Best place to start implementing OVERLAPS?

[d2a-raudenaerde]

I'm trying to implement OVERLAPS, which looks like this:

(TIME '2:55:00', INTERVAL '1' HOUR)
OVERLAPS
(TIME '3:30:00', INTERVAL '2' HOUR)

I think the OverlapsCondition would look like this:
"(" SimpleExpression() "," SimpleExpression() ")" <K_OVERLAPS> "(" SimpleExpression() "," SimpleExpression() ")"
where the expressions are stored as peroid1start, peroid1end, peroid2start, peroid2end.

However, I find it a bit difficult to find the right place to implement this in, because it is a bit of a different type than regular operators, like <, > etc.

I currently think the best place is in:

Condition():

Where it would be a 3th branch next to the

    (
        LOOKAHEAD(RegularCondition()) result=RegularCondition()
        | result=SQLCondition()
    )

LOOKAHEAD(OverlapsCondition()) result = OverlapsCondition()

However, I'm not really sure about this approach.
WDYT?

[d2a-raudenaerde]

Ok while that works for my simple use-case, I looked it up in the sql2003 standard:

There it is:
<row value predicand 1> OVERLAPS <row value predicand 2>,

Where

<row value predicand> ::=
		<row value special case>
	|	<row value constructor predicand>

And

<row value constructor predicand> ::=
		<common value expression>
	|	<boolean predicand>
	|	<explicit row value constructor>

And

<explicit row value constructor> ::=
		<left paren> <row value constructor element> <comma> <row value constructor element list> <right paren>
	|	ROW <left paren> <row value constructor element list> <right paren>
	|	<row subquery>

Which makes sense.

So I tried to refactor to:

RowConstructor() <K_OVERLAPS> RowConstructor()

But the RowConstructor() does not accept stuff like:

        String sql = "(t1.col1, t1.col2)";
        CCJSqlParser parser = new CCJSqlParser(new StringProvider(sql)).withAllowComplexParsing(false);
        Expression e =  parser.RowConstructor();
        System.out.println(e.toString());

Any hints?

[d2a-raudenaerde]

RowConstructor probably has to be split into RowValueConstructor and RowTypeConstructor, where the latter is used in CastExpression()

[manticore-projects]

As far as I do understand JSQLParser, our best match for <row value constructor predicand> was Expression.
I think you are looking for something like:

"(" ExpressionList() ")" <OVERLAPS> "(" ExpressionList() ")"

Please refer to JSQLParser/src/main/jjtree/net/sf/jsqlparser/parser/JSqlParserCC.jjt:3580
Alternatively JSQLParser/src/main/jjtree/net/sf/jsqlparser/parser/JSqlParserCC.jjt:3595

[d2a-raudenaerde]

Ah, great pointers.

[manticore-projects]

Rob,

please let me apologize, I should have pointed that out earlier. I know how frustrating it is to work on such stuff and be forced to move it into a different direction after. I will try to respond more timely, sorry again.

[d2a-raudenaerde]

Thanks and no worries, I cannot expect ppl to react immediately :)

[d2a-raudenaerde]

I have created a new pull-request incorporating all feedback, I think it is much nicer as well like this!