diff options
Diffstat (limited to 'contrib/xml/pgxml_dom.c')
| -rw-r--r-- | contrib/xml/pgxml_dom.c | 265 |
1 files changed, 265 insertions, 0 deletions
diff --git a/contrib/xml/pgxml_dom.c b/contrib/xml/pgxml_dom.c new file mode 100644 index 00000000000..2b11b1d6468 --- /dev/null +++ b/contrib/xml/pgxml_dom.c @@ -0,0 +1,265 @@ +/* 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); +} |