Class: REXML::QuickPath

Inherits:

Object

• Object
• REXML::QuickPath

Includes:

Functions, XMLTokens

Defined in:

lib/rexml/quickpath.rb

Constant Summary

EMPTY_HASH =

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

{}

OPERAND_ =

'((?=(?:(?!and|or).)*[^\s<>=])[^\s<>=]+)'

Constants included from XMLTokens

XMLTokens::NAME, XMLTokens::NAMECHAR, XMLTokens::NAME_CHAR, XMLTokens::NAME_START_CHAR, XMLTokens::NAME_STR, XMLTokens::NCNAME_STR, XMLTokens::NMTOKEN, XMLTokens::NMTOKENS, XMLTokens::REFERENCE

Class Method Summary

• .attribute(name) ⇒ Object
• .axe(elements, axe_name, rest) ⇒ Object
• .each(element, path, namespaces = EMPTY_HASH, &block) ⇒ Object
• .filter(elements, path) ⇒ Object

  Given an array of nodes it filters the array based on the path.

• .first(element, path, namespaces = EMPTY_HASH) ⇒ Object
• .function(elements, fname, rest) ⇒ Object
• .match(element, path, namespaces = EMPTY_HASH) ⇒ Object
• .method_missing(id, *args) ⇒ Object
• .name ⇒ Object
• .parse_args(element, string) ⇒ Object
• .predicate(elements, path) ⇒ Object

  A predicate filters a node-set with respect to an axis to produce a new node-set.

Methods included from Functions

boolean, ceiling, compare_language, concat, contains, context=, count, false, floor, get_namespace, id, lang, last, local_name, namespace_context, namespace_context=, namespace_uri, normalize_space, not, number, position, processing_instruction, round, starts_with, string, string_length, string_value, substring, substring_after, substring_before, sum, text, translate, true, variables, variables=

Class Method Details

.attribute(name) ⇒ Object

# File '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) ⇒ Object

# File '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) ⇒ Object

# File '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) ⇒ Object

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 '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) ⇒ Object

# File 'lib/rexml/quickpath.rb', line 14

def QuickPath::first element, path, namespaces=EMPTY_HASH
  match(element, path, namespaces)[0]
end

.function(elements, fname, rest) ⇒ Object

# File '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 Fixnum
      results << element if Functions.pair[0] == res
    end
  end
  return results
end

.match(element, path, namespaces = EMPTY_HASH) ⇒ Object

# File '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) ⇒ Object

# File '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 ⇒ Object

# File 'lib/rexml/quickpath.rb', line 210

def QuickPath::name()
  return Functions.node.name if Functions.node.kind_of? Element
end

.parse_args(element, string) ⇒ Object

# File '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) ⇒ Object

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 '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 Fixnum
      results << element if Functions.pair[0] == res
    when String
      results << element
    end
  end
  return filter( results, rest )
end