Re: xpath improvement V2 with xml.c - Mailing list pgsql-hackers
| From | Arie Bikker |
|---|---|
| Subject | Re: xpath improvement V2 with xml.c |
| Date | |
| Msg-id | 4B75D0F8.5040705@abikker.nl Whole thread Raw |
| In response to | xpath improvement V2 (Arie Bikker <arie@abikker.nl>) |
| List | pgsql-hackers |
And a patch for the code implementing this
*** doc/src/sgml/func.sgml.org Tue Feb 2 12:53:59 2010
--- doc/src/sgml/func.sgml Fri Feb 12 21:49:01 2010
***************
*** 1,4 ****
! <!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.482.2.2 2009/11/24 19:21:04 petere Exp $ -->
<chapter id="functions">
<title>Functions and Operators</title>
--- 1,4 ----
! <!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.482 2009/06/17 21:58:49 tgl Exp $ -->
<chapter id="functions">
<title>Functions and Operators</title>
***************
*** 821,827 ****
<row>
<entry><literal><function>random</function>()</literal></entry>
<entry><type>dp</type></entry>
! <entry>random value in the range 0.0 <= x < 1.0</entry>
<entry><literal>random()</literal></entry>
<entry></entry>
</row>
--- 821,827 ----
<row>
<entry><literal><function>random</function>()</literal></entry>
<entry><type>dp</type></entry>
! <entry>random value between 0.0 and 1.0, inclusive</entry>
<entry><literal>random()</literal></entry>
<entry></entry>
</row>
***************
*** 5251,5259 ****
<listitem>
<para>
<function>to_char(..., 'ID')</function>'s day of the week numbering
! matches the <function>extract(isodow from ...)</function> function, but
<function>to_char(..., 'D')</function>'s does not match
! <function>extract(dow from ...)</function>'s day numbering.
</para>
</listitem>
--- 5251,5259 ----
<listitem>
<para>
<function>to_char(..., 'ID')</function>'s day of the week numbering
! matches the <function>extract('isodow', ...)</function> function, but
<function>to_char(..., 'D')</function>'s does not match
! <function>extract('dow', ...)</function>'s day numbering.
</para>
</listitem>
***************
*** 8464,8474 ****
</indexterm>
<para>
! To process values of data type <type>xml</type>, PostgreSQL offers
! the function <function>xpath</function>, which evaluates XPath 1.0
! expressions.
</para>
<synopsis>
<function>xpath</function>(<replaceable>xpath</replaceable>, <replaceable>xml</replaceable><optional>,
<replaceable>nsarray</replaceable></optional>)
</synopsis>
--- 8464,8486 ----
</indexterm>
<para>
! To retrieve information from an <type>xml</type> document an Xpath 1.0
! expression evaluation can be caried out. The result of this evaluation
! can have several data types depending on the expression and the content
! of the document. The functions implementing this all use an expression
! and a document as input and an optional namespace array.
! They differ in the type of expression they interpret and, consequently, the result they provide.
</para>
+ <sect3 id="functions-xml-processing-nodeset">
+ <title>Nodeset processing</title>
+
+ <para>
+ To process expressions returning a nodeset, PostgreSQL offers
+ the function <function>xpath</function>, which returns an array of
+ <type>xml</type> values.
+ </para>
+
<synopsis>
<function>xpath</function>(<replaceable>xpath</replaceable>, <replaceable>xml</replaceable><optional>,
<replaceable>nsarray</replaceable></optional>)
</synopsis>
***************
*** 8506,8511 ****
--- 8518,8699 ----
(1 row)
]]></screen>
</para>
+ </sect3>
+
+ <sect3 id="functions-xml-processing-values">
+ <title>Value returning functions</title>
+ <para>
+ To retrieve single values from data type <type>xml</type> PostgreSQL offers two
+ functions akin to <function>xpath</function>.
+ The function <function>xpath_value_text</function> returns a single
+ as <type>text</type> result; the function <function>xpath_value_strict</function> returns a specific type governed
byan input parameter used as type example.
+ </para>
+
+ <synopsis>
+ <function>xpath_value_text</function>(<replaceable>xpath</replaceable>, <replaceable>xml</replaceable><optional>,
<replaceable>nsarray</replaceable></optional>)
+ </synopsis>
+ <synopsis>
+ <function>xpath_value_strict</function>(<replaceable>typexample</replaceable>, <replaceable>xpath</replaceable>,
<replaceable>xml</replaceable><optional>,<replaceable>nsarray</replaceable></optional>)
+ </synopsis>
+
+ <para>
+ The function <function>xpath_value_text</function> evaluates the XPath
+ expression <replaceable>xpath</replaceable> against the XML value
+ <replaceable>xml</replaceable>. It returns a text value
+ corresponding to the evaluation produced by the XPath expression.
+ <replaceable>xpath</replaceable> must be an expression that returns
+ a single value, not a nodeset.
+ <replaceable>xpath</replaceable> expressions resulting in boolean, string or number are supported.
+ </para>
+
+ <para>
+ The second argument must be a well formed XML document. In particular,
+ it must have a single root node element.
+ </para>
+
+ <para>
+ The third argument of the function is an array of namespace
+ mappings with the same restrictions as for the <replaceable>xpath</replaceable> function.
+ </para>
+
+ <para>
+ This example will return the tagname of the root element:
+ <screen><![CDATA[
+ SELECT xpath_value_text('name()', '<my:a xmlns:my="http://example.com">test</my:a>',
+ ARRAY[ARRAY['my', 'http://example.com']]);
+
+ xpath_value_text
+ ------------------
+ my:a
+ (1 row)
+ ]]></screen>
+ </para>
+
+ <para>
+ The function <function>xpath_value_strict</function> evaluates the XPath
+ expression <replaceable>xpath</replaceable> against the XML value
+ <replaceable>xml</replaceable>. It returns a value
+ of the same type as <replaceable>typexample</replaceable>.
+ <replaceable>xpath</replaceable> must be an expression that returns
+ a single value of the same type as <replaceable>typexample</replaceable>.
+ When <replaceable>typexample</replaceable> is of type <type>regtype</type>
+ the function does not return the result value of the expression evaluation,
+ but the type of the result value.
+ </para>
+
+ <para>
+ The first argument serves as an example of the output required by this function.
+ It can be any constant or variable of type <type>boolean</type>,
+ <type>text</type> or <type>float8</type> corresponding to the basic value
+ type used in libxml2. Or it can be a <type>regtype</type> to retrieve type
+ information of the expression evaluation result.
+ </para>
+
+ <para>
+ The second argument must be a XPath expression with a result value
+ corresponding to the example offered.
+ An error is genereated if <replaceable>typexample</replaceable> and
+ the result of <replaceable>xpath</replaceable> do not match in type.
+ </para>
+
+ <para>
+ The third argument must be a well formed XML document with a single
+ root node element.
+ </para>
+
+ <para>
+ The fourth argument of the function is an (optional) array of namespace
+ mappings.
+ </para>
+
+ <para>
+ The following table shows some valid input/output combinations:
+
+ <informaltable>
+ <tgroup cols="5">
+ <thead>
+ <row>
+ <entry><replaceable>typexample</replaceable></entry>
+ <entry><replaceable>xpath</replaceable></entry>
+ <entry><replaceable>xml</replaceable></entry>
+ <entry>result value</entry>
+ <entry>result type</entry>
+ </row>
+ </thead>
+
+ <tbody>
+ <row>
+ <entry>TRUE::boolean</entry>
+ <entry>'1=1'</entry>
+ <entry><![CDATA['<foo/>']]></entry>
+ <entry>TRUE</entry>
+ <entry><type>boolean</type></entry>
+ </row>
+ <row>
+ <entry>1::float8</entry>
+ <entry>'1 div 3'</entry>
+ <entry><![CDATA['<foo/>']]></entry>
+ <entry>0.333333333333333</entry>
+ <entry><type>float8</type></entry>
+ </row>
+ <row>
+ <entry>'a'::text</entry>
+ <entry>'name()'</entry>
+ <entry><![CDATA['<foo/>']]></entry>
+ <entry>foo</entry>
+ <entry><type>text</type></entry>
+ </row>
+ <row>
+ <entry>'text'::regtype</entry>
+ <entry>'1=1'</entry>
+ <entry><![CDATA['<foo/>']]></entry>
+ <entry>boolean</entry>
+ <entry><type>regtype</type></entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </informaltable>
+ </para>
+
+ <para>
+ An error is generated if if the types of <replaceable>typexample</replaceable> and the expression result do not
match.Some examples are shown in the following table:
+
+ <informaltable>
+ <tgroup cols="4">
+ <thead>
+ <row>
+ <entry><replaceable>typexample</replaceable></entry>
+ <entry><replaceable>xpath</replaceable></entry>
+ <entry><replaceable>xml</replaceable></entry>
+ <entry>fail reason</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry>'a'::text</entry>
+ <entry>'/'</entry>
+ <entry><![CDATA['<foo/>']]></entry>
+ <entry>expression evaluates to nodeset, not string</entry>
+ </row>
+ <row>
+ <entry>'a'::text</entry>
+ <entry>'/@width'</entry>
+ <entry><![CDATA['<foo width="20"/>']]></entry>
+ <entry>expression evaluates to nodeset, albeit with a single node</entry>
+ </row>
+ <row>
+ <entry>1::float8</entry>
+ <entry>'number(@height)'</entry>
+ <entry><![CDATA['<foo width="20"/>']]></entry>
+ <entry>returns NaN because argument for number() is empty nodeset</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </informaltable>
+
+ </para>
+
+ </sect3>
</sect2>
<sect2 id="functions-xml-mapping">
*** src/include/catalog/pg_proc.h.org Thu Jan 21 23:12:07 2010
--- src/include/catalog/pg_proc.h Fri Jan 29 22:50:38 2010
***************
*** 4305,4314 ****
DESCR("map database contents and structure to XML and XML Schema");
DATA(insert OID = 2931 ( xpath PGNSP PGUID 12 1 0 0 f f f t f i 3 0 143 "25 142 1009" _null_ _null_ _null_
_null_xpath _null_ _null_ _null_ ));
! DESCR("evaluate XPath expression, with namespaces support");
DATA(insert OID = 2932 ( xpath PGNSP PGUID 14 1 0 0 f f f t f i 2 0 143 "25 142" _null_ _null_ _null_ _null_
"selectpg_catalog.xpath($1, $2, ''{}''::pg_catalog.text[])" _null_ _null_ _null_ ));
! DESCR("evaluate XPath expression");
/* uuid */
DATA(insert OID = 2952 ( uuid_in PGNSP PGUID 12 1 0 0 f f f t f i 1 0 2950 "2275" _null_ _null_ _null_
_null_uuid_in _null_ _null_ _null_ ));
DESCR("I/O");
--- 4305,4323 ----
DESCR("map database contents and structure to XML and XML Schema");
DATA(insert OID = 2931 ( xpath PGNSP PGUID 12 1 0 0 f f f t f i 3 0 143 "25 142 1009" _null_ _null_ _null_
_null_xpath _null_ _null_ _null_ ));
! DESCR("evaluate XPath nodeset expression, with namespaces support");
DATA(insert OID = 2932 ( xpath PGNSP PGUID 14 1 0 0 f f f t f i 2 0 143 "25 142" _null_ _null_ _null_ _null_
"selectpg_catalog.xpath($1, $2, ''{}''::pg_catalog.text[])" _null_ _null_ _null_ ));
! DESCR("evaluate XPath nodeset expression");
+ DATA(insert OID = 2995 ( xpath_value_text PGNSP PGUID 12 1 0 0 f f f t f i 3 0 25 "25 142 1009" _null_
_null__null_ _null_ xpath_value_text _null_ _null_ _null_ ));
+ DESCR("evaluate XPath value expression, with namespaces support");
+ DATA(insert OID = 2996 ( xpath_value_text PGNSP PGUID 14 1 0 0 f f f t f i 2 0 25 "25 142" _null_ _null_
_null__null_ "select pg_catalog.xpath_value_text($1, $2, ''{}''::pg_catalog.text[])" _null_ _null_ _null_ ));
+ DESCR("evaluate XPath value expression");
+ DATA(insert OID = 2997 ( xpath_value_strict PGNSP PGUID 12 1 0 0 f f f t f i 4 0 2283 "2283 25 142 1009" _null_
_null__null_ _null_ xpath_value_strict _null_ _null_ _null_ ));
+ DESCR("evaluate XPath value expression by type example, with namespaces support");
+ DATA(insert OID = 2998 ( xpath_value_strict PGNSP PGUID 14 1 0 0 f f f t f i 3 0 2283 "2283 25 142" _null_
_null__null_ _null_ "select pg_catalog.xpath_value_strict($1, $2, $3, ''{}''::pg_catalog.text[])" _null_ _null_ _null_
));
+ DESCR("evaluate XPath value expression by type example");
+
/* uuid */
DATA(insert OID = 2952 ( uuid_in PGNSP PGUID 12 1 0 0 f f f t f i 1 0 2950 "2275" _null_ _null_ _null_
_null_uuid_in _null_ _null_ _null_ ));
DESCR("I/O");
*** src/include/utils/xml.h.org Sat Jan 16 23:57:35 2010
--- src/include/utils/xml.h Fri Jan 29 00:11:52 2010
***************
*** 37,42 ****
--- 37,44 ----
extern Datum xmltotext(PG_FUNCTION_ARGS);
extern Datum xmlvalidate(PG_FUNCTION_ARGS);
extern Datum xpath(PG_FUNCTION_ARGS);
+ extern Datum xpath_value_text(PG_FUNCTION_ARGS);
+ extern Datum xpath_value_strict(PG_FUNCTION_ARGS);
extern Datum table_to_xml(PG_FUNCTION_ARGS);
extern Datum query_to_xml(PG_FUNCTION_ARGS);
*** src/backend/utils/fmgrtab.c.org Tue Jan 5 21:52:42 2010
--- src/backend/utils/fmgrtab.c Fri Jan 29 22:51:07 2010
***************
*** 1686,1691 ****
--- 1686,1693 ----
extern Datum record_le (PG_FUNCTION_ARGS);
extern Datum record_ge (PG_FUNCTION_ARGS);
extern Datum btrecordcmp (PG_FUNCTION_ARGS);
+ extern Datum xpath_value_text (PG_FUNCTION_ARGS);
+ extern Datum xpath_value_strict (PG_FUNCTION_ARGS);
extern Datum has_foreign_data_wrapper_privilege_name_name (PG_FUNCTION_ARGS);
extern Datum has_foreign_data_wrapper_privilege_name_id (PG_FUNCTION_ARGS);
extern Datum has_foreign_data_wrapper_privilege_id_name (PG_FUNCTION_ARGS);
***************
*** 3752,3757 ****
--- 3754,3761 ----
{ 2985, "record_le", 2, true, false, record_le },
{ 2986, "record_ge", 2, true, false, record_ge },
{ 2987, "btrecordcmp", 2, true, false, btrecordcmp },
+ { 2995, "xpath_value_text", 3, true, false, xpath_value_text },
+ { 2997, "xpath_value_strict", 4, true, false, xpath_value_strict },
{ 3000, "has_foreign_data_wrapper_privilege_name_name", 3, true, false,
has_foreign_data_wrapper_privilege_name_name},
{ 3001, "has_foreign_data_wrapper_privilege_name_id", 3, true, false, has_foreign_data_wrapper_privilege_name_id },
{ 3002, "has_foreign_data_wrapper_privilege_id_name", 3, true, false, has_foreign_data_wrapper_privilege_id_name },
*** src/backend/utils/adt/xml.c.org Fri Sep 4 12:49:43 2009
--- src/backend/utils/adt/xml.c Wed Feb 10 13:33:32 2010
***************
*** 111,116 ****
--- 111,118 ----
static xmlDocPtr xml_parse(text *data, XmlOptionType xmloption_arg,
bool preserve_whitespace, int encoding);
static text *xml_xmlnodetoxmltype(xmlNodePtr cur);
+ xmlXPathObjectPtr xml_xpathinternal(xmlChar *xpath, xmlChar *datastr, int datasize, ArrayType *nsarray);
+ static xmlXPathContextPtr xml_xmlxpathcontextaddns(xmlXPathContextPtr xpctxt, ArrayType *nsarray);
#endif /* USE_LIBXML */
static StringInfo query_to_xml_internal(const char *query, char *tablename,
***************
*** 3265,3308 ****
return result;
}
- #endif
-
/*
! * Evaluate XPath expression and return array of XML values.
! *
! * As we have no support of XQuery sequences yet, this function seems
! * to be the most useful one (array of XML functions plays a role of
! * some kind of substitution for XQuery sequences).
! *
! * It is up to the user to ensure that the XML passed is in fact
! * an XML document - XPath doesn't work easily on fragments without
! * a context node being known.
*/
! Datum
! xpath(PG_FUNCTION_ARGS)
! {
! #ifdef USE_LIBXML
! text *xpath_expr_text = PG_GETARG_TEXT_P(0);
! xmltype *data = PG_GETARG_XML_P(1);
! ArrayType *namespaces = PG_GETARG_ARRAYTYPE_P(2);
! ArrayBuildState *astate = NULL;
xmlParserCtxtPtr ctxt = NULL;
xmlDocPtr doc = NULL;
xmlXPathContextPtr xpathctx = NULL;
xmlXPathCompExprPtr xpathcomp = NULL;
xmlXPathObjectPtr xpathobj = NULL;
! char *datastr;
! int32 len;
! int32 xpath_len;
! xmlChar *string;
! xmlChar *xpath_expr;
! int i;
! int res_nitems;
int ndim;
Datum *ns_names_uris;
bool *ns_names_uris_nulls;
! int ns_count;
/*
* Namespace mappings are passed as text[]. If an empty array is passed
--- 3267,3359 ----
return result;
}
/*
! * Retrieve an the result of a query (xpath) on xmldata (datastr) within a given
! * context.
! * See function xml_xpathexprtoxmlchar for the creation of the xpath argument
! * See function xml_xmlctxtmanipulate for the creation of the xpathctxt argument
*/
! xmlXPathObjectPtr xml_xpathinternal(xmlChar *xpath, xmlChar *datastr, int datasize, ArrayType *nsarray) {
xmlParserCtxtPtr ctxt = NULL;
xmlDocPtr doc = NULL;
xmlXPathContextPtr xpathctx = NULL;
xmlXPathCompExprPtr xpathcomp = NULL;
xmlXPathObjectPtr xpathobj = NULL;
!
! xml_init();
! xmlInitParser();
!
! PG_TRY();
! {
! /*
! * redundant XML parsing (two parsings for the same value during one
! * command execution are possible)
! */
! ctxt = xmlNewParserCtxt();
! if (ctxt == NULL)
! xml_ereport(ERROR, ERRCODE_OUT_OF_MEMORY,
! "could not allocate parser context");
! doc = xmlCtxtReadMemory(ctxt, (char *) datastr, datasize, NULL, NULL, 0);
! if (doc == NULL)
! xml_ereport(ERROR, ERRCODE_INVALID_XML_DOCUMENT,
! "could not parse XML document");
! xpathctx = xmlXPathNewContext(doc);
! if (xpathctx == NULL)
! xml_ereport(ERROR, ERRCODE_OUT_OF_MEMORY,
! "could not allocate XPath context");
! xpathctx->node = xmlDocGetRootElement(doc);
! if (xpathctx->node == NULL)
! xml_ereport(ERROR, ERRCODE_INTERNAL_ERROR,
! "could not find root XML element");
!
! /* register namespaces, if any */
! xpathctx = xml_xmlxpathcontextaddns(xpathctx, nsarray);
!
! xpathcomp = xmlXPathCompile(xpath);
! if (xpathcomp == NULL) /* TODO: show proper XPath error details */
! xml_ereport(ERROR, ERRCODE_INTERNAL_ERROR,
! "invalid XPath expression");
!
! xpathobj = xmlXPathCompiledEval(xpathcomp, xpathctx);
! if (xpathobj == NULL) /* TODO: reason? */
! xml_ereport(ERROR, ERRCODE_INTERNAL_ERROR,
! "could not create XPath object");
! }
! PG_CATCH();
! {
! if (xpathobj)
! xmlXPathFreeObject(xpathobj);
! if (xpathcomp)
! xmlXPathFreeCompExpr(xpathcomp);
! if (xpathctx)
! xmlXPathFreeContext(xpathctx);
! if (doc)
! xmlFreeDoc(doc);
! if (ctxt)
! xmlFreeParserCtxt(ctxt);
! PG_RE_THROW();
! }
! PG_END_TRY();
!
! xmlXPathFreeCompExpr(xpathcomp);
! xmlXPathFreeContext(xpathctx);
! xmlFreeDoc(doc);
! xmlFreeParserCtxt(ctxt);
!
! return(xpathobj);
! }
!
! /*
! * Registers the namespaces in nsarray into the context xpctxt
! * returns xpctxt
! */
! static xmlXPathContextPtr xml_xmlxpathcontextaddns(xmlXPathContextPtr xpctxt, ArrayType *nsarray) {
int ndim;
Datum *ns_names_uris;
bool *ns_names_uris_nulls;
! int i;
! int ns_count;
/*
* Namespace mappings are passed as text[]. If an empty array is passed
***************
*** 3313,3324 ****
* ARRAY[ARRAY['myns', 'http://example.com'], ARRAY['myns2',
* 'http://example2.com']].
*/
! ndim = ARR_NDIM(namespaces);
if (ndim != 0)
{
int *dims;
! dims = ARR_DIMS(namespaces);
if (ndim != 2 || dims[1] != 2)
ereport(ERROR,
--- 3364,3375 ----
* ARRAY[ARRAY['myns', 'http://example.com'], ARRAY['myns2',
* 'http://example2.com']].
*/
! ndim = ARR_NDIM(nsarray);
if (ndim != 0)
{
int *dims;
! dims = ARR_DIMS(nsarray);
if (ndim != 2 || dims[1] != 2)
ereport(ERROR,
***************
*** 3326,3390 ****
errmsg("invalid array for XML namespace mapping"),
errdetail("The array must be two-dimensional with length of the second axis equal to 2.")));
! Assert(ARR_ELEMTYPE(namespaces) == TEXTOID);
! deconstruct_array(namespaces, TEXTOID, -1, false, 'i',
&ns_names_uris, &ns_names_uris_nulls,
&ns_count);
Assert((ns_count % 2) == 0); /* checked above */
ns_count /= 2; /* count pairs only */
- }
- else
- {
- ns_names_uris = NULL;
- ns_names_uris_nulls = NULL;
- ns_count = 0;
- }
-
- datastr = VARDATA(data);
- len = VARSIZE(data) - VARHDRSZ;
- xpath_len = VARSIZE(xpath_expr_text) - VARHDRSZ;
- if (xpath_len == 0)
- ereport(ERROR,
- (errcode(ERRCODE_DATA_EXCEPTION),
- errmsg("empty XPath expression")));
-
- string = (xmlChar *) palloc((len + 1) * sizeof(xmlChar));
- memcpy(string, datastr, len);
- string[len] = '\0';
-
- xpath_expr = (xmlChar *) palloc((xpath_len + 1) * sizeof(xmlChar));
- memcpy(xpath_expr, VARDATA(xpath_expr_text), xpath_len);
- xpath_expr[xpath_len] = '\0';
-
- xml_init();
- xmlInitParser();
-
- PG_TRY();
- {
- /*
- * redundant XML parsing (two parsings for the same value during one
- * command execution are possible)
- */
- ctxt = xmlNewParserCtxt();
- if (ctxt == NULL)
- xml_ereport(ERROR, ERRCODE_OUT_OF_MEMORY,
- "could not allocate parser context");
- doc = xmlCtxtReadMemory(ctxt, (char *) string, len, NULL, NULL, 0);
- if (doc == NULL)
- xml_ereport(ERROR, ERRCODE_INVALID_XML_DOCUMENT,
- "could not parse XML document");
- xpathctx = xmlXPathNewContext(doc);
- if (xpathctx == NULL)
- xml_ereport(ERROR, ERRCODE_OUT_OF_MEMORY,
- "could not allocate XPath context");
- xpathctx->node = xmlDocGetRootElement(doc);
- if (xpathctx->node == NULL)
- xml_ereport(ERROR, ERRCODE_INTERNAL_ERROR,
- "could not find root XML element");
-
- /* register namespaces, if any */
if (ns_count > 0)
{
for (i = 0; i < ns_count; i++)
--- 3377,3390 ----
errmsg("invalid array for XML namespace mapping"),
errdetail("The array must be two-dimensional with length of the second axis equal to 2.")));
! Assert(ARR_ELEMTYPE(nsarray) == TEXTOID);
! deconstruct_array(nsarray, TEXTOID, -1, false, 'i',
&ns_names_uris, &ns_names_uris_nulls,
&ns_count);
Assert((ns_count % 2) == 0); /* checked above */
ns_count /= 2; /* count pairs only */
if (ns_count > 0)
{
for (i = 0; i < ns_count; i++)
***************
*** 3399,3405 ****
errmsg("neither namespace name nor URI may be null")));
ns_name = TextDatumGetCString(ns_names_uris[i * 2]);
ns_uri = TextDatumGetCString(ns_names_uris[i * 2 + 1]);
! if (xmlXPathRegisterNs(xpathctx,
(xmlChar *) ns_name,
(xmlChar *) ns_uri) != 0)
ereport(ERROR, /* is this an internal error??? */
--- 3399,3405 ----
errmsg("neither namespace name nor URI may be null")));
ns_name = TextDatumGetCString(ns_names_uris[i * 2]);
ns_uri = TextDatumGetCString(ns_names_uris[i * 2 + 1]);
! if (xmlXPathRegisterNs(xpctxt,
(xmlChar *) ns_name,
(xmlChar *) ns_uri) != 0)
ereport(ERROR, /* is this an internal error??? */
***************
*** 3407,3423 ****
ns_name, ns_uri)));
}
}
! xpathcomp = xmlXPathCompile(xpath_expr);
! if (xpathcomp == NULL) /* TODO: show proper XPath error details */
! xml_ereport(ERROR, ERRCODE_INTERNAL_ERROR,
! "invalid XPath expression");
! xpathobj = xmlXPathCompiledEval(xpathcomp, xpathctx);
! if (xpathobj == NULL) /* TODO: reason? */
! xml_ereport(ERROR, ERRCODE_INTERNAL_ERROR,
! "could not create XPath object");
!
/* return empty array in cases when nothing is found */
if (xpathobj->nodesetval == NULL)
res_nitems = 0;
--- 3407,3450 ----
ns_name, ns_uri)));
}
}
+ }
+ return (xpctxt);
+ }
+ #endif
! /*
! * Evaluate XPath expression and return array of XML values.
! *
! * As we have no support of XQuery sequences yet, this function seems
! * to be the most useful one (array of XML functions plays a role of
! * some kind of substitution for XQuery sequences).
! *
! * It is up to the user to ensure that the XML passed is in fact
! * an XML document - XPath doesn't work easily on fragments without
! * a context node being known.
! */
! Datum
! xpath(PG_FUNCTION_ARGS)
! {
! #ifdef USE_LIBXML
! text *xpath_expr_text = PG_GETARG_TEXT_P(0);
! xmltype *data = PG_GETARG_XML_P(1);
! ArrayType *namespaces = PG_GETARG_ARRAYTYPE_P(2);
! ArrayBuildState *astate = NULL;
! xmlXPathObjectPtr xpathobj = NULL;
! xmlChar *string;
! xmlChar *xpath_expr;
! int res_nitems, i;
! string = xml_text2xmlChar(data);
! if ((VARSIZE(xpath_expr_text) - VARHDRSZ) == 0)
! ereport(ERROR,
! (errcode(ERRCODE_DATA_EXCEPTION),
! errmsg("empty XPath expression")));
! xpath_expr = xml_text2xmlChar(xpath_expr_text);
! xpathobj = xml_xpathinternal(xpath_expr, string, (VARSIZE(data)-VARHDRSZ), namespaces);
! if (xpathobj->type == XPATH_NODESET)
! {
/* return empty array in cases when nothing is found */
if (xpathobj->nodesetval == NULL)
res_nitems = 0;
***************
*** 3432,3471 ****
bool elemisnull = false;
elem = PointerGetDatum(xml_xmlnodetoxmltype(xpathobj->nodesetval->nodeTab[i]));
! astate = accumArrayResult(astate, elem,
! elemisnull, XMLOID,
! CurrentMemoryContext);
}
}
}
! PG_CATCH();
{
! if (xpathobj)
! xmlXPathFreeObject(xpathobj);
! if (xpathcomp)
! xmlXPathFreeCompExpr(xpathcomp);
! if (xpathctx)
! xmlXPathFreeContext(xpathctx);
! if (doc)
! xmlFreeDoc(doc);
! if (ctxt)
! xmlFreeParserCtxt(ctxt);
! PG_RE_THROW();
}
- PG_END_TRY();
-
xmlXPathFreeObject(xpathobj);
- xmlXPathFreeCompExpr(xpathcomp);
- xmlXPathFreeContext(xpathctx);
- xmlFreeDoc(doc);
- xmlFreeParserCtxt(ctxt);
! if (res_nitems == 0)
PG_RETURN_ARRAYTYPE_P(construct_empty_array(XMLOID));
else
PG_RETURN_ARRAYTYPE_P(makeArrayResult(astate, CurrentMemoryContext));
#else
NO_XML_SUPPORT();
return 0;
#endif
}
--- 3459,3641 ----
bool elemisnull = false;
elem = PointerGetDatum(xml_xmlnodetoxmltype(xpathobj->nodesetval->nodeTab[i]));
! astate = accumArrayResult(astate, elem, elemisnull, XMLOID, CurrentMemoryContext);
}
}
}
! else
{
! xmlXPathFreeObject(xpathobj);
! ereport(ERROR,
! (errcode(ERRCODE_DATA_EXCEPTION),
! errmsg("evaluation returned non-nodeset")));
}
xmlXPathFreeObject(xpathobj);
! if (astate == NULL)
PG_RETURN_ARRAYTYPE_P(construct_empty_array(XMLOID));
else
PG_RETURN_ARRAYTYPE_P(makeArrayResult(astate, CurrentMemoryContext));
#else
NO_XML_SUPPORT();
+ return 0;
+ #endif
+ }
+
+ /*
+ * Evaluate XPath expression and return the text representation
+ * of a single XML value. A warning is logged and NULL returned
+ * if XPath expression does not result in one of the supported types
+ * (boolean, numeric or string)
+ *
+ * It is up to the user to ensure that the XML passed is in fact
+ * an XML document - XPath doesn't work easily on fragments without
+ * a context node being known.
+ */
+ Datum
+ xpath_value_text(PG_FUNCTION_ARGS)
+ {
+ #ifdef USE_LIBXML
+ text *xpath_expr_text = PG_GETARG_TEXT_P(0);
+ xmltype *data = PG_GETARG_XML_P(1);
+ ArrayType *namespaces = PG_GETARG_ARRAYTYPE_P(2);
+ xmlXPathObjectPtr xpathobj = NULL;
+ xmlChar *string;
+ xmlChar *xpath_expr;
+
+ string = xml_text2xmlChar(data);
+ if ((VARSIZE(xpath_expr_text) - VARHDRSZ) == 0)
+ ereport(ERROR,
+ (errcode(ERRCODE_DATA_EXCEPTION),
+ errmsg("empty XPath expression")));
+ xpath_expr = xml_text2xmlChar(xpath_expr_text);
+ xpathobj = xml_xpathinternal(xpath_expr, string, (VARSIZE(data)-VARHDRSZ), namespaces);
+ switch (xpathobj->type)
+ {
+ case XPATH_BOOLEAN:
+ {
+ bool retval = (xpathobj->boolval != 0);
+ xmlXPathFreeObject(xpathobj);
+ PG_RETURN_TEXT_P(cstring_to_text(retval?"t":"f"));
+ /* not reached */
+ break;
+ }
+ case XPATH_NUMBER:
+ {
+ float8 fval = xpathobj->floatval;
+ xmlXPathFreeObject(xpathobj);
+ PG_RETURN_DATUM(CStringGetTextDatum(DatumGetCString(DirectFunctionCall1(float8out,
Float8GetDatumFast(fval)))));
+ /* not reached */
+ break;
+ }
+ case XPATH_STRING:
+ {
+ text *retval = cstring_to_text(xpathobj->stringval);
+ xmlXPathFreeObject(xpathobj);
+ PG_RETURN_TEXT_P(retval);
+ /* not reached */
+ break;
+ }
+ case XPATH_NODESET:
+ {
+ xmlXPathFreeObject(xpathobj);
+ ereport(ERROR,
+ (errcode(ERRCODE_DATA_EXCEPTION),
+ errmsg("evaluation returned nodeset")));
+ }
+ default:
+ {
+ ereport(WARNING, (errmsg("Unknown PathObjectType (%d)", xpathobj->type)));
+ }
+ }
+
+ xmlXPathFreeObject(xpathobj);
+ PG_RETURN_NULL();
+ #else
+ NO_XML_SUPPORT();
+ return 0;
+ #endif
+ }
+
+ Datum
+ xpath_value_strict(PG_FUNCTION_ARGS)
+ {
+ #ifdef USE_LIBXML
+ Oid reqtype = get_fn_expr_argtype(fcinfo->flinfo, 0);
+ text *xpath_expr_text = PG_GETARG_TEXT_P(1);
+ xmltype *data = PG_GETARG_XML_P(2);
+ ArrayType *namespaces = PG_GETARG_ARRAYTYPE_P(3);
+ xmlXPathObjectPtr xpathobj = NULL;
+ xmlChar *string;
+ xmlChar *xpath_expr;
+ Datum retdatum;
+ Oid retdirect = InvalidOid;
+
+ string = xml_text2xmlChar(data);
+ if ((VARSIZE(xpath_expr_text) - VARHDRSZ) == 0)
+ ereport(ERROR,
+ (errcode(ERRCODE_DATA_EXCEPTION),
+ errmsg("empty XPath expression")));
+ xpath_expr = xml_text2xmlChar(xpath_expr_text);
+ xpathobj = xml_xpathinternal(xpath_expr, string, (VARSIZE(data)-VARHDRSZ), namespaces);
+ switch (xpathobj->type)
+ {
+ case XPATH_BOOLEAN:
+ {
+ retdatum = BoolGetDatum(xpathobj->boolval != 0);
+ retdirect = BOOLOID;
+ break;
+ }
+ case XPATH_NUMBER:
+ {
+ double xval = xpathobj->floatval;
+ float8 fval = xval;
+ retdatum = Float8GetDatumFast(fval);
+ retdirect = FLOAT8OID;
+ break;
+ }
+ case XPATH_STRING:
+ {
+ retdatum = CStringGetTextDatum(xpathobj->stringval);
+ retdirect = TEXTOID;
+ break;
+ }
+ case XPATH_NODESET:
+ {
+ xmlXPathFreeObject(xpathobj);
+ ereport(ERROR,
+ (errcode(ERRCODE_DATA_EXCEPTION),
+ errmsg("evaluation returned nodeset")));
+ }
+ default:
+ {
+ ereport(ERROR,
+ (errcode(ERRCODE_DATA_EXCEPTION),
+ errmsg("Unknown PathObjectType (%d)", xpathobj->type)));
+ }
+ }
+
+ xmlXPathFreeObject(xpathobj);
+ if (OidIsValid(retdirect))
+ {
+ if (reqtype == REGTYPEOID)
+ {
+ /* for regtype example return the result type */
+ retdatum = Int32GetDatum(retdirect);
+ retdirect = REGTYPEOID;
+ }
+ if (reqtype == retdirect) PG_RETURN_DATUM(retdatum);
+ ereport(ERROR,
+ (errcode(ERRCODE_DATA_EXCEPTION),
+ errmsg("evaluation result type mismatch (%d <> %d)", retdirect, reqtype)));
+ PG_RETURN_DATUM(0);
+ }
+ ereport(ERROR,
+ (errcode(ERRCODE_DATA_EXCEPTION),
+ errmsg("evaluation result type failed (%d)", reqtype)));
+ PG_RETURN_DATUM(0);
+ #else
+ NO_XML_SUPPORT();
return 0;
#endif
}
*** src/test/regress/sql/xml.sql.org Tue Jan 26 21:46:48 2010
--- src/test/regress/sql/xml.sql Tue Feb 2 12:50:55 2010
***************
*** 163,165 ****
--- 163,185 ----
SELECT xpath('//text()', '<local:data xmlns:local="http://127.0.0.1"><local:piece id="1">number
one</local:piece><local:pieceid="2" /></local:data>');
SELECT xpath('//loc:piece/@id', '<local:data xmlns:local="http://127.0.0.1"><local:piece id="1">number
one</local:piece><local:pieceid="2" /></local:data>', ARRAY[ARRAY['loc', 'http://127.0.0.1']]);
SELECT xpath('//b', '<a>one <b>two</b> three <b>etc</b></a>');
+
+ -- Test XPath expressions for non-nodeset results
+ -- These test only the interface, not the abundant possibilities in xpath
+
+ -- Test expression output for basic types as text
+ SELECT xpath_value_text('count(/a)','<a/>');
+ SELECT xpath_value_text('1=0','<a/>');
+ SELECT xpath_value_text('name()','<a/>');
+
+ -- Test resulting type for basic expressions
+ SELECT pg_typeof(xpath_value_strict(TRUE::boolean,'1=1','<a/>'));
+ SELECT pg_typeof(xpath_value_strict(1::float8,'count(/)','<a/>'));
+ SELECT pg_typeof(xpath_value_strict('a'::text,'name()','<a/>'));
+
+ -- Test obtaining the result type of an expression
+ SELECT xpath_value_strict('anyelement'::regtype,'1=1','<a/>');
+ SELECT xpath_value_strict('anyelement'::regtype,'count(/)','<a/>');
+ SELECT xpath_value_strict('anyelement'::regtype,'name()','<a/>');
+ SELECT xpath_value_strict('a'::text,'text()',data) FROM xmltest;
+ SELECT xpath_value_strict('a'::text,'string()',data) FROM xmltest;
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