1# parseListString.py
2#
3# Copyright, 2006, by Paul McGuire
4#
5
6from pyparsing import *
7
8# first pass
9lbrack = Literal("[")
10rbrack = Literal("]")
11integer = Word(nums).setName("integer")
12real = Combine(Optional(oneOf("+ -")) + Word(nums) + "." +
13               Optional(Word(nums))).setName("real")
14
15listItem = real | integer | quotedString
16
17listStr = lbrack + delimitedList(listItem) + rbrack
18
19test = "['a', 100, 3.14]"
20
21print(listStr.parseString(test))
22
23
24# second pass, cleanup and add converters
25lbrack = Literal("[").suppress()
26rbrack = Literal("]").suppress()
27cvtInt = lambda s,l,toks: int(toks[0])
28integer = Word(nums).setName("integer").setParseAction( cvtInt )
29cvtReal = lambda s,l,toks: float(toks[0])
30real = Regex(r'[+-]?\d+\.\d*').setName("floating-point number").setParseAction( cvtReal )
31listItem = real | integer | quotedString.setParseAction( removeQuotes )
32
33listStr = lbrack + delimitedList(listItem) + rbrack
34
35test = "['a', 100, 3.14]"
36
37print(listStr.parseString(test))
38
39# third pass, add nested list support, and tuples, too!
40cvtInt = lambda s,l,toks: int(toks[0])
41cvtReal = lambda s,l,toks: float(toks[0])
42
43lbrack = Literal("[").suppress()
44rbrack = Literal("]").suppress()
45integer = Word(nums).setName("integer").setParseAction( cvtInt )
46real = Regex(r'[+-]?\d+\.\d*').setName("floating-point number").setParseAction( cvtReal )
47tupleStr = Forward()
48listStr = Forward()
49listItem = real | integer | quotedString.setParseAction(removeQuotes) | Group(listStr) | tupleStr
50tupleStr << ( Suppress("(") + delimitedList(listItem) + Optional(Suppress(",")) + Suppress(")") )
51tupleStr.setParseAction( lambda t:tuple(t.asList()) )
52listStr << lbrack + delimitedList(listItem) + Optional(Suppress(",")) + rbrack
53
54test = "['a', 100, ('A', [101,102]), 3.14, [ +2.718, 'xyzzy', -1.414] ]"
55print(listStr.parseString(test))
56
57# fourth pass, add parsing of dicts
58cvtInt = lambda s,l,toks: int(toks[0])
59cvtReal = lambda s,l,toks: float(toks[0])
60cvtDict = lambda s,l,toks: dict(toks[0])
61
62lbrack = Literal("[").suppress()
63rbrack = Literal("]").suppress()
64lbrace = Literal("{").suppress()
65rbrace = Literal("}").suppress()
66colon = Literal(":").suppress()
67integer = Word(nums).setName("integer").setParseAction( cvtInt )
68real = Regex(r'[+-]?\d+\.\d*').setName("real").setParseAction( cvtReal )
69
70tupleStr = Forward()
71listStr = Forward()
72dictStr = Forward()
73listItem = real | integer | quotedString.setParseAction(removeQuotes) | Group(listStr) | tupleStr | dictStr
74tupleStr <<= ( Suppress("(") + delimitedList(listItem) + Optional(Suppress(",")) + Suppress(")") )
75tupleStr.setParseAction( lambda t:tuple(t.asList()) )
76listStr <<= (lbrack + Optional(delimitedList(listItem)) + Optional(Suppress(",")) + rbrack)
77dictKeyStr = real | integer | quotedString.setParseAction(removeQuotes)
78dictStr <<= lbrace + Optional(delimitedList( Group( dictKeyStr + colon + listItem ))) + Optional(Suppress(",")) + rbrace
79dictStr.setParseAction(lambda t: {k_v[0]:(k_v[1].asList() if isinstance(k_v[1],ParseResults) else k_v[1]) for k_v in t})
80
81test = '[{0: [2], 1: []}, {0: [], 1: [], 2: [,]}, {0: [1, 2,],}]'
82print(listStr.parseString(test))
83