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44 lines
1.6 KiB
Mathematica
44 lines
1.6 KiB
Mathematica
%---------------------------------------------------------------------------%
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% vim: ts=4 sw=4 et ft=mercury
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%---------------------------------------------------------------------------%
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% Author: Dirk Ziegemeyer <dirk@ziegemeyer.de>
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%---------------------------------------------------------------------------%
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:- module bug538.
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:- interface.
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:- import_module list.
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%---------------------------------------------------------------------------%
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% Html content categories modelled as subtypes (simplified)
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% 1. All html elements belong to the base type flow_content
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% 2. Phrasing_content is a subset of flow_content
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% 3. Nesting of <a> elements (hyperlinks) is invalid. Neither direct nor
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% indirect nesting is allowed.
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%
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:- type flow_content
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---> p(list(phrasing_content))
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; div(list(flow_content))
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; a(list(flow_content_without_a))
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; text(string).
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:- type flow_content_without_a =< flow_content
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---> p(list(phrasing_content_without_a))
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; div(list(flow_content_without_a))
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; text(string).
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:- type phrasing_content =< flow_content
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---> a(list(phrasing_content_without_a))
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; text(string).
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% 1. Explicitly declared subtype of phrasing_content
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% 2. Implicit subtype of flow_content_without_a, because both share the
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% same base type (flow_content) and the subtype only omits constructor
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% definitions
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%
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:- type phrasing_content_without_a =< phrasing_content
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---> text(string).
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%---------------------------------------------------------------------------%
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