NAME

VCP::Filter::sort - Sort revs by field, order

SYNOPSIS

  ## From the command line:
   vcp <source> sort: name ascending rev_id ascending -- <dest>

  ## In a .vcp file:

    Sort:
       name     ascending
       rev_id   ascending

DESCRIPTION

NOTE: this filter is primarily for development and testing, it is not designed for large datasets (it can use a lot of RAM if fed enough data).

Useful with the revml: destination to get RevML output in a desired order. Otherwise the sorting built in to the change aggregator should suffice.

The default sort spec is "name,rev_id" which is what is handy to VCP's test suite as it puts all revisions in a predictable order so the output revml can be compared to the input revml.

NOTE: this is primarily for development use; not all fields may work right. All plain string fields should work right as well as name, rev_id, change_id and their source_... equivalents (which are parsed and compared piece-wise) and time, and mod_tome (which are stored as integers internally).

Plain case sensitive string comparison is used for all fields other than those mentioned in the preceding paragraphs.

This sort may be slow for extremely large data sets; it sorts things by comparing revs to eachother field by field instead of by generating indexes and VCP::Rev is not designed to be super fast when accessing fields one by one. This can be altered if need be.

How rev_id and change_id are sorted

"change_id" or "rev_id" are split in to segments suitable for sorting.

The splits occur at the following points:

   1. Before and after each substring of consecutive digits
   2. Before and after each substring of consecutive letters
   3. Before and after each non-alpha-numeric character

The substrings are greedy: each is as long as possible and non-alphanumeric characters are discarded. So "11..22aa33" is split in to 5 segments: ( 11, "", 22, "aa", 33 ).

If a segment is numeric, it is left padded with 10 NUL characters.

This algorithm makes 1.52 be treated like revision 1, minor revision 52, not like a floating point 1.52. So the following sort order is maintained:

The substring "pre" might be treated specially at some point.

(At least) the following cases are not handled by this algorithm:

   1. floating point rev_ids: 1.0, 1.1, 1.11, 1.12, 1.2
   2. letters as "prereleases": 1.0a, 1.0b, 1.0, 1.1a, 1.1

LIMITATIONS

Stores all metadata in RAM.

AUTHOR

Barrie Slaymaker <barries@slaysys.com>

COPYRIGHT

See VCP::License ("vcp help license") for the terms of use.