【Python技巧系列】用parse处理文本

parse是python中的一个文本处理工具包，其中包括 findall(), parse(), format() 等等，  findall() 比较常用（对我来说）， format(), parse() 互为逆。

来看看 parse() 的用法：（代码摘抄自文档）

 1 >>> from parse import *
 2
 3 >>> parse("It‘s {}, I love it!", "It‘s spam, I love it!")
 4 <Result (‘spam‘,) {}>
 5 >>> _[0]
 6 ‘spam‘
 7
 8 >>> r = parse("The {} who say {}", "The knights who say Ni!")
 9 >>> print(r)
10 <Result (‘knights‘, ‘Ni!‘) {}>
11
12 #Dotted names are possible though the application must make additional sense of the result:
13 >>> r = parse("Mmm, {food.type}, I love it!", "Mmm, spam, I love it!")
14 >>> print(r)
15 <Result () {‘food.type‘: ‘spam‘}>
16 >>> print(r.named)
17 {‘food.type‘: ‘spam‘}
18 >>> print(r[‘food.type‘])
19 spam
20
21
22 >>> ‘‘.join(r.fixed[0] for r in findall(">{}<", "<p>the <b>bold</b> text</p>"))
23 ‘the bold text‘
24
25
26 #If you’re going to use the same pattern to match lots of strings you can compile it once:
27
28 >>> from parse import compile
29 >>> p = compile("It‘s {}, I love it!")
30 >>> print(p)
31 <Parser "It‘s {}, I love it!">
32 >>> p.parse("It‘s spam, I love it!")
33 <Result (‘spam‘,) {}>
34
35
36 ##use format specification
37 >>> search(‘Age: {:d}\n‘, ‘Name: Rufus\nAge: 42\nColor: red\n‘)
38 <Result (42,) {}>
39
40 #will return None if typing does not match
41 >>> parse(‘Our {:d} {:w} are...‘, ‘Our 3 weapons are...‘)
42 <Result (3, ‘weapons‘) {}>
43
44 >>> parse(‘Our {:d} {:w} are...‘, ‘Our three weapons are...‘)
45 #none
46
47 >>> parse(‘Meet at {:tg}‘, ‘Meet at 1/2/2011 11:00 PM‘)
48 <Result (datetime.datetime(2011, 2, 1, 23, 0),) {}>
49
50 #alignment
51 >>> parse(‘with {:>} herring‘, ‘with     a herring‘)
52 <Result (‘a‘,) {}>
53 >>> parse(‘spam {:^} spam‘, ‘spam    lovely     spam‘)
54 <Result (‘lovely‘,) {}>
55
56 #use a dictionary to do some type-convert
57 >>> def shouty(string):
58 ...    return string.upper()
59 ...
60 >>> parse(‘{:shouty} world‘, ‘hello world‘, dict(shouty=shouty))
61 <Result (‘HELLO‘,) {}>
62
63 #if the type converter has the pattern attribute
64 >>> def parse_number(text):
65 ...    return int(text)
66 >>> parse_number.pattern = r‘\d+‘
67 >>> parse(‘Answer: {number:Number}‘, ‘Answer: 42‘, dict(Number=parse_number))
68 <Result () {‘number‘: 42}>
69 >>> _ = parse(‘Answer: {:Number}‘, ‘Answer: Alice‘, dict(Number=parse_number))
70 >>> assert _ is None, "MISMATCH"
71
72
73 #use with_pattern(pattern) decorator
74 >>> from parse import with_pattern
75 >>> @with_pattern(r‘\d+‘)
76 ... def parse_number(text):
77 ...    return int(text)
78 >>> parse(‘Answer: {number:Number}‘, ‘Answer: 42‘, dict(Number=parse_number))
79 <Result () {‘number‘: 42}>