1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
|
from distutils.version import StrictVersion
from pyparsing import (
ParserElement, Forward, Combine, Optional, Word, Literal, CaselessKeyword,
CaselessLiteral, Group, FollowedBy, LineEnd, OneOrMore, ZeroOrMore,
nums, alphas, alphanums, printables, delimitedList, quotedString,
__version__
)
ParserElement.enablePackrat()
grammar = Forward()
expression = Forward()
# Literals
intNumber = Combine(
Optional('-') + Word(nums)
)('integer')
floatNumber = Combine(
Optional('-') + Word(nums) + Literal('.') + Word(nums)
)('float')
sciNumber = Combine(
(floatNumber | intNumber) + CaselessLiteral('e') + intNumber
)('scientific')
aString = quotedString('string')
# Use lookahead to match only numbers in a list (can't remember why this
# is necessary)
afterNumber = FollowedBy(",") ^ FollowedBy(")") ^ FollowedBy(LineEnd())
number = Group(
(sciNumber + afterNumber) |
(floatNumber + afterNumber) |
(intNumber + afterNumber)
)('number')
boolean = Group(
CaselessKeyword("true") |
CaselessKeyword("false")
)('boolean')
argname = Word(alphas + '_', alphanums + '_')('argname')
funcname = Word(alphas + '_', alphanums + '_')('funcname')
# Symbols
leftParen = Literal('(').suppress()
rightParen = Literal(')').suppress()
comma = Literal(',').suppress()
equal = Literal('=').suppress()
# Function calls
# Symbols
leftBrace = Literal('{')
rightBrace = Literal('}')
leftParen = Literal('(').suppress()
rightParen = Literal(')').suppress()
comma = Literal(',').suppress()
equal = Literal('=').suppress()
backslash = Literal('\\').suppress()
symbols = '''(){},=.'"\\'''
arg = Group(
boolean |
number |
aString |
expression
)('args*')
kwarg = Group(argname + equal + arg)('kwargs*')
args = delimitedList(~kwarg + arg) # lookahead to prevent failing on equals
kwargs = delimitedList(kwarg)
call = Group(
funcname + leftParen +
Optional(
args + Optional(
comma + kwargs
)
) + rightParen
)('call')
# Metric pattern (aka. pathExpression)
validMetricChars = ''.join((set(printables) - set(symbols)))
escapedChar = backslash + Word(symbols, exact=1)
partialPathElem = Combine(
OneOrMore(
escapedChar | Word(validMetricChars)
)
)
matchEnum = Combine(
leftBrace +
delimitedList(partialPathElem, combine=True) +
rightBrace
)
pathElement = Combine(
Group(partialPathElem | matchEnum) +
ZeroOrMore(matchEnum | partialPathElem)
)
pathExpression = delimitedList(pathElement,
delim='.', combine=True)('pathExpression')
if StrictVersion(__version__) >= StrictVersion('2.0.0'):
expression <<= Group(call | pathExpression)('expression')
grammar <<= expression
else:
expression << (Group(call | pathExpression)('expression'))
grammar << expression
|
