Thanks to the generous support of Torchbox (http://www.torchbox.com), I

have been able to significantly improve the contrib/xml XPath
integration code.

New features:

* XPath set-returning function allows multiple results from an several
XPath queries to be used as a virtual table.
* Using libxslt, XSLT transformations (with and without parameters) are
supported. (Caution: This support allows generic URL fetching from
within the backend as well).

I've removed the old code so that it is all libxml based. Rather than
attach as a patch, I've put the tar.gz (10k!) at
http://www.azuli.co.uk/pgxml-1.0.tar.gz
(all files in archive are xml/....).

I think this is worth replacing the contrib version with, even though
the function names have changed (though the same functionality is
there), because it includes a SRF and some SPI usage, in addition to
linking to an external library. And it isn't a big module! Obviously, I
understand that people might prefer to move it elsewhere, or might have
reservations about replacing an existing contrib module with an
incompatible one. I'm open to suggestions.

John Gray

1 files changed, 0 insertions, 265 deletions

diff --git a/contrib/xml/pgxml_dom.c b/contrib/xml/pgxml_dom.c
deleted file mode 100644
index 2b11b1d646..0000000000
--- a/contrib/xml/pgxml_dom.c
+++ /dev/null
@@ -1,265 +0,0 @@
-/* Parser interface for DOM-based parser (libxml) rather than
-   stream-based SAX-type parser */
-
-#include "postgres.h"
-#include "fmgr.h"
-
-/* libxml includes */
-
-#include <libxml/xpath.h>
-#include <libxml/tree.h>
-#include <libxml/xmlmemory.h>
-
-/* declarations */
-
-static void *pgxml_palloc(size_t size);
-static void *pgxml_repalloc(void *ptr, size_t size);
-static void pgxml_pfree(void *ptr);
-static char *pgxml_pstrdup(const char *string);
-
-static void pgxml_parser_init();
-
-static xmlChar *pgxmlNodeSetToText(xmlNodeSetPtr nodeset, xmlDocPtr doc,
-				   xmlChar * toptagname, xmlChar * septagname,
-				   int format);
-
-static xmlChar *pgxml_texttoxmlchar(text *textstring);
-
-
-Datum		pgxml_parse(PG_FUNCTION_ARGS);
-Datum		pgxml_xpath(PG_FUNCTION_ARGS);
-
-/* memory handling passthrough functions (e.g. palloc, pstrdup are
-   currently macros, and the others might become so...) */
-
-static void *
-pgxml_palloc(size_t size)
-{
-	return palloc(size);
-}
-
-static void *
-pgxml_repalloc(void *ptr, size_t size)
-{
-	return repalloc(ptr, size);
-}
-
-static void
-pgxml_pfree(void *ptr)
-{
-	return pfree(ptr);
-}
-
-static char *
-pgxml_pstrdup(const char *string)
-{
-	return pstrdup(string);
-}
-
-static void
-pgxml_parser_init()
-{
-	/*
-	 * This code should also set parser settings from  user-supplied info.
-	 * Quite how these settings are made is another matter :)
-	 */
-
-	xmlMemSetup(pgxml_pfree, pgxml_palloc, pgxml_repalloc, pgxml_pstrdup);
-	xmlInitParser();
-
-}
-
-
-/* Returns true if document is well-formed */
-
-PG_FUNCTION_INFO_V1(pgxml_parse);
-
-Datum
-pgxml_parse(PG_FUNCTION_ARGS)
-{
-	/* called as pgxml_parse(document) */
-	xmlDocPtr	doctree;
-	text	   *t = PG_GETARG_TEXT_P(0);		/* document buffer */
-	int32		docsize = VARSIZE(t) - VARHDRSZ;
-
-	pgxml_parser_init();
-
-	doctree = xmlParseMemory((char *) VARDATA(t), docsize);
-	if (doctree == NULL)
-	{
-		xmlCleanupParser();
-		PG_RETURN_BOOL(false);	/* i.e. not well-formed */
-	}
-	xmlCleanupParser();
-	xmlFreeDoc(doctree);
-	PG_RETURN_BOOL(true);
-}
-
-static xmlChar
-*
-pgxmlNodeSetToText(xmlNodeSetPtr nodeset,
-				   xmlDocPtr doc,
-				   xmlChar * toptagname,
-				   xmlChar * septagname,
-				   int format)
-{
-	/* Function translates a nodeset into a text representation */
-
-	/*
-	 * iterates over each node in the set and calls xmlNodeDump to write
-	 * it to an xmlBuffer -from which an xmlChar * string is returned.
-	 */
-	/* each representation is surrounded by <tagname> ... </tagname> */
-	/* if format==0, add a newline between nodes?? */
-
-	xmlBufferPtr buf;
-	xmlChar    *result;
-	int			i;
-
-	buf = xmlBufferCreate();
-
-	if ((toptagname != NULL) && (xmlStrlen(toptagname) > 0))
-	{
-		xmlBufferWriteChar(buf, "<");
-		xmlBufferWriteCHAR(buf, toptagname);
-		xmlBufferWriteChar(buf, ">");
-	}
-	if (nodeset != NULL)
-	{
-		for (i = 0; i < nodeset->nodeNr; i++)
-		{
-			if ((septagname != NULL) && (xmlStrlen(septagname) > 0))
-			{
-				xmlBufferWriteChar(buf, "<");
-				xmlBufferWriteCHAR(buf, septagname);
-				xmlBufferWriteChar(buf, ">");
-			}
-			xmlNodeDump(buf, doc, nodeset->nodeTab[i], 1, (format == 2));
-
-			if ((septagname != NULL) && (xmlStrlen(septagname) > 0))
-			{
-				xmlBufferWriteChar(buf, "</");
-				xmlBufferWriteCHAR(buf, septagname);
-				xmlBufferWriteChar(buf, ">");
-			}
-			if (format)
-				xmlBufferWriteChar(buf, "\n");
-		}
-	}
-
-	if ((toptagname != NULL) && (xmlStrlen(toptagname) > 0))
-	{
-		xmlBufferWriteChar(buf, "</");
-		xmlBufferWriteCHAR(buf, toptagname);
-		xmlBufferWriteChar(buf, ">");
-	}
-	result = xmlStrdup(buf->content);
-	xmlBufferFree(buf);
-	return result;
-}
-
-static xmlChar *
-pgxml_texttoxmlchar(text *textstring)
-{
-	xmlChar    *res;
-	int32		txsize;
-
-	txsize = VARSIZE(textstring) - VARHDRSZ;
-	res = (xmlChar *) palloc(txsize + 1);
-	memcpy((char *) res, VARDATA(textstring), txsize);
-	res[txsize] = '\0';
-	return res;
-}
-
-
-PG_FUNCTION_INFO_V1(pgxml_xpath);
-
-Datum
-pgxml_xpath(PG_FUNCTION_ARGS)
-{
-	xmlDocPtr	doctree;
-	xmlXPathContextPtr ctxt;
-	xmlXPathObjectPtr res;
-	xmlChar    *xpath,
-			   *xpresstr,
-			   *toptag,
-			   *septag;
-	xmlXPathCompExprPtr comppath;
-
-	int32		docsize,
-				ressize;
-	text	   *t,
-			   *xpres;
-
-	t = PG_GETARG_TEXT_P(0);	/* document buffer */
-	xpath = pgxml_texttoxmlchar(PG_GETARG_TEXT_P(1));	/* XPath expression */
-	toptag = pgxml_texttoxmlchar(PG_GETARG_TEXT_P(2));
-	septag = pgxml_texttoxmlchar(PG_GETARG_TEXT_P(3));
-
-	docsize = VARSIZE(t) - VARHDRSZ;
-
-	pgxml_parser_init();
-
-	doctree = xmlParseMemory((char *) VARDATA(t), docsize);
-	if (doctree == NULL)
-	{							/* not well-formed */
-		xmlCleanupParser();
-		PG_RETURN_NULL();
-	}
-
-	ctxt = xmlXPathNewContext(doctree);
-	ctxt->node = xmlDocGetRootElement(doctree);
-
-	/* compile the path */
-	comppath = xmlXPathCompile(xpath);
-	if (comppath == NULL)
-	{
-		elog(WARNING, "XPath syntax error");
-		xmlFreeDoc(doctree);
-		pfree((void *) xpath);
-		xmlCleanupParser();
-		PG_RETURN_NULL();
-	}
-
-	/* Now evaluate the path expression. */
-	res = xmlXPathCompiledEval(comppath, ctxt);
-	xmlXPathFreeCompExpr(comppath);
-
-	if (res == NULL)
-	{
-		xmlFreeDoc(doctree);
-		pfree((void *) xpath);
-		xmlCleanupParser();
-		PG_RETURN_NULL();		/* seems appropriate */
-	}
-	/* now we dump this node, ?surrounding by tags? */
-	/* To do this, we look first at the type */
-	switch (res->type)
-	{
-		case XPATH_NODESET:
-			xpresstr = pgxmlNodeSetToText(res->nodesetval,
-										  doctree,
-										  toptag, septag, 0);
-			break;
-		case XPATH_STRING:
-			xpresstr = xmlStrdup(res->stringval);
-			break;
-		default:
-			elog(WARNING, "Unsupported XQuery result: %d", res->type);
-			xpresstr = xmlStrdup("<unsupported/>");
-	}
-
-
-	/* Now convert this result back to text */
-	ressize = strlen(xpresstr);
-	xpres = (text *) palloc(ressize + VARHDRSZ);
-	memcpy(VARDATA(xpres), xpresstr, ressize);
-	VARATT_SIZEP(xpres) = ressize + VARHDRSZ;
-
-	/* Free various storage */
-	xmlFreeDoc(doctree);
-	pfree((void *) xpath);
-	xmlFree(xpresstr);
-	xmlCleanupParser();
-	PG_RETURN_TEXT_P(xpres);
-}