lib/nokogiri/html5.rb
# coding: utf-8
# frozen_string_literal: true
#
# Copyright 2013-2021 Sam Ruby, Stephen Checkoway
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
require_relative "html5/document"
require_relative "html5/document_fragment"
require_relative "html5/node"
require_relative "html5/builder"
module Nokogiri
# Since v1.12.0
#
# ⚠ HTML5 functionality is not available when running JRuby.
#
# Parse an HTML5 document. Convenience method for {Nokogiri::HTML5::Document.parse}
def self.HTML5(input, url = nil, encoding = nil, **options, &block)
Nokogiri::HTML5::Document.parse(input, url, encoding, **options, &block)
end
# == Usage
#
# ⚠ HTML5 functionality is not available when running JRuby.
#
# Parse an HTML5 document:
#
# doc = Nokogiri.HTML5(string)
#
# Parse an HTML5 fragment:
#
# fragment = Nokogiri::HTML5.fragment(string)
#
# == Parsing options
#
# The document and fragment parsing methods support options that are different from Nokogiri's.
#
# - <tt>Nokogiri.HTML5(html, url = nil, encoding = nil, options = {})</tt>
# - <tt>Nokogiri::HTML5.parse(html, url = nil, encoding = nil, options = {})</tt>
# - <tt>Nokogiri::HTML5::Document.parse(html, url = nil, encoding = nil, options = {})</tt>
# - <tt>Nokogiri::HTML5.fragment(html, encoding = nil, options = {})</tt>
# - <tt>Nokogiri::HTML5::DocumentFragment.parse(html, encoding = nil, options = {})</tt>
#
# The three currently supported options are +:max_errors+, +:max_tree_depth+ and
# +:max_attributes+, described below.
#
# === Error reporting
#
# Nokogiri contains an experimental HTML5 parse error reporting facility. By default, no parse
# errors are reported but this can be configured by passing the +:max_errors+ option to
# {HTML5.parse} or {HTML5.fragment}.
#
# For example, this script:
#
# doc = Nokogiri::HTML5.parse('<span/>Hi there!</span foo=bar />', max_errors: 10)
# doc.errors.each do |err|
# puts(err)
# end
#
# Emits:
#
# 1:1: ERROR: Expected a doctype token
# <span/>Hi there!</span foo=bar />
# ^
# 1:1: ERROR: Start tag of nonvoid HTML element ends with '/>', use '>'.
# <span/>Hi there!</span foo=bar />
# ^
# 1:17: ERROR: End tag ends with '/>', use '>'.
# <span/>Hi there!</span foo=bar />
# ^
# 1:17: ERROR: End tag contains attributes.
# <span/>Hi there!</span foo=bar />
# ^
#
# Using <tt>max_errors: -1</tt> results in an unlimited number of errors being returned.
#
# The errors returned by {HTML5::Document#errors} are instances of {Nokogiri::XML::SyntaxError}.
#
# The {https://html.spec.whatwg.org/multipage/parsing.html#parse-errors HTML standard} defines a
# number of standard parse error codes. These error codes only cover the "tokenization" stage of
# parsing HTML. The parse errors in the "tree construction" stage do not have standardized error
# codes (yet).
#
# As a convenience to Nokogiri users, the defined error codes are available via
# {Nokogiri::XML::SyntaxError#str1} method.
#
# doc = Nokogiri::HTML5.parse('<span/>Hi there!</span foo=bar />', max_errors: 10)
# doc.errors.each do |err|
# puts("#{err.line}:#{err.column}: #{err.str1}")
# end
# # => 1:1: generic-parser
# # 1:1: non-void-html-element-start-tag-with-trailing-solidus
# # 1:17: end-tag-with-trailing-solidus
# # 1:17: end-tag-with-attributes
#
# Note that the first error is +generic-parser+ because it's an error from the tree construction
# stage and doesn't have a standardized error code.
#
# For the purposes of semantic versioning, the error messages, error locations, and error codes
# are not part of Nokogiri's public API. That is, these are subject to change without Nokogiri's
# major version number changing. These may be stabilized in the future.
#
# === Maximum tree depth
#
# The maximum depth of the DOM tree parsed by the various parsing methods is configurable by the
# +:max_tree_depth+ option. If the depth of the tree would exceed this limit, then an
# {::ArgumentError} is thrown.
#
# This limit (which defaults to <tt>Nokogiri::Gumbo::DEFAULT_MAX_TREE_DEPTH = 400</tt>) can be
# removed by giving the option <tt>max_tree_depth: -1</tt>.
#
# html = '<!DOCTYPE html>' + '<div>' * 1000
# doc = Nokogiri.HTML5(html)
# # raises ArgumentError: Document tree depth limit exceeded
# doc = Nokogiri.HTML5(html, max_tree_depth: -1)
#
# === Attribute limit per element
#
# The maximum number of attributes per DOM element is configurable by the +:max_attributes+
# option. If a given element would exceed this limit, then an {::ArgumentError} is thrown.
#
# This limit (which defaults to <tt>Nokogiri::Gumbo::DEFAULT_MAX_ATTRIBUTES = 400</tt>) can be
# removed by giving the option <tt>max_attributes: -1</tt>.
#
# html = '<!DOCTYPE html><div ' + (1..1000).map { |x| "attr-#{x}" }.join(' ') + '>'
# # "<!DOCTYPE html><div attr-1 attr-2 attr-3 ... attr-1000>"
# doc = Nokogiri.HTML5(html)
# # raises ArgumentError: Attributes per element limit exceeded
# doc = Nokogiri.HTML5(html, max_attributes: -1)
#
# == HTML Serialization
#
# After parsing HTML, it may be serialized using any of the {Nokogiri::XML::Node} serialization
# methods. In particular, {XML::Node#serialize}, {XML::Node#to_html}, and {XML::Node#to_s} will
# serialize a given node and its children. (This is the equivalent of JavaScript's
# +Element.outerHTML+.) Similarly, {XML::Node#inner_html} will serialize the children of a given
# node. (This is the equivalent of JavaScript's +Element.innerHTML+.)
#
# doc = Nokogiri::HTML5("<!DOCTYPE html><span>Hello world!</span>")
# puts doc.serialize
# # => <!DOCTYPE html><html><head></head><body><span>Hello world!</span></body></html>
#
# Due to quirks in how HTML is parsed and serialized, it's possible for a DOM tree to be
# serialized and then re-parsed, resulting in a different DOM. Mostly, this happens with DOMs
# produced from invalid HTML. Unfortunately, even valid HTML may not survive serialization and
# re-parsing.
#
# In particular, a newline at the start of +pre+, +listing+, and +textarea+ elements is ignored by
# the parser.
#
# doc = Nokogiri::HTML5(<<-EOF)
# <!DOCTYPE html>
# <pre>
# Content</pre>
# EOF
# puts doc.at('/html/body/pre').serialize
# # => <pre>Content</pre>
#
# In this case, the original HTML is semantically equivalent to the serialized version. If the
# +pre+, +listing+, or +textarea+ content starts with two newlines, the first newline will be
# stripped on the first parse and the second newline will be stripped on the second, leading to
# semantically different DOMs. Passing the parameter <tt>preserve_newline: true</tt> will cause
# two or more newlines to be preserved. (A single leading newline will still be removed.)
#
# doc = Nokogiri::HTML5(<<-EOF)
# <!DOCTYPE html>
# <listing>
#
# Content</listing>
# EOF
# puts doc.at('/html/body/listing').serialize(preserve_newline: true)
# # => <listing>
# #
# # Content</listing>
#
# == Encodings
#
# Nokogiri always parses HTML5 using {https://en.wikipedia.org/wiki/UTF-8 UTF-8}; however, the
# encoding of the input can be explicitly selected via the optional +encoding+ parameter. This is
# most useful when the input comes not from a string but from an IO object.
#
# When serializing a document or node, the encoding of the output string can be specified via the
# +:encoding+ options. Characters that cannot be encoded in the selected encoding will be encoded
# as {https://en.wikipedia.org/wiki/List_of_XML_and_HTML_character_entity_references HTML numeric
# entities}.
#
# frag = Nokogiri::HTML5.fragment('<span>아는 길도 물어가라</span>')
# html = frag.serialize(encoding: 'US-ASCII')
# puts html
# # => <span>아는 길도 물어가라</span>
# frag = Nokogiri::HTML5.fragment(html)
# puts frag.serialize
# # => <span>아는 길도 물어가라</span>
#
# (There's a {https://bugs.ruby-lang.org/issues/15033 bug} in all current versions of Ruby that
# can cause the entity encoding to fail. Of the mandated supported encodings for HTML, the only
# encoding I'm aware of that has this bug is <tt>'ISO-2022-JP'</tt>. We recommend avoiding this
# encoding.)
#
# == Notes
#
# * The {Nokogiri::HTML5.fragment} function takes a string and parses it
# as a HTML5 document. The +<html>+, +<head>+, and +<body>+ elements are
# removed from this document, and any children of these elements that remain
# are returned as a {Nokogiri::HTML5::DocumentFragment}.
#
# * The {Nokogiri::HTML5.parse} function takes a string and passes it to the
# <code>gumbo_parse_with_options</code> method, using the default options.
# The resulting Gumbo parse tree is then walked.
#
# * Instead of uppercase element names, lowercase element names are produced.
#
# * Instead of returning +unknown+ as the element name for unknown tags, the
# original tag name is returned verbatim.
#
# Since v1.12.0
module HTML5
class << self
# Parse an HTML 5 document. Convenience method for {Nokogiri::HTML5::Document.parse}
def parse(string, url = nil, encoding = nil, **options, &block)
Document.parse(string, url, encoding, **options, &block)
end
# Parse a fragment from +string+. Convenience method for
# {Nokogiri::HTML5::DocumentFragment.parse}.
def fragment(string, encoding = nil, **options)
DocumentFragment.parse(string, encoding, options)
end
# :nodoc:
def read_and_encode(string, encoding)
# Read the string with the given encoding.
if string.respond_to?(:read)
string = if encoding.nil?
string.read
else
string.read(encoding: encoding)
end
else
# Otherwise the string has the given encoding.
string = string.to_s
if encoding
string = string.dup
string.force_encoding(encoding)
end
end
# convert to UTF-8
if string.encoding != Encoding::UTF_8
string = reencode(string)
end
string
end
private
# Charset sniffing is a complex and controversial topic that understandably isn't done _by
# default_ by the Ruby Net::HTTP library. This being said, it is a very real problem for
# consumers of HTML as the default for HTML is iso-8859-1, most "good" producers use utf-8, and
# the Gumbo parser *only* supports utf-8.
#
# Accordingly, Nokogiri::HTML4::Document.parse provides limited encoding detection. Following
# this lead, Nokogiri::HTML5 attempts to do likewise, while attempting to more closely follow
# the HTML5 standard.
#
# http://bugs.ruby-lang.org/issues/2567
# http://www.w3.org/TR/html5/syntax.html#determining-the-character-encoding
#
def reencode(body, content_type = nil)
if body.encoding == Encoding::ASCII_8BIT
encoding = nil
# look for a Byte Order Mark (BOM)
initial_bytes = body[0..2].bytes
if initial_bytes[0..2] == [0xEF, 0xBB, 0xBF]
encoding = Encoding::UTF_8
elsif initial_bytes[0..1] == [0xFE, 0xFF]
encoding = Encoding::UTF_16BE
elsif initial_bytes[0..1] == [0xFF, 0xFE]
encoding = Encoding::UTF_16LE
end
# look for a charset in a content-encoding header
if content_type
encoding ||= content_type[/charset=["']?(.*?)($|["';\s])/i, 1]
end
# look for a charset in a meta tag in the first 1024 bytes
unless encoding
data = body[0..1023].gsub(/<!--.*?(-->|\Z)/m, "")
data.scan(/<meta.*?>/im).each do |meta|
encoding ||= meta[/charset=["']?([^>]*?)($|["'\s>])/im, 1]
end
end
# if all else fails, default to the official default encoding for HTML
encoding ||= Encoding::ISO_8859_1
# change the encoding to match the detected or inferred encoding
body = body.dup
begin
body.force_encoding(encoding)
rescue ArgumentError
body.force_encoding(Encoding::ISO_8859_1)
end
end
body.encode(Encoding::UTF_8)
end
end
end
end
require_relative "gumbo"