1 /**
2 * section: XPath
3 * synopsis: Evaluate XPath expression and prints result node set.
4 * purpose: Shows how to evaluate XPath expression and register
5 * known namespaces in XPath context.
6 * usage: xpath1 <xml-file> <xpath-expr> [<known-ns-list>]
7 * test: xpath1 test3.xml '//child2' > xpath1.tmp && diff xpath1.tmp $(srcdir)/xpath1.res
8 * author: Aleksey Sanin
9 * copy: see Copyright for the status of this software.
10 */
11 #include <stdlib.h>
12 #include <stdio.h>
13 #include <string.h>
14 #include <assert.h>
15
16 #include <libxml/tree.h>
17 #include <libxml/parser.h>
18 #include <libxml/xpath.h>
19 #include <libxml/xpathInternals.h>
20
21 #if defined(LIBXML_XPATH_ENABLED) && defined(LIBXML_SAX1_ENABLED)
22
23
24 static void usage(const char *name);
25 int execute_xpath_expression(const char* filename, const xmlChar* xpathExpr, const xmlChar* nsList);
26 int register_namespaces(xmlXPathContextPtr xpathCtx, const xmlChar* nsList);
27 void print_xpath_nodes(xmlNodeSetPtr nodes, FILE* output);
28
29 int
main(int argc,char ** argv)30 main(int argc, char **argv) {
31 /* Parse command line and process file */
32 if((argc < 3) || (argc > 4)) {
33 fprintf(stderr, "Error: wrong number of arguments.\n");
34 usage(argv[0]);
35 return(-1);
36 }
37
38 /* Init libxml */
39 xmlInitParser();
40 LIBXML_TEST_VERSION
41
42 /* Do the main job */
43 if(execute_xpath_expression(argv[1], BAD_CAST argv[2], (argc > 3) ? BAD_CAST argv[3] : NULL) < 0) {
44 usage(argv[0]);
45 return(-1);
46 }
47
48 /* Shutdown libxml */
49 xmlCleanupParser();
50
51 /*
52 * this is to debug memory for regression tests
53 */
54 xmlMemoryDump();
55 return 0;
56 }
57
58 /**
59 * usage:
60 * @name: the program name.
61 *
62 * Prints usage information.
63 */
64 static void
usage(const char * name)65 usage(const char *name) {
66 assert(name);
67
68 fprintf(stderr, "Usage: %s <xml-file> <xpath-expr> [<known-ns-list>]\n", name);
69 fprintf(stderr, "where <known-ns-list> is a list of known namespaces\n");
70 fprintf(stderr, "in \"<prefix1>=<href1> <prefix2>=href2> ...\" format\n");
71 }
72
73 /**
74 * execute_xpath_expression:
75 * @filename: the input XML filename.
76 * @xpathExpr: the xpath expression for evaluation.
77 * @nsList: the optional list of known namespaces in
78 * "<prefix1>=<href1> <prefix2>=href2> ..." format.
79 *
80 * Parses input XML file, evaluates XPath expression and prints results.
81 *
82 * Returns 0 on success and a negative value otherwise.
83 */
84 int
execute_xpath_expression(const char * filename,const xmlChar * xpathExpr,const xmlChar * nsList)85 execute_xpath_expression(const char* filename, const xmlChar* xpathExpr, const xmlChar* nsList) {
86 xmlDocPtr doc;
87 xmlXPathContextPtr xpathCtx;
88 xmlXPathObjectPtr xpathObj;
89
90 assert(filename);
91 assert(xpathExpr);
92
93 /* Load XML document */
94 doc = xmlParseFile(filename);
95 if (doc == NULL) {
96 fprintf(stderr, "Error: unable to parse file \"%s\"\n", filename);
97 return(-1);
98 }
99
100 /* Create xpath evaluation context */
101 xpathCtx = xmlXPathNewContext(doc);
102 if(xpathCtx == NULL) {
103 fprintf(stderr,"Error: unable to create new XPath context\n");
104 xmlFreeDoc(doc);
105 return(-1);
106 }
107
108 /* Register namespaces from list (if any) */
109 if((nsList != NULL) && (register_namespaces(xpathCtx, nsList) < 0)) {
110 fprintf(stderr,"Error: failed to register namespaces list \"%s\"\n", nsList);
111 xmlXPathFreeContext(xpathCtx);
112 xmlFreeDoc(doc);
113 return(-1);
114 }
115
116 /* Evaluate xpath expression */
117 xpathObj = xmlXPathEvalExpression(xpathExpr, xpathCtx);
118 if(xpathObj == NULL) {
119 fprintf(stderr,"Error: unable to evaluate xpath expression \"%s\"\n", xpathExpr);
120 xmlXPathFreeContext(xpathCtx);
121 xmlFreeDoc(doc);
122 return(-1);
123 }
124
125 /* Print results */
126 print_xpath_nodes(xpathObj->nodesetval, stdout);
127
128 /* Cleanup */
129 xmlXPathFreeObject(xpathObj);
130 xmlXPathFreeContext(xpathCtx);
131 xmlFreeDoc(doc);
132
133 return(0);
134 }
135
136 /**
137 * register_namespaces:
138 * @xpathCtx: the pointer to an XPath context.
139 * @nsList: the list of known namespaces in
140 * "<prefix1>=<href1> <prefix2>=href2> ..." format.
141 *
142 * Registers namespaces from @nsList in @xpathCtx.
143 *
144 * Returns 0 on success and a negative value otherwise.
145 */
146 int
register_namespaces(xmlXPathContextPtr xpathCtx,const xmlChar * nsList)147 register_namespaces(xmlXPathContextPtr xpathCtx, const xmlChar* nsList) {
148 xmlChar* nsListDup;
149 xmlChar* prefix;
150 xmlChar* href;
151 xmlChar* next;
152
153 assert(xpathCtx);
154 assert(nsList);
155
156 nsListDup = xmlStrdup(nsList);
157 if(nsListDup == NULL) {
158 fprintf(stderr, "Error: unable to strdup namespaces list\n");
159 return(-1);
160 }
161
162 next = nsListDup;
163 while(next != NULL) {
164 /* skip spaces */
165 while((*next) == ' ') next++;
166 if((*next) == '\0') break;
167
168 /* find prefix */
169 prefix = next;
170 next = (xmlChar*)xmlStrchr(next, '=');
171 if(next == NULL) {
172 fprintf(stderr,"Error: invalid namespaces list format\n");
173 xmlFree(nsListDup);
174 return(-1);
175 }
176 *(next++) = '\0';
177
178 /* find href */
179 href = next;
180 next = (xmlChar*)xmlStrchr(next, ' ');
181 if(next != NULL) {
182 *(next++) = '\0';
183 }
184
185 /* do register namespace */
186 if(xmlXPathRegisterNs(xpathCtx, prefix, href) != 0) {
187 fprintf(stderr,"Error: unable to register NS with prefix=\"%s\" and href=\"%s\"\n", prefix, href);
188 xmlFree(nsListDup);
189 return(-1);
190 }
191 }
192
193 xmlFree(nsListDup);
194 return(0);
195 }
196
197 /**
198 * print_xpath_nodes:
199 * @nodes: the nodes set.
200 * @output: the output file handle.
201 *
202 * Prints the @nodes content to @output.
203 */
204 void
print_xpath_nodes(xmlNodeSetPtr nodes,FILE * output)205 print_xpath_nodes(xmlNodeSetPtr nodes, FILE* output) {
206 xmlNodePtr cur;
207 int size;
208 int i;
209
210 assert(output);
211 size = (nodes) ? nodes->nodeNr : 0;
212
213 fprintf(output, "Result (%d nodes):\n", size);
214 for(i = 0; i < size; ++i) {
215 assert(nodes->nodeTab[i]);
216
217 if(nodes->nodeTab[i]->type == XML_NAMESPACE_DECL) {
218 xmlNsPtr ns;
219
220 ns = (xmlNsPtr)nodes->nodeTab[i];
221 cur = (xmlNodePtr)ns->next;
222 if(cur->ns) {
223 fprintf(output, "= namespace \"%s\"=\"%s\" for node %s:%s\n",
224 ns->prefix, ns->href, cur->ns->href, cur->name);
225 } else {
226 fprintf(output, "= namespace \"%s\"=\"%s\" for node %s\n",
227 ns->prefix, ns->href, cur->name);
228 }
229 } else if(nodes->nodeTab[i]->type == XML_ELEMENT_NODE) {
230 cur = nodes->nodeTab[i];
231 if(cur->ns) {
232 fprintf(output, "= element node \"%s:%s\"\n",
233 cur->ns->href, cur->name);
234 } else {
235 fprintf(output, "= element node \"%s\"\n",
236 cur->name);
237 }
238 } else {
239 cur = nodes->nodeTab[i];
240 fprintf(output, "= node \"%s\": type %d\n", cur->name, cur->type);
241 }
242 }
243 }
244
245 #else
main(void)246 int main(void) {
247 fprintf(stderr, "XPath support not compiled in\n");
248 exit(1);
249 }
250 #endif
251