class REXML::Parsers::XPathParser

You don’t want to use this class. Really. Use XPath, which is a wrapper for this class. Believe me. You don’t want to poke around in here. There is strange, dark magic at work in this code. Beware. Go back! Go back while you still can!

Constants

AXIS

RelativeLocationPath

|                                                    Step
  | (AXIS_NAME '::' | '@' | '')                     AxisSpecifier
    NodeTest
      Predicate
  | '.' | '..'                                      AbbreviatedStep
|  RelativeLocationPath '/' Step
| RelativeLocationPath '//' Step

LITERAL

LOCAL_NAME_WILDCARD

NODE_TYPE

NT

NUMBER

PI

PREFIX_WILDCARD

Returns a 1-1 map of the nodeset
The contents of the resulting array are either:
  true/false, if a positive match
  String, if a name match

NodeTest

| ('*' | NCNAME ':' '*' | QNAME)                NameTest
| '*' ':' NCNAME                                NameTest since XPath 2.0
| NODE_TYPE '(' ')'                             NodeType
| PI '(' LITERAL ')'                            PI
  | '[' expr ']'                                Predicate

QNAME

VARIABLE_REFERENCE

Public Instance Methods

abbreviate(path_or_parsed) click to toggle source

# File rexml-3.3.8/lib/rexml/parsers/xpathparser.rb, line 42
def abbreviate(path_or_parsed)
  if path_or_parsed.kind_of?(String)
    parsed = parse(path_or_parsed)
  else
    parsed = path_or_parsed
  end
  components = []
  component = nil
  while parsed.size > 0
    op = parsed.shift
    case op
    when :node
      component << "node()"
    when :attribute
      component = "@"
      components << component
    when :child
      component = ""
      components << component
    when :descendant_or_self
      next_op = parsed[0]
      if next_op == :node
        parsed.shift
        component = ""
        components << component
      else
        component = "descendant-or-self::"
        components << component
      end
    when :self
      next_op = parsed[0]
      if next_op == :node
        parsed.shift
        components << "."
      else
        component = "self::"
        components << component
      end
    when :parent
      next_op = parsed[0]
      if next_op == :node
        parsed.shift
        components << ".."
      else
        component = "parent::"
        components << component
      end
    when :any
      component << "*"
    when :text
      component << "text()"
    when :following, :following_sibling,
          :ancestor, :ancestor_or_self, :descendant,
          :namespace, :preceding, :preceding_sibling
      component = op.to_s.tr("_", "-") << "::"
      components << component
    when :qname
      prefix = parsed.shift
      name = parsed.shift
      component << prefix+":" if prefix.size > 0
      component << name
    when :predicate
      component << '['
      component << predicate_to_path(parsed.shift) {|x| abbreviate(x)}
      component << ']'
    when :document
      components << ""
    when :function
      component << parsed.shift
      component << "( "
      component << predicate_to_path(parsed.shift[0]) {|x| abbreviate(x)}
      component << " )"
    when :literal
      component << quote_literal(parsed.shift)
    else
      component << "UNKNOWN("
      component << op.inspect
      component << ")"
    end
  end
  case components
  when [""]
    "/"
  when ["", ""]
    "//"
  else
    components.join("/")
  end
end

expand(path_or_parsed) click to toggle source

# File rexml-3.3.8/lib/rexml/parsers/xpathparser.rb, line 132
def expand(path_or_parsed)
  if path_or_parsed.kind_of?(String)
    parsed = parse(path_or_parsed)
  else
    parsed = path_or_parsed
  end
  path = ""
  document = false
  while parsed.size > 0
    op = parsed.shift
    case op
    when :node
      path << "node()"
    when :attribute, :child, :following, :following_sibling,
          :ancestor, :ancestor_or_self, :descendant, :descendant_or_self,
          :namespace, :preceding, :preceding_sibling, :self, :parent
      path << "/" unless path.size == 0
      path << op.to_s.tr("_", "-")
      path << "::"
    when :any
      path << "*"
    when :qname
      prefix = parsed.shift
      name = parsed.shift
      path << prefix+":" if prefix.size > 0
      path << name
    when :predicate
      path << '['
      path << predicate_to_path( parsed.shift ) { |x| expand(x) }
      path << ']'
    when :document
      document = true
    else
      path << "UNKNOWN("
      path << op.inspect
      path << ")"
    end
  end
  path = "/"+path if document
  path
end

namespaces=( namespaces ) click to toggle source

# File rexml-3.3.8/lib/rexml/parsers/xpathparser.rb, line 16
def namespaces=( namespaces )
  Functions::namespace_context = namespaces
  @namespaces = namespaces
end

parse(path) click to toggle source

# File rexml-3.3.8/lib/rexml/parsers/xpathparser.rb, line 21
def parse path
  path = path.dup
  path.gsub!(/([\(\[])\s+/, '\1') # Strip ignorable spaces
  path.gsub!( /\s+([\]\)])/, '\1')
  parsed = []
  rest = OrExpr(path, parsed)
  if rest
    unless rest.strip.empty?
      raise ParseException.new("Garbage component exists at the end: " +
                               "<#{rest}>: <#{path}>")
    end
  end
  parsed
end

preciate_to_string(parsed, &block)

For backward compatibility

Alias for: predicate_to_path

predicate(path) click to toggle source

# File rexml-3.3.8/lib/rexml/parsers/xpathparser.rb, line 36
def predicate path
  parsed = []
  Predicate( "[#{path}]", parsed )
  parsed
end

predicate_to_path(parsed) { |parsed| ... } click to toggle source

# File rexml-3.3.8/lib/rexml/parsers/xpathparser.rb, line 174
def predicate_to_path(parsed, &block)
  path = ""
  case parsed[0]
  when :and, :or, :mult, :plus, :minus, :neq, :eq, :lt, :gt, :lteq, :gteq, :div, :mod, :union
    op = parsed.shift
    case op
    when :eq
      op = "="
    when :lt
      op = "<"
    when :gt
      op = ">"
    when :lteq
      op = "<="
    when :gteq
      op = ">="
    when :neq
      op = "!="
    when :union
      op = "|"
    end
    left = predicate_to_path( parsed.shift, &block )
    right = predicate_to_path( parsed.shift, &block )
    path << left
    path << " "
    path << op.to_s
    path << " "
    path << right
  when :function
    parsed.shift
    name = parsed.shift
    path << name
    path << "("
    parsed.shift.each_with_index do |argument, i|
      path << ", " if i > 0
      path << predicate_to_path(argument, &block)
    end
    path << ")"
  when :literal
    parsed.shift
    path << quote_literal(parsed.shift)
  else
    path << yield( parsed )
  end
  return path.squeeze(" ")
end

Also aliased as: preciate_to_string

Private Instance Methods

AdditiveExpr(path, parsed) click to toggle source

| AdditiveExpr (‘+’ | ‘-’) MultiplicativeExpr | MultiplicativeExpr

# File rexml-3.3.8/lib/rexml/parsers/xpathparser.rb, line 505
def AdditiveExpr path, parsed
  n = []
  rest = MultiplicativeExpr( path, n )
  if rest != path
    while rest =~ /^\s*(\+|-)\s*/
      if $1[0] == ?+
        n = [ :plus, n, [] ]
      else
        n = [ :minus, n, [] ]
      end
      rest = MultiplicativeExpr( $', n[-1] )
    end
  end
  if parsed.size == 0 and n.size != 0
    parsed.replace(n)
  elsif n.size > 0
    parsed << n
  end
  rest
end

AndExpr(path, parsed) click to toggle source

| AndExpr S ‘and’ S EqualityExpr | EqualityExpr

# File rexml-3.3.8/lib/rexml/parsers/xpathparser.rb, line 438
def AndExpr path, parsed
  n = []
  rest = EqualityExpr( path, n )
  if rest != path
    while rest =~ /^\s*( and )/
      n = [ :and, n, [] ]
      rest = EqualityExpr( $', n[-1] )
    end
  end
  if parsed.size == 0 and n.size != 0
    parsed.replace(n)
  elsif n.size > 0
    parsed << n
  end
  rest
end

EqualityExpr(path, parsed) click to toggle source

| EqualityExpr (‘=’ | ‘!=’) RelationalExpr | RelationalExpr

# File rexml-3.3.8/lib/rexml/parsers/xpathparser.rb, line 457
def EqualityExpr path, parsed
  n = []
  rest = RelationalExpr( path, n )
  if rest != path
    while rest =~ /^\s*(!?=)\s*/
      if $1[0] == ?!
        n = [ :neq, n, [] ]
      else
        n = [ :eq, n, [] ]
      end
      rest = RelationalExpr( $', n[-1] )
    end
  end
  if parsed.size == 0 and n.size != 0
    parsed.replace(n)
  elsif n.size > 0
    parsed << n
  end
  rest
end

FilterExpr(path, parsed) click to toggle source

| FilterExpr Predicate | PrimaryExpr

# File rexml-3.3.8/lib/rexml/parsers/xpathparser.rb, line 608
def FilterExpr path, parsed
  n = []
  path_before_primary_expr = path
  path = PrimaryExpr(path, n)
  return path_before_primary_expr if path == path_before_primary_expr
  path = Predicate(path, n)
  parsed.concat(n)
  path
end

FunctionCall(rest, parsed) click to toggle source

| FUNCTION_NAME ‘(’ ( expr ( ‘,’ expr )* )? ‘)’

# File rexml-3.3.8/lib/rexml/parsers/xpathparser.rb, line 663
def FunctionCall rest, parsed
  path, arguments = parse_args(rest)
  argset = []
  for argument in arguments
    args = []
    OrExpr( argument, args )
    argset << args
  end
  parsed << argset
  path
end

LocationPath(path, parsed) click to toggle source

LocationPath

| RelativeLocationPath
| '/' RelativeLocationPath?
| '//' RelativeLocationPath

# File rexml-3.3.8/lib/rexml/parsers/xpathparser.rb, line 243
def LocationPath path, parsed
  path = path.lstrip
  if path[0] == ?/
    parsed << :document
    if path[1] == ?/
      parsed << :descendant_or_self
      parsed << :node
      path = path[2..-1]
    else
      path = path[1..-1]
    end
  end
  return RelativeLocationPath( path, parsed ) if path.size > 0
end

MultiplicativeExpr(path, parsed) click to toggle source

| MultiplicativeExpr (‘*’ | S (‘div’ | ‘mod’) S) UnaryExpr | UnaryExpr

# File rexml-3.3.8/lib/rexml/parsers/xpathparser.rb, line 528
def MultiplicativeExpr path, parsed
  n = []
  rest = UnaryExpr( path, n )
  if rest != path
    while rest =~ /^\s*(\*| div | mod )\s*/
      if $1[0] == ?*
        n = [ :mult, n, [] ]
      elsif $1.include?( "div" )
        n = [ :div, n, [] ]
      else
        n = [ :mod, n, [] ]
      end
      rest = UnaryExpr( $', n[-1] )
    end
  end
  if parsed.size == 0 and n.size != 0
    parsed.replace(n)
  elsif n.size > 0
    parsed << n
  end
  rest
end

NodeTest(path, parsed) click to toggle source

# File rexml-3.3.8/lib/rexml/parsers/xpathparser.rb, line 343
def NodeTest path, parsed
  original_path = path
  path = path.lstrip
  case path
  when PREFIX_WILDCARD
    prefix = nil
    name = $1
    path = $'
    parsed << :qname
    parsed << prefix
    parsed << name
  when /^\*/
    path = $'
    parsed << :any
  when NODE_TYPE
    type = $1
    path = $'
    parsed << type.tr('-', '_').intern
  when PI
    path = $'
    literal = nil
    if path =~ /^\s*\)/
      path = $'
    else
      path =~ LITERAL
      literal = $1
      path = $'
      raise ParseException.new("Missing ')' after processing instruction") if path[0] != ?)
      path = path[1..-1]
    end
    parsed << :processing_instruction
    parsed << (literal || '')
  when LOCAL_NAME_WILDCARD
    prefix = $1
    path = $'
    parsed << :namespace
    parsed << prefix
  when QNAME
    prefix = $1
    name = $2
    path = $'
    prefix = "" unless prefix
    parsed << :qname
    parsed << prefix
    parsed << name
  else
    path = original_path
  end
  return path
end

OrExpr(path, parsed) click to toggle source

| OrExpr S ‘or’ S AndExpr | AndExpr

# File rexml-3.3.8/lib/rexml/parsers/xpathparser.rb, line 419
def OrExpr path, parsed
  n = []
  rest = AndExpr( path, n )
  if rest != path
    while rest =~ /^\s*( or )/
      n = [ :or, n, [] ]
      rest = AndExpr( $', n[-1] )
    end
  end
  if parsed.size == 0 and n.size != 0
    parsed.replace(n)
  elsif n.size > 0
    parsed << n
  end
  rest
end

PathExpr(path, parsed) click to toggle source

| LocationPath | FilterExpr (‘/’ | ‘//’) RelativeLocationPath

# File rexml-3.3.8/lib/rexml/parsers/xpathparser.rb, line 590
def PathExpr path, parsed
  path = path.lstrip
  n = []
  rest = FilterExpr( path, n )
  if rest != path
    if rest and rest[0] == ?/
      rest = RelativeLocationPath(rest, n)
      parsed.concat(n)
      return rest
    end
  end
  rest = LocationPath(rest, n) if rest =~ /\A[\/\.\@\[\w*]/
  parsed.concat(n)
  return rest
end

Predicate(path, parsed) click to toggle source

Filters the supplied nodeset on the predicate(s)

# File rexml-3.3.8/lib/rexml/parsers/xpathparser.rb, line 395
def Predicate path, parsed
  original_path = path
  path = path.lstrip
  return original_path unless path[0] == ?[
  predicates = []
  while path[0] == ?[
    path, expr = get_group(path)
    predicates << expr[1..-2] if expr
  end
  predicates.each{ |pred|
    preds = []
    parsed << :predicate
    parsed << preds
    OrExpr(pred, preds)
  }
  path
end

PrimaryExpr(path, parsed) click to toggle source

# File rexml-3.3.8/lib/rexml/parsers/xpathparser.rb, line 626
def PrimaryExpr path, parsed
  case path
  when VARIABLE_REFERENCE
    varname = $1
    path = $'
    parsed << :variable
    parsed << varname
    #arry << @variables[ varname ]
  when /^(\w[-\w]*)(?:\()/
    fname = $1
    tmp = $'
    return path if fname =~ NT
    path = tmp
    parsed << :function
    parsed << fname
    path = FunctionCall(path, parsed)
  when NUMBER
    varname = $1.nil? ? $2 : $1
    path = $'
    parsed << :literal
    parsed << (varname.include?('.') ? varname.to_f : varname.to_i)
  when LITERAL
    varname = $1.nil? ? $2 : $1
    path = $'
    parsed << :literal
    parsed << varname
  when /^\(/                                               #/
    path, contents = get_group(path)
    contents = contents[1..-2]
    n = []
    OrExpr( contents, n )
    parsed.concat(n)
  end
  path
end

RelationalExpr(path, parsed) click to toggle source

# File rexml-3.3.8/lib/rexml/parsers/xpathparser.rb, line 480
def RelationalExpr path, parsed
  n = []
  rest = AdditiveExpr( path, n )
  if rest != path
    while rest =~ /^\s*([<>]=?)\s*/
      if $1[0] == ?<
        sym = "lt"
      else
        sym = "gt"
      end
      sym << "eq" if $1[-1] == ?=
      n = [ sym.intern, n, [] ]
      rest = AdditiveExpr( $', n[-1] )
    end
  end
  if parsed.size == 0 and n.size != 0
    parsed.replace(n)
  elsif n.size > 0
    parsed << n
  end
  rest
end

RelativeLocationPath(path, parsed) click to toggle source

# File rexml-3.3.8/lib/rexml/parsers/xpathparser.rb, line 267
def RelativeLocationPath path, parsed
  loop do
    original_path = path
    path = path.lstrip

    return original_path if path.empty?

    # (axis or @ or <child::>) nodetest predicate  >
    # OR                                          >  / Step
    # (. or ..)                                    >
    if path[0] == ?.
      if path[1] == ?.
        parsed << :parent
        parsed << :node
        path = path[2..-1]
      else
        parsed << :self
        parsed << :node
        path = path[1..-1]
      end
    else
      path_before_axis_specifier = path
      parsed_not_abberviated = []
      if path[0] == ?@
        parsed_not_abberviated << :attribute
        path = path[1..-1]
        # Goto Nodetest
      elsif path =~ AXIS
        parsed_not_abberviated << $1.tr('-','_').intern
        path = $'
        # Goto Nodetest
      else
        parsed_not_abberviated << :child
      end

      path_before_node_test = path
      path = NodeTest(path, parsed_not_abberviated)
      if path == path_before_node_test
        return path_before_axis_specifier
      end
      path = Predicate(path, parsed_not_abberviated)

      parsed.concat(parsed_not_abberviated)
    end

    original_path = path
    path = path.lstrip
    return original_path if path.empty?

    return original_path if path[0] != ?/

    if path[1] == ?/
      parsed << :descendant_or_self
      parsed << :node
      path = path[2..-1]
    else
      path = path[1..-1]
    end
  end
end

UnaryExpr(path, parsed) click to toggle source

| ‘-’ UnaryExpr | UnionExpr

# File rexml-3.3.8/lib/rexml/parsers/xpathparser.rb, line 553
def UnaryExpr path, parsed
  path =~ /^(\-*)/
  path = $'
  if $1 and (($1.size % 2) != 0)
    mult = -1
  else
    mult = 1
  end
  parsed << :neg if mult < 0

  n = []
  path = UnionExpr( path, n )
  parsed.concat( n )
  path
end

UnionExpr(path, parsed) click to toggle source

| UnionExpr ‘|’ PathExpr | PathExpr

# File rexml-3.3.8/lib/rexml/parsers/xpathparser.rb, line 571
def UnionExpr path, parsed
  n = []
  rest = PathExpr( path, n )
  if rest != path
    while rest =~ /^\s*(\|)\s*/
      n = [ :union, n, [] ]
      rest = PathExpr( $', n[-1] )
    end
  end
  if parsed.size == 0 and n.size != 0
    parsed.replace( n )
  elsif n.size > 0
    parsed << n
  end
  rest
end

get_group(string) click to toggle source

get_group( ‘[foo]bar’ ) -> [‘bar’, ‘[foo]’]

# File rexml-3.3.8/lib/rexml/parsers/xpathparser.rb, line 676
def get_group string
  ind = 0
  depth = 0
  st = string[0,1]
  en = (st == "(" ? ")" : "]")
  begin
    case string[ind,1]
    when st
      depth += 1
    when en
      depth -= 1
    end
    ind += 1
  end while depth > 0 and ind < string.length
  return nil unless depth==0
  [string[ind..-1], string[0..ind-1]]
end

parse_args( string ) click to toggle source

# File rexml-3.3.8/lib/rexml/parsers/xpathparser.rb, line 694
def parse_args( string )
  arguments = []
  ind = 0
  inquot = false
  inapos = false
  depth = 1
  begin
    case string[ind]
    when ?"
      inquot = !inquot unless inapos
    when ?'
      inapos = !inapos unless inquot
    else
      unless inquot or inapos
        case string[ind]
        when ?(
          depth += 1
          if depth == 1
            string = string[1..-1]
            ind -= 1
          end
        when ?)
          depth -= 1
          if depth == 0
            s = string[0,ind].strip
            arguments << s unless s == ""
            string = string[ind+1..-1]
          end
        when ?,
          if depth == 1
            s = string[0,ind].strip
            arguments << s unless s == ""
            string = string[ind+1..-1]
            ind = -1
          end
        end
      end
    end
    ind += 1
  end while depth > 0 and ind < string.length
  return nil unless depth==0
  [string,arguments]
end

quote_literal( literal ) click to toggle source

# File rexml-3.3.8/lib/rexml/parsers/xpathparser.rb, line 224
def quote_literal( literal )
  case literal
  when String
    # XPath 1.0 does not support escape characters.
    # Assumes literal does not contain both single and double quotes.
    if literal.include?("'")
      "\"#{literal}\""
    else
      "'#{literal}'"
    end
  else
    literal.inspect
  end
end