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/* $Id: rxml_xpath.c 461 2008-07-15 21:35:56Z cfis $ */

/* Please see the LICENSE file for copyright and distribution information */

#include "ruby_libxml.h"
#include "ruby_xml_xpath.h"
#include "ruby_xml_xpath_expression.h"

/*
 * Document-class: LibXML::XML::XPath::Expression
 *
 * The XML::XPath::Expression class is used to compile
 * XPath expressions so they can be parsed only once
 * but reused multiple times.
 *
 *  doc = XML::Document.string(IO.read('some xml file'))
 *  expr = XPath::Expression.new('//first')
 *  doc.root.each do |node|
 *   result = node.find(expr) # many, many, many times
 *   # ...
 *  end
 */

VALUE cXMLXPathExpression;

static void rxml_xpath_expression_free(xmlXPathCompExprPtr expr)
{
  xmlXPathFreeCompExpr(expr);
}

static VALUE rxml_xpath_expression_alloc(VALUE klass)
{
  return Data_Wrap_Struct(cXMLXPathExpression, NULL,
      rxml_xpath_expression_free, NULL);
}

/* call-seq:
 *    XPath::Expression.new(expression) -> XPath::Expression
 *
 * Compiled XPatch expression. Work faster when find called many times
 * same expression.
 *
 *  doc = XML::Document.string('<header><first>hi</first></header>')
 *  expr = XPath::Expression.new('//first')
 *  nodes = doc.find(expr)
 */
static VALUE rxml_xpath_expression_initialize(VALUE self, VALUE expression)
{
  xmlXPathCompExprPtr compexpr = xmlXPathCompile(StringValueCStr(expression));

  if (compexpr == NULL)
  {
    xmlErrorPtr xerror = xmlGetLastError();
    rxml_raise(xerror);
  }

  DATA_PTR( self) = compexpr;
  return self;
}

void ruby_init_xml_xpath_expression(void)
{
  cXMLXPathExpression = rb_define_class_under(mXPath, "Expression", rb_cObject);
  rb_define_alloc_func(cXMLXPathExpression, rxml_xpath_expression_alloc);
  rb_define_singleton_method(cXMLXPathExpression, "compile",
      rb_class_new_instance, 1);
  rb_define_method(cXMLXPathExpression, "initialize",
      rxml_xpath_expression_initialize, 1);
}

Version data entries

2 entries across 2 versions & 1 rubygems

Version	Path
libxml-ruby-0.9.5	ext/libxml/ruby_xml_xpath_expression.c
libxml-ruby-0.9.5-x86-mswin32-60	ext/libxml/ruby_xml_xpath_expression.c