class Nokogiri::XML::Reader
The Reader
parser allows you to effectively pull parse an XML
document. Once instantiated, call Nokogiri::XML::Reader#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.
The Reader
parser might be good for when you need the speed and low memory usage of the SAX
parser, but do not want to write a Document
handler.
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
⚠ Nokogiri::XML::Reader#each
can only be called once! Once the cursor moves through the entire document, you must parse the document again. It may be better to capture all information you need during a single iteration.
⚠ libxml2 does not support error recovery in the Reader
parser. The ‘RECOVER` ParseOption is ignored. If a syntax error is encountered during parsing, an exception will be raised.
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
A list of errors encountered while parsing
The XML
source
Public Class Methods
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)noko_io_read, (xmlInputCloseCallback)noko_io_close, (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 = TypedData_Wrap_Struct(klass, &xml_reader_type, reader); args[0] = rb_io; args[1] = rb_url; args[2] = encoding; rb_obj_call_init(rb_reader, 3, args); return rb_reader; }
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 = TypedData_Wrap_Struct(klass, &xml_reader_type, 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
Get the value of attribute named name
static VALUE reader_attribute(VALUE self, VALUE name) { xmlTextReaderPtr reader; xmlChar *value ; VALUE rb_value; TypedData_Get_Struct(self, xmlTextReader, &xml_reader_type, 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; }
Get the value of attribute at index
static VALUE attribute_at(VALUE self, VALUE index) { xmlTextReaderPtr reader; xmlChar *value; VALUE rb_value; TypedData_Get_Struct(self, xmlTextReader, &xml_reader_type, 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; }
Get the number of attributes for the current node
static VALUE attribute_count(VALUE self) { xmlTextReaderPtr reader; int count; TypedData_Get_Struct(self, xmlTextReader, &xml_reader_type, reader); count = xmlTextReaderAttributeCount(reader); if (count == -1) { return Qnil; } return INT2NUM(count); }
Get the attributes of the current node as a Hash of names and values.
See related: #attributes
and #namespaces
static VALUE rb_xml_reader_attribute_hash(VALUE rb_reader) { VALUE rb_attributes = rb_hash_new(); xmlTextReaderPtr c_reader; xmlNodePtr c_node; xmlAttrPtr c_property; VALUE rb_errors; TypedData_Get_Struct(rb_reader, xmlTextReader, &xml_reader_type, c_reader); if (!has_attributes(c_reader)) { return rb_attributes; } rb_errors = rb_funcall(rb_reader, rb_intern("errors"), 0); xmlSetStructuredErrorFunc((void *)rb_errors, Nokogiri_error_array_pusher); c_node = xmlTextReaderExpand(c_reader); xmlSetStructuredErrorFunc(NULL, NULL); if (c_node == NULL) { if (RARRAY_LEN(rb_errors) > 0) { VALUE rb_error = rb_ary_entry(rb_errors, 0); VALUE exception_message = rb_funcall(rb_error, rb_intern("to_s"), 0); rb_exc_raise(rb_class_new_instance(1, &exception_message, cNokogiriXmlSyntaxError)); } return Qnil; } c_property = c_node->properties; while (c_property != NULL) { VALUE rb_name = NOKOGIRI_STR_NEW2(c_property->name); VALUE rb_value = Qnil; xmlChar *c_value = xmlNodeGetContent((xmlNode *)c_property); if (c_value) { rb_value = NOKOGIRI_STR_NEW2(c_value); xmlFree(c_value); } rb_hash_aset(rb_attributes, rb_name, rb_value); c_property = c_property->next; } return rb_attributes; }
Get the attributes and namespaces of the current node as a Hash.
This is the union of Reader#attribute_hash
and Reader#namespaces
- Returns
-
(Hash<String, String>) Attribute names and values, and namespace prefixes and hrefs.
# File lib/nokogiri/xml/reader.rb, line 93 def attributes attribute_hash.merge(namespaces) end
Does this node have attributes?
static VALUE attributes_eh(VALUE self) { xmlTextReaderPtr reader; int eh; TypedData_Get_Struct(self, xmlTextReader, &xml_reader_type, reader); eh = has_attributes(reader); if (eh == 0) { return Qfalse; } if (eh == 1) { return Qtrue; } return Qnil; }
Get the xml:base of the node
static VALUE rb_xml_reader_base_uri(VALUE rb_reader) { VALUE rb_base_uri; xmlTextReaderPtr c_reader; xmlChar *c_base_uri; TypedData_Get_Struct(rb_reader, xmlTextReader, &xml_reader_type, c_reader); c_base_uri = xmlTextReaderBaseUri(c_reader); if (c_base_uri == NULL) { return Qnil; } rb_base_uri = NOKOGIRI_STR_NEW2(c_base_uri); xmlFree(c_base_uri); return rb_base_uri; }
Was an attribute generated from the default value in the DTD
or schema?
static VALUE default_eh(VALUE self) { xmlTextReaderPtr reader; int eh; TypedData_Get_Struct(self, xmlTextReader, &xml_reader_type, reader); eh = xmlTextReaderIsDefault(reader); if (eh == 0) { return Qfalse; } if (eh == 1) { return Qtrue; } return Qnil; }
Get the depth of the node
static VALUE depth(VALUE self) { xmlTextReaderPtr reader; int depth; TypedData_Get_Struct(self, xmlTextReader, &xml_reader_type, reader); depth = xmlTextReaderDepth(reader); if (depth == -1) { return Qnil; } return INT2NUM(depth); }
Move the cursor through the document yielding the cursor to the block
# File lib/nokogiri/xml/reader.rb, line 99 def each while (cursor = read) yield cursor end end
Returns true if the current node is empty, otherwise false.
static VALUE empty_element_p(VALUE self) { xmlTextReaderPtr reader; TypedData_Get_Struct(self, xmlTextReader, &xml_reader_type, reader); if (xmlTextReaderIsEmptyElement(reader)) { return Qtrue; } return Qfalse; }
static VALUE rb_xml_reader_encoding(VALUE rb_reader) { xmlTextReaderPtr c_reader; const char *parser_encoding; VALUE constructor_encoding; TypedData_Get_Struct(rb_reader, xmlTextReader, &xml_reader_type, c_reader); parser_encoding = (const char *)xmlTextReaderConstEncoding(c_reader); if (parser_encoding) { return NOKOGIRI_STR_NEW2(parser_encoding); } constructor_encoding = rb_iv_get(rb_reader, "@encoding"); if (RTEST(constructor_encoding)) { return constructor_encoding; } return Qnil; }
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; TypedData_Get_Struct(self, xmlTextReader, &xml_reader_type, reader); value = xmlTextReaderReadInnerXml(reader); str = Qnil; if (value) { str = NOKOGIRI_STR_NEW2((char *)value); xmlFree(value); } return str; }
Get the xml:lang scope within which the node resides.
static VALUE lang(VALUE self) { xmlTextReaderPtr reader; const char *lang; TypedData_Get_Struct(self, xmlTextReader, &xml_reader_type, reader); lang = (const char *)xmlTextReaderConstXmlLang(reader); if (lang == NULL) { return Qnil; } return NOKOGIRI_STR_NEW2(lang); }
Get the local name of the node
static VALUE local_name(VALUE self) { xmlTextReaderPtr reader; const char *name; TypedData_Get_Struct(self, xmlTextReader, &xml_reader_type, reader); name = (const char *)xmlTextReaderConstLocalName(reader); if (name == NULL) { return Qnil; } return NOKOGIRI_STR_NEW2(name); }
Get the name of the node. Returns a utf-8 encoded string.
static VALUE name(VALUE self) { xmlTextReaderPtr reader; const char *name; TypedData_Get_Struct(self, xmlTextReader, &xml_reader_type, reader); name = (const char *)xmlTextReaderConstName(reader); if (name == NULL) { return Qnil; } return NOKOGIRI_STR_NEW2(name); }
Get the URI defining the namespace associated with the node
static VALUE namespace_uri(VALUE self) { xmlTextReaderPtr reader; const char *uri; TypedData_Get_Struct(self, xmlTextReader, &xml_reader_type, reader); uri = (const char *)xmlTextReaderConstNamespaceUri(reader); if (uri == NULL) { return Qnil; } return NOKOGIRI_STR_NEW2(uri); }
Get a hash of namespaces for this Node
static VALUE rb_xml_reader_namespaces(VALUE rb_reader) { VALUE rb_namespaces = rb_hash_new() ; xmlTextReaderPtr c_reader; xmlNodePtr c_node; VALUE rb_errors; TypedData_Get_Struct(rb_reader, xmlTextReader, &xml_reader_type, c_reader); if (! has_attributes(c_reader)) { return rb_namespaces ; } rb_errors = rb_funcall(rb_reader, rb_intern("errors"), 0); xmlSetStructuredErrorFunc((void *)rb_errors, Nokogiri_error_array_pusher); c_node = xmlTextReaderExpand(c_reader); xmlSetStructuredErrorFunc(NULL, NULL); if (c_node == NULL) { if (RARRAY_LEN(rb_errors) > 0) { VALUE rb_error = rb_ary_entry(rb_errors, 0); VALUE exception_message = rb_funcall(rb_error, rb_intern("to_s"), 0); rb_exc_raise(rb_class_new_instance(1, &exception_message, cNokogiriXmlSyntaxError)); } return Qnil; } Nokogiri_xml_node_namespaces(c_node, rb_namespaces); return rb_namespaces ; }
Get the type of readers current node
static VALUE node_type(VALUE self) { xmlTextReaderPtr reader; TypedData_Get_Struct(self, xmlTextReader, &xml_reader_type, reader); return INT2NUM(xmlTextReaderNodeType(reader)); }
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; TypedData_Get_Struct(self, xmlTextReader, &xml_reader_type, reader); value = xmlTextReaderReadOuterXml(reader); if (value) { str = NOKOGIRI_STR_NEW2((char *)value); xmlFree(value); } return str; }
Get the shorthand reference to the namespace associated with the node.
static VALUE prefix(VALUE self) { xmlTextReaderPtr reader; const char *prefix; TypedData_Get_Struct(self, xmlTextReader, &xml_reader_type, reader); prefix = (const char *)xmlTextReaderConstPrefix(reader); if (prefix == NULL) { return Qnil; } return NOKOGIRI_STR_NEW2(prefix); }
Move the Reader
forward through the XML
document.
static VALUE read_more(VALUE self) { xmlTextReaderPtr reader; xmlErrorConstPtr error; VALUE error_list; int ret; xmlDocPtr c_document; TypedData_Get_Struct(self, xmlTextReader, &xml_reader_type, reader); error_list = rb_funcall(self, rb_intern("errors"), 0); xmlSetStructuredErrorFunc((void *)error_list, Nokogiri_error_array_pusher); ret = xmlTextReaderRead(reader); xmlSetStructuredErrorFunc(NULL, NULL); c_document = xmlTextReaderCurrentDoc(reader); if (c_document && c_document->encoding == NULL) { VALUE constructor_encoding = rb_iv_get(self, "@encoding"); if (RTEST(constructor_encoding)) { c_document->encoding = xmlStrdup(BAD_CAST StringValueCStr(constructor_encoding)); } else { rb_iv_set(self, "@encoding", NOKOGIRI_STR_NEW2("UTF-8")); c_document->encoding = xmlStrdup(BAD_CAST "UTF-8"); } } 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; }
Get the state of the reader
static VALUE state(VALUE self) { xmlTextReaderPtr reader; TypedData_Get_Struct(self, xmlTextReader, &xml_reader_type, reader); return INT2NUM(xmlTextReaderReadState(reader)); }
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; TypedData_Get_Struct(self, xmlTextReader, &xml_reader_type, reader); value = (const char *)xmlTextReaderConstValue(reader); if (value == NULL) { return Qnil; } return NOKOGIRI_STR_NEW2(value); }
Does this node have a text value?
static VALUE value_eh(VALUE self) { xmlTextReaderPtr reader; int eh; TypedData_Get_Struct(self, xmlTextReader, &xml_reader_type, reader); eh = xmlTextReaderHasValue(reader); if (eh == 0) { return Qfalse; } if (eh == 1) { return Qtrue; } return Qnil; }
Get the XML
version of the document being read
static VALUE xml_version(VALUE self) { xmlTextReaderPtr reader; const char *version; TypedData_Get_Struct(self, xmlTextReader, &xml_reader_type, reader); version = (const char *)xmlTextReaderConstXmlVersion(reader); if (version == NULL) { return Qnil; } return NOKOGIRI_STR_NEW2(version); }