/**

 * section: xmlReader

 * synopsis: Show how to extract subdocuments with xmlReader

 * purpose: Demonstrate the use of xmlTextReaderPreservePattern() 

 *          to parse an XML file with the xmlReader while collecting

 *          only some subparts of the document.

 *          (Note that the XMLReader functions require libxml2 version later

 *          than 2.6.)

 * usage: reader3

 * test: reader3 > reader3.tmp && diff reader3.tmp $(srcdir)/reader3.res

 * author: Daniel Veillard

 * copy: see Copyright for the status of this software.

 */

#include <stdio.h>

#include <libxml/xmlreader.h>

#if defined(LIBXML_READER_ENABLED) && defined(LIBXML_PATTERN_ENABLED) && defined(LIBXML_OUTPUT_ENABLED)

/**

 * streamFile:

 * @filename: the file name to parse

 *

 * Parse and print information about an XML file.

 *

 * Returns the resulting doc with just the elements preserved.

 */

static xmlDocPtr

extractFile(const char *filename, const xmlChar *pattern) {

    xmlDocPtr doc;

    xmlTextReaderPtr reader;

    int ret;

    /*

     * build an xmlReader for that file

     */

    reader = xmlReaderForFile(filename, NULL, 0);

    if (reader != NULL) {

        /*

	 * add the pattern to preserve

	 */

        if (xmlTextReaderPreservePattern(reader, pattern, NULL) < 0) {

            fprintf(stderr, "%s : failed add preserve pattern %s\n",

	            filename, (const char *) pattern);

	}

	/*

	 * Parse and traverse the tree, collecting the nodes in the process

	 */

        ret = xmlTextReaderRead(reader);

        while (ret == 1) {

            ret = xmlTextReaderRead(reader);

        }

        if (ret != 0) {

            fprintf(stderr, "%s : failed to parse\n", filename);

	    xmlFreeTextReader(reader);

	    return(NULL);

        }

	/*

	 * get the resulting nodes

	 */

	doc = xmlTextReaderCurrentDoc(reader);

	/*

	 * Free up the reader

	 */

        xmlFreeTextReader(reader);

    } else {

        fprintf(stderr, "Unable to open %s\n", filename);

	return(NULL);

    }

    return(doc);

}

int main(int argc, char **argv) {

    const char *filename = "test3.xml";

    const char *pattern = "preserved";

    xmlDocPtr doc;

    if (argc == 3) {

        filename = argv[1];

	pattern = argv[2];

    }

    /*

     * this initialize the library and check potential ABI mismatches

     * between the version it was compiled for and the actual shared

     * library used.

     */

    LIBXML_TEST_VERSION

    doc = extractFile(filename, (const xmlChar *) pattern);

    if (doc != NULL) {

        /*

	 * ouptut the result.

	 */

        xmlDocDump(stdout, doc);

	/*

	 * don't forget to free up the doc

	 */

	xmlFreeDoc(doc);

    }

    /*

     * Cleanup function for the XML library.

     */

    xmlCleanupParser();

    /*

     * this is to debug memory for regression tests

     */

    xmlMemoryDump();

    return(0);

}

#else

int main(void) {

    fprintf(stderr, "Reader, Pattern or output support not compiled in\n");

    exit(1);

}

#endif