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+/**
+ * section: XPath
+ * synopsis: Evaluate XPath expression and prints result node set.
+ * purpose: Shows how to evaluate XPath expression and register
+ * known namespaces in XPath context.
+ * usage: xpath1 <xml-file> <xpath-expr> [<known-ns-list>]
+ * test: xpath1 test3.xml '//child2' > xpath1.tmp && diff xpath1.tmp $(srcdir)/xpath1.res
+ * author: Aleksey Sanin
+ * copy: see Copyright for the status of this software.
+ */
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <assert.h>
+
+#include <libxml/tree.h>
+#include <libxml/parser.h>
+#include <libxml/xpath.h>
+#include <libxml/xpathInternals.h>
+
+#if defined(LIBXML_XPATH_ENABLED) && defined(LIBXML_SAX1_ENABLED)
+
+
+static void usage(const char *name);
+int execute_xpath_expression(const char* filename, const xmlChar* xpathExpr, const xmlChar* nsList);
+int register_namespaces(xmlXPathContextPtr xpathCtx, const xmlChar* nsList);
+void print_xpath_nodes(xmlNodeSetPtr nodes, FILE* output);
+
+int
+main(int argc, char **argv) {
+ /* Parse command line and process file */
+ if((argc < 3) || (argc > 4)) {
+ fprintf(stderr, "Error: wrong number of arguments.\n");
+ usage(argv[0]);
+ return(-1);
+ }
+
+ /* Init libxml */
+ xmlInitParser();
+ LIBXML_TEST_VERSION
+
+ /* Do the main job */
+ if(execute_xpath_expression(argv[1], BAD_CAST argv[2], (argc > 3) ? BAD_CAST argv[3] : NULL) < 0) {
+ usage(argv[0]);
+ return(-1);
+ }
+
+ /* Shutdown libxml */
+ xmlCleanupParser();
+
+ /*
+ * this is to debug memory for regression tests
+ */
+ xmlMemoryDump();
+ return 0;
+}
+
+/**
+ * usage:
+ * @name: the program name.
+ *
+ * Prints usage information.
+ */
+static void
+usage(const char *name) {
+ assert(name);
+
+ fprintf(stderr, "Usage: %s <xml-file> <xpath-expr> [<known-ns-list>]\n", name);
+ fprintf(stderr, "where <known-ns-list> is a list of known namespaces\n");
+ fprintf(stderr, "in \"<prefix1>=<href1> <prefix2>=href2> ...\" format\n");
+}
+
+/**
+ * execute_xpath_expression:
+ * @filename: the input XML filename.
+ * @xpathExpr: the xpath expression for evaluation.
+ * @nsList: the optional list of known namespaces in
+ * "<prefix1>=<href1> <prefix2>=href2> ..." format.
+ *
+ * Parses input XML file, evaluates XPath expression and prints results.
+ *
+ * Returns 0 on success and a negative value otherwise.
+ */
+int
+execute_xpath_expression(const char* filename, const xmlChar* xpathExpr, const xmlChar* nsList) {
+ xmlDocPtr doc;
+ xmlXPathContextPtr xpathCtx;
+ xmlXPathObjectPtr xpathObj;
+
+ assert(filename);
+ assert(xpathExpr);
+
+ /* Load XML document */
+ doc = xmlParseFile(filename);
+ if (doc == NULL) {
+ fprintf(stderr, "Error: unable to parse file \"%s\"\n", filename);
+ return(-1);
+ }
+
+ /* Create xpath evaluation context */
+ xpathCtx = xmlXPathNewContext(doc);
+ if(xpathCtx == NULL) {
+ fprintf(stderr,"Error: unable to create new XPath context\n");
+ xmlFreeDoc(doc);
+ return(-1);
+ }
+
+ /* Register namespaces from list (if any) */
+ if((nsList != NULL) && (register_namespaces(xpathCtx, nsList) < 0)) {
+ fprintf(stderr,"Error: failed to register namespaces list \"%s\"\n", nsList);
+ xmlXPathFreeContext(xpathCtx);
+ xmlFreeDoc(doc);
+ return(-1);
+ }
+
+ /* Evaluate xpath expression */
+ xpathObj = xmlXPathEvalExpression(xpathExpr, xpathCtx);
+ if(xpathObj == NULL) {
+ fprintf(stderr,"Error: unable to evaluate xpath expression \"%s\"\n", xpathExpr);
+ xmlXPathFreeContext(xpathCtx);
+ xmlFreeDoc(doc);
+ return(-1);
+ }
+
+ /* Print results */
+ print_xpath_nodes(xpathObj->nodesetval, stdout);
+
+ /* Cleanup */
+ xmlXPathFreeObject(xpathObj);
+ xmlXPathFreeContext(xpathCtx);
+ xmlFreeDoc(doc);
+
+ return(0);
+}
+
+/**
+ * register_namespaces:
+ * @xpathCtx: the pointer to an XPath context.
+ * @nsList: the list of known namespaces in
+ * "<prefix1>=<href1> <prefix2>=href2> ..." format.
+ *
+ * Registers namespaces from @nsList in @xpathCtx.
+ *
+ * Returns 0 on success and a negative value otherwise.
+ */
+int
+register_namespaces(xmlXPathContextPtr xpathCtx, const xmlChar* nsList) {
+ xmlChar* nsListDup;
+ xmlChar* prefix;
+ xmlChar* href;
+ xmlChar* next;
+
+ assert(xpathCtx);
+ assert(nsList);
+
+ nsListDup = xmlStrdup(nsList);
+ if(nsListDup == NULL) {
+ fprintf(stderr, "Error: unable to strdup namespaces list\n");
+ return(-1);
+ }
+
+ next = nsListDup;
+ while(next != NULL) {
+ /* skip spaces */
+ while((*next) == ' ') next++;
+ if((*next) == '\0') break;
+
+ /* find prefix */
+ prefix = next;
+ next = (xmlChar*)xmlStrchr(next, '=');
+ if(next == NULL) {
+ fprintf(stderr,"Error: invalid namespaces list format\n");
+ xmlFree(nsListDup);
+ return(-1);
+ }
+ *(next++) = '\0';
+
+ /* find href */
+ href = next;
+ next = (xmlChar*)xmlStrchr(next, ' ');
+ if(next != NULL) {
+ *(next++) = '\0';
+ }
+
+ /* do register namespace */
+ if(xmlXPathRegisterNs(xpathCtx, prefix, href) != 0) {
+ fprintf(stderr,"Error: unable to register NS with prefix=\"%s\" and href=\"%s\"\n", prefix, href);
+ xmlFree(nsListDup);
+ return(-1);
+ }
+ }
+
+ xmlFree(nsListDup);
+ return(0);
+}
+
+/**
+ * print_xpath_nodes:
+ * @nodes: the nodes set.
+ * @output: the output file handle.
+ *
+ * Prints the @nodes content to @output.
+ */
+void
+print_xpath_nodes(xmlNodeSetPtr nodes, FILE* output) {
+ xmlNodePtr cur;
+ int size;
+ int i;
+
+ assert(output);
+ size = (nodes) ? nodes->nodeNr : 0;
+
+ fprintf(output, "Result (%d nodes):\n", size);
+ for(i = 0; i < size; ++i) {
+ assert(nodes->nodeTab[i]);
+
+ if(nodes->nodeTab[i]->type == XML_NAMESPACE_DECL) {
+ xmlNsPtr ns;
+
+ ns = (xmlNsPtr)nodes->nodeTab[i];
+ cur = (xmlNodePtr)ns->next;
+ if(cur->ns) {
+ fprintf(output, "= namespace \"%s\"=\"%s\" for node %s:%s\n",
+ ns->prefix, ns->href, cur->ns->href, cur->name);
+ } else {
+ fprintf(output, "= namespace \"%s\"=\"%s\" for node %s\n",
+ ns->prefix, ns->href, cur->name);
+ }
+ } else if(nodes->nodeTab[i]->type == XML_ELEMENT_NODE) {
+ cur = nodes->nodeTab[i];
+ if(cur->ns) {
+ fprintf(output, "= element node \"%s:%s\"\n",
+ cur->ns->href, cur->name);
+ } else {
+ fprintf(output, "= element node \"%s\"\n",
+ cur->name);
+ }
+ } else {
+ cur = nodes->nodeTab[i];
+ fprintf(output, "= node \"%s\": type %d\n", cur->name, cur->type);
+ }
+ }
+}
+
+#else
+int main(void) {
+ fprintf(stderr, "XPath support not compiled in\n");
+ exit(1);
+}
+#endif
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