Source code for libpgm.dictionary

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'''
Nearly all of the functions of this library require key indexing, which means it deals with dictionaries internally. This module deals with loading dictionaries and handles automatically converting from python-style dictionaries to condensed (no excess white space) JSON-style dictionaries.

'''
import sys
import json
import string

class Dictionary(object):
    '''
    This class represents a JSON-style, key-indexable dictionary of data. It contains the attribute *alldata* and the method *dictload*. 
    '''

    def __init__(self):
        self.alldata = None
        '''An internal representation of a key-indexable dictionary.'''

    def dictload(self, path):
        '''
        Load a dictionary from a JSON-like text in a text file located at *path* into the attribute *alldata*.
        
        In order for this function to execute successfully, the text file must have the proper formatting, particularly with regard to quotation marks. See :doc:`unittestdict` for an example. Specifically, the function can get rid of excess whitespace, convert ``.x`` to ``0.x`` in decimals, and convert ``None`` to ``null``, but nothing else.

        Arguments:
            
            1. *path* -- Path to the text file (e.g. "mydictionary.txt")
        
        Attributes modified: 
        
            1. *alldata* -- The entire loaded dictionary.
        
        The function also returns an error if nothing was loaded into *alldata*.

        '''
        f = open(path, 'r')
        ftext = f.read() 
        assert (ftext and isinstance(ftext, str)), "Input file is empty or could not be read."


        # alter for json input, if necessary
        loaded = False
        try:
            self.alldata = json.loads(ftext)
            loaded = True
        except ValueError:
            pass

        if not loaded:
            try: 
                ftext = ftext.translate(None, '\t\n ')
                ftext = ftext.replace(':', ': ')
                ftext = ftext.replace(',', ', ')
                ftext = ftext.replace('None', 'null')
                ftext = ftext.replace('.', '0.')
                self.alldata = json.loads(ftext)
            except ValueError:
                raise ValueError, "Convert to JSON from input file failed. Check formatting."
        f.close()
        
        assert isinstance(self.alldata, dict), "In method dictload, path did not direct to a proper text file."