pyparsing

I'm writing a parser for a query language using PyParsing, and I've gotten stuck on (what I believe to be) an issue with lookaheads. One clause type in the query is intended to split strings into 3 parts (fieldname,operator, value) such that fieldname is one word, operator is one or more words, and value is a word, a quoted string, or a parenthesized list of these. My data look like author is william author is 'william shakespeare' author is not shakespeare author is in (william,'the bard',shakespeare) And my current parser for this clause is written as: fieldname = Word(alphas) operator =

I have a bunch of sentences which I need to parse and convert to corresponding regex search code. Examples of my sentences - LINE_CONTAINS phrase one BEFORE {phrase2 AND phrase3} AND LINE_STARTSWITH Therefore we -This means in the line, phrase one comes somewhere before phrase2 and phrase3 . Also, the line must start with Therefore we LINE_CONTAINS abc {upto 4 words} xyz {upto 3 words} pqr -This means I need to allow upto 4 words between the first 2 phrases and upto 3 words between last 2 phrases Using help from Paul Mcguire ( here ), the following grammar was written - from pyparsing import

I'd like to be able to parse two (or any number) of expressions, each with their own set of variable definitions or other context. There doesn't seem to be an obvious way to associate a context with a particular invocation of pyparsing.ParseExpression.parseString() . The most natural way seems to be to use an instancemethod of some class as the parse actions. The problem with this approach is that the grammar must be redefined for each parse context (for instance, in the class's __init__ ), which seems terribly inefficient. Using pyparsing.ParseExpression.copy() on the rules doesn't help; the

Forgive me if I have the incorrect terminology; perhaps just getting the "right" words to describe what I want is enough for me to find the answer on my own. I am working on a parser for ODL (Object Description Language), an arcane language that as far as I can tell is now used only by NASA PDS (Planetary Data Systems; it's how NASA makes its data available to the public). Fortunately, PDS is finally moving to XML, but I still have to write software for a mission that fell just before the cutoff. ODL defines objects in something like the following manner: OBJECT = TABLE ROWS = 128 ROW_BYTES =

It is my first attempt to use pyparsing and I'd like to ask how to filter this sample line: survey = '''GPS,PN1,LA52.125133215643,LN21.031048525561,EL116.898812''' to get output like: 1,52.125133215643,21.031048525561,116.898812 In general I have problem with understanding pyparsing logic so any help with this example will be appreciated. Thanks You could start with something like this: from pyparsing import * survey = '''GPS,PN1,LA52.125133215643,LN21.031048525561,EL116.898812''' number = Word(nums+'.').setParseAction(lambda t: float(t[0])) separator = Suppress(',') latitude = Suppress('LA')