From e88ec6736c12dd8b6afe07e8a80230988d24fe77 Mon Sep 17 00:00:00 2001
From: Mark Thom <markjordanthom@gmail.com>
Date: Sun, 13 Mar 2022 12:53:31 -0600
Subject: [PATCH] add (:) meta-predicate argument indicator (#1302)

---
 src/forms.rs                | 1 +
 src/loader.pl               | 5 +++++
 src/machine/loader.rs       | 1 +
 src/machine/preprocessor.rs | 1 +
 4 files changed, 8 insertions(+)

diff --git a/src/forms.rs b/src/forms.rs
index aef5ad95..a3c2b354 100644
--- a/src/forms.rs
+++ b/src/forms.rs
@@ -267,6 +267,7 @@ pub enum MetaSpec {
     Minus,
     Plus,
     Either,
+    Colon,
     RequiresExpansionWithArgument(usize),
 }
 
diff --git a/src/loader.pl b/src/loader.pl
index cb872035..b0bc5a6d 100644
--- a/src/loader.pl
+++ b/src/loader.pl
@@ -213,6 +213,9 @@ inner_meta_specs(0, HeadArg, InnerHeadArgs, InnerMetaSpecs) :-
     InnerMetaSpecs0 =.. [_ | InnerMetaSpecs],
     HeadArg =.. [_ | InnerHeadArgs].
 
+inner_meta_specs((:), _, [], []) :-
+    !.
+
 inner_meta_specs(N, HeadArg, InnerHeadArgs, InnerMetaSpecs) :-
     integer(N),
     N >= 0,
@@ -636,6 +639,7 @@ expand_module_name(ESG0, MS, M, ESG) :-
     ;  ESG0 = _:_ ->
        ESG = ESG0
     ;  functor(ESG0, F, A0),
+       integer(MS),
        A is A0 + MS,
        functor(EESG0, F, A),
        predicate_property(EESG0, built_in) ->
@@ -647,6 +651,7 @@ expand_module_name(ESG0, MS, M, ESG) :-
 expand_meta_predicate_subgoals([SG | SGs], [MS | MSs], M, [ESG | ESGs], HeadVars) :-
     (  (  integer(MS),
           MS >= 0
+       ;  MS == (:)
        )  ->
        (  var(SG),
           pairs:same_key(SG, HeadVars, [_|_], _) ->
diff --git a/src/machine/loader.rs b/src/machine/loader.rs
index ce251e84..2ab85de4 100644
--- a/src/machine/loader.rs
+++ b/src/machine/loader.rs
@@ -2200,6 +2200,7 @@ impl Machine {
                         MetaSpec::Minus => atom_as_cell!(atom!("+")),
                         MetaSpec::Plus => atom_as_cell!(atom!("-")),
                         MetaSpec::Either => atom_as_cell!(atom!("?")),
+                        MetaSpec::Colon => atom_as_cell!(atom!(":")),
                         MetaSpec::RequiresExpansionWithArgument(ref arg_num) => {
                             fixnum_as_cell!(Fixnum::build_with(*arg_num as i64))
                         }
diff --git a/src/machine/preprocessor.rs b/src/machine/preprocessor.rs
index 50a46947..bd3c9211 100644
--- a/src/machine/preprocessor.rs
+++ b/src/machine/preprocessor.rs
@@ -296,6 +296,7 @@ fn setup_meta_predicate<'a, LS: LoadState<'a>>(
                         atom!("+") => MetaSpec::Plus,
                         atom!("-") => MetaSpec::Minus,
                         atom!("?") => MetaSpec::Either,
+                        atom!(":") => MetaSpec::Colon,
                         _ => return Err(CompilationError::InvalidMetaPredicateDecl),
                     };
 
-- 
2.54.0