Re: [Pyparsing] Order problem in binary operation withoperationPrecedence()

[Paul M. <pt...@au...>]

Gustavo -

The first issue you have is your definition of identifier0, which you define
using the Unicode regex "\w", but which cannot start with a numeric digit.
Unfortunately, there are a lot more numeric digits in Unicode than just "0"
through "9" - over 300 of them!  Here is how I replaced your identifier0
expression, and got your code to at least start working:

    unidigit = Regex(u"[" + "".join(unichr(c) for c in xrange(0x10000) if
unichr(c).isdigit()) + "]", re.UNICODE)
    identifier0 = Combine(~unidigit + Regex("[\w]+", re.UNICODE))


Some other comments:

1. 

    eq = CaselessLiteral("==")
    ne = CaselessLiteral("!=")
    lt = CaselessLiteral("<")
    gt = CaselessLiteral(">")
    le = CaselessLiteral("<=")
    ge = CaselessLiteral(">=")

Why are these not just plain Literal's?  Making them caseless just makes
pyparsing do extra work trying to match upper or lower case "==".


2. 
    relationals = eq ^ ne ^ lt ^ gt ^ le ^ ge

'^' can be relatively expensive for pyparsing if there are many
alternatives, since all alternatives will be checked.  This version is
equivalent:

    relationals = eq | ne | le | ge | lt | gt

(I *did* have to be careful about the order, having to check for "<=" before
"<", and ">=" before ">".)


3. 
    not_ = Suppress("~")
    and_ = Suppress("&")
    in_or = Suppress("|")
    ex_or = Suppress("^")

Do you really want to suppress these operators?  Without them, you will have
a dickens of a time evaluating the parsed expression.  These should probably
be Literal's, too.


4. The parsed results show an empty [] before every identifier, I think this
is to represent the empty leading namespace for each.  You might want to try
this for identifier:

    identifier = Combine(namespace.setResultsName("namespace_parts") +
                  identifier0.setResultsName("identifier"))

Combine will return the match as a single string, but you can still access
the individual parts of the identifier by their results names if you need
to.  (Combine will also ensure that you match only contiguous characters as
an identifier.)


Looks interesting, keep us posted.

-- Paul