Merge pull request #1070 from triska/open_stream

ENHANCED: open/4 to allow opening a stream by specifying stream(S).

src/clause_types.rs

@@ -221,6 +221,7 @@ pub(crate) enum SystemClauseType {
     NumberToCodes,
     OpDeclaration,
     Open,
+    SetStreamOptions,
     NextStream,
     PartialStringTail,
     PeekByte,
@@ -479,6 +480,7 @@ impl SystemClauseType {
             &SystemClauseType::Halt => clause_name!("$halt"),
             &SystemClauseType::HeadIsDynamic => clause_name!("$head_is_dynamic"),
             &SystemClauseType::Open => clause_name!("$open"),
+            &SystemClauseType::SetStreamOptions => clause_name!("$set_stream_options"),
             &SystemClauseType::OpDeclaration => clause_name!("$op"),
             &SystemClauseType::InstallSCCCleaner => clause_name!("$install_scc_cleaner"),
             &SystemClauseType::InstallInferenceCounter => {
@@ -703,6 +705,7 @@ impl SystemClauseType {
             ("$number_to_codes", 2) => Some(SystemClauseType::NumberToCodes),
             ("$op", 3) => Some(SystemClauseType::OpDeclaration),
             ("$open", 7) => Some(SystemClauseType::Open),
+            ("$set_stream_options", 5) => Some(SystemClauseType::SetStreamOptions),
             ("$redo_attr_var_binding", 2) => Some(SystemClauseType::RedoAttrVarBinding),
             ("$remove_call_policy_check", 1) => Some(SystemClauseType::RemoveCallPolicyCheck),
             ("$remove_inference_counter", 2) => Some(SystemClauseType::RemoveInferenceCounter),

src/lib/builtins.pl

@@ -1466,7 +1466,11 @@ open(SourceSink, Mode, Stream, StreamOptions) :-
        throw(error(uninstantiation_error(Stream), open/4)) % 8.11.5.3f)
     ;
        parse_stream_options(StreamOptions, [Alias, EOFAction, Reposition, Type], open/4),
-       '$open'(SourceSink, Mode, Stream, Alias, EOFAction, Reposition, Type)
+       (   SourceSink = stream(S0) ->
+           '$set_stream_options'(S0, Alias, EOFAction, Reposition, Type),
+           Stream = S0
+       ;   '$open'(SourceSink, Mode, Stream, Alias, EOFAction, Reposition, Type)
+       )
     ).
 
 

src/machine/system_calls.rs

@@ -3208,6 +3208,22 @@ impl MachineState {
 
                 self.bind(stream_var.as_var().unwrap(), stream);
             }
+            &SystemClauseType::SetStreamOptions => {
+                let mut stream = self.get_stream_or_alias(
+                    self[temp_v!(1)],
+                    &indices.stream_aliases,
+                    "open",
+                    4,
+                )?;
+
+                let alias = self[temp_v!(2)];
+                let eof_action = self[temp_v!(3)];
+                let reposition = self[temp_v!(4)];
+                let stream_type = self[temp_v!(5)];
+
+                let options = self.to_stream_options(alias, eof_action, reposition, stream_type);
+                *stream.options_mut() = options;
+            }
             &SystemClauseType::TruncateIfNoLiftedHeapGrowthDiff => {
                 self.truncate_if_no_lifted_heap_diff(|h| Addr::HeapCell(h))
             }