CQL Parsing Questions

["Hammond, Tony" <t.hammond@nature.com>]

Hi:

I have two CQL questions which may be parser issues rather than CQL spec
issues per se. (I am using Mike Taylor's Java parser.)


1. Unrecognized booleans

I can't seem to get an error from the parser on unrecognized booleans (here
'but'):

% cql 'foo=1 but bar=2'
<searchClause>
  <index>bar</index>
  <relation>
    <value>=</value>
  </relation>
  <term>2</term>
</searchClause>

I asked Mike about this and he said:

    "It interacts badly with another, better rule, which says that
index-relation pairs nested within a clause override those outside the
clause -- so that
        title=(author=kernighan)
is equivalent to
        author=kernighan
"

and following up with him he claimed this was cooked into the BNF although I
don't pretend to understand the original BNF (my head hurts with all the
recursion).

The parser can be coaxed though to give an error by grouping as:

% cql '(foo=1) but (bar=2)'
Syntax error: expected boolean, got word: but

(For reference a recognized boolean, 'and' say, is parsed as given below at
end of message.) 


2. Legal term characters

From the production rule for simple strings I am assuming that a term such
as '2009-09-09' should be valid (without quotes), and yet the parser
complains as:

% cql 'x=2009-09-09'
Syntax error: expected boolean, got -9

Is that incorrect behaviour?

Quoting the term of course produces a valid parse:

% cql 'x="2009-09-09"'
<searchClause>
  <index>x</index>
  <relation>
    <value>=</value>
  </relation>
  <term>2009-09-09</term>
</searchClause>


I wasn't sure where to send these questions. Like I said I did ask Mike
about the first.

Cheers,

Tony


* Recognized boolean (for reference)

% cql 'foo=1 and bar=2'
<triple>
  <boolean>
    <value>and</value>
  </boolean>
  <leftOperand>
    <searchClause>
      <index>foo</index>
      <relation>
        <value>=</value>
      </relation>
      <term>1</term>
    </searchClause>
  </leftOperand>
  <rightOperand>
    <searchClause>
      <index>bar</index>
      <relation>
        <value>=</value>
      </relation>
      <term>2</term>
    </searchClause>
  </rightOperand>
</triple>



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