530 lines
17 KiB
Ruby
530 lines
17 KiB
Ruby
require 'strscan'
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module XHTML #:nodoc:
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class Conditions < Hash #:nodoc:
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def initialize(hash)
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super()
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hash = { :content => hash } unless Hash === hash
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hash = keys_to_symbols(hash)
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hash.each do |k,v|
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case k
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when :tag, :content then
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# keys are valid, and require no further processing
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when :attributes then
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hash[k] = keys_to_strings(v)
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when :parent, :child, :ancestor, :descendant, :sibling, :before,
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:after
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hash[k] = Conditions.new(v)
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when :children
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hash[k] = v = keys_to_symbols(v)
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v.each do |k,v2|
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case k
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when :count, :greater_than, :less_than
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# keys are valid, and require no further processing
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when :only
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v[k] = Conditions.new(v2)
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else
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raise "illegal key #{k.inspect} => #{v2.inspect}"
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end
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end
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else
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raise "illegal key #{k.inspect} => #{v.inspect}"
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end
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end
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update hash
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end
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private
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def keys_to_strings(hash)
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hash.keys.inject({}) do |h,k|
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h[k.to_s] = hash[k]
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h
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end
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end
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def keys_to_symbols(hash)
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hash.keys.inject({}) do |h,k|
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raise "illegal key #{k.inspect}" unless k.respond_to?(:to_sym)
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h[k.to_sym] = hash[k]
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h
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end
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end
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end
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# The base class of all nodes, textual and otherwise, in an HTML document.
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class Node #:nodoc:
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# The array of children of this node. Not all nodes have children.
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attr_reader :children
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# The parent node of this node. All nodes have a parent, except for the
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# root node.
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attr_reader :parent
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# The line number of the input where this node was begun
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attr_reader :line
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# The byte position in the input where this node was begun
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attr_reader :position
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# Create a new node as a child of the given parent.
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def initialize(parent, line=0, pos=0)
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@parent = parent
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@children = []
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@line, @position = line, pos
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end
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# Return a textual representation of the node.
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def to_s
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s = ""
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@children.each { |child| s << child.to_s }
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s
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end
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# Return false (subclasses must override this to provide specific matching
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# behavior.) +conditions+ may be of any type.
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def match(conditions)
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false
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end
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# Search the children of this node for the first node for which #find
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# returns non +nil+. Returns the result of the #find call that succeeded.
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def find(conditions)
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conditions = validate_conditions(conditions)
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@children.each do |child|
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node = child.find(conditions)
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return node if node
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end
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nil
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end
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# Search for all nodes that match the given conditions, and return them
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# as an array.
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def find_all(conditions)
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conditions = validate_conditions(conditions)
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matches = []
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matches << self if match(conditions)
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@children.each do |child|
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matches.concat child.find_all(conditions)
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end
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matches
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end
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# Returns +false+. Subclasses may override this if they define a kind of
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# tag.
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def tag?
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false
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end
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def validate_conditions(conditions)
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Conditions === conditions ? conditions : Conditions.new(conditions)
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end
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def ==(node)
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return false unless self.class == node.class && children.size == node.children.size
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equivalent = true
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children.size.times do |i|
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equivalent &&= children[i] == node.children[i]
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end
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equivalent
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end
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class <<self
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def parse(parent, line, pos, content, strict=true)
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if content !~ /^<\S/
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Text.new(parent, line, pos, content)
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else
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scanner = StringScanner.new(content)
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unless scanner.skip(/</)
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if strict
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raise "expected <"
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else
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return Text.new(parent, line, pos, content)
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end
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end
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if scanner.skip(/!\[CDATA\[/)
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scanner.scan_until(/\]\]>/)
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return CDATA.new(parent, line, pos, scanner.pre_match.gsub(/<!\[CDATA\[/, ''))
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end
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closing = ( scanner.scan(/\//) ? :close : nil )
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return Text.new(parent, line, pos, content) unless name = scanner.scan(/[\w:-]+/)
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name
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unless closing
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scanner.skip(/\s*/)
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attributes = {}
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while attr = scanner.scan(/[-\w:]+/)
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value = true
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if scanner.scan(/\s*=\s*/)
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if delim = scanner.scan(/['"]/)
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value = ""
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while text = scanner.scan(/[^#{delim}\\]+|./)
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case text
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when "\\" then
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value << text
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value << scanner.getch
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when delim
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break
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else value << text
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end
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end
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else
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value = scanner.scan(/[^\s>\/]+/)
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end
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end
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attributes[attr] = value
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scanner.skip(/\s*/)
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end
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closing = ( scanner.scan(/\//) ? :self : nil )
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end
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unless scanner.scan(/\s*>/)
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if strict
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raise "expected > (got #{scanner.rest.inspect} for #{content}, #{attributes.inspect})"
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else
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# throw away all text until we find what we're looking for
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scanner.skip_until(/>/) or scanner.terminate
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end
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end
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Tag.new(parent, line, pos, name, attributes, closing)
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end
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end
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end
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end
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# A node that represents text, rather than markup.
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class Text < Node #:nodoc:
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attr_reader :content
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# Creates a new text node as a child of the given parent, with the given
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# content.
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def initialize(parent, line, pos, content)
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super(parent, line, pos)
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@content = content
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end
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# Returns the content of this node.
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def to_s
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@content
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end
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# Returns +self+ if this node meets the given conditions. Text nodes support
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# conditions of the following kinds:
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#
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# * if +conditions+ is a string, it must be a substring of the node's
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# content
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# * if +conditions+ is a regular expression, it must match the node's
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# content
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# * if +conditions+ is a hash, it must contain a <tt>:content</tt> key that
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# is either a string or a regexp, and which is interpreted as described
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# above.
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def find(conditions)
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match(conditions) && self
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end
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# Returns non-+nil+ if this node meets the given conditions, or +nil+
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# otherwise. See the discussion of #find for the valid conditions.
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def match(conditions)
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case conditions
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when String
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@content == conditions
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when Regexp
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@content =~ conditions
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when Hash
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conditions = validate_conditions(conditions)
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# Text nodes only have :content, :parent, :ancestor
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unless (conditions.keys - [:content, :parent, :ancestor]).empty?
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return false
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end
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match(conditions[:content])
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else
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nil
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end
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end
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def ==(node)
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return false unless super
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content == node.content
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end
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end
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# A CDATA node is simply a text node with a specialized way of displaying
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# itself.
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class CDATA < Text #:nodoc:
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def to_s
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"<![CDATA[#{super}]>"
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end
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end
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# A Tag is any node that represents markup. It may be an opening tag, a
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# closing tag, or a self-closing tag. It has a name, and may have a hash of
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# attributes.
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class Tag < Node #:nodoc:
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# Either +nil+, <tt>:close</tt>, or <tt>:self</tt>
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attr_reader :closing
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# Either +nil+, or a hash of attributes for this node.
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attr_reader :attributes
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# The name of this tag.
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attr_reader :name
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# Create a new node as a child of the given parent, using the given content
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# to describe the node. It will be parsed and the node name, attributes and
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# closing status extracted.
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def initialize(parent, line, pos, name, attributes, closing)
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super(parent, line, pos)
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@name = name
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@attributes = attributes
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@closing = closing
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end
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# A convenience for obtaining an attribute of the node. Returns +nil+ if
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# the node has no attributes.
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def [](attr)
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@attributes ? @attributes[attr] : nil
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end
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# Returns non-+nil+ if this tag can contain child nodes.
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def childless?(xml = false)
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return false if xml && @closing.nil?
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!@closing.nil? ||
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@name =~ /^(img|br|hr|link|meta|area|base|basefont|
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col|frame|input|isindex|param)$/ox
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end
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# Returns a textual representation of the node
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def to_s
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if @closing == :close
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"</#{@name}>"
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else
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s = "<#{@name}"
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@attributes.each do |k,v|
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s << " #{k}"
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s << "=\"#{v}\"" if String === v
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end
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s << " /" if @closing == :self
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s << ">"
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@children.each { |child| s << child.to_s }
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s << "</#{@name}>" if @closing != :self && !@children.empty?
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s
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end
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end
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# If either the node or any of its children meet the given conditions, the
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# matching node is returned. Otherwise, +nil+ is returned. (See the
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# description of the valid conditions in the +match+ method.)
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def find(conditions)
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match(conditions) && self || super
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end
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# Returns +true+, indicating that this node represents an HTML tag.
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def tag?
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true
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end
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# Returns +true+ if the node meets any of the given conditions. The
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# +conditions+ parameter must be a hash of any of the following keys
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# (all are optional):
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#
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# * <tt>:tag</tt>: the node name must match the corresponding value
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# * <tt>:attributes</tt>: a hash. The node's values must match the
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# corresponding values in the hash.
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# * <tt>:parent</tt>: a hash. The node's parent must match the
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# corresponding hash.
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# * <tt>:child</tt>: a hash. At least one of the node's immediate children
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# must meet the criteria described by the hash.
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# * <tt>:ancestor</tt>: a hash. At least one of the node's ancestors must
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# meet the criteria described by the hash.
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# * <tt>:descendant</tt>: a hash. At least one of the node's descendants
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# must meet the criteria described by the hash.
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# * <tt>:sibling</tt>: a hash. At least one of the node's siblings must
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# meet the criteria described by the hash.
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# * <tt>:after</tt>: a hash. The node must be after any sibling meeting
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# the criteria described by the hash, and at least one sibling must match.
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# * <tt>:before</tt>: a hash. The node must be before any sibling meeting
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# the criteria described by the hash, and at least one sibling must match.
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# * <tt>:children</tt>: a hash, for counting children of a node. Accepts the
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# keys:
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# ** <tt>:count</tt>: either a number or a range which must equal (or
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# include) the number of children that match.
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# ** <tt>:less_than</tt>: the number of matching children must be less than
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# this number.
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# ** <tt>:greater_than</tt>: the number of matching children must be
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# greater than this number.
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# ** <tt>:only</tt>: another hash consisting of the keys to use
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# to match on the children, and only matching children will be
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# counted.
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#
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# Conditions are matched using the following algorithm:
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#
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# * if the condition is a string, it must be a substring of the value.
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# * if the condition is a regexp, it must match the value.
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# * if the condition is a number, the value must match number.to_s.
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# * if the condition is +true+, the value must not be +nil+.
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# * if the condition is +false+ or +nil+, the value must be +nil+.
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#
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# Usage:
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#
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# # test if the node is a "span" tag
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# node.match :tag => "span"
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#
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# # test if the node's parent is a "div"
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# node.match :parent => { :tag => "div" }
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#
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# # test if any of the node's ancestors are "table" tags
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# node.match :ancestor => { :tag => "table" }
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#
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# # test if any of the node's immediate children are "em" tags
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# node.match :child => { :tag => "em" }
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#
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# # test if any of the node's descendants are "strong" tags
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# node.match :descendant => { :tag => "strong" }
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#
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# # test if the node has between 2 and 4 span tags as immediate children
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# node.match :children => { :count => 2..4, :only => { :tag => "span" } }
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#
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# # get funky: test to see if the node is a "div", has a "ul" ancestor
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# # and an "li" parent (with "class" = "enum"), and whether or not it has
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# # a "span" descendant that contains # text matching /hello world/:
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# node.match :tag => "div",
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# :ancestor => { :tag => "ul" },
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# :parent => { :tag => "li",
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# :attributes => { :class => "enum" } },
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# :descendant => { :tag => "span",
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# :child => /hello world/ }
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def match(conditions)
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conditions = validate_conditions(conditions)
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# check content of child nodes
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if conditions[:content]
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if children.empty?
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return false unless match_condition("", conditions[:content])
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else
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return false unless children.find { |child| child.match(conditions[:content]) }
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end
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end
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# test the name
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return false unless match_condition(@name, conditions[:tag]) if conditions[:tag]
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# test attributes
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(conditions[:attributes] || {}).each do |key, value|
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return false unless match_condition(self[key], value)
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end
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# test parent
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return false unless parent.match(conditions[:parent]) if conditions[:parent]
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# test children
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return false unless children.find { |child| child.match(conditions[:child]) } if conditions[:child]
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# test ancestors
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if conditions[:ancestor]
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return false unless catch :found do
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p = self
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throw :found, true if p.match(conditions[:ancestor]) while p = p.parent
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end
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end
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# test descendants
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if conditions[:descendant]
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return false unless children.find do |child|
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# test the child
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child.match(conditions[:descendant]) ||
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# test the child's descendants
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child.match(:descendant => conditions[:descendant])
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end
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end
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# count children
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if opts = conditions[:children]
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matches = children.select do |c|
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(c.kind_of?(HTML::Tag) and (c.closing == :self or ! c.childless?))
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end
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matches = matches.select { |c| c.match(opts[:only]) } if opts[:only]
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opts.each do |key, value|
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next if key == :only
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case key
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when :count
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if Integer === value
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return false if matches.length != value
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else
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return false unless value.include?(matches.length)
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end
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when :less_than
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return false unless matches.length < value
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when :greater_than
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return false unless matches.length > value
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else raise "unknown count condition #{key}"
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end
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end
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end
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# test siblings
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if conditions[:sibling] || conditions[:before] || conditions[:after]
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siblings = parent ? parent.children : []
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self_index = siblings.index(self)
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if conditions[:sibling]
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return false unless siblings.detect do |s|
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s != self && s.match(conditions[:sibling])
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end
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end
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if conditions[:before]
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return false unless siblings[self_index+1..-1].detect do |s|
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s != self && s.match(conditions[:before])
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end
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end
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if conditions[:after]
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return false unless siblings[0,self_index].detect do |s|
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s != self && s.match(conditions[:after])
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end
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end
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end
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true
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end
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def ==(node)
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return false unless super
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return false unless closing == node.closing && self.name == node.name
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attributes == node.attributes
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end
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private
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# Match the given value to the given condition.
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def match_condition(value, condition)
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case condition
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when String
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value && value == condition
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when Regexp
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value && value.match(condition)
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when Numeric
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value == condition.to_s
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when true
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!value.nil?
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when false, nil
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value.nil?
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else
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false
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end
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end
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end
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end
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