/**

 * section: Parsing

 * synopsis: Parse an XML document chunk by chunk to a tree and free it

 * purpose: Demonstrate the use of xmlCreatePushParserCtxt() and

 *          xmlParseChunk() to read an XML file progressively

 *          into a tree and and xmlFreeDoc() to free the resulting tree

 * usage: parse4 test3.xml

 * test: parse4 test3.xml

 * author: Daniel Veillard

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

 */

#include <stdio.h>

#include <libxml/parser.h>

#include <libxml/tree.h>

#ifdef LIBXML_PUSH_ENABLED

static FILE *desc;

/**

 * readPacket:

 * @mem: array to store the packet

 * @size: the packet size

 *

 * read at most @size bytes from the document and store it in @mem

 *

 * Returns the number of bytes read

 */

static int

readPacket(char *mem, int size) {

    int res;

    res = fread(mem, 1, size, desc);

    return(res);

}

/**

 * example4Func:

 * @filename: a filename or an URL

 *

 * Parse the resource and free the resulting tree

 */

static void

example4Func(const char *filename) {

    xmlParserCtxtPtr ctxt;

    char chars[4];

    xmlDocPtr doc; /* the resulting document tree */

    int res;

    /*

     * Read a few first byte to check the input used for the

     * encoding detection at the parser level.

     */

    res = readPacket(chars, 4);

    if (res <= 0) {

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

	return;

    }

    /*

     * Create a progressive parsing context, the 2 first arguments

     * are not used since we want to build a tree and not use a SAX

     * parsing interface. We also pass the first bytes of the document

     * to allow encoding detection when creating the parser but this

     * is optional.

     */

    ctxt = xmlCreatePushParserCtxt(NULL, NULL,

                                   chars, res, filename);

    if (ctxt == NULL) {

        fprintf(stderr, "Failed to create parser context !\n");

	return;

    }

    /*

     * loop on the input getting the document data, of course 4 bytes

     * at a time is not realistic but allows to verify testing on small

     * documents.

     */

    while ((res = readPacket(chars, 4)) > 0) {

        xmlParseChunk(ctxt, chars, res, 0);

    }

    /*

     * there is no more input, indicate the parsing is finished.

     */

    xmlParseChunk(ctxt, chars, 0, 1);

    /*

     * collect the document back and if it was wellformed

     * and destroy the parser context.

     */

    doc = ctxt->myDoc;

    res = ctxt->wellFormed;

    xmlFreeParserCtxt(ctxt);

    if (!res) {

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

    }

    /*

     * since we don't use the document, destroy it now.

     */

    xmlFreeDoc(doc);

}

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

    if (argc != 2)

        return(1);

    /*

     * 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

    /*

     * simulate a progressive parsing using the input file.

     */

    desc = fopen(argv[1], "rb");

    if (desc != NULL) {

	example4Func(argv[1]);

	fclose(desc);

    } else {

        fprintf(stderr, "Failed to parse %s\n", argv[1]);

    }

    /*

     * Cleanup function for the XML library.

     */

    xmlCleanupParser();

    /*

     * this is to debug memory for regression tests

     */

    xmlMemoryDump();

    return(0);

}

#else /* ! LIBXML_PUSH_ENABLED */

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

    fprintf(stderr, "Library not compiled with push parser support\n");

    return(1);

}

#endif