extend minify: minify subshells to backticks

include/struc.hpp

@@ -599,10 +599,11 @@ public:
 class subshell_subarg : public subarg
 {
 public:
-  subshell_subarg(subshell* in=nullptr, bool inq=false) { type=_obj::subarg_subshell; sbsh=in; quoted=inq; }
+  subshell_subarg(subshell* in=nullptr, bool inq=false, bool is_backtick=false) { type=_obj::subarg_subshell; sbsh=in; quoted=inq; backtick=is_backtick; }
   ~subshell_subarg() { if(sbsh != nullptr) delete sbsh; }
 
   subshell* sbsh;
+  bool backtick;
 
   std::string generate(int ind);
 };

src/generate.cpp

@@ -398,7 +398,14 @@ std::string cmd::generate(int ind, generate_context* ctx)
 
 std::string subshell_subarg::generate(int ind)
 {
-  return '$' + sbsh->generate(ind);
+  std::string r = sbsh->generate(ind);
+  if(backtick) {
+    r[0] = '`';
+    r[r.size()-1] = '`';
+    return r;
+  }
+  else
+    return '$' + r;
 }
 
 std::string procsub_subarg::generate(int ind)

src/minify.cpp

@@ -523,6 +523,44 @@ bool r_minify_single_block(_obj* in)
   return true;
 }
 
+bool r_has_backtick(_obj* in, bool* r)
+{
+  if(*r)
+    return false;
+  switch(in->type)
+  {
+    case _obj::subarg_subshell: {
+      subshell_subarg* t = dynamic_cast<subshell_subarg*>(in);
+      if(t->backtick) {
+        *r = true;
+        return false;
+      }
+    }; break;
+    default: break;
+  }
+  return true;
+}
+
+bool r_minify_backtick(_obj* in)
+{
+  switch(in->type)
+  {
+    case _obj::subarg_subshell: {
+      subshell_subarg* t = dynamic_cast<subshell_subarg*>(in);
+      if(!t->backtick) {
+        bool has_backtick_child=false;
+        recurse(r_has_backtick, t->sbsh, &has_backtick_child);
+        if(has_backtick_child)
+          return false;
+        t->backtick = true;
+      }
+      return false;
+    }; break;
+    default: break;
+  }
+  return true;
+}
+
 bool r_minify(_obj* in)
 {
   r_minify_empty_manip(in);
@@ -535,4 +573,5 @@ bool r_minify(_obj* in)
 void minify_generic(_obj* in)
 {
   recurse(r_minify, in);
+  recurse(r_minify_backtick, in);
 }

src/parse.cpp

@@ -444,7 +444,7 @@ inline parse_context do_one_subarg_step(arg* ret, parse_context ctx, uint32_t& j
     parse_context newct = ctx;
     newct.size=k;
     auto r=parse_list_until(newct);
-    ret->add(new subshell_subarg(new subshell(std::get<0>(r)), is_quoted));
+    ret->add(new subshell_subarg(new subshell(std::get<0>(r)), is_quoted, true));
     uint64_t tsize=ctx.size;
     ctx = std::get<1>(r);
     ctx.size = tsize;