The Script’s Data Structure
The first interesting thing in the script is the section at the top where the data structure that will hold the site’s metainformation is defined:
my %page_data; # HoH w/ primary keys: path # secondary keys: page template params # values: corresponding content my %teacher_students; # HoL, w/ keys of teacher short_name and values # of arrays of student page paths. my %student_profiles; # HoHoL, w/ primary keys of teacher/student # string, secondary key of @attribute element, # and values of leader page paths. my %cat_leaders; # HoL, w/ keys of leader cat short_names, and # values of arrays of leader page paths.
The
comments here make use of a form
of shorthand popular with Perl programmers when they are talking
about
multilevel data structures.
HoH
means
“hash of hashes,”
HoL
means
“hash of lists” (another name for a
"hash of
arrays”), and the jolly-sounding
HoHoL
means “hash of hash of lists.”
The %page_data
hash of hashes is really the heart of
the script. It is built up during the script’s first cycle
through the site’s HTML pages. In effect, it is a little
database that embodies all the
META
headers,
TITLE
tags, and comment-delimited content blocks
of the site’s HTML pages. That hash of hashes has a first-level
key consisting of the page’s path and filename, a second-level
key of the name of the page attribute, and a value of the
corresponding content. That is, for the Al Gore leader page whose
META
headers we looked at earlier, the entry ...
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