operand = number | int_variables_ref | misc_variables_ref
operand.setName('r-value')
rvalue << myOperatorPrecedence(operand, [
('-', 1, opAssoc.RIGHT, Unary.parse_action),
('*', 2, opAssoc.LEFT, Binary.parse_action),
('-', 2, opAssoc.LEFT, Binary.parse_action),
('+', 2, opAssoc.LEFT, Binary.parse_action),
])
# I want
# - BindVariable to have precedence to EqualTo(VariableRef)
# but I also want:
# - Arithmetic to have precedence w.r.t BindVariable
# last is variables
add_contract(misc_variables_contract)
add_contract(int_variables_contract)
add_contract(rvalue.copy().setParseAction(EqualTo.parse_action))
hardwired = MatchFirst(ParsingTmp.contract_types)
hardwired.setName('Predefined contract expression')
simple_contract << (hardwired | identifier_contract)
simple_contract.setName('simple contract expression')
any_contract = composite_contract | simple_contract
any_contract.setName('Any simple or composite contract')
contract_expression << (any_contract) # Parentheses before << !!
op = operatorPrecedence
# op = myOperatorPrecedence
rvalue << op(operand, [
('-', 1, opAssoc.RIGHT, Unary.parse_action),
('*', 2, opAssoc.LEFT, Binary.parse_action),
('-', 2, opAssoc.LEFT, Binary.parse_action),
('+', 2, opAssoc.LEFT, Binary.parse_action),
('^', 2, opAssoc.LEFT, Binary.parse_action),
])
# I want
# - BindVariable to have precedence to EqualTo(VariableRef)
# but I also want:
# - Arithmetic to have precedence w.r.t BindVariable
# last is variables
add_contract(misc_variables_contract)
add_contract(int_variables_contract)
add_contract(rvalue.copy().setParseAction(EqualTo.parse_action))
hardwired = MatchFirst(ParsingTmp.contract_types)
hardwired.setName('Predefined contract expression')
simple_contract << (hardwired | identifier_contract)
simple_contract.setName('simple contract expression')
any_contract = composite_contract | simple_contract
any_contract.setName('Any simple or composite contract')
contract_expression << (any_contract) # Parentheses before << !!
class WebParser(object):
boolMaps = {"false": False, "true": True, "yes": True, "no": False}
PSTYPE_DEFAULT = "DEFAULT"
PSTYPE_JS = "JS"
PSTYPE_DICT = "dict"
PSTYPE_RATINGS = "ratings"
def __init__(self, fromFile=False):
self.fromFile = fromFile
self.parseTypes = dict()
self.__defineBasicTypes()
self.__defineDictGrammar()
self.__defineJSGrammar()
quoteit = lambda self, v, lq='"', rq=None: \
Suppress(lq) + Optional(v) + Suppress(rq) \
if rq is not None else \
Suppress(lq) + v + Suppress(lq)
quoteitno = lambda self, v, lq='"', rq=None: \
Suppress(lq) + v + Suppress(rq) \
if rq is not None else \
Suppress(lq) + v + Suppress(lq)
datatypeAndQuote = lambda self, v, lq='"', rq=None: \
MatchFirst([v, self.quoteitno(v, lq, rq)])
completeType = lambda self, bt, name="", fn=None, lq='"', rq=None: \
(self.datatypeAndQuote(bt, lq, rq)).setName(name).setParseAction(fn) \
if fn is not None else \
(self.datatypeAndQuote(bt, lq, rq)).setName(name)
@logtrace
def __defineBasicTypes(self):
self.KDELIM = Suppress(":")
sign = Word("+-", max=1) + FollowedBy(Word(nums))
crncy = Word(nums) + ZeroOrMore(Suppress(",") + Word(nums)) + \
Optional(Literal(".") + Word(nums))
baseUnknownValue = Keyword("?")
self.unknown = self.completeType(baseUnknownValue, "UNKNOWN_VAL",
lambda t: np.nan)
floatNumberBasic = Combine(Optional(sign) + \
Or([Word(nums),
crncy,
Regex(r'[0-9]+(\.\d*)?([eE]\d+)?')])) + \
Optional(Suppress("%"))
self.floatNumber = self.completeType(floatNumberBasic, "float",
lambda t: float(t[0]))
baseBoolValue = Or([
CaselessKeyword("false"),
CaselessKeyword("true"),
CaselessKeyword("yes"),
CaselessKeyword("no")
])
self.boolean = self.completeType(baseBoolValue, "bool",
lambda t: WebParser.boolMaps[t[0]])
ratingKeywords = [CaselessKeyword(k).setParseAction( \
lambda t: Ratings.ratingMaps[t[0].lower()]) \
for k in Ratings.ratingMaps.keys()]
ratingKeywords.append(Keyword("--").setParseAction(lambda t: np.nan))
self.ratings = self.completeType(Or(ratingKeywords), "ratings")
self.parseTypes[WebParser.PSTYPE_RATINGS] = self.ratings
@logtrace
def __defineDictGrammar(self):
"""Function defines the grammar for parsing a string(mainly) into:
1. Value: Value could be any one of the following
1. Simple types such as:
a. numbers: all are floating point
b. boolean: [true,false], [yes, no]
c. Strings within double quotes
d. alphanumerics
2. Dictionary
3. List
2. Dictionary: Set of key value pairs. ':' delimits values from keys.
',' delimites different pairs. '{}' delimits a dictionary.
3. List: Ordered list of values delimited by ','
pyparsing parse actions are used to convert the tokens into pyton native
datatype such 'float' for floating point, 'dict' for dictionary and
'list' for list. The parser supports arbitrary nesting of the above
tokens. Both the nesting and datastructure type integrity is preserved
in the resulting python representation.
Application:
One of the main use of the grammar is to scrap web pages and extract a
combination of JSON and javascript-like HTML attributes into python
data structures. Simpler use cases include extracting supported simple
data types from say, HTML tables.
"""
dictDefn = Forward()
listDefn = Forward()
key = (QuotedString('"') | Word(alphas)) + FollowedBy(Literal(":"))
key.setName("key")
self.value = MatchFirst([
self.unknown, self.floatNumber, self.boolean,
QuotedString('"'),
Word(alphanums), dictDefn, listDefn
])
self.value.setName("value")
# dict_element = Group(key + self.KDELIM + self.value)
dict_element = Group(key + self.KDELIM + self.value) + \
FollowedBy(Or([Literal(","), Literal("}")]))
lde = Group(Dict(delimitedList(dict_element)))
dictDefn << ((self.quoteit(lde, '{', '}')) | lde)
self.dictDefn = dictDefn
self.dictDefn.setName("Dictionary")
listDefn << self.quoteit(Group(delimitedList(self.value)), '[', ']')
self.listDefn = listDefn
self.listDefn.setName("List")
self.topElement = Or([self.dictDefn, self.listDefn, self.value])
self.parseTypes[WebParser.PSTYPE_DEFAULT] = self.topElement
self.parseTypes[WebParser.PSTYPE_DICT] = self.dictDefn
return
@logtrace
def __defineJSGrammar(self):
identifier = Word(alphas + "_", alphanums + "_")
jsFn = identifier + Suppress(".") + identifier
jsArgs = Suppress("(") + self.topElement + Suppress(")")
jsStmt = jsFn + jsArgs + Suppress(";")
self.jsStmt = jsStmt.setName("JS_Statement")
self.parseTypes[WebParser.PSTYPE_JS] = self.jsStmt
@logtrace
def __parse(self, inputStr, parseType):
if self.fromFile:
parsed = self.parseTypes[parseType].parseFile(inputStr)
else:
parsed = self.parseTypes[parseType].parseString(inputStr)
if parseType == WebParser.PSTYPE_DEFAULT or \
parseType == WebParser.PSTYPE_RATINGS:
return parsed[0]
return parsed
@logtrace
def parse(self, inputStr, parseType=None):
if parseType is None:
parseType = WebParser.PSTYPE_DEFAULT
return self.__parse(inputStr, parseType)
