release/src/router/libxml2/doc/examples/reader3.c

   1 /**
   2  * section: xmlReader
   3  * synopsis: Show how to extract subdocuments with xmlReader
   4  * purpose: Demonstrate the use of xmlTextReaderPreservePattern()
   5  *          to parse an XML file with the xmlReader while collecting
   6  *          only some subparts of the document.
   7  *          (Note that the XMLReader functions require libxml2 version later
   8  *          than 2.6.)
   9  * usage: reader3
  10  * test: reader3 > reader3.tmp && diff reader3.tmp $(srcdir)/reader3.res
  11  * author: Daniel Veillard
  12  * copy: see Copyright for the status of this software.
  13  */
  14
  15 #include <stdio.h>
  16 #include <libxml/xmlreader.h>
  17
  18 #if defined(LIBXML_READER_ENABLED) && defined(LIBXML_PATTERN_ENABLED) && defined(LIBXML_OUTPUT_ENABLED)
  19
  20
  21 /**
  22  * streamFile:
  23  * @filename: the file name to parse
  24  *
  25  * Parse and print information about an XML file.
  26  *
  27  * Returns the resulting doc with just the elements preserved.
  28  */
  29 static xmlDocPtr
  30 extractFile(const char *filename, const xmlChar *pattern) {
  31     xmlDocPtr doc;
  32     xmlTextReaderPtr reader;
  33     int ret;
  34
  35     /*
  36      * build an xmlReader for that file
  37      */
  38     reader = xmlReaderForFile(filename, NULL, 0);
  39     if (reader != NULL) {
  40         /*
  41          * add the pattern to preserve
  42          */
  43         if (xmlTextReaderPreservePattern(reader, pattern, NULL) < 0) {
  44             fprintf(stderr, "%s : failed add preserve pattern %s\n",
  45                     filename, (const char *) pattern);
  46         }
  47         /*
  48          * Parse and traverse the tree, collecting the nodes in the process
  49          */
  50         ret = xmlTextReaderRead(reader);
  51         while (ret == 1) {
  52             ret = xmlTextReaderRead(reader);
  53         }
  54         if (ret != 0) {
  55             fprintf(stderr, "%s : failed to parse\n", filename);
  56             xmlFreeTextReader(reader);
  57             return(NULL);
  58         }
  59         /*
  60          * get the resulting nodes
  61          */
  62         doc = xmlTextReaderCurrentDoc(reader);
  63         /*
  64          * Free up the reader
  65          */
  66         xmlFreeTextReader(reader);
  67     } else {
  68         fprintf(stderr, "Unable to open %s\n", filename);
  69         return(NULL);
  70     }
  71     return(doc);
  72 }
  73
  74 int main(int argc, char **argv) {
  75     const char *filename = "test3.xml";
  76     const char *pattern = "preserved";
  77     xmlDocPtr doc;
  78
  79     if (argc == 3) {
  80         filename = argv[1];
  81         pattern = argv[2];
  82     }
  83
  84     /*
  85      * this initialize the library and check potential ABI mismatches
  86      * between the version it was compiled for and the actual shared
  87      * library used.
  88      */
  89     LIBXML_TEST_VERSION
  90
  91     doc = extractFile(filename, (const xmlChar *) pattern);
  92     if (doc != NULL) {
  93         /*
  94          * ouptut the result.
  95          */
  96         xmlDocDump(stdout, doc);
  97         /*
  98          * don't forget to free up the doc
  99          */
 100         xmlFreeDoc(doc);
 101     }
 102
 103
 104     /*
 105      * Cleanup function for the XML library.
 106      */
 107     xmlCleanupParser();
 108     /*
 109      * this is to debug memory for regression tests
 110      */
 111     xmlMemoryDump();
 112     return(0);
 113 }
 114
 115 #else
 116 int main(void) {
 117     fprintf(stderr, "Reader, Pattern or output support not compiled in\n");
 118     exit(1);
 119 }
 120 #endif