Function pgxml_xpath

contrib/xml2/xpath.c:413–463

/* Core function to evaluate XPath query */

static xmlXPathObjectPtr
pgxml_xpath(text *document, xmlChar *xpath, xpath_workspace *workspace)
{
	int32		docsize = VARSIZE_ANY_EXHDR(document);
	PgXmlErrorContext *xmlerrcxt;
	xmlXPathCompExprPtr comppath;

	workspace->doctree = NULL;
	workspace->ctxt = NULL;
	workspace->res = NULL;

	xmlerrcxt = pgxml_parser_init(PG_XML_STRICTNESS_LEGACY);

	PG_TRY();
	{
		workspace->doctree = xmlParseMemory((char *) VARDATA_ANY(document),
											docsize);
		if (workspace->doctree != NULL)
		{
			workspace->ctxt = xmlXPathNewContext(workspace->doctree);
			workspace->ctxt->node = xmlDocGetRootElement(workspace->doctree);

			/* compile the path */
			comppath = xmlXPathCompile(xpath);
			if (comppath == NULL)
				xml_ereport(xmlerrcxt, ERROR, ERRCODE_EXTERNAL_ROUTINE_EXCEPTION,
							"XPath Syntax Error");

			/* Now evaluate the path expression. */
			workspace->res = xmlXPathCompiledEval(comppath, workspace->ctxt);

			xmlXPathFreeCompExpr(comppath);
		}
	}
	PG_CATCH();
	{
		cleanup_workspace(workspace);

		pg_xml_done(xmlerrcxt, true);

		PG_RE_THROW();
	}
	PG_END_TRY();

	if (workspace->res == NULL)
		cleanup_workspace(workspace);

	pg_xml_done(xmlerrcxt, false);

	return workspace->res;
}

/* Clean up after processing the result of pgxml_xpath() */
static void