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from pyparsing import *
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')
# Function calls
arg = Group(
boolean |
number |
aString |
expression
)
args = delimitedList(arg)('args')
func = Word(alphas+'_', alphanums+'_')('func')
call = Group(
func + Literal('(').suppress() +
args + Literal(')').suppress()
)('call')
# Metric pattern (aka. pathExpression)
validMetricChars = alphanums + r'''!#$%&"'*+-.:;<=>?@[\]^_`|~'''
pathExpression = Combine(
Optional(Word(validMetricChars)) +
Combine(
ZeroOrMore(
Group(
Literal('{') +
Word(validMetricChars + ',') +
Literal('}') + Optional( Word(validMetricChars) )
)
)
)
)('pathExpression')
expression << Group(call | pathExpression)('expression')
grammar << expression
def enableDebug():
for name,obj in globals().items():
try:
obj.setName(name)
obj.setDebug(True)
except:
pass
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