bin: add -0 option for LTL output

* src/bin/common_output.cc: Add option -0.
* src/tests/ltlfilt.test: Test it.
* NEWS: Document it.

NEWS

@@ -117,7 +117,10 @@ New in spot 1.99b (not yet released)
       the same %-escape sequences that are available for --stats or
       --format.
 
-    - All tools that output automata have a --check option that
+    - all tools that output formulas have a -0 option to separate
+      formulas with \0.  This helps in conjunction with xargs -0.
+
+    - all tools that output automata have a --check option that
       request extra checks to be performed on the output to fill
       in properties values for the HOA format.  This options
       implies -H for HOA output.  For instance

src/bin/common_output.cc

@@ -39,6 +39,7 @@ enum {
 output_format_t output_format = spot_output;
 bool full_parenth = false;
 bool escape_csv = false;
+char output_terminator = '\n';
 
 static const argp_option options[] =
   {
@@ -58,6 +59,9 @@ static const argp_option options[] =
       "send output to a file named FORMAT instead of standard output.  The"
       " first formula sent to a file truncates it unless FORMAT starts"
       " with '>>'.", 0 },
+    { "zero-terminated-output", '0', 0, 0,
+      "separate output formulas with \\0 instead of \\n "
+      "(for use with xargs -0)", 0 },
     { 0, 0, 0, 0, 0, 0 }
   };
 
@@ -212,6 +216,9 @@ parse_opt_output(int key, char* arg, struct argp_state*)
   // This switch is alphabetically-ordered.
   switch (key)
     {
+    case '0':
+      output_terminator = 0;
+      break;
     case '8':
       output_format = utf8_output;
       break;
@@ -304,7 +311,7 @@ output_formula_checked(const spot::ltl::formula* f,
       out = &p.first->second->ostream();
     }
   output_formula(*out, f, filename, linenum, prefix, suffix);
-  *out << '\n';
+  *out << output_terminator;
   // Make sure we abort if we can't write to std::cout anymore
   // (like disk full or broken pipe with SIGPIPE ignored).
   check_cout();

src/tests/ltlfilt.test

@@ -25,10 +25,12 @@
 
 set -e
 
+ltlfilt=../../bin/ltlfilt
+
 checkopt()
 {
   cat >exp
-  run 0 ../../bin/ltlfilt "$@" formulas > out
+  run 0 $ltlfilt "$@" formulas > out
   diff exp out
 }
 
@@ -168,7 +170,7 @@ p0 & GFp1 & FGp1
 p0 | Gp1 | FG(p2 | Xp3)
 EOF
 
-run 0 ../../bin/ltlfilt -u --nnf --relabel-bool=pnn in >out
+run 0 $ltlfilt -u --nnf --relabel-bool=pnn in >out
 diff exp out
 
 cat >exp <<EOF
@@ -189,7 +191,7 @@ p0 && []<>p1 && <>[]p1
 p0 || []p1 || <>[](p2 || Xp3)
 EOF
 
-run 0 ../../bin/ltlfilt -s -u --nnf --relabel-bool=pnn --define in >out
+run 0 $ltlfilt -s -u --nnf --relabel-bool=pnn --define in >out
 diff exp out
 
 cat >exp <<EOF
@@ -219,28 +221,40 @@ cat >exp <<EOF
 #define p4 ((c=1))
 (p0=1) * (p1=1) * ((p2=1) + (p3=1)) * (X(p4=0))
 EOF
-run 0 ../../bin/ltlfilt -p --wring -u --nnf --relabel=pnn --define in >out
+run 0 $ltlfilt -p --wring -u --nnf --relabel=pnn --define in >out
+diff exp out
+
+run 0 $ltlfilt -0 in > out
+perl -i -pe 's/\0/@\n/g' out
+cat >exp <<EOF
+a & c & Xb@
+a & b & GF(a | c) & FG(a | c)@
+b & GF(a | c) & FG(a | c)@
+h | i | G(d & e) | FG(!c | Xf)@
+b & e & (f | g) & !Xc@
+b & GF(a | c) & !GF!(a | c)@
+EOF
 diff exp out
 
 SPOT_STUTTER_CHECK=0 \
-../../bin/ltlfilt --stutter-invariant -f '!{a:b*:c}' 2> stderr && exit 1
+$ltlfilt --stutter-invariant -f '!{a:b*:c}' 2> stderr && exit 1
 test $? = 2
 grep 'non-LTL' stderr
 
 SPOT_STUTTER_CHECK=555 \
-../../bin/ltlfilt --stutter-invariant -f '!{a:b*:c}' 2> stderr && exit 1
+$ltlfilt --stutter-invariant -f '!{a:b*:c}' 2> stderr && exit 1
 test $? = 2
 grep 'invalid' stderr
 
 SPOT_STUTTER_CHECK=5 \
-../../bin/ltlfilt --stutter-invariant -f '!{a:b*:c}'
+$ltlfilt --stutter-invariant -f '!{a:b*:c}'
 
 # This one was incorrectly diagnosed as stutter invariant because of a
 # bug in the bitvectors.
-../../bin/ltlfilt --stutter-invariant -f 'F(a & XXXXXX!a)' && exit 1
+$ltlfilt --stutter-invariant -f 'F(a & XXXXXX!a)' && exit 1
 
 
-../../bin/ltlfilt -c -o 'foo' -f a 2>stderr && exit 1
+$ltlfilt -c -o 'foo' -f a 2>stderr && exit 1
 grep 'ltlfilt: options --output and --count are incompatible' stderr
 
 true