parser 2

p2.py

from collections import namedtuple

Action = namedtuple('Action', ['verb', 'noun', 'adjective', 'indirect'])


NOUNS = ['sword', 'dog', 'hat']
VERBS = ['get', 'go', 'eat', 'north', 'east']

PREPOSITIONS = [
                    'below', 'off', 'toward', 'above', 'beneath', 'on', 'under', 
                    'across', 'beside', 'from', 'onto', 'underneath', 'between', 
                    'in', 'out', 'until', 'against', 'beyond', 
                    'outside', 'along', 'inside', 'over', 'upon', 'among', 
                    'by', 'past', 'around', 'with', 'at ', 'into', 
                    'within', 'down', 'through', 'without', 'before', 
                    'near', 'throughout', 'behind', 'except', 'of', 'to'
                    ]

CINNAMONS = {'walk':'go', 'consume':'eat', 'n': 'north'}

ELIDE = ['the', 'a']

def parse(command):
    ''' break words into a list, substituing common synonyms, and 
        return Action '''

    words = [CINNAMONS.get(w, w) for w in command.split() if w not in ELIDE]
    return create_action(words)

def parse_preposition(words):
    '''parses prepositional phrases 
    works by finding the last preposition and then cutting off remainder of
    words
    '''
    last = None
    for idx, word in enumerate(words):
        if word in PREPOSITIONS:
            last = idx
    
    if last is None or last > len(words)-2:
        return words, None, None

    remaining = [w for idx, w in enumerate(words) if idx < last]

    preposition = words[last]
    indirect = words[last+1]

    return remaining, preposition, indirect

def parse_adjective(words):
    '''In a sufficiently long string, treat the word preceding a noun as an
    adjective'''

    if len(words) == 0:
        return [], None, None

    found, noun = None, None

    remaining = []
    for idx, word in enumerate(words):
        if word in NOUNS:
            found = idx
            noun = word
            break
    
    if len(words)<2:
        # only one owrd left so no adjective
        if noun is not None:
            return [], noun, None
        return [], words[0], None

    if noun is None:
        # if we don't match a noun, just make a guess that it is the last word
        noun = word[-1]
        idx = len(words) - 1


    used = (idx, idx -1)
    remaining = [w for idx, w in enumerate(words) if idx not in used]
    return remaining, words[idx], words[idx-1]

def parse_verb(words):

    remaining = []
    verb = None

    for word in words:
        if word in VERBS:
            verb = word
        else:
            remaining.append(word)

    if verb is None:
        # hmm, could not match a verb, so just assume the first word of words is
        # a verb and return that
        return words[1:], words[0]

    return remaining, verb

def create_action(words):
    #print('create_action called on {}, kws = {}'.format(words, [(k,v) for k,v in kws.items()]))

    words, verb = parse_verb(words)
    words, preposition, indirect = parse_preposition(words)
    words, noun, adjective = parse_adjective(words)

    return Action(verb, noun, adjective, indirect)





check = [
        'north',
        'n',
        'eat hat',
        'consume hat',
        'consume green hat',
        'get dog from table',
        'get orange dog from table',
        'get orange dog from under',
        'get orange dog from under table',
        'get orange dog from under pink table', # doesn't work too complex
        'get the really, really big sword',
        ]

for phrase in check:
    print('"{}" => {}'.format(phrase, parse(phrase)))
    print('-'*10)