On Sun, Oct 28, 2018 at 09:43:27PM +0100, Karsten Hilbert wrote:
> Let my try to explain the expression I am actually after
> (assuming .compile with re.VERBOSE):
>
> rx_works = '
> \$< # start of match is literal '$<'
> anywhere inside string
> [^<:]+?:: # followed by at least one "character", except
> '<' or ':', until the next '::' (this is the placeholder "name")
> .*?:: # followed by any number of any "character",
> until the next '::' (this is the
> placeholder "options")
> \d*? # followed by any number of digits
>
> (the max length of placeholder output)
> >\$ # followed by '>$'
> | # -- OR (in *either* order) --
> \$< # start of match is literal '$<'
> anywhere inside string
> [^<:]+?:: # followed by at least one "character", except
> '<' or ':', until the next '::' (this is the placeholder "name")
> .*?:: # followed by any number of any "character",
> until the next '::' (this is the
> placeholder "options")
> # now the difference:
> \d+-\d+ # followed by one-or-many digits, a '-', and
> one-or-many digits (this is the
> *range* from with placeholder output)
> >\$' # followed by '>$'
Another try:
- lines can contain several placeholders
- placeholders start and end with '$'
- placeholders are parsed in three passes
- the pass in which a placeholder is parsed is denoted by the number of '<' and
'>' next to the '$':
$<...>$ / $<<...>>$ / $<<<...>>>$
- placeholders for different parsing passes must be nestable:
$<<<...$<...>$...>>>$
....
(lower=earlier parsing passes will be inside)
- the internal structure is "name::options::range"
$<name::options::range>$
- name will *not* contain '$' '<' '>' ':'
- range can be either a length or a "from-until"
- a length will be a positive integer (no bounds checking)
- "from-until" is: a positive integer, a '-', and a positive integer (no sanity
checking)
- options needs to be able to contain nearly anything, except '::'
Is that sufficiently defined and helpful to design the regular expression ?
Karsten
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