diff options
| -rw-r--r-- | contrib/xml/pgxml_dom.c | 238 | ||||
| -rw-r--r-- | contrib/xml/pgxml_dom.source | 7 |
2 files changed, 245 insertions, 0 deletions
diff --git a/contrib/xml/pgxml_dom.c b/contrib/xml/pgxml_dom.c new file mode 100644 index 00000000000..b01368a52ce --- /dev/null +++ b/contrib/xml/pgxml_dom.c @@ -0,0 +1,238 @@ +/* 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 */ + PG_RETURN_NULL(); + } + + ctxt = xmlXPathNewContext(doctree); + ctxt->node = xmlDocGetRootElement(doctree); + + /* compile the path */ + comppath = xmlXPathCompile(xpath); + if (comppath == NULL) { + elog(NOTICE, "XPath syntax error"); + xmlFreeDoc(doctree); + pfree((void *) xpath); + PG_RETURN_NULL(); + } + + /* Now evaluate the path expression. */ + res = xmlXPathCompiledEval(comppath,ctxt); + xmlXPathFreeCompExpr(comppath); + + if (res==NULL) { + xmlFreeDoc(doctree); + pfree((void *)xpath); + 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(NOTICE,"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); + + PG_RETURN_TEXT_P(xpres); +} + + + + diff --git a/contrib/xml/pgxml_dom.source b/contrib/xml/pgxml_dom.source new file mode 100644 index 00000000000..a8582398b1e --- /dev/null +++ b/contrib/xml/pgxml_dom.source @@ -0,0 +1,7 @@ +--SQL for XML parser + +CREATE FUNCTION pgxml_parse(text) RETURNS bool + AS '_OBJWD_/pgxml_dom_DLSUFFIX_' LANGUAGE 'c' WITH (isStrict); + +CREATE FUNCTION pgxml_xpath(text,text,text,text) RETURNS text + AS '_OBJWD_/pgxml_dom_DLSUFFIX_' LANGUAGE 'c' WITH (isStrict);
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