class REXML::QuickPath - rexml: Ruby Standard Library Documentation

# class REXML::QuickPath

### Constants

EMPTY_HASH

  A base Hash object to be used when initializing a default empty namespaces set.

OPERAND_

### Public Class Methods

attribute( name ) click to toggle source

    # File rexml-3.4.0/lib/rexml/quickpath.rb, line 206
    def QuickPath::attribute( name )
      return Functions.node.attributes[name] if Functions.node.kind_of? Element
    end

axe( elements, axe_name, rest ) click to toggle source

    # File rexml-3.4.0/lib/rexml/quickpath.rb, line 106
    def QuickPath::axe( elements, axe_name, rest )
      matches = []
      matches = filter( elements.dup, rest ) if axe_name =~ /-or-self$/u
      case axe_name
      when /^descendant/u
        elements.each do |element|
          matches |= filter( element.to_a, "descendant-or-self::#{rest}" ) if element.kind_of? Element
        end
      when /^ancestor/u
        elements.each do |element|
          while element.parent
            matches << element.parent
            element = element.parent
          end
        end
        matches = filter( matches, rest )
      when "self"
        matches = filter( elements, rest )
      when "child"
        elements.each do |element|
          matches |= filter( element.to_a, rest ) if element.kind_of? Element
        end
      when "attribute"
        elements.each do |element|
          matches << element.attributes[ rest ] if element.kind_of? Element
        end
      when "parent"
        matches = filter(elements.collect{|element| element.parent}.uniq, rest)
      when "following-sibling"
        matches = filter(elements.collect{|element| element.next_sibling}.uniq,
          rest)
      when "previous-sibling"
        matches = filter(elements.collect{|element|
          element.previous_sibling}.uniq, rest )
      end
      return matches.uniq
    end

each(element, path, namespaces=EMPTY_HASH, &block) click to toggle source

    # File rexml-3.4.0/lib/rexml/quickpath.rb, line 18
    def QuickPath::each element, path, namespaces=EMPTY_HASH, &block
      path = "*" unless path
      match(element, path, namespaces).each( &block )
    end

filter(elements, path) click to toggle source

Given an array of nodes it filters the array based on the path. The result is that when this method returns, the array will contain elements which match the path

    # File rexml-3.4.0/lib/rexml/quickpath.rb, line 50
    def QuickPath::filter elements, path
      return elements if path.nil? or path == '' or elements.size == 0
      case path
      when /^\/\//u                                                                                     # Descendant
        return axe( elements, "descendant-or-self", $' )
      when /^\/?\b(\w[-\w]*)\b::/u                                                      # Axe
        return axe( elements, $1, $' )
      when /^\/(?=\b([:!\w][-\.\w]*:)?[-!\*\.\w]*\b([^:(]|$)|\*)/u      # Child
        rest = $'
        results = []
        elements.each do |element|
          results |= filter( element.to_a, rest )
        end
        return results
      when /^\/?(\w[-\w]*)\(/u                                                  # / Function
        return function( elements, $1, $' )
      when Namespace::NAMESPLIT         # Element name
        name = $2
        ns = $1
        rest = $'
        elements.delete_if do |element|
          !(element.kind_of? Element and
            (element.expanded_name == name or
             (element.name == name and
              element.namespace == Functions.namespace_context[ns])))
        end
        return filter( elements, rest )
      when /^\/\[/u
        matches = []
        elements.each do |element|
          matches |= predicate( element.to_a, path[1..-1] ) if element.kind_of? Element
        end
        return matches
      when /^\[/u                                                                                               # Predicate
        return predicate( elements, path )
      when /^\/?\.\.\./u                                                                                # Ancestor
        return axe( elements, "ancestor", $' )
      when /^\/?\.\./u                                                                                  # Parent
        return filter( elements.collect{|e|e.parent}, $' )
      when /^\/?\./u                                                                                            # Self
        return filter( elements, $' )
      when /^\*/u                                                                                                       # Any
        results = []
        elements.each do |element|
          results |= filter( [element], $' ) if element.kind_of? Element
          #if element.kind_of? Element
          #     children = element.to_a
          #     children.delete_if { |child| !child.kind_of?(Element) }
          #     results |= filter( children, $' )
          #end
        end
        return results
      end
      return []
    end

first(element, path, namespaces=EMPTY_HASH) click to toggle source

    # File rexml-3.4.0/lib/rexml/quickpath.rb, line 14
    def QuickPath::first element, path, namespaces=EMPTY_HASH
      match(element, path, namespaces)[0]
    end

function( elements, fname, rest ) click to toggle source

    # File rexml-3.4.0/lib/rexml/quickpath.rb, line 222
    def QuickPath::function( elements, fname, rest )
      args = parse_args( elements, rest )
      Functions.pair = [0, elements.size]
      results = []
      elements.each do |element|
        Functions.pair[0] += 1
        Functions.node = element
        res = Functions.send( fname, *args )
        case res
        when true
          results << element
        when Integer
          results << element if Functions.pair[0] == res
        end
      end
      return results
    end

match(element, path, namespaces=EMPTY_HASH) click to toggle source

    # File rexml-3.4.0/lib/rexml/quickpath.rb, line 23
    def QuickPath::match element, path, namespaces=EMPTY_HASH
      raise "nil is not a valid xpath" unless path
      results = nil
      Functions::namespace_context = namespaces
      case path
      when /^\/([^\/]|$)/u
        # match on root
        path = path[1..-1]
        return [element.root.parent] if path == ''
        results = filter([element.root], path)
      when /^[-\w]*::/u
        results = filter([element], path)
      when /^\*/u
        results = filter(element.to_a, path)
      when /^[\[!\w:]/u
        # match on child
        children = element.to_a
        results = filter(children, path)
      else
        results = filter([element], path)
      end
      return results
    end

method_missing( id, *args ) click to toggle source

    # File rexml-3.4.0/lib/rexml/quickpath.rb, line 214
    def QuickPath::method_missing( id, *args )
      begin
        Functions.send( id.id2name, *args )
      rescue Exception
        raise "METHOD: #{id.id2name}(#{args.join ', '})\n#{$!.message}"
      end
    end

name() click to toggle source

    # File rexml-3.4.0/lib/rexml/quickpath.rb, line 210
    def QuickPath::name()
      return Functions.node.name if Functions.node.kind_of? Element
    end

parse_args( element, string ) click to toggle source

    # File rexml-3.4.0/lib/rexml/quickpath.rb, line 240
    def QuickPath::parse_args( element, string )
      # /.*?(?:\)|,)/
      arguments = []
      buffer = ""
      while string and string != ""
        c = string[0]
        string.sub!(/^./u, "")
        case c
        when ?,
          # if depth = 1, then we start a new argument
          arguments << evaluate( buffer )
          #arguments << evaluate( string[0..count] )
        when ?(
          # start a new method call
          function( element, buffer, string )
          buffer = ""
        when ?)
          # close the method call and return arguments
          return arguments
        else
          buffer << c
        end
      end
      ""
    end

predicate( elements, path ) click to toggle source

A predicate filters a node-set with respect to an axis to produce a new node-set. For each node in the node-set to be filtered, the PredicateExpr is evaluated with that node as the context node, with the number of nodes in the node-set as the context size, and with the proximity position of the node in the node-set with respect to the axis as the context position; if PredicateExpr evaluates to true for that node, the node is included in the new node-set; otherwise, it is not included.

A PredicateExpr is evaluated by evaluating the Expr and converting the result to a boolean. If the result is a number, the result will be converted to true if the number is equal to the context position and will be converted to false otherwise; if the result is not a number, then the result will be converted as if by a call to the boolean function. Thus a location path para is equivalent to para.

    # File rexml-3.4.0/lib/rexml/quickpath.rb, line 161
    def QuickPath::predicate( elements, path )
      ind = 1
      bcount = 1
      while bcount > 0
        bcount += 1 if path[ind] == ?[
        bcount -= 1 if path[ind] == ?]
        ind += 1
      end
      ind -= 1
      predicate = path[1..ind-1]
      rest = path[ind+1..-1]

      # have to change 'a [=<>] b [=<>] c' into 'a [=<>] b and b [=<>] c'
      #
      predicate.gsub!(
        /#{OPERAND_}\s*([<>=])\s*#{OPERAND_}\s*([<>=])\s*#{OPERAND_}/u,
        '\1 \2 \3 and \3 \4 \5' )
      # Let's do some Ruby trickery to avoid some work:
      predicate.gsub!( /&/u, "&&" )
      predicate.gsub!( /=/u, "==" )
      predicate.gsub!( /@(\w[-\w.]*)/u, 'attribute("\1")' )
      predicate.gsub!( /\bmod\b/u, "%" )
      predicate.gsub!( /\b(\w[-\w.]*\()/u ) {
        fname = $1
        fname.gsub( /-/u, "_" )
      }

      Functions.pair = [ 0, elements.size ]
      results = []
      elements.each do |element|
        Functions.pair[0] += 1
        Functions.node = element
        res = eval( predicate )
        case res
        when true
          results << element
        when Integer
          results << element if Functions.pair[0] == res
        when String
          results << element
        end
      end
      return filter( results, rest )
    end