FMPS v1.0 and triple colon escaping

[Jeff Mitchell]

On 9/17/2010 8:02 AM, Jeff Mitchell wrote:
> On 09/17/2010 01:12 AM, Quentin Sculo wrote:
>> Hi
>> I'm implementing parts of the FMPS specs, and I'm wondering about the
>> escaping of lists.
>> How is a string such as ":::" (3 colons) escaped ?
>> 1) "\:\::"
>> or
>> 2) "\:\:\:"
>> The specs only talk about escaping double colons (and double
>> semicolons), so that would mean 1) but 1) is difficult to split correctly.
> 
> 1) is the correct answer, according to the spec, but I see why you say
> that it's more difficult to split correctly. I wish you'd brought this
> up earlier sometime in the past year of the spec's development... :-)
> 
>> I realize strings such as ":::" are not a very common occurrence, but
>> I'm sure some lyrics contain it.
>>
>> Personally I would prefer to escape all ";", ":" and "\" with a "\",
>> simple and effective.
> 
> This was discussed at some point but that solution wasn't preferred,
> because you still have to do a replacement over the string, and it makes
> it less readable for the far more common case of single colons or
> semicolons. We were also trying to keep it simple in that escaping a
> block of two \:\: characters is not something you will likely find
> anywhere else, whereas possibly you'll find \: somewhere -- so then do
> you escape the escape, and have \\\: if you actually want a backslash
> and a colon? (IOW we didn't want to get into escaping hell.)
> 
> However, I don't think anyone thought of how the triple-colon case makes
> the splitting harder. I also don't think that it's likely that you'll
> find \: or \; as a literal string in lyrics; I think you're more likely
> (although still not likely) to see :::
> 
> Considering that 1.0 was just released, implementation can't be *too*
> far progressed for those working on it, so it probably wouldn't be too
> big a burden to issue a v1.0.1 and change the behavior. I'd like to see
> if others have opinions on the matter -- what do others think; should we
> change to #2 above?

Quentin,

As nobody else seems to have an issue with it (or care? :-) ) I'll
release an updated spec that escapes all :, ;, and \. It'll still use ::
and ;; for list/field separators; escaping will be done in identifiers
and field values only.

Does that sound good?

--Jeff

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