Hi,
I'm trying to construct a parser, but I'm stuck with some basic stuff... For
example, I want to match the following:
letter = "A"..."Z" | "a"..."z"
literal = letter+
include_bool := "+" | "-"
term = [include_bool] literal
So I defined this as:
literal = Word(alphas)
include_bool = Optional(oneOf("+ -"))
term = include_bool + literal
The problem is that:
term.parseString("+a") -> (['+', 'a'], {}) # OK
term.parseString("+ a") -> (['+', 'a'], {}) # KO. It shouldn't recognize any
token since I didn't said the SPACE was allowed between include_bool and
literal.
Can anyone give me an hand here?
Cheers!
Hugo Ferreira
BTW, the following is the complete grammar I'm trying to implement with
pyparsing:
## L ::= expr | expr L
## expr ::= term | binary_expr
## binary_expr ::= term " " binary_op " " term
## binary_op ::= "*" | "OR" | "AND"
## include_bool ::= "+" | "-"
## term ::= ([include_bool] [modifier ":"] (literal | range)) | ("~"
literal)
## modifier ::= (letter | "_")+
## literal ::= word | quoted_words
## quoted_words ::= '"' word (" " word)* '"'
## word ::= (letter | digit | "_")+
## number ::= digit+
## range ::= number (".." | "...") number
## letter ::= "A"..."Z" | "a"..."z"
## digit ::= "0"..."9"
And this is where I got so far:
word = Word(nums + alphas + "_")
binary_op = oneOf("* and or", caseless=True).setResultsName("operator")
include_bool = oneOf("+ -")
literal = (word | quotedString).setResultsName("literal")
modifier = Word(alphas + "_")
rng = Word(nums) + (Literal("..") | Literal("...")) + Word(nums)
term = ((Optional(include_bool) + Optional(modifier + ":") + (literal |
rng)) | ("~" + literal)).setResultsName("Term")
binary_expr = (term + binary_op + term).setResultsName("binary")
expr = (binary_expr | term).setResultsName("Expr")
L = OneOrMore(expr)
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