/
xpath_visitor.rb
156 lines (135 loc) · 4.43 KB
/
xpath_visitor.rb
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module Nokogiri
module CSS
class XPathVisitor
def visit_function node
# note that nth-child and nth-last-child are preprocessed in css/node.rb.
case node.value.first
when /^text\(/
'child::text()'
when /^self\(/
"self::#{node.value[1]}"
when /^(eq|nth|nth-of-type|nth-child)\(/
if node.value[1].is_a?(Nokogiri::CSS::Node) and node.value[1].type == :AN_PLUS_B
an_plus_b(node.value[1])
else
"position() = " + node.value[1]
end
when /^(first|first-of-type)\(/
"position() = 1"
when /^(last|last-of-type)\(/
"position() = last()"
when /^(nth-last-child|nth-last-of-type)\(/
"position() = last() - #{node.value[1]}"
when /^contains\(/
"contains(., #{node.value[1]})"
when /^gt\(/
"position() > #{node.value[1]}"
when /^only-child\(/
"last() = 1"
else
node.value.first + ')'
end
end
def visit_not node
'not(' + node.value.first.accept(self) + ')'
end
def visit_preceding_selector node
node.value.last.accept(self) +
'[preceding-sibling::' +
node.value.first.accept(self) +
']'
end
def visit_direct_adjacent_selector node
node.value.first.accept(self) +
"/following-sibling::*[1]/self::" +
node.value.last.accept(self)
end
def visit_id node
node.value.first =~ /^#(.*)$/
"@id = '#{$1}'"
end
def visit_attribute_condition node
# attribute = if (node.value.first.type == :FUNCTION) or (node.value.first.value.first =~ /^@/)
# ''
# else
# 'child::'
# end
attribute = "@#{node.value.first.accept(self)}"
# Support non-standard css
attribute.gsub!(/^@@/, '@')
return attribute unless node.value.length == 3
value = node.value.last
value = "'#{value}'" if value !~ /^['"]/
case node.value[1]
when '*='
"contains(#{attribute}, #{value})"
when '~='
"contains(concat(\" \", #{attribute}, \" \"),concat(\" \", #{value}, \" \"))"
when '$='
"substring(#{attribute}, string-length(#{attribute}) - " +
"string-length(#{value}) + 1, string-length(#{value})) = #{value}"
when '^='
"starts-with(#{attribute}, #{value})"
else
attribute + " #{node.value[1]} " + "#{value}"
end
end
def visit_pseudo_class node
if node.value.first.is_a?(Nokogiri::CSS::Node) and node.value.first.type == :FUNCTION
node.value.first.accept(self)
else
case node.value.first
when "first" then "position() = 1"
when "last" then "position() = last()"
when "first-of-type" then "position() = 1"
when "last-of-type" then "position() = last()"
when "only-of-type" then "last() = 1"
when "empty" then "not(node())"
when "parent" then "node()"
else
'1 = 1'
end
end
end
def visit_class_condition node
"contains(concat(' ', @class, ' '), ' #{node.value.first} ')"
end
def visit_combinator node
node.value.first.accept(self) + ' and ' +
node.value.last.accept(self)
end
def visit_conditional_selector node
node.value.first.accept(self) + '[' +
node.value.last.accept(self) + ']'
end
def visit_descendant_selector node
node.value.first.accept(self) +
'//' +
node.value.last.accept(self)
end
def visit_child_selector node
node.value.first.accept(self) +
'/' +
node.value.last.accept(self)
end
def visit_element_name node
node.value.first
end
def accept node
node.accept(self)
end
private
def an_plus_b node
raise ArgumentError, "expected an+b node to contain 4 tokens, but is #{node.value.inspect}" unless node.value.size == 4
a = node.value[0].to_i
b = node.value[3].to_i
if (b == 0)
return "(position() mod #{a}) = 0"
else
compare = (a < 0) ? "<=" : ">="
return "(position() #{compare} #{b}) and (((position()-#{b}) mod #{a.abs}) = 0)"
end
end
end
end
end