From 6ae7ae0210f24d55fd49636298b7b7d1ec6ec75e Mon Sep 17 00:00:00 2001
From: notoria <notoria@users.noreply.github.com>
Date: Fri, 1 May 2020 16:46:31 +0200
Subject: [PATCH] Enhanced version

---
 src/main.rs                        | 5 -----
 src/prolog/clause_types.rs         | 3 +++
 src/prolog/machine/system_calls.rs | 9 +++++++++
 src/prolog/toplevel.pl             | 3 ++-
 4 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index c8866b38..fc85a959 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -36,11 +36,6 @@ fn main() {
     let handler = signal::SigHandler::Handler(handle_sigint);
     unsafe { signal::signal(signal::Signal::SIGINT, handler) }.unwrap();
 
-    if env::args().skip(1).any(|a| a == "-v" || a == "--version") {
-        println!("{:}", git_version!(cargo_prefix = "cargo:", fallback = "unknown"));
-        return;
-    }
-
     let mut wam = Machine::new(readline::input_stream(), Stream::stdout());
     wam.run_top_level();
 }
diff --git a/src/prolog/clause_types.rs b/src/prolog/clause_types.rs
index 9b550c35..83e144eb 100644
--- a/src/prolog/clause_types.rs
+++ b/src/prolog/clause_types.rs
@@ -264,6 +264,7 @@ pub enum SystemClauseType {
     WAMInstructions,
     WriteTerm,
     WriteTermToChars,
+    ScryerPrologVersion,
 }
 
 impl SystemClauseType {
@@ -418,6 +419,7 @@ impl SystemClauseType {
             &SystemClauseType::WAMInstructions => clause_name!("$wam_instructions"),
             &SystemClauseType::WriteTerm => clause_name!("$write_term"),
             &SystemClauseType::WriteTermToChars => clause_name!("$write_term_to_chars"),
+            &SystemClauseType::ScryerPrologVersion => clause_name!("$scryer_prolog_version"),
         }
     }
 
@@ -552,6 +554,7 @@ impl SystemClauseType {
             ("$wam_instructions", 3) => Some(SystemClauseType::WAMInstructions),
             ("$write_term", 6) => Some(SystemClauseType::WriteTerm),
             ("$write_term_to_chars", 7) => Some(SystemClauseType::WriteTermToChars),
+            ("$scryer_prolog_version", 1) => Some(SystemClauseType::ScryerPrologVersion),
             _ => None,
         }
     }
diff --git a/src/prolog/machine/system_calls.rs b/src/prolog/machine/system_calls.rs
index a0e5762a..144bcd8b 100644
--- a/src/prolog/machine/system_calls.rs
+++ b/src/prolog/machine/system_calls.rs
@@ -3515,6 +3515,15 @@ impl MachineState {
                     unreachable!()
                 }
             }
+            &SystemClauseType::ScryerPrologVersion => {
+                use crate::git_version::git_version;
+                let version = self[temp_v!(1)];
+                let buffer =
+                    git_version!(cargo_prefix = "cargo:", fallback = "unknown");
+                let chars = buffer.chars().map(|c| Addr::Char(c));
+                let result = Addr::HeapCell(self.heap.to_list(chars));
+                self.unify(version, result);
+            }
         };
 
         return_from_clause!(self.last_call, self)
diff --git a/src/prolog/toplevel.pl b/src/prolog/toplevel.pl
index 05cb6b6e..d691c66e 100644
--- a/src/prolog/toplevel.pl
+++ b/src/prolog/toplevel.pl
@@ -54,7 +54,8 @@ print_help(Args) :-
     halt.
 
 print_version(Args) :-
-    write('v0.8.120'), nl, % TODO: Something better is required here.
+    '$scryer_prolog_version'(Version),
+    write(Version), nl,
     halt.
 
 gather_goal(Type, Args0, Goals) :-
-- 
2.54.0