=head1 NAME

recs-annotate

=head1 recs-annotate --help-all

 Help from: --help-basic:
 Usage: recs-annotate <args> <expr> [<files>]
    <expr> is evaluated as perl on each record of input (or records from <files>) with $r set to a App::RecordStream::Record object
    and $line set to the current line number (starting at 1). Records are analyzed for changes, those changes are applied to each
    successive record that matches --keys
 
    Only use this script if you have --keys fields that are repeated, otherwise recs-xform will be faster
 
 IMPORTANT SNIPPET NOTE
    Because of the way annotations are recorded, you cannot use UNSHIFT or SPLICE on array refs that already exist in the record you
    are modifiying. Additinally, deletes, removes, unshifts, and other 'removing' operations will not apply to later records. If you
    need this behavior, consider using recs-xform
 
    --keys                       Keys to match records by, maybe specified multiple times, may be a keygroup or keyspec
    --filename-key|fk <keyspec>  Add a key with the source filename (if no filename is applicable will put NONE)
 
   Help Options:
       --help-all        Output all help for this script
       --help            This help screen
       --help-keygroups  Help on keygroups, a way of specifying multiple keys
       --help-keys       Help on keygroups and keyspecs
       --help-keyspecs   Help on keyspecs, a way to index deeply and with regexes
       --help-snippet    Help on code snippets
 
 Examples:
    # Annotate records with IPs with hostnames, only doing lookup once
    ... | recs-annotate --key ip '{{hostname}} = `host {{ip}}`'
 
    # Record md5sums of files
    ... | recs-annotate --key filename '{{md5}} = `md5sum {{filename}}`'
 
    # Add url contents to records
    ... | recs-annotate --key url '{{contents}} = `curl {{url}}`'
 
 Help from: --help-keygroups:
 KEY GROUPS
    SYNTAX: !regex!opt1!opt2... Key groups are a way of specifying multiple fields to a recs command with a single argument or
    function. They are generally regexes, and have several options to control what fields they match. By default you give a regex,
    and it will be matched against all first level keys of a record to come up with the record list. For instance, in a record
    like this:
 
    { 'zip': 1, 'zap': 2, 'foo': { 'bar': 3 } }
 
    Key group: !z! would get the keys 'zip' and 'zap'
 
    You can have a literal '!' in your regex, just escape it with a \.
 
    Normally, key groups will only match keys whose values are scalars. This can be changed with the 'returnrefs' or rr flag.
 
    With the above record !f! would match no fields, but !f!rr would match foo (which has a value of a hash ref)
 
    Options on KeyGroups:
       returnrefs, rr  - Return keys that have reference values (default:off)
       full, f         - Regex should match against full keys (recurse fully)
       depth=NUM,d=NUM - Only match keys at NUM depth (regex will match against
                         full keyspec)
       sort, s         - sort keyspecs lexically
 
 Help from: --help-keyspecs:
   KEY SPECS
    A key spec is short way of specifying a field with prefixes or regular expressions, it may also be nested into hashes and
    arrays. Use a '/' to nest into a hash and a '#NUM' to index into an array (i.e. #2)
 
    An example is in order, take a record like this:
 
      {"biz":["a","b","c"],"foo":{"bar 1":1},"zap":"blah1"}
      {"biz":["a","b","c"],"foo":{"bar 1":2},"zap":"blah2"}
      {"biz":["a","b","c"],"foo":{"bar 1":3},"zap":"blah3"}
 
    In this case a key spec of 'foo/bar 1' would have the values 1,2, and 3 in the respective records.
 
    Similarly, 'biz/#0' would have the value of 'a' for all 3 records
 
    You can also prefix key specs with '@' to engage the fuzzy matching logic
 
    Fuzzy matching works like this in order, first key to match wins
      1. Exact match ( eq )
      2. Prefix match ( m/^/ )
      3. Match anywehre in the key (m//)
 
    So, in the above example '@b/#2', the 'b' portion would expand to 'biz' and 2 would be the index into the array, so all records
    would have the value of 'c'
 
    Simiarly, @f/b would have values 1, 2, and 3
 
    You can escape / with a \. For example, if you have a record:
    {"foo/bar":2}
 
    You can address that key with foo\/bar
 
 Help from: --help-snippet:
    CODE SNIPPETS:
     Recs code snippets are perl code, with one exception. There a couple of variables predefined for you, and one piece of special
     syntax to assist in modifying hashes.
 
 Special Variables:
     $r - the current record object. This may be used exactly like a hash, or you can use some of the special record functions, see
     App::RecordStream::Record for more information
 
     $line - This is the number of records run through the code snippet, starting at 1. For most scripts this corresponds to the
     line number of the input to the script.
 
     $filename - The filename of the originating record. Note: This is only useful if you're passing filenames directly to the recs
     script, piping from other recs scripts or from cat, for instance, will not have a useful filename.
 
 Special Syntax
     Use {{search_string}} to look for a string in the keys of a record, use / to nest keys. You can nest into arrays by using an
     index. If you are vivifying arrays (if the array doesn't exist, prefix your key with # so that an array rather than a hash will
     be created to put a / in your key, escape it twice, i.e. \/
 
     This is exactly the same as a key spec that is always prefaced with a @, see 'man recs' for more info on key specs
 
     For example: A record that looks like:
     { "foo" : { "bar 1" : 1 }, "zoo" : 2}
     Could be accessed like this:
 
     # value of zoo  # value of $r->{foo}->{bar 1}: (comma separate nested keys)
     {{zoo}}         {{foo/ar 1}}
 
     # Even assign to values (set the foo key to the value 1)
     {{foo}} = 1
 
     # And auto, vivify
     {{new_key/array_key/#0}} = 3 # creates an array within a hash within a hash
 
     # Index into an array
     {{array_key/#3}} # The value of index 3 of the array ref under the
     'array_key' hash key.
 
     This matching is a fuzzy keyspec matching, see --help-keyspecs for more details.
 

=head1 See Also

=over

=item  L<RecordStream(3)> - Overview of the scripts and the system

=item  L<recs-examples(3)> - A set of simple recs examples

=item  L<recs-story(3)> - A humorous introduction to RecordStream

=item SCRIPT --help - every script has a --help option, like the output above

=back

