jetxee

#!/usr/bin/env python

"""
Trying funcparserlib parser combinator library. I skip lexing step and
use funcparserlib in pyparsing style (I had to define some one-line helpers to
do so).

Number parsers:

Read sign of the number
>>> [ sign.parse(c) for c in ["+42","42", "-42"] ]
[1, 1, -1]

Parse integer
>>> int_num.parse("-42")
-42

Parse fractional number (float)
>>> [ frac_num.parse(c) for c in ["-1.25", "1.25", "42"] ]
[-1.25, 1.25, 42.0]

Helpers:

>>> to_int(['4','2'])
42

>>> powers(['4','2'])
[('4', 1), ('2', 0)]

>>> add_digit(1,(2,3))
2001

Custom format parser:

Using `ws` to skip whitespaces
>>> ws.parse("   ")
_Ignored([' ', ' ', ' '])

Using `literal` to build literal parsers (to avoid explicit lexing)
>>> literal("abc").parse("abc def")
'abc'

Packing a list of characters as a string
>>> pack(['a','b','c'])
'abc'

Read a string of characters which satisfy given predicate
>>> word(lambda c: c.isalpha() and c.isupper()).parse("ABCdef")
'ABC'

Read the rest of the input as a string
>>> whatever.parse("abcdef")
'abcdef'

Finally,
>>> raw = 'Inspection\\n#   2  SHOULD      Ref. Sys    1\\n' + \
          'X 28.75 \\nY  78.500 \\nZ     -1.25 \\n\\n'
>>> custom_format.parse(raw)
(2, 1, [('X', 28.75), ('Y', 78.5), ('Z', -1.25)])


"""

import sys
from funcparserlib.parser import *

### helpers

powers = lambda digs: zip(digs,xrange(len(digs)-1,-1,-1))
add_digit = lambda acc, dp: acc+int(dp[0])*10**dp[1]
to_int = lambda digs: reduce(add_digit, powers(digs), 0)
mk_int = lambda (s,i): s*i
to_frac = lambda digs: to_int(digs)*1.0/10**len(digs)
mk_frac = lambda (s,i,f): s*(i+f)
pack = lambda cs: ''.join(cs)

### parsers

sign = maybe(a("-")|a("+")) >> (lambda c: c == "-" and -1 or +1)
digits = many(some(lambda c: c.isdigit()))
int_num = sign + (digits >> to_int) >> mk_int
frac_num = sign + (digits >> to_int) + (skip(maybe(a("."))) + (digits >> to_frac)) >> mk_frac

ws = skip(many(some(lambda c: c.isspace())))
literal = lambda s: reduce(lambda a,b: a+b, map(a,s)) >> pack
word = lambda p: oneplus(some(p)) >> pack
whatever = word(lambda x:True)

### custom format parser

varname = word(lambda c: c.isalpha())
var = (ws + varname + ws + frac_num + ws)

custom_format = skip(literal("Inspection")) + \
    ws + skip(literal("#")) + \
    ws + int_num + \
    ws + skip(literal("SHOULD")) + \
    ws + skip(literal("Ref. Sys")) + \
    ws + int_num + \
    many(var)

if __name__ == '__main__':
    if "--test" in sys.argv:
        import doctest
        doctest.testmod()
    else:
        raw = sys.stdin.read()
        print custom_format.parse(raw)