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.. This file is part of Logtalk https://logtalk.org/ SPDX-FileCopyrightText: 1998-2024 Paulo Moura <pmoura@logtalk.org> SPDX-License-Identifier: Apache-2.0
Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
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.. rst-class:: align-right
directive
.. index:: pair: meta_non_terminal/1; Directive .. _directives_meta_non_terminal_1:
::
meta_non_terminal(Template)
meta_non_terminal((Template, ...))
meta_non_terminal([Template, ...])
meta_non_terminal(Entity::Template) meta_non_terminal((Entity::Template, ...)) meta_non_terminal([Entity::Template, ...])
meta_non_terminal(Module:Template)
meta_non_terminal((Module:Template, ...))
meta_non_terminal([Module:Template, ...])
Declares meta-non-terminals, i.e., non-terminals that have arguments
that will be called as non-terminals (or grammar rule bodies). An
argument may also be a :term:closure
instead of a goal if the
non-terminal uses the :ref:methods_call_1
built-in methods to
construct and call the actual non-terminal from the closure and the
additional arguments or the :ref:methods_phrase_1
built-in method.
Meta-arguments which are non-terminals are represented by the integer
0
. Meta-arguments which are closures are represented by a positive
integer, N
, representing the number of additional arguments that
will be appended to the closure in order to construct the corresponding
meta-call. Normal arguments are represented by the atom *
.
Meta-arguments are always called in the meta-non-terminal calling
context, not in the meta-non-terminal definition context.
::
meta_non_terminal(+meta_non_terminal_template_term)
meta_non_terminal(+object_identifier::+meta_non_terminal_template_term) meta_non_terminal(+category_identifier::+meta_non_terminal_template_term)
meta_non_terminal(+module_identifier:+meta_non_terminal_template_term)
::
:- meta_non_terminal(phrase(1, *))
.
phrase(X, T)
--> call(X, T)
.
.. seealso::
:ref:directives_meta_predicate_1
,
:ref:methods_predicate_property_2