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HATX-0.0.3
River stage zero No dependents
/ HATX

NAME

HATX - A fluent interface for Hash and Array Transformations

SYNOPSIS

use HATX qw/hatx/;

# Multiple versions of journal.html and projmgmt.html
my $files = [
  'journal-v1.0.tar.gz  1201',
  'journal-v1.1.tar.gz  1999',
  'journal-v1.2.tar.gz  3100',
  'projmgmt-v0.1.tar.gz  250',
  'projmgmt-v0.2.tar.gz  350'
];

# Declare a helper object
my $max = { journal => '0.0', projmgmt => '0.0' };

# hatx($obj) clones $obj; no clobbering
my $h = hatx($files)
  # Internal object becomes equivalent to:
  # [ 'journal-v1.0.tar.gz  1201',
  #   'journal-v1.1.tar.gz  1999',
  #   'journal-v1.2.tar.gz  3100',
  #   'projmgmt-v0.1.tar.gz  250',
  #   'projmgmt-v0.2.tar.gz  350' ]

 # Extract components: file, version, bytes
 ->map(sub {
    $_[0] =~ /(journal|projmgmt)-v(.+).tar.gz\s+(\d+)/;
    return [$1, $2, $3];      # e.g. ['journal', '1.0', 1201]
  })
  # Internal object becomes equivalent to:
  # [ ['journal', '1.0', 1201]
  #   ['journal', '1.1', 1999]
  #   ['journal', '1.2', 3100]
  #   ['projmgmt', '0.1', 250]
  #   ['projmgmt', '0.2', 350] ]

# Accumulate file count and file sizes
->apply(sub {
    my ($v, $res) = @_;
    $res->{count}++;
    $res->{bytes} += $v->[2];
  }, my $stats = { count => 0, bytes => 0 })
  # Internal object unchanged
  # The $stats variable becomes { count => 5, bytes => 6900 }

# Determine the max version of each file, store into $max
->apply(sub {
    my ($v, $res) = @_;
    my ($file, $ver, $size) = @$v;
    if ($ver gt $res->{$file}) { $res->{$file} = $ver }
  }, $max)
  # Internal object unchanged
  # $max variable becomes { journal => '1.2', projmgmt => '0.2' }

# Keep only the max version
->grep(sub {
    my ($v, $res) = @_;
    my ($file, $ver, $size) = @$v;
    return $ver eq $res->{$file};
  }, $max)
  # Internal object reduced to:
  # [ ['journal', '1.2', 3100]
  #   ['projmgmt', '0.2', 350] ]
;

METHODS

map

Apply the given function to each item in the href/aref.

The given function has the following signature:

fn($k,$v) -> ($k,$v)    # Applied to href
fn($v)    -> ($v)       # Applied to aref

The internal href/aref IS modified.

grep

Apply the given function to each item in the href/aref.

The given function has the following signature:

fn->($k,$v[,@args]) -> BOOLEAN     # Applied to hashref
fn->($v[,@args])    -> BOOLEAN     # Applied to arrayref

WHERE
  fn     A function reference that returns a boolean value
  $k,$v  The key-value pair of a hash
  $v     An item of an array
  @args  An optional list of user variables

Items where the fn returns a True value are kept.

sort( $fn )

DESCRIPTION

Sorts contents of arrayref. Hashrefs are unmodified.

ARGUMENTS

$fn - A function reference with prototype ($$). See https://perldoc.perl.org/functions/sort.

EXAMPLES

# Sort descending alphabetically
hatx($aref)->sort(sub ($$) { $_[1] cmp $_[0] });

# Sort ascending numerically
hatx($aref)->sort(sub ($$) { $_[0] <=> $_[1] });

# Sort descending numerically
hatx($aref)->sort(sub ($$) { $_[1] <=> $_[0] });

to_href

Convert internal aref to href using the given function.

$fn->($val) -> ($key, $val)
$fn is a FUNCTIONREF that takes a single value and returns two values

to_aref( $fn [,@args] )

DESCRIPTION

Convert internal hashref to an arrayref.

ARGUMENTS

$fn - A user-provided function reference with signature:

  $fn->($hkey, $hval [,@args]) return ($val)

  WHERE
    $hkey   Key of source hashref pair
    $hval   Value of source hashref pair
    @args   Optional user variables
    $val    An element of the target arrayref

@args - Optional arguments that are passed through to $fn

apply

Apply the given function to each item in the href/aref. Arguments can be provided to store results of the function application e.g. finding the max value.

The internal href/aref is not modified.

fn($k,$v,@args) -> ()
fn($v,@args)    -> ()

AUTHOR

Hoe Kit CHEW <hoekit@gmail.com>

COPYRIGHT

Copyright 2024- Hoe Kit CHEW

LICENSE

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

SEE ALSO