Class Verbs

pattern/text/en/inflect.py:628–723

#### VERB CONJUGATION ##############################################################################

class Verbs(_Verbs):
    
    def __init__(self):
        _Verbs.__init__(self, os.path.join(MODULE, "en-verbs.txt"),
            language = "en",
              format = [0, 1, 2, 3, 7, 8, 17, 18, 19, 23, 25, 24, 16, 9, 10, 11, 15, 33, 26, 27, 28, 32],
             default = {
                 1: 0,   2: 0,   3: 0,   7: 0,  # present singular => infinitive ("I walk")
                 4: 7,   5: 7,   6: 7,          # present plural
                17: 25, 18: 25, 19: 25, 23: 25, # past singular
                20: 23, 21: 23, 22: 23,         # past plural
                 9: 16, 10: 16, 11: 16, 15: 16, # present singular negated
                12: 15, 13: 15, 14: 15,         # present plural negated
                26: 33, 27: 33, 28: 33,         # past singular negated
                29: 32, 30: 32, 31: 32, 32: 33  # past plural negated
            })
    
    def find_lemma(self, verb):
        """ Returns the base form of the given inflected verb, using a rule-based approach.
            This is problematic if a verb ending in -e is given in the past tense or gerund.
        """
        v = verb.lower()
        b = False
        if v in ("'m", "'re", "'s", "n't"):
            return "be"
        if v in ("'d", "'ll"):
            return "will"
        if v in  ("'ve"):
            return "have"
        if v.endswith("s"):
            if v.endswith("ies") and len(v) > 3 and v[-4] not in VOWELS:
                return v[:-3]+"y" # complies => comply
            if v.endswith(("sses", "shes", "ches", "xes")):
                return v[:-2]     # kisses => kiss
            return v[:-1]
        if v.endswith("ied") and re_vowel.search(v[:-3]) is not None:
            return v[:-3]+"y"     # envied => envy
        if v.endswith("ing") and re_vowel.search(v[:-3]) is not None:
            v = v[:-3]; b=True;   # chopping => chopp
        if v.endswith("ed") and re_vowel.search(v[:-2]) is not None:
            v = v[:-2]; b=True;   # danced => danc
        if b:
            # Doubled consonant after short vowel: chopp => chop.
            if len(v) > 3 and v[-1] == v[-2] and v[-3] in VOWELS and v[-4] not in VOWELS and not v.endswith("ss"):
                return v[:-1]
            if v.endswith(("ick", "ack")):
                return v[:-1]     # panick => panic
            # Guess common cases where the base form ends in -e:
            if v.endswith(("v", "z", "c", "i")):
                return v+"e"      # danc => dance
            if v.endswith("g") and v.endswith(("dg", "lg", "ng", "rg")):
                return v+"e"      # indulg => indulge
            if v.endswith(("b", "d", "g", "k", "l", "m", "r", "s", "t")) \
              and len(v) > 2 and v[-2] in VOWELS and not v[-3] in VOWELS \
              and not v.endswith("er"): 
                return v+"e"      # generat => generate
            if v.endswith("n") and v.endswith(("an", "in")) and not v.endswith(("ain", "oin", "oan")):
                return v+"e"      # imagin => imagine