Thank you for the new patch.
- The latest patch is missing xpath_parser.h at least since
ns-3. That of the first (not-numbered) version was still
usable.
- c29c578 conflicts on doc/src/sgml/func.sgml
At Sun, 15 Oct 2017 12:06:11 +0200, Pavel Stehule <[email protected]>
wrote in <cafj8prcybh+a6ojoeyufdupbq1yswtt2cfnfzxs2ab9efon...@mail.gmail.com>
> 2017-10-02 12:22 GMT+02:00 Kyotaro HORIGUCHI <
> [email protected]>:
>
> > Hi, thanks for the new patch.
> >
> > # The patch is missing xpath_parser.h. That of the first patch was usable.
> >
> > At Thu, 28 Sep 2017 07:59:41 +0200, Pavel Stehule <[email protected]>
> > wrote in <CAFj8pRBMQa07a=+qQAVMtz5M_hqkJBhiQSOP76+-BrFDj37pvg@
> > mail.gmail.com>
> > > Hi
> > >
> > > now xpath and xpath_exists supports default namespace too
> >
> > At Wed, 27 Sep 2017 22:41:52 +0200, Pavel Stehule <[email protected]>
> > wrote in <CAFj8pRCZ8oneG7g2vxs9ux71n8A9twwUO7zQpJiuz+7RGSpSuw@mail.
> > gmail.com>
> > > > 1. Uniformity among simliar features
> > > >
> > > > As mentioned in the proposal, but it is lack of uniformity that
> > > > the xpath transformer is applied only to xmltable and not for
> > > > other xpath related functions.
> > > >
> > >
> > > I have to fix the XPath function. The SQL/XML function Xmlexists doesn't
> > > support namespaces/
> >
> > Sorry, I forgot to care about that. (And the definition of
> > namespace array is of course fabricated by me). I'd like to leave
> > this to committers. Anyway it is working but the syntax (or
> > whether it is acceptable) is still arguable.
> >
> > SELECT xpath('/a/text()', '<my:a xmlns:my="http://example.com";>
> > test</my:a>',
> > ARRAY[ARRAY['', 'http://example.com']]);
> > | xpath
> > | --------
> > | {test}
> > | (1 row)
> >
> >
> > The internal name is properly rejected, but the current internal
> > name (pgdefnamespace.pgsqlxml.internal) seems a bit too long. We
> > are preserving some short names and reject them as
> > user-defined. Doesn't just 'pgsqlxml' work?
> >
> >
> > Default namespace correctly become to be applied on bare
> > attribute names.
> >
> > > updated doc,
> > > fixed all variants of expected result test file
> >
> > Sorry for one by one comment but I found another misbehavior.
> >
> > create table t1 (id int, doc xml);
> > insert into t1
> > values
> > (5, '<rows xmlns="http://x.y";><row><a hoge="haha">50</a></row></
> > rows>');
> > select x.* from t1, xmltable(XMLNAMESPACES('http://x.y' AS x),
> > '/x:rows/x:row' passing t1.doc columns data int PATH
> > 'child::x:a[1][attribute::hoge="haha"]') as x;
> > | data
> > | ------
> > | 50
> >
> > but the following fails.
> >
> > select x.* from t1, xmltable(XMLNAMESPACES(DEFAULT 'http://x.y'),
> > '/rows/row' passing t1.doc columns data int PATH
> > 'child::a[1][attribute::hoge="haha"]') as x;
> > | data
> > | ------
> > |
> > | (1 row)
> >
> > Perhaps child::a is not prefixed by the transformation.
> >
>
> the problem was in unwanted attribute modification. The parser didn't
> detect "attribute::hoge" as attribute. Updated parser does it. I reduce
> duplicated code there more.
It worked as expected. But the comparison of "attribute" is
missing t1.length = 9 so the following expression wrongly passes.
child::a[1][attributeabcdefg::hoge="haha"
It is confusing that is_qual_name becomes true when t2 is not a
"qual name", and the way it treats a double-colon is hard to
understand.
It essentially does inserting the default namespace before
unqualified non-attribute name. I believe we can easily
look-ahead to detect a double colon and it would make things
simpler. Could you consider something like the attached patch?
(applies on top of ns-4 patch.)
> > XPath might be complex enough so that it's worth switching to
> > yacc/lex based transformer that is formally verifiable and won't
> > need a bunch of cryptic tests that finally cannot prove the
> > completeness. synchronous_standy_names is far simpler than XPath
> > but using yacc/lex parser.
> >
> >
> > Anyway the following is nitpicking of the current xpath_parser.c.
> >
> > - NODENAME_FIRSTCHAR allows '-' as the first char but it is
> > excluded from NameStartChar (https://www.w3.org/TR/REC-
> > xml/#NT-NameStartChar)
> > I think characters with high-bit set is okay.
> > Also IS_NODENAME_CHAR should be changed.
> >
>
> fixed
>
>
> > - NODENAME_FIRSTCHAR and IS_NODENAME_CHAR is in the same category
> > but have different naming schemes. Can these are named in the same way?
> >
>
> fixed
>
>
> > - The current transoformer seems to using up to one token stack
> > depth. Maybe the stack is needless. (pushed token is always
> > popped just after)
> >
>
> fixed
Thank you.
I found another (and should be the last, so sorry..) functional
defect in this. This doesn't add default namespace if the tag
name in a predicate is 'and' or 'or'. It needs to be fixed, or
wrote in the documentation as a restriction. (seem hard to fix
it..)
create table t1 (id int, doc xml);
insert into t1 values (1, '<rows
xmlns="http://x.y";><row><val>50</val><and>60</and></row></rows>');
select x.* from t1, xmltable(XMLNAMESPACES('http://x.y' AS x),
'/x:rows/x:row' passing t1.doc columns data int PATH
'x:val[../x:and = 60]') as x;
data
------
50
(1 row)
select x.* from t1, xmltable(XMLNAMESPACES(DEFAULT 'http://x.y'),
'/rows/row' passing t1.doc columns data int PATH
'val[../and = 60]') as x;
data
------
(1 row)
Other comments are follows.
- Please add more comments. XPATH_TOKEN_NAME in _transformXPath
in my patch has more
- Debug output might be needed.
# sorry now time's up. will continue tomorrow.
regards,
--
Kyotaro Horiguchi
NTT Open Source Software Center
diff --git a/src/backend/utils/adt/xpath_parser.c b/src/backend/utils/adt/xpath_parser.c
index f22ec76..1d8d93c 100644
--- a/src/backend/utils/adt/xpath_parser.c
+++ b/src/backend/utils/adt/xpath_parser.c
@@ -41,6 +41,8 @@ typedef enum
XPATH_TOKEN_NAME,
XPATH_TOKEN_STRING,
XPATH_TOKEN_NUMBER,
+ XPATH_TOKEN_COLON,
+ XPATH_TOKEN_DCOLON,
XPATH_TOKEN_OTHER
} XPathTokenType;
@@ -68,6 +70,7 @@ typedef struct ParserData
#define IS_NODENAME_CHAR(c) (IS_NODENAME_FIRSTCHAR(c) || (c) == '-' || (c) == '.' || \
((c) >= '0' && (c) <= '9'))
+#define TOKEN_IS_EMPTY(t) ((t)->ttype == XPATH_TOKEN_NONE)
/*
* Returns next char after last char of token - XPath lexer
@@ -112,6 +115,17 @@ getXPathToken(char *str, XPathTokenInfo * ti)
ti->ttype = XPATH_TOKEN_STRING;
}
+ else if (c == ':')
+ {
+ /* look ahead to detect a doulbe-colon */
+ if (*str == ':')
+ {
+ ti->ttype = XPATH_TOKEN_DCOLON;
+ str++;
+ }
+ else
+ ti->ttype = XPATH_TOKEN_COLON;
+ }
else
ti->ttype = XPATH_TOKEN_OTHER;
@@ -165,6 +179,7 @@ pushXPathToken(XPathParserData * parser, XPathTokenInfo * ti)
memcpy(&parser->buffer, ti, sizeof(XPathTokenInfo));
parser->buffer_is_empty = false;
+ ti->ttype = XPATH_TOKEN_NONE;
}
/*
@@ -179,6 +194,9 @@ writeXPathToken(StringInfo str, XPathTokenInfo * ti)
appendBinaryStringInfo(str, ti->start, ti->length);
else
appendStringInfoChar(str, *ti->start);
+
+ /* this token is comsumed */
+ ti->ttype = XPATH_TOKEN_NONE;
}
/*
@@ -192,7 +210,7 @@ _transformXPath(StringInfo str, XPathParserData * parser,
{
XPathTokenInfo t1,
t2;
- bool token_is_tagname = false;
+ bool tagname_needs_defnsp = false;
bool token_is_tagattrib = false;
nextXPathToken(parser, &t1);
@@ -203,7 +221,11 @@ _transformXPath(StringInfo str, XPathParserData * parser,
{
case XPATH_TOKEN_NUMBER:
case XPATH_TOKEN_STRING:
- token_is_tagname = false;
+ /*
+ * string cannot be a tag name. write out it immediately and
+ * go ahead
+ */
+ tagname_needs_defnsp = false;
token_is_tagattrib = false;
writeXPathToken(str, &t1);
@@ -212,8 +234,6 @@ _transformXPath(StringInfo str, XPathParserData * parser,
case XPATH_TOKEN_NAME:
{
- bool is_qual_name = false;
-
/* inside predicate ignore keywords "and" "or" */
if (inside_predicate)
{
@@ -226,53 +246,56 @@ _transformXPath(StringInfo str, XPathParserData * parser,
}
}
- token_is_tagname = true;
+ /* look ahead what is following the name token */
+ tagname_needs_defnsp = true;
nextXPathToken(parser, &t2);
- if (t2.ttype == XPATH_TOKEN_OTHER)
+ if (t2.ttype == XPATH_TOKEN_COLON)
+ {
+ /* t1 is a quilified node name. no need to add default one. */
+ tagname_needs_defnsp = false;
+ writeXPathToken(str, &t1); /* namespace name */
+ writeXPathToken(str, &t2); /* colon */
+ /* get node name */
+ nextXPathToken(parser, &t1);
+ }
+ else if (t2.ttype == XPATH_TOKEN_DCOLON)
+ {
+ /* t1 is an axis name. write out as it is */
+ if (strncmp(t1.start, "attribute", 9) == 0 && t1.length == 9)
+ token_is_tagattrib = true;
+
+ writeXPathToken(str, &t1); /* axis name */
+ writeXPathToken(str, &t2); /* double colon */
+
+ /*
+ * The next token may be qualified tag name, process
+ * it as a fresh token.
+ */
+ nextXPathToken(parser, &t1);
+ break;
+ }
+ else if (t2.ttype == XPATH_TOKEN_OTHER)
{
+ /* function name doesn't require namespace */
if (*t2.start == '(')
- token_is_tagname = false;
- else if (*t2.start == ':')
- {
- XPathTokenInfo t3;
-
- nextXPathToken(parser, &t3);
- if (t3.ttype == XPATH_TOKEN_OTHER && *t3.start == ':'
- && strncmp(t1.start, "attribute", 9) == 0)
- {
- /* other syntax for attribute, where we should not apply def namespace */
- appendStringInfo(str, "attribute::");
- nextXPathToken(parser, &t1);
- token_is_tagattrib = true;
- break;
- }
- else
- {
- pushXPathToken(parser, &t3);
- is_qual_name = true;
- }
- }
+ tagname_needs_defnsp = false;
+ else
+ pushXPathToken(parser, &t2);
}
- if (token_is_tagname && !token_is_tagattrib
- && !is_qual_name && def_namespace_name != NULL)
+ if (tagname_needs_defnsp && !token_is_tagattrib &&
+ def_namespace_name != NULL)
appendStringInfo(str, "%s:", def_namespace_name);
token_is_tagattrib = false;
- writeXPathToken(str, &t1);
+ /* write maybe-tagname if not consumed */
+ if (!TOKEN_IS_EMPTY(&t1))
+ writeXPathToken(str, &t1);
- if (is_qual_name)
- {
+ /* output t2 if not consumed yet */
+ if (!TOKEN_IS_EMPTY(&t2))
writeXPathToken(str, &t2);
- nextXPathToken(parser, &t1);
- if (t1.ttype == XPATH_TOKEN_NAME)
- writeXPathToken(str, &t1);
- else
- pushXPathToken(parser, &t1);
- }
- else
- pushXPathToken(parser, &t2);
nextXPathToken(parser, &t1);
}
@@ -283,7 +306,6 @@ _transformXPath(StringInfo str, XPathParserData * parser,
char c = *t1.start;
token_is_tagattrib = false;
- token_is_tagname = false;
writeXPathToken(str, &t1);
@@ -307,10 +329,14 @@ _transformXPath(StringInfo str, XPathParserData * parser,
}
break;
+ case XPATH_TOKEN_COLON:
+ case XPATH_TOKEN_DCOLON:
case XPATH_TOKEN_NONE:
elog(ERROR, "should not be here");
}
}
+
+ elog(LOG, "\"%s\"", str->data);
}
void
--
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