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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
extractFile(const char * filename,const xmlChar * pattern)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 
main(int argc,char ** argv)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
main(void)116 int main(void) {
117     fprintf(stderr, "Reader, Pattern or output support not compiled in\n");
118     exit(1);
119 }
120 #endif
121