----- Original Message -----
From: "Gerard Cote" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Friday, June 17, 2005 8:48 PM
Subject: [REBOL] Nedd to use an indirection like operation during parsing
Hello list,
Below is some relatively easy parsing rules even if it took long for me to put
pieces in place.
The object of these rules is to recognize between different representations of
numbers.
Up to now I succeeded to let REBOL distinguish between the followinf reps: a
binary number, an octal number, a decimal number, an
hexadecimal number and an identifier too.
However even if REBOL can catch the identifier I am unable to get the value
associated with it.
Can someone help with an explanation or better with a solution to get the
requested value.
Thanks in advance!
Gerard
issue-rules: make object! [
expr: [copy my-num1 bin-number (print-info my-num1 "bin") to end |
copy my-num2 oct-number (print-info my-num2 "oct") to end |
copy my-num3 hex-number (print-info my-num3 "hex") to end |
copy my-num4 dec-number (print-info my-num4 "dec") to end |
copy my-ident identifier (print-info my-ident "ident") to end
]
letter-b: charset "bB"
letter-o: charset "oO"
letter-x: charset "xX"
bin-digit: charset "01"
bin-digits: [some bin-digit]
bin-number: [bin-digits letter-b]
oct-digit: charset "01234567"
oct-digits: [some oct-digit]
oct-number: [oct-digits letter-o]
dec-digit: charset "0123456789"
hex-digit: union charset "abcdefABCDEF" dec-digit
hex-digits: [some hex-digit]
hex-number: [hex-digits letter-x]
dec-number: [0 1 "-" [unsigned-integer | decimal-number |
scientific-notation-decimal-number]]
unsigned-integer: [some digit]
decimal-number: [0 1 unsigned-integer decimal-fraction]
decimal-fraction: ["." unsigned-integer]
scientific-notation-decimal-number: [mantissa "E" ["+" | "-" | none]
exponent]
mantissa: [unsigned-integer | decimal-number]
exponent: [unsigned-integer]
identifier: [letter any [digit | letter | letter-sep]]
letter: charset [#"A" - #"Z" #"a" - #"z"]
letter-sep: charset "_-"
digit: charset "0123456789"
print-info: func [info info-type][
either any [info-type = "bin" info-type = "oct" info-type = "hex"][
info-num: remove back tail info
info-num: head info
][
info-num: info
]
either [info-type = "ident"][
print :info
][
print info
]
print info-type
]
]
; Calls to the above parsing rules follow for each "data representation" (Bin,
oct, hex, dec, Ident)
; The only remaining problem - for the moment - is : I can't get the Ident
value in addition
; to its name and type as was done for the other datatypes
nom: 250
parse to-string [43.21] issue-rules/expr
parse to-string [1.23E4] issue-rules/expr
parse to-string [#c2x] issue-rules/expr
parse to-string [#123o] issue-rules/expr
parse to-string [#0101b] issue-rules/expr
parse to-string [var-name] issue-rules/expr
Here is an exec of the above code:
>> nom: 250
== 250
>> parse to-string [43.21] issue-rules/expr
43
dec
== true
>> parse to-string [1.23E4] issue-rules/expr
12300
dec
== true
>> parse to-string [#c2x] issue-rules/expr
c2
hex
== true
>> parse to-string [#123o] issue-rules/expr
123
oct
== true
>> parse to-string [#0101b] issue-rules/expr
0101
bin
== true
>> parse to-string [var-name] issue-rules/expr
var-name
ident
== true
>
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