Class: REXML::Parsers::XPathParser

Inherits:
Object
  • Object
show all
Includes:
XMLTokens
Defined in:
lib/rexml/parsers/xpathparser.rb

Overview

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!

Constant Summary collapse

LITERAL = 
/^'([^']*)'|^"([^"]*)"/u

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

Instance Method Summary collapse

Instance Method Details

#abbreviate(path_or_parsed) ⇒ Object 



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# File '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) ⇒ Object 



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# File '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) ⇒ Object 



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# File 'lib/rexml/parsers/xpathparser.rb', line 16

def namespaces=( namespaces )
  Functions::namespace_context = namespaces
  @namespaces = namespaces
end

#parse(path) ⇒ Object 



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# File '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

#predicate(path) ⇒ Object 



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# File 'lib/rexml/parsers/xpathparser.rb', line 36

def predicate path
  parsed = []
  Predicate( "[#{path}]", parsed )
  parsed
end

#predicate_to_path(parsed, &block) ⇒ Object Also known as: preciate_to_string 



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# File '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