potluck.phrasing

 1"""
 2Functions for phrasing feedback (e.g., pluralization).
 3
 4phrasing.py
 5"""
 6
 7
 8#--------------------------#
 9# Basic English management #
10#--------------------------#
11
12def a_an(string):
13    """
14    Returns the given string it 'a ' prepended, unless it starts with a
15    vowel in which case 'an ' will be prepended.
16    """
17    if string[0].lower() in 'aeiou':
18        return 'an ' + string
19    else:
20        return 'a ' + string
21
22
23def plural(n, singular, plural=None):
24    """
25    Uses a number n to determine whether to use the given singular or
26    plural phrasing. If the plural phrasing is omitted, it is assumed to
27    be just the singular phrasing plus 's'.
28    """
29    if plural is None:
30        plural = singular + 's'
31
32    if n == 0:
33        return plural
34    elif n == 1:
35        return singular
36    else:
37        return plural
38
39
40def obj_num(n, singular, plural=None):
41    """
42    Translates a number n into a string describing that many objects with
43    the given singular and plural phrasing. If the plural phrasing is
44    omitted, it is assumed to be just the singular phrasing plus 's'.
45    """
46    if plural is None:
47        plural = singular + 's'
48
49    if n == 0:
50        return "zero " + plural
51    elif n == 1:
52        return "one " + singular
53    else:
54        return "{} {}".format(n, plural)
55
56
57def comma_list(strings, junction="and"):
58    """
59    Turns a list of strings into a comma-separated list using the word
60    'and' (or the given junction word) before the final item and an
61    Oxford comma, but also does the correct thing for 1- or 2-element
62    lists. Returns an empty string if given an empty list.
63    """
64    strings = list(strings)
65    if len(strings) == 0:
66        return ""
67    if len(strings) == 1:
68        return strings[0]
69    elif len(strings) == 2:
70        return strings[0] + " " + junction + " " + strings[1]
71    else:
72        return ', '.join(strings[:-1]) + ", " + junction + " " + strings[-1]
73
74
75def ordinal(n):
76    """
77    Returns the ordinal string for the number n (i.e., 0th, 1st, 2nd,
78    etc.)
79    """
80    digits = str(n)
81    if digits.endswith('11'):
82        return digits + 'th'
83    elif digits.endswith('12'):
84        return digits + 'th'
85    elif digits.endswith('13'):
86        return digits + 'th'
87    elif digits.endswith('1'):
88        return digits + 'st'
89    elif digits.endswith('2'):
90        return digits + 'nd'
91    elif digits.endswith('3'):
92        return digits + 'rd'
93    else:
94        return digits + 'th'