadState(reader));
    }

value click to toggle source

Get the text value of the node if present. Returns a utf-8 encoded string.

    static VALUE value(VALUE self)
    {
      xmlTextReaderPtr reader;
      const char *value;

      Data_Get_Struct(self, xmlTextReader, reader);
      value = (const char *)xmlTextReaderConstValue(reader);
      if(value == NULL) return Qnil;

      return NOKOGIRI_STR_NEW2(value);
    }

value? click to toggle source

Does this node have a text value?

    static VALUE value_eh(VALUE self)
    {
      xmlTextReaderPtr reader;
      int eh;

      Data_Get_Struct(self, xmlTextReader, reader);
      eh = xmlTextReaderHasValue(reader);
      if(eh == 0) return Qfalse;
      if(eh == 1) return Qtrue;

      return Qnil;
    }

xml_version click to toggle source

Get the XML version of the document being read

    static VALUE xml_version(VALUE self)
    {
      xmlTextReaderPtr reader;
      const char *version;

      Data_Get_Struct(self, xmlTextReader, reader);
      version = (const char *)xmlTextReaderConstXmlVersion(reader);
      if(version == NULL) return Qnil;

      return NOKOGIRI_STR_NEW2(version);
    }

### Private Instance Methods

attribute_nodes click to toggle source

Get a list of attributes for this Node

    static VALUE attribute_nodes(VALUE self)
    {
      xmlTextReaderPtr reader;
      xmlNodePtr ptr;
      VALUE attr ;

      Data_Get_Struct(self, xmlTextReader, reader);

      attr = rb_ary_new() ;

      if (! has_attributes(reader))
        return attr ;

      ptr = xmlTextReaderExpand(reader);
      if(ptr == NULL) return Qnil;

      Nokogiri_xml_node_properties(ptr, attr);

      return attr ;
    }