/**

 * section: InputOutput

 * synopsis: Example of custom Input/Output

 * purpose: Demonstrate the use of xmlRegisterInputCallbacks

 *          to build a custom I/O layer, this is used in an

 *          XInclude method context to show how dynamic document can

 *          be built in a clean way.

 * usage: io1

 * test: io1 > io1.tmp && diff io1.tmp $(srcdir)/io1.res

 * author: Daniel Veillard

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

 */

#include <stdio.h>

#include <string.h>

#include <libxml/parser.h>

#include <libxml/tree.h>

#include <libxml/xinclude.h>

#include <libxml/xmlIO.h>

#ifdef LIBXML_XINCLUDE_ENABLED

static const char *result = "<list><people>a</people><people>b</people></list>";

static const char *cur = NULL;

static int rlen;

/**

 * sqlMatch:

 * @URI: an URI to test

 *

 * Check for an sql: query

 *

 * Returns 1 if yes and 0 if another Input module should be used

 */

static int

sqlMatch(const char * URI) {

    if ((URI != NULL) && (!strncmp(URI, "sql:", 4)))

        return(1);

    return(0);

}

/**

 * sqlOpen:

 * @URI: an URI to test

 *

 * Return a pointer to the sql: query handler, in this example simply

 * the current pointer...

 *

 * Returns an Input context or NULL in case or error

 */

static void *

sqlOpen(const char * URI) {

    if ((URI == NULL) || (strncmp(URI, "sql:", 4)))

        return(NULL);

    cur = result;

    rlen = strlen(result);

    return((void *) cur);

}

/**

 * sqlClose:

 * @context: the read context

 *

 * Close the sql: query handler

 *

 * Returns 0 or -1 in case of error

 */

static int

sqlClose(void * context) {

    if (context == NULL) return(-1);

    cur = NULL;

    rlen = 0;

    return(0);

}

/**

 * sqlRead:

 * @context: the read context

 * @buffer: where to store data

 * @len: number of bytes to read

 *

 * Implement an sql: query read.

 *

 * Returns the number of bytes read or -1 in case of error

 */

static int

sqlRead(void * context, char * buffer, int len) {

   const char *ptr = (const char *) context;

   if ((context == NULL) || (buffer == NULL) || (len < 0))

       return(-1);

   if (len > rlen) len = rlen;

   memcpy(buffer, ptr, len);

   rlen -= len;

   return(len);

}

const char *include = "\n\

<document xmlns:xi=\"http://www.w3.org/2003/XInclude\">\n\

  
List of people:
\n\

  <xi:include href=\"sql:select_name_from_people\"/>\n\

</document>\n";

int main(void) {

    xmlDocPtr doc;

    /*

     * 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

    /*

     * register the new I/O handlers

     */

    if (xmlRegisterInputCallbacks(sqlMatch, sqlOpen, sqlRead, sqlClose) < 0) {

        fprintf(stderr, "failed to register SQL handler\n");

	exit(1);

    }

    /*

     * parse include into a document

     */

    doc = xmlReadMemory(include, strlen(include), "include.xml", NULL, 0);

    if (doc == NULL) {

        fprintf(stderr, "failed to parse the including file\n");

	exit(1);

    }

    /*

     * apply the XInclude process, this should trigger the I/O just

     * registered.

     */

    if (xmlXIncludeProcess(doc) <= 0) {

        fprintf(stderr, "XInclude processing failed\n");

	exit(1);

    }

#ifdef LIBXML_OUTPUT_ENABLED

    /*

     * save the output for checking to stdout

     */

    xmlDocDump(stdout, doc);

#endif

    /*

     * Free the document

     */

    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, "XInclude support not compiled in\n");

    exit(1);

}

#endif