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libxml2

    1: /**
    2:  * section: Parsing
    3:  * synopsis: Parse an XML document chunk by chunk to a tree and free it
    4:  * purpose: Demonstrate the use of xmlCreatePushParserCtxt() and
    5:  *          xmlParseChunk() to read an XML file progressively
    6:  *          into a tree and and xmlFreeDoc() to free the resulting tree
    7:  * usage: parse4 test3.xml
    8:  * test: parse4 test3.xml
    9:  * author: Daniel Veillard
   10:  * copy: see Copyright for the status of this software.
   11:  */
   12: 
   13: #include <stdio.h>
   14: #include <libxml/parser.h>
   15: #include <libxml/tree.h>
   16: 
   17: #ifdef LIBXML_PUSH_ENABLED
   18: static FILE *desc;
   19: 
   20: /**
   21:  * readPacket:
   22:  * @mem: array to store the packet
   23:  * @size: the packet size
   24:  *
   25:  * read at most @size bytes from the document and store it in @mem
   26:  *
   27:  * Returns the number of bytes read
   28:  */
   29: static int
   30: readPacket(char *mem, int size) {
   31:     int res;
   32: 
   33:     res = fread(mem, 1, size, desc);
   34:     return(res);
   35: }
   36: 
   37: /**
   38:  * example4Func:
   39:  * @filename: a filename or an URL
   40:  *
   41:  * Parse the resource and free the resulting tree
   42:  */
   43: static void
   44: example4Func(const char *filename) {
   45:     xmlParserCtxtPtr ctxt;
   46:     char chars[4];
   47:     xmlDocPtr doc; /* the resulting document tree */
   48:     int res;
   49: 
   50:     /*
   51:      * Read a few first byte to check the input used for the
   52:      * encoding detection at the parser level.
   53:      */
   54:     res = readPacket(chars, 4);
   55:     if (res <= 0) {
   56:         fprintf(stderr, "Failed to parse %s\n", filename);
   57: 	return;
   58:     }
   59: 
   60:     /*
   61:      * Create a progressive parsing context, the 2 first arguments
   62:      * are not used since we want to build a tree and not use a SAX
   63:      * parsing interface. We also pass the first bytes of the document
   64:      * to allow encoding detection when creating the parser but this
   65:      * is optional.
   66:      */
   67:     ctxt = xmlCreatePushParserCtxt(NULL, NULL,
   68:                                    chars, res, filename);
   69:     if (ctxt == NULL) {
   70:         fprintf(stderr, "Failed to create parser context !\n");
   71: 	return;
   72:     }
   73: 
   74:     /*
   75:      * loop on the input getting the document data, of course 4 bytes
   76:      * at a time is not realistic but allows to verify testing on small
   77:      * documents.
   78:      */
   79:     while ((res = readPacket(chars, 4)) > 0) {
   80:         xmlParseChunk(ctxt, chars, res, 0);
   81:     }
   82: 
   83:     /*
   84:      * there is no more input, indicate the parsing is finished.
   85:      */
   86:     xmlParseChunk(ctxt, chars, 0, 1);
   87: 
   88:     /*
   89:      * collect the document back and if it was wellformed
   90:      * and destroy the parser context.
   91:      */
   92:     doc = ctxt->myDoc;
   93:     res = ctxt->wellFormed;
   94:     xmlFreeParserCtxt(ctxt);
   95: 
   96:     if (!res) {
   97:         fprintf(stderr, "Failed to parse %s\n", filename);
   98:     }
   99: 
  100:     /*
  101:      * since we don't use the document, destroy it now.
  102:      */
  103:     xmlFreeDoc(doc);
  104: }
  105: 
  106: int main(int argc, char **argv) {
  107:     if (argc != 2)
  108:         return(1);
  109: 
  110:     /*
  111:      * this initialize the library and check potential ABI mismatches
  112:      * between the version it was compiled for and the actual shared
  113:      * library used.
  114:      */
  115:     LIBXML_TEST_VERSION
  116: 
  117:     /*
  118:      * simulate a progressive parsing using the input file.
  119:      */
  120:     desc = fopen(argv[1], "rb");
  121:     if (desc != NULL) {
  122: 	example4Func(argv[1]);
  123: 	fclose(desc);
  124:     } else {
  125:         fprintf(stderr, "Failed to parse %s\n", argv[1]);
  126:     }
  127: 
  128:     /*
  129:      * Cleanup function for the XML library.
  130:      */
  131:     xmlCleanupParser();
  132:     /*
  133:      * this is to debug memory for regression tests
  134:      */
  135:     xmlMemoryDump();
  136:     return(0);
  137: }
  138: #else /* ! LIBXML_PUSH_ENABLED */
  139: int main(int argc, char **argv) {
  140:     fprintf(stderr, "Library not compiled with push parser support\n");
  141:     return(1);
  142: }
  143: #endif