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(*************************************************************************
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* Copyright (C)
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* 2019-2021 University of Exeter
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* 2018-2021 University of Paris-Saclay
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2019-08-15 14:09:55 +00:00
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* 2018 The University of Sheffield
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*
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* License:
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* This program can be redistributed and/or modified under the terms
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* of the 2-clause BSD-style license.
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*************************************************************************)
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(*<*)
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theory "05_Implementation"
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imports "04_RefMan"
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begin
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(*>*)
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chapter*[isadof_developers::text_section]\<open>Extending \<^isadof>\<close>
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text\<open>
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In this chapter, we describe the basic implementation aspects of \<^isadof>, which is based on
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the following design-decisions:
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\<^item> the entire \<^isadof> is a ``pure add-on,'' \<^ie>, we deliberately resign on the possibility to
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modify Isabelle itself.
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\<^item> we made a small exception to this rule: the \<^isadof> package modifies in its installation
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about 10 lines in the \LaTeX-generator (\path{src/patches/thy_output.ML}).
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\<^item> we decided to make the markup-generation by itself to adapt it as well as possible to the
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needs of tracking the linking in documents.
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\<^item> \<^isadof> is deeply integrated into the Isabelle's IDE (PIDE) to give immediate feedback during
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editing and other forms of document evolution.
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\<close>
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text\<open>
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Semantic macros, as required by our document model, are called \<^emph>\<open>document antiquotations\<close>
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in the Isabelle literature~@{cite "wenzel:isabelle-isar:2020"}. While Isabelle's code-antiquotations
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are an old concept going back to Lisp and having found via SML and OCaml their ways into modern
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proof systems, special annotation syntax inside documentation comments have their roots in
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documentation generators such as Javadoc. Their use, however, as a mechanism to embed
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machine-checked \<^emph>\<open>formal content\<close> is usually very limited and also lacks
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IDE support.
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\<close>
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section\<open>\<^isadof>: A User-Defined Plugin in Isabelle/Isar\<close>
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text\<open>
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A plugin in Isabelle starts with defining the local data and registering it in the framework. As
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mentioned before, contexts are structures with independent cells/compartments having three
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primitives \<^boxed_sml>\<open>init\<close>, \<^boxed_sml>\<open>extend\<close> and \<^boxed_sml>\<open>merge\<close>. Technically this is done by
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instantiating a functor \<^boxed_sml>\<open>Generic_Data\<close>, and the following fairly typical code-fragment
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is drawn from \<^isadof>:
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@{boxed_sml [display]
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\<open>structure Data = Generic_Data
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( type T = docobj_tab * docclass_tab * ...
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val empty = (initial_docobj_tab, initial_docclass_tab, ...)
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val extend = I
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fun merge((d1,c1,...),(d2,c2,...)) = (merge_docobj_tab (d1,d2,...),
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merge_docclass_tab(c1,c2,...))
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);\<close>}
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where the table \<^boxed_sml>\<open>docobj_tab\<close> manages document classes and \<^boxed_sml>\<open>docclass_tab\<close> the
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environment for class definitions (inducing the inheritance relation). Other tables capture, \eg,
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the class invariants, inner-syntax antiquotations. Operations follow the MVC-pattern, where
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Isabelle/Isar provides the controller part. A typical model operation has the type:
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@{boxed_sml [display]
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\<open>val opn :: <args_type> -> Context.generic -> Context.generic\<close>}
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representing a transformation on system contexts. For example, the operation of declaring a local
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reference in the context is presented as follows:
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@{boxed_sml [display]
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\<open>fun declare_object_local oid ctxt =
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let fun decl {tab,maxano} = {tab=Symtab.update_new(oid,NONE) tab,
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maxano=maxano}
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in (Data.map(apfst decl)(ctxt)
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handle Symtab.DUP _ =>
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error("multiple declaration of document reference"))
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end\<close>}
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where \<^boxed_theory_text>\<open>Data.map\<close> is the update function resulting from the instantiation of the
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functor \<^boxed_sml>\<open>Generic_Data\<close>. This code fragment uses operations from a library structure
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\<^boxed_sml>\<open>Symtab\<close> that were used to update the appropriate table for document objects in
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the plugin-local state. Possible exceptions to the update operation were mapped to a system-global
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error reporting function.
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Finally, the view-aspects were handled by an API for parsing-combinators. The library structure
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\<^boxed_sml>\<open>Scan\<close> provides the operators:
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@{boxed_sml [display]
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\<open>op || : ('a -> 'b) * ('a -> 'b) -> 'a -> 'b
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op -- : ('a -> 'b * 'c) * ('c -> 'd * 'e) -> 'a -> ('b * 'd) * 'e
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op >> : ('a -> 'b * 'c) * ('b -> 'd) -> 'a -> 'd * 'c
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op option : ('a -> 'b * 'a) -> 'a -> 'b option * 'a
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op repeat : ('a -> 'b * 'a) -> 'a -> 'b list * 'a \<close>}
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for alternative, sequence, and piping, as well as combinators for option and repeat. Parsing
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combinators have the advantage that they can be smoothlessly integrated into standard programs,
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and they enable the dynamic extension of the grammar. There is a more high-level structure
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\inlinesml{Parse} providing specific combinators for the command-language Isar:
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\begin{sml}[mathescape=false]
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val attribute = Parse.position Parse.name
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-- Scan.optional(Parse.$$$ "=" |-- Parse.!!! Parse.name)"";
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val reference = Parse.position Parse.name
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-- Scan.option (Parse.$$$ "::" |-- Parse.!!!
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(Parse.position Parse.name));
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val attributes =(Parse.$$$ "[" |-- (reference
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-- (Scan.optional(Parse.$$$ ","
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|--(Parse.enum ","attribute)))[]))--| Parse.$$$ "]"
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\end{sml}
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The ``model'' \<^boxed_theory_text>\<open>declare_reference_opn\<close> and ``new'' \<^boxed_theory_text>\<open>attributes\<close> parts were
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combined via the piping operator and registered in the Isar toplevel:
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@{boxed_sml [display]
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\<open>fun declare_reference_opn (((oid,_),_),_) =
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(Toplevel.theory (DOF_core.declare_object_global oid))
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val _ = Outer_Syntax.command <@>{command_keyword "declare_reference"}
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"declare document reference"
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(attributes >> declare_reference_opn);\<close>}
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Altogether, this gives the extension of Isabelle/HOL with Isar syntax and semantics for the
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new \emph{command}:
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@{boxed_theory_text [display]\<open>
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declare_reference [lal::requirement, alpha="main", beta=42]
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\<close>}
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The construction also generates implicitly some markup information; for example, when hovering
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over the \<^boxed_theory_text>\<open>declare_reference\<close> command in the IDE, a popup window with the text:
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``declare document reference'' will appear.
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\<close>
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section\<open>Programming Antiquotations\<close>
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text\<open>
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The definition and registration of text antiquotations and ML-antiquotations is similar in
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principle: based on a number of combinators, new user-defined antiquotation syntax and semantics
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can be added to the system that works on the internal plugin-data freely. For example, in
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@{boxed_sml [display]
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\<open>val _ = Theory.setup(
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Thy_Output.antiquotation <@>{binding docitem}
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docitem_antiq_parser
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(docitem_antiq_gen default_cid) #>
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ML_Antiquotation.inline <@>{binding docitem_value}
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ML_antiq_docitem_value)\<close>}
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the text antiquotation \<^boxed_theory_text>\<open>docitem\<close> is declared and bounded to a parser for the argument
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syntax and the overall semantics. This code defines a generic antiquotation to be used in text
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elements such as
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@{boxed_theory_text [display]\<open>
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text\<open>as defined in <@>{docitem \<open>d1\<close>} ...\<close>
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\<close>}
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The subsequent registration \<^boxed_theory_text>\<open>docitem_value\<close> binds code to a ML-antiquotation usable
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in an ML context for user-defined extensions; it permits the access to the current ``value''
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of document element, \ie; a term with the entire update history.
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It is possible to generate antiquotations \emph{dynamically}, as a consequence of a class
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definition in ODL. The processing of the ODL class \<^boxed_theory_text>\<open>definition\<close> also \emph{generates}
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a text antiquotation \<^boxed_theory_text>\<open>@{definition \<open>d1\<close>}\<close>, which works similar to
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\<^boxed_theory_text>\<open>@{docitem \<open>d1\<close>}\<close> except for an additional type-check that assures that
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\<^boxed_theory_text>\<open>d1\<close> is a reference to a definition. These type-checks support the subclass hierarchy.
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\<close>
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section\<open>Implementing Second-level Type-Checking\<close>
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text\<open>
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On expressions for attribute values, for which we chose to use HOL syntax to avoid that users
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need to learn another syntax, we implemented an own pass over type-checked terms. Stored in the
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late-binding table \<^boxed_theory_text>\<open>ISA_transformer_tab\<close>, we register for each inner-syntax-annotation
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(ISA's), a function of type
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@{boxed_sml [display]
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\<open> theory -> term * typ * Position.T -> term option\<close>}
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Executed in a second pass of term parsing, ISA's may just return \<^boxed_theory_text>\<open>None\<close>. This is
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adequate for ISA's just performing some checking in the logical context \<^boxed_theory_text>\<open>theory\<close>;
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ISA's of this kind report errors by exceptions. In contrast, \<^emph>\<open>transforming\<close> ISA's will
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yield a term; this is adequate, for example, by replacing a string-reference to some term denoted
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by it. This late-binding table is also used to generate standard inner-syntax-antiquotations from
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a \<^boxed_theory_text>\<open>doc_class\<close>.
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\<close>
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section\<open>Programming Class Invariants\<close>
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text\<open>
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See \<^technical>\<open>sec:low_level_inv\<close>.
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\<close>
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section\<open>Implementing Monitors\<close>
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text\<open>
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Since monitor-clauses have a regular expression syntax, it is natural to implement them as
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deterministic automata. These are stored in the \<^boxed_theory_text>\<open>docobj_tab\<close> for monitor-objects
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in the \<^isadof> component. We implemented the functions:
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@{boxed_sml [display]
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\<open> val enabled : automaton -> env -> cid list
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val next : automaton -> env -> cid -> automaton\<close>}
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where \<^boxed_theory_text>\<open>env\<close> is basically a map between internal automaton states and class-id's
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(\<^boxed_theory_text>\<open>cid\<close>'s). An automaton is said to be \<^emph>\<open>enabled\<close> for a class-id,
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iff it either occurs in its accept-set or its reject-set (see @{docitem "sec:monitors"}). During
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top-down document validation, whenever a text-element is encountered, it is checked if a monitor
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is \emph{enabled} for this class; in this case, the \<^boxed_theory_text>\<open>next\<close>-operation is executed. The
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transformed automaton recognizing the rest-language is stored in \<^boxed_theory_text>\<open>docobj_tab\<close> if
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possible; otherwise, if \<^boxed_theory_text>\<open>next\<close> fails, an error is reported. The automata implementation
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is, in large parts, generated from a formalization of functional automata~\cite{nipkow.ea:functional-Automata-afp:2004}.
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\<close>
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section\<open>The \LaTeX-Core of \<^isadof>\<close>
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text\<open>
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The \LaTeX-implementation of \<^isadof> heavily relies on the
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``keycommand''~@{cite "chervet:keycommand:2010"} package. In fact, the core \<^isadof> \LaTeX-commands
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are just wrappers for the corresponding commands from the keycommand package:
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@{boxed_latex [display]
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\<open>\newcommand\newisadof[1]{%
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\expandafter\newkeycommand\csname isaDof.#1\endcsname}%
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\newcommand\renewisadof[1]{%
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\expandafter\renewkeycommand\csname isaDof.#1\endcsname}%
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\newcommand\provideisadof[1]{%
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\expandafter\providekeycommand\csname isaDof.#1\endcsname}%\<close>}
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The \LaTeX-generator of \<^isadof> maps each \<^boxed_theory_text>\<open>doc_item\<close> to an \LaTeX-environment (recall
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@{docitem "text-elements"}). As generic \<^boxed_theory_text>\<open>doc_item\<close> are derived from the text element,
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the enviornment \inlineltx|{isamarkuptext*}| builds the core of \<^isadof>'s \LaTeX{} implementation.
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For example, the @{docitem "ass123"} from page \pageref{ass123} is mapped to
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2019-08-11 17:06:13 +00:00
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@{boxed_latex [display]
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\<open>\begin{isamarkuptext*}%
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[label = {ass122},type = {CENELEC_50128.SRAC},
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args={label = {ass122}, type = {CENELEC_50128.SRAC},
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CENELEC_50128.EC.assumption_kind = {formal}}
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] The overall sampling frequence of the odometer subsystem is therefore
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14 khz, which includes sampling, computing and result communication
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times ...
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\end{isamarkuptext*}\<close>}
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This environment is mapped to a plain \LaTeX command via (again, recall @{docitem "text-elements"}):
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@{boxed_latex [display]
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\<open> \NewEnviron{isamarkuptext*}[1][]{\isaDof[env={text},#1]{\BODY}} \<close>}
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2020-09-08 12:45:09 +00:00
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For the command-based setup, \<^isadof> provides a dispatcher that selects the most specific
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implementation for a given \<^boxed_theory_text>\<open>doc_class\<close>:
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@{boxed_latex [display]
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\<open>%% The Isabelle/DOF dispatcher:
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\newkeycommand+[\|]\isaDof[env={UNKNOWN},label=,type={dummyT},args={}][1]{%
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\ifcsname isaDof.\commandkey{type}\endcsname%
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\csname isaDof.\commandkey{type}\endcsname%
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[label=\commandkey{label},\commandkey{args}]{#1}%
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\else\relax\fi%
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\ifcsname isaDof.\commandkey{env}.\commandkey{type}\endcsname%
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\csname isaDof.\commandkey{env}.\commandkey{type}\endcsname%
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[label=\commandkey{label},\commandkey{args}]{#1}%
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\else%
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\message{Isabelle/DOF: Using default LaTeX representation for concept %
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"\commandkey{env}.\commandkey{type}".}%
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\ifcsname isaDof.\commandkey{env}\endcsname%
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\csname isaDof.\commandkey{env}\endcsname%
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[label=\commandkey{label}]{#1}%
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\else%
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\errmessage{Isabelle/DOF: No LaTeX representation for concept %
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"\commandkey{env}.\commandkey{type}" defined and no default %
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definition for "\commandkey{env}" available either.}%
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\fi%
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\fi%
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}\<close>}
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\<close>
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(*<*)
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2019-08-02 10:12:16 +00:00
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end
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(*>*)
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