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eHTML: A HTML formatting library for SmallEiffel |
Written by Lyn Headley.
Version 0.1
ehtml_0_1.tar.gz (5,000 bytes) - source code
laheadle@cs.uchicago.edu Lyn Headley (maintainer) mail address.
I've written the core functionality and inheritance hierarchy for an HTML formatting library (tentatively called eHTML). The basic idea is that there is a class for each HTML entity, plus a few base classes for behavior and implementation.
The (preliminary but working) code can be found here (tested under SE, requires GOBO):
The base class of any HTML element is HT_ELEMENT. This has features dealing with attributes (key=value pairs found in basically all elements) and has a feature which generates a tag, from a (deferred) feature tag_text, so e.g. the <title> tag has tag_text title. HT_ELEMENT also declares the feature to_html, which is the main method clients call to get a stringified version of the markup which encodes the object.
Right beneath HT_ELEMENT is HT_CONTAINER, the base class for elements which contain other elements (including the special case of HT_RAW, which is just a way to type strings as HT_ELEMENTs so they can be put into HT_CONTAINERs). This does all the work of inserting and rendering the contained elements. It also introduces the notion of an end tag, which of course container elements require. HT_CONTAINER also inherits from the gobo class DS_ARRAYED_LIST[HT_ELEMENT].
One step below HT_CONTAINER is HT_RAW_WRAPPER, a base class for things like <title> and <b>, which (usually) simply surround some text. for this common case, HT_RAW_WRAPPER provides the creation function make_with(text: STRING).
Once this infrastructure has been set up, the concrete HTML classes become really simple. Here is HT_TITLE, for instance:
class HT_TITLE
inherit
HT_RAW_WRAPPER
redefine tag_text
end
creation
make_with
feature
tag_text: STRING is "title"
end -- class HT_TITLE
here is how you might use the library(simplified version of a real feature in my soon-to-be-released Web app):
feature
succeeded is
local
html: HT_HTML
bold: HT_B
br: HT_BR
link: HT_A
do
!!html.make
html.set_title("Referendum: Login Successful")
!!bold.make_with("Thank you. You are now logged in")
html.force_last(bold)
!!bold.make_with("(Assuming your browser supports cookies)")
html.force_last(bold)
!!br.make
html.force_last(br)
!!link.make_with("/cgi-bin/referendum?propose"
"Continue")
html.force_last(link)
print(html.to_html)
end -- succeeded
I find all those temporaries and creation routines a bit jangly. Maybe I'll make a factory class.
Check out the code. I'd appreciate any comments, criticism, or beer.
Lyn Headley: laheadle@cs.uchicago.edu
Lyn's Homepage: http://www.cs.uchicago.edu/~laheadle/
29 September 1999 (Added to Eiffel Forum Archive: 23 December 1999)
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