Class: Hexp::CssSelector::Parser

Inherits:
Object
  • Object
show all
Defined in:
lib/hexp/css_selector/parser.rb

Overview

A parser of CSS selectors

This is a wrapper around the SASS parser. This way we are isolated from changes in SASS. It also makes things easier should we decide to switch to a different parsing library or roll our own parser. We only use a fraction of the functionality of SASS so this might be worth it, although at this point I want to avoid reinventing that wheel.

The classes that make up the parse tree largely mimic the ones from SASS, like CommaSequence, SimpleSequence, Class, Id, etc. By having them in our own namespace however we can easily add Hexp-specific functionality to them.

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(selector) ⇒ Parser

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Initialize the parser with the selector to parse

Parameters:

  • selector (String) 


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# File 'lib/hexp/css_selector/parser.rb', line 21

def initialize(selector)
  @selector = selector.freeze
end

Class Method Details

.call(selector) ⇒ Hexp::CssSelector::CommaSequence

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Parse a CSS selector in one go

Parameters:

  • selector (String)

Returns:



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# File 'lib/hexp/css_selector/parser.rb', line 44

def self.call(selector)
  new(selector).parse
end

Instance Method Details

#parse ⇒ Hexp::CssSelector::CommaSequence

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Parse the selector

Returns:



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# File 'lib/hexp/css_selector/parser.rb', line 30

def parse
  CommaSequence.new(
    ::Nokogiri::CSS.parse(@selector).map do |node|
      node.accept(self)
    end
  )
end

#visit_attribute_condition(node) ⇒ Object

href^=“http://” 


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# File 'lib/hexp/css_selector/parser.rb', line 90

def visit_attribute_condition(node)
  element, operator, value = node.value
  name = element.value.first
  Attribute.new(name.sub(/^@/, ''), operator, value)
end

#visit_child_selector(node) ⇒ Object

ul > li



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# File 'lib/hexp/css_selector/parser.rb', line 85

def visit_child_selector(node)
  raise "not implemented"
end

#visit_class_condition(node) ⇒ Object 



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# File 'lib/hexp/css_selector/parser.rb', line 76

def visit_class_condition(node)
  Class.new(node.value.first)
end

#visit_conditional_selector(node) ⇒ Object 



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# File 'lib/hexp/css_selector/parser.rb', line 54

def visit_conditional_selector(node)
  head, tail = node.value
  children = [head]
  while tail.type == :COMBINATOR
    head, tail = tail.value
    children << head
  end
  children << tail

  SimpleSequence.new(
    children.map {|child| child.accept(self) }
  )
end

#visit_descendant_selector(node) ⇒ Object 



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# File 'lib/hexp/css_selector/parser.rb', line 48

def visit_descendant_selector(node)
  Sequence.new(
    node.value.map {|child| child.accept(self) }
  )
end

#visit_element_name(node) ⇒ Object 



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# File 'lib/hexp/css_selector/parser.rb', line 68

def visit_element_name(node)
  if node.value == ["*"]
    Universal.new
  else
    Element.new(node.value.first)
  end
end

#visit_id(node) ⇒ Object 



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# File 'lib/hexp/css_selector/parser.rb', line 80

def visit_id(node)
  Id.new(node.value.first.sub(/^#/, ''))
end

#visit_pseudo_selector(node) ⇒ Object

li:first / li:nth-child(3n)



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# File 'lib/hexp/css_selector/parser.rb', line 97

def visit_pseudo_selector(node)
  raise "not implemented"
end