64 lines
2.4 KiB
Plaintext
64 lines
2.4 KiB
Plaintext
(*
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* Copyright 2020, Data61, CSIRO (ABN 41 687 119 230)
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*)
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theory Locale_Abbrev
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imports Main
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keywords "revert_abbrev" :: thy_decl and "locale_abbrev" :: thy_decl
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begin
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(*
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"Normal" abbreviations in locales provide input syntax only, i.e. they are not contracted on
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pretty printing. Presumably this is because a) this would not work with fixed variables on locale
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export and b) one cannot make a global decision whether everything is to be abbreviated only
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inside the locale or inside and outside, and so the safe option is to provide input only.
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This theory provides two commands:
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- revert_abbrev (print-mode) name (:: lthy \<Rightarrow> lthy)
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causes an already defined abbreviation \<open>name\<close> to always be contracted on pretty printing
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for the specified optional print mode. This only works when the abbreviation does not
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mention any fixed variables of the locale.
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- locale_abbrev spec (:: lthy \<Rightarrow> lthy)
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is an alias for the standard abbreviation command, followed by revert_abbrev.
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This is the command to use for abbreviations that should be contracted inside locales.
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Contrary to standard abbreviations, this command cannot mention fixed variables of the
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locale.
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*)
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ML \<open>
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local
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fun revert_abbrev (mode,name) lthy =
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let
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val the_const = (fst o dest_Const) oo Proof_Context.read_const {proper = true, strict = false};
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in
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Local_Theory.raw_theory (Sign.revert_abbrev (fst mode) (the_const lthy name)) lthy
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end
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fun name_of spec lthy = Local_Defs.abs_def (Syntax.read_term lthy spec) |> #1 |> #1
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in
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val _ =
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Outer_Syntax.local_theory @{command_keyword revert_abbrev}
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"make an abbreviation available for output"
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(Parse.syntax_mode -- Parse.const >> revert_abbrev)
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val _ =
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Outer_Syntax.local_theory' @{command_keyword locale_abbrev}
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"constant abbreviation that provides also provides printing in locales"
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(Parse.syntax_mode -- Scan.option Parse_Spec.constdecl -- Parse.prop -- Parse.for_fixes
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>> (fn (((mode, decl), spec), params) => fn restricted => fn lthy =>
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lthy
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|> Local_Theory.begin_nested |> snd
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|> Specification.abbreviation_cmd mode decl params spec restricted
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|> Local_Theory.end_nested (* commit new abbrev. name *)
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|> revert_abbrev (mode, name_of spec lthy)));
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end
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\<close>
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end |