Class: Nokogiri::CSS::XPathVisitor

Inherits:
Object
  • Object
show all
Defined in:
lib/nokogiri/css/xpath_visitor.rb

Overview

When translating CSS selectors to XPath queries with Nokogiri::CSS.xpath_for, the XPathVisitor class allows for changing some of the behaviors related to builtin xpath functions and quirks of HTML5.

Defined Under Namespace

Modules: BuiltinsConfig, DoctypeConfig

Constant Summary collapse

WILDCARD_NAMESPACES =

:nodoc:

Nokogiri.libxml2_patches.include?("0009-allow-wildcard-namespaces.patch")

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(builtins: BuiltinsConfig::NEVER, doctype: DoctypeConfig::XML, prefix: Nokogiri::XML::XPath::GLOBAL_SEARCH_PREFIX, namespaces: nil) ⇒ XPathVisitor

:call-seq:

new() → XPathVisitor
new(builtins:, doctype:) → XPathVisitor
Parameters

  • builtins: (BuiltinsConfig) Determine when to use Nokogiri’s built-in xpath functions for performance improvements.

  • doctype: (DoctypeConfig) Make document-type-specific accommodations for CSS queries.

Returns

XPathVisitor



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# File 'lib/nokogiri/css/xpath_visitor.rb', line 69

def initialize(
  builtins: BuiltinsConfig::NEVER,
  doctype: DoctypeConfig::XML,
  prefix: Nokogiri::XML::XPath::GLOBAL_SEARCH_PREFIX,
  namespaces: nil
)
  unless BuiltinsConfig::VALUES.include?(builtins)
    raise(ArgumentError, "Invalid values #{builtins.inspect} for builtins: keyword parameter")
  end
  unless DoctypeConfig::VALUES.include?(doctype)
    raise(ArgumentError, "Invalid values #{doctype.inspect} for doctype: keyword parameter")
  end

  @builtins = builtins
  @doctype = doctype
  @prefix = prefix
  @namespaces = namespaces
end

Instance Attribute Details

#builtins ⇒ Object (readonly)

The visitor configuration set via the builtins: keyword argument to XPathVisitor.new.



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# File 'lib/nokogiri/css/xpath_visitor.rb', line 48

def builtins
  @builtins
end

#doctype ⇒ Object (readonly)

The visitor configuration set via the doctype: keyword argument to XPathVisitor.new.



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# File 'lib/nokogiri/css/xpath_visitor.rb', line 51

def doctype
  @doctype
end

#namespaces ⇒ Object (readonly)

The visitor configuration set via the namespaces: keyword argument to XPathVisitor.new.



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# File 'lib/nokogiri/css/xpath_visitor.rb', line 57

def namespaces
  @namespaces
end

#prefix ⇒ Object (readonly)

The visitor configuration set via the prefix: keyword argument to XPathVisitor.new.



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# File 'lib/nokogiri/css/xpath_visitor.rb', line 54

def prefix
  @prefix
end

Instance Method Details

#accept(node) ⇒ Object 



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# File 'lib/nokogiri/css/xpath_visitor.rb', line 297

def accept(node)
  node.accept(self)
end

#config ⇒ Object

:call-seq: config() → Hash

Returns

a Hash representing the configuration of the XPathVisitor, suitable for use as part of the CSS cache key.



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# File 'lib/nokogiri/css/xpath_visitor.rb', line 93

def config
  { builtins: @builtins, doctype: @doctype, prefix: @prefix, namespaces: @namespaces }
end

#visit_attrib_name(node) ⇒ Object 



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# File 'lib/nokogiri/css/xpath_visitor.rb', line 293

def visit_attrib_name(node)
  "@#{node.value.first}"
end

#visit_attribute_condition(node) ⇒ Object 



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# File 'lib/nokogiri/css/xpath_visitor.rb', line 175

def visit_attribute_condition(node)
  attribute = node.value.first.accept(self)
  return attribute if node.value.length == 1

  value = node.value.last
  value = "'#{value}'" unless /^['"]/.match?(value)

  # quoted values - see test_attribute_value_with_quotes in test/css/test_parser.rb
  if (value[0] == value[-1]) && %q{"'}.include?(value[0])
    str_value = value[1..-2]
    if str_value.include?(value[0])
      value = 'concat("' + str_value.split('"', -1).join(%q{",'"',"}) + '","")'
    end
  end

  case node.value[1]
  when :equal
    attribute + "=" + value.to_s
  when :not_equal
    attribute + "!=" + value.to_s
  when :substring_match
    "contains(#{attribute},#{value})"
  when :prefix_match
    "starts-with(#{attribute},#{value})"
  when :dash_match
    "#{attribute}=#{value} or starts-with(#{attribute},concat(#{value},'-'))"
  when :includes
    value = value[1..-2] # strip quotes
    css_class(attribute, value)
  when :suffix_match
    "substring(#{attribute},string-length(#{attribute})-string-length(#{value})+1,string-length(#{value}))=#{value}"
  else
    attribute + " #{node.value[1]} " + value.to_s
  end
end

#visit_class_condition(node) ⇒ Object 



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# File 'lib/nokogiri/css/xpath_visitor.rb', line 237

def visit_class_condition(node)
  css_class("@class", node.value.first)
end

#visit_combinator(node) ⇒ Object 



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# File 'lib/nokogiri/css/xpath_visitor.rb', line 241

def visit_combinator(node)
  if is_of_type_pseudo_class?(node.value.last)
    "#{node.value.first&.accept(self)}][#{node.value.last.accept(self)}"
  else
    "#{node.value.first&.accept(self)} and #{node.value.last.accept(self)}"
  end
end

#visit_conditional_selector(node) ⇒ Object 



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# File 'lib/nokogiri/css/xpath_visitor.rb', line 262

def visit_conditional_selector(node)
  node.value.first.accept(self) + "[" +
    node.value.last.accept(self) + "]"
end

#visit_element_name(node) ⇒ Object 



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# File 'lib/nokogiri/css/xpath_visitor.rb', line 267

def visit_element_name(node)
  if @doctype == DoctypeConfig::HTML5 && html5_element_name_needs_namespace_handling(node)
    # HTML5 has namespaces that should be ignored in CSS queries
    # https://github.com/sparklemotion/nokogiri/issues/2376
    if @builtins == BuiltinsConfig::ALWAYS || (@builtins == BuiltinsConfig::OPTIMAL && Nokogiri.uses_libxml?)
      if WILDCARD_NAMESPACES
        "*:#{node.value.first}"
      else
        "*[nokogiri-builtin:local-name-is('#{node.value.first}')]"
      end
    else
      "*[local-name()='#{node.value.first}']"
    end
  elsif node.value.length == 2 # has a namespace prefix
    if node.value.first.nil? # namespace prefix is empty
      node.value.last
    else
      node.value.join(":")
    end
  elsif @namespaces&.key?("xmlns") # apply the default namespace if it's declared
    "xmlns:#{node.value.first}"
  else
    node.value.first
  end
end

#visit_function(node) ⇒ Object

:stopdoc:



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# File 'lib/nokogiri/css/xpath_visitor.rb', line 98

def visit_function(node)
  msg = :"visit_function_#{node.value.first.gsub(/[(]/, "")}"
  return send(msg, node) if respond_to?(msg)

  case node.value.first
  when /^text\(/
    "child::text()"
  when /^self\(/
    "self::#{node.value[1]}"
  when /^eq\(/
    "position()=#{node.value[1]}"
  when /^(nth|nth-of-type)\(/
    if node.value[1].is_a?(Nokogiri::CSS::Node) && (node.value[1].type == :NTH)
      nth(node.value[1])
    else
      "position()=#{node.value[1]}"
    end
  when /^nth-child\(/
    if node.value[1].is_a?(Nokogiri::CSS::Node) && (node.value[1].type == :NTH)
      nth(node.value[1], child: true)
    else
      "count(preceding-sibling::*)=#{node.value[1].to_i - 1}"
    end
  when /^nth-last-of-type\(/
    if node.value[1].is_a?(Nokogiri::CSS::Node) && (node.value[1].type == :NTH)
      nth(node.value[1], last: true)
    else
      index = node.value[1].to_i - 1
      index == 0 ? "position()=last()" : "position()=last()-#{index}"
    end
  when /^nth-last-child\(/
    if node.value[1].is_a?(Nokogiri::CSS::Node) && (node.value[1].type == :NTH)
      nth(node.value[1], last: true, child: true)
    else
      "count(following-sibling::*)=#{node.value[1].to_i - 1}"
    end
  when /^(first|first-of-type)\(/
    "position()=1"
  when /^(last|last-of-type)\(/
    "position()=last()"
  when /^contains\(/
    "contains(.,#{node.value[1]})"
  when /^gt\(/
    "position()>#{node.value[1]}"
  when /^only-child\(/
    "last()=1"
  when /^comment\(/
    "comment()"
  when /^has\(/
    is_direct = node.value[1].value[0].nil? # e.g. "has(> a)", "has(~ a)", "has(+ a)"
    ".#{"//" unless is_direct}#{node.value[1].accept(self)}"
  else
    validate_xpath_function_name(node.value.first)

    # xpath function call, let's marshal those arguments
    args = ["."]
    args += node.value[1..-1].map do |n|
      n.is_a?(Nokogiri::CSS::Node) ? n.accept(self) : n
    end
    "nokogiri:#{node.value.first}#{args.join(",")})"
  end
end

#visit_id(node) ⇒ Object 



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# File 'lib/nokogiri/css/xpath_visitor.rb', line 170

def visit_id(node)
  node.value.first =~ /^#(.*)$/
  "@id='#{Regexp.last_match(1)}'"
end

#visit_not(node) ⇒ Object 



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# File 'lib/nokogiri/css/xpath_visitor.rb', line 161

def visit_not(node)
  child = node.value.first
  if :ELEMENT_NAME == child.type
    "not(self::#{child.accept(self)})"
  else
    "not(#{child.accept(self)})"
  end
end

#visit_pseudo_class(node) ⇒ Object 



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# File 'lib/nokogiri/css/xpath_visitor.rb', line 211

def visit_pseudo_class(node)
  if node.value.first.is_a?(Nokogiri::CSS::Node) && (node.value.first.type == :FUNCTION)
    node.value.first.accept(self)
  else
    msg = :"visit_pseudo_class_#{node.value.first.gsub(/[(]/, "")}"
    return send(msg, node) if respond_to?(msg)

    case node.value.first
    when "first" then "position()=1"
    when "first-child" then "count(preceding-sibling::*)=0"
    when "last" then "position()=last()"
    when "last-child" then "count(following-sibling::*)=0"
    when "first-of-type" then "position()=1"
    when "last-of-type" then "position()=last()"
    when "only-child" then "count(preceding-sibling::*)=0 and count(following-sibling::*)=0"
    when "only-of-type" then "last()=1"
    when "empty" then "not(node())"
    when "parent" then "node()"
    when "root" then "not(parent::*)"
    else
      validate_xpath_function_name(node.value.first)
      "nokogiri:#{node.value.first}(.)"
    end
  end
end