kc3-lang/libxml2/example/io1.c

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• Hash : d381e5de
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  Date : 2024-04-28T21:14:32
  

  doc: Move doc/examples to example
  

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• example/io1.c

• /**
   * 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 <stdlib.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 = "<?xml version='1.0'?>\n\
  <document xmlns:xi=\"http://www.w3.org/2003/XInclude\">\n\
    <p>List of people:</p>\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);
  
      return(0);
  }
  #else
  int main(void) {
      fprintf(stderr, "XInclude support not compiled in\n");
      return(0);
  }
  #endif
  

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