Class: VCDOM::XPath::XPathExpression

Inherits:
Object
  • Object
show all
Defined in:
lib/vcdom/xpath/xpath_expression.rb

Overview

This class implements the interface XPathExpression of W3C DOM XPath.

Way to create a XPathExpression object

When you want a XPathExpression object, please use XPathEvaluatorMod#create_expression method. The class Document implements the module XPathEvaluatorMod when you required “vcdom/xpath”, so you can use this method as the following:

require "vcdom"
require "vcdom/xpath"
# doc is a Document object
expr = doc.create_expression( "/test/abc", nil )

Instance Method Summary collapse

Constructor Details

#initialize(expr) ⇒ XPathExpression

:nodoc:



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# File 'lib/vcdom/xpath/xpath_expression.rb', line 23

def initialize( expr ) # :nodoc:
  @expr = expr
end

Instance Method Details

#evaluate(context_node, type, result = nil) ⇒ Object

Evaluates the XPath expression.

Usage:

# expr is a XPathExpression object, and elem is an Element object.
result   = expr.evaluate( elem, :first_ordered_node_type )
res_node = result.single_node_value



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# File 'lib/vcdom/xpath/xpath_expression.rb', line 34

def evaluate( context_node, type, result = nil )
  res = Internal::Evaluator.new( context_node ).evaluate_expr( @expr )
  case type
  when :any_type
    case res.value_type
    when :number
      type = :number_type
    when :string
      type = :string_type
    when :boolean
      type = :boolean_type
    when :node_set
      type = :unordered_node_iterator_type
    else
      raise "INTERNAL ERROR"
    end
  when :number_type
    res = res.to_number_value if res.value_type != :number
    xpath_result = XPathResult::ResultNumber.new( res.value )
  when :string_type
    res = res.to_string_value if res.value_type != :string
    xpath_result = XPathResult::ResultString.new( res.value )
  when :boolean_type
    res = res.to_boolean_value if res.value_type != :boolean
    xpath_result = XPathResult::ResultBoolean.new( res.value )
  when :first_ordered_node_type
    res.sort
    xpath_result = XPathResult::ResultSingleNode.new( res.value[0], :first_ordered_node_type )
  when :any_unordered_node_type
    xpath_result = XPathResult::ResultSingleNode.new( res.value[0], :any_unordered_node_type )
  when :ordered_node_snapshot_type
    res.sort
    xpath_result = XPathResult::ResultNodesSnapshot.new( res.value, :ordered_node_snapshot_type )
  when :unordered_node_snapshot_type
    xpath_result = XPathResult::ResultNodesSnapshot.new( res.value, :unordered_node_snapshot_type )
  when :ordered_node_iterator_type, :unordered_node_iterator_type
    raise "not still be supported" # TODO
  else
    raise "USER ERROR"
  end
  return xpath_result
end