1  /**
  2   * section: xmlReader
  3   * synopsis: Show how to extract subdocuments with xmlReader
  4   * purpose: Demonstrate the use of xmlTextReaderPreservePattern() 
  5   *          to parse an XML file with the xmlReader while collecting
  6   *          only some subparts of the document.
  7   *          (Note that the XMLReader functions require libxml2 version later
  8   *          than 2.6.)
  9   * usage: reader3
 10   * test: reader3 > reader3.tmp && diff reader3.tmp $(srcdir)/reader3.res
 11   * author: Daniel Veillard
 12   * copy: see Copyright for the status of this software.
 13   */
 14  
 15  #include <stdio.h>
 16  #include <libxml/xmlreader.h>
 17  
 18  #if defined(LIBXML_READER_ENABLED) && defined(LIBXML_PATTERN_ENABLED) && defined(LIBXML_OUTPUT_ENABLED)
 19  
 20  
 21  /**
 22   * streamFile:
 23   * @filename: the file name to parse
 24   *
 25   * Parse and print information about an XML file.
 26   *
 27   * Returns the resulting doc with just the elements preserved.
 28   */
 29  static xmlDocPtr
 30  extractFile(const char *filename, const xmlChar *pattern) {
 31      xmlDocPtr doc;
 32      xmlTextReaderPtr reader;
 33      int ret;
 34  
 35      /*
 36       * build an xmlReader for that file
 37       */
 38      reader = xmlReaderForFile(filename, NULL, 0);
 39      if (reader != NULL) {
 40          /*
 41  	 * add the pattern to preserve
 42  	 */
 43          if (xmlTextReaderPreservePattern(reader, pattern, NULL) < 0) {
 44              fprintf(stderr, "%s : failed add preserve pattern %s\n",
 45  	            filename, (const char *) pattern);
 46  	}
 47  	/*
 48  	 * Parse and traverse the tree, collecting the nodes in the process
 49  	 */
 50          ret = xmlTextReaderRead(reader);
 51          while (ret == 1) {
 52              ret = xmlTextReaderRead(reader);
 53          }
 54          if (ret != 0) {
 55              fprintf(stderr, "%s : failed to parse\n", filename);
 56  	    xmlFreeTextReader(reader);
 57  	    return(NULL);
 58          }
 59  	/*
 60  	 * get the resulting nodes
 61  	 */
 62  	doc = xmlTextReaderCurrentDoc(reader);
 63  	/*
 64  	 * Free up the reader
 65  	 */
 66          xmlFreeTextReader(reader);
 67      } else {
 68          fprintf(stderr, "Unable to open %s\n", filename);
 69  	return(NULL);
 70      }
 71      return(doc);
 72  }
 73  
 74  int main(int argc, char **argv) {
 75      const char *filename = "test3.xml";
 76      const char *pattern = "preserved";
 77      xmlDocPtr doc;
 78  
 79      if (argc == 3) {
 80          filename = argv[1];
 81  	pattern = argv[2];
 82      }
 83  
 84      /*
 85       * this initialize the library and check potential ABI mismatches
 86       * between the version it was compiled for and the actual shared
 87       * library used.
 88       */
 89      LIBXML_TEST_VERSION
 90  
 91      doc = extractFile(filename, (const xmlChar *) pattern);
 92      if (doc != NULL) {
 93          /*
 94  	 * ouptut the result.
 95  	 */
 96          xmlDocDump(stdout, doc);
 97  	/*
 98  	 * don't forget to free up the doc
 99  	 */
100  	xmlFreeDoc(doc);
101      }
102  
103  
104      /*
105       * Cleanup function for the XML library.
106       */
107      xmlCleanupParser();
108      /*
109       * this is to debug memory for regression tests
110       */
111      xmlMemoryDump();
112      return(0);
113  }
114  
115  #else
116  int main(void) {
117      fprintf(stderr, "Reader, Pattern or output support not compiled in\n");
118      exit(1);
119  }
120  #endif