Use s.clear() instead of s=""

tautschnig · tautschnig · commit 7e5b60fb6909 · 2019-04-30T22:34:56.000Z
This avoids string table lookups.
diff --git a/src/ansi-c/expr2c.cpp b/src/ansi-c/expr2c.cpp
@@ -287,13 +287,13 @@ std::string expr2ct::convert_rec(
     if(width==config.ansi_c.int_width)
     {
       if(is_signed)
-        sign_str="";
+        sign_str.clear();
       return q+sign_str+"int"+d;
     }
     else if(width==config.ansi_c.long_int_width)
     {
       if(is_signed)
-        sign_str="";
+        sign_str.clear();
       return q+sign_str+"long int"+d;
     }
     else if(width==config.ansi_c.char_width)
@@ -304,19 +304,19 @@ std::string expr2ct::convert_rec(
     else if(width==config.ansi_c.short_int_width)
     {
       if(is_signed)
-        sign_str="";
+        sign_str.clear();
       return q+sign_str+"short int"+d;
     }
     else if(width==config.ansi_c.long_long_int_width)
     {
       if(is_signed)
-        sign_str="";
+        sign_str.clear();
       return q+sign_str+"long long int"+d;
     }
     else if(width==128)
     {
       if(is_signed)
-        sign_str="";
+        sign_str.clear();
       return q + sign_str + "__int128" + d;
     }
     else
diff --git a/src/cpp/cpp_name.cpp b/src/cpp/cpp_name.cpp
@@ -66,7 +66,7 @@ void cpp_namet::convert(
     identifier+=name_component;
 
     if(id=="::")
-      base_name="";
+      base_name.clear();
     else
       base_name+=name_component;
   }
diff --git a/src/cpp/cpp_token.h b/src/cpp/cpp_token.h
@@ -29,9 +29,9 @@ class cpp_tokent
   {
     kind=0;
     data.clear();
-    text="";
+    text.clear();
     line_no=0;
-    filename="";
+    filename.clear();
   }
 
   void swap(cpp_tokent &token)
diff --git a/src/cpp/cpp_typecheck_resolve.cpp b/src/cpp/cpp_typecheck_resolve.cpp
@@ -1270,7 +1270,7 @@ void cpp_typecheck_resolvet::show_identifiers(
       else if(id_expr.id() == ID_pod_constructor)
       {
         out << "constructor ";
-        id="";
+        id.clear();
       }
       else if(id_expr.id()==ID_template_function_instance)
       {
diff --git a/src/goto-cc/armcc_mode.cpp b/src/goto-cc/armcc_mode.cpp
@@ -129,7 +129,7 @@ int armcc_modet::doit()
   }
   else
   {
-    compiler.output_file_object="";
+    compiler.output_file_object.clear();
     compiler.output_file_executable="a.out";
   }
 
diff --git a/src/goto-cc/cw_mode.cpp b/src/goto-cc/cw_mode.cpp
@@ -94,7 +94,7 @@ int cw_modet::doit()
   }
   else
   {
-    compiler.output_file_object="";
+    compiler.output_file_object.clear();
     compiler.output_file_executable="a.out";
   }
 
diff --git a/src/goto-cc/gcc_mode.cpp b/src/goto-cc/gcc_mode.cpp
@@ -659,7 +659,7 @@ int gcc_modet::doit()
   }
   else
   {
-    compiler.output_file_object="";
+    compiler.output_file_object.clear();
     compiler.output_file_executable="a.out";
   }
 
@@ -721,14 +721,14 @@ int gcc_modet::doit()
         {
           language=arg_it->arg;
           if(language=="none")
-            language="";
+            language.clear();
         }
       }
       else if(has_prefix(arg_it->arg, "-x"))
       {
         language=std::string(arg_it->arg, 2, std::string::npos);
         if(language=="none")
-          language="";
+          language.clear();
       }
     }
   }
diff --git a/src/goto-cc/ld_mode.cpp b/src/goto-cc/ld_mode.cpp
@@ -123,7 +123,7 @@ int ld_modet::doit()
   }
   else
   {
-    compiler.output_file_object = "";
+    compiler.output_file_object.clear();
     compiler.output_file_executable = "a.out";
   }
 
diff --git a/src/goto-cc/ms_cl_cmdline.cpp b/src/goto-cc/ms_cl_cmdline.cpp
@@ -438,7 +438,7 @@ void ms_cl_cmdlinet::process_cl_option(const std::string &s)
       if(s.size()==2)
       {
         option.islong=false;
-        option.optstring="";
+        option.optstring.clear();
         option.optchar=s[1];
         optnr=getoptnr(option.optchar);
       }
@@ -474,7 +474,7 @@ void ms_cl_cmdlinet::process_cl_option(const std::string &s)
       if(ms_cl_prefix.size()==1)
       {
         option.islong=false;
-        option.optstring="";
+        option.optstring.clear();
         option.optchar=ms_cl_prefix[0];
         optnr=getoptnr(option.optchar);
       }
diff --git a/src/goto-instrument/dump_c.cpp b/src/goto-instrument/dump_c.cpp
@@ -454,7 +454,7 @@ void dump_ct::convert_compound(
     if(comp_type.id()==ID_c_bit_field &&
        to_c_bit_field_type(comp_type).get_width()==0)
     {
-      comp_name="";
+      comp_name.clear();
       s=type_to_string(comp_type);
     }
 
@@ -504,7 +504,7 @@ void dump_ct::convert_compound(
       typedef_map.insert({typedef_str, typedef_infot(typedef_str)});
     PRECONDITION(!td_map_entry.second);
     if(!td_map_entry.first->second.early)
-      td_map_entry.first->second.type_decl_str="";
+      td_map_entry.first->second.type_decl_str.clear();
     os << "typedef ";
   }
 
diff --git a/src/pointer-analysis/value_set.cpp b/src/pointer-analysis/value_set.cpp
@@ -139,12 +139,12 @@ void value_sett::output(const namespacet &ns, std::ostream &out) const
     if(has_prefix(id2string(e.identifier), "value_set::dynamic_object"))
     {
       display_name = id2string(e.identifier) + e.suffix;
-      identifier = "";
+      identifier.clear();
     }
     else if(e.identifier == "value_set::return_value")
     {
       display_name = "RETURN_VALUE" + e.suffix;
-      identifier = "";
+      identifier.clear();
     }
     else
     {
diff --git a/src/pointer-analysis/value_set_fi.cpp b/src/pointer-analysis/value_set_fi.cpp
@@ -57,7 +57,7 @@ void value_set_fit::output(
     if(has_prefix(id2string(e.identifier), "value_set::dynamic_object"))
     {
       display_name=id2string(e.identifier)+e.suffix;
-      identifier="";
+      identifier.clear();
     }
     else
     {
diff --git a/src/util/cmdline.cpp b/src/util/cmdline.cpp
@@ -169,7 +169,7 @@ bool cmdlinet::parse(int argc, const char **argv, const char *optstring)
       option.islong=true;
       option.optchar=0;
       option.isset=false;
-      option.optstring="";
+      option.optstring.clear();
 
       for(optstring++; optstring[0]!=')' && optstring[0]!=0; optstring++)
         option.optstring+=optstring[0];
@@ -181,7 +181,7 @@ bool cmdlinet::parse(int argc, const char **argv, const char *optstring)
     {
       option.islong=false;
       option.optchar=optstring[0];
-      option.optstring="";
+      option.optstring.clear();
       option.isset=false;
 
       optstring++;
diff --git a/src/util/identifier.cpp b/src/util/identifier.cpp
@@ -43,6 +43,6 @@ void identifiert::parse(const std::string &s)
     }
 
     components.push_back(component);
-    component="";
+    component.clear();
   }
 }
diff --git a/src/util/lispexpr.cpp b/src/util/lispexpr.cpp
@@ -62,7 +62,7 @@ bool lispexprt::parse(
   std::string::size_type &ptr)
 {
   clear();
-  value="";
+  value.clear();
 
   if(ptr==std::string::npos || ptr>=s.size())
     return true;
@@ -156,7 +156,7 @@ int test_lispexpr()
 
   while(true)
   {
-    line="";
+    line.clear();
 
     while(true)
     {
diff --git a/src/util/lispirep.cpp b/src/util/lispirep.cpp
@@ -43,7 +43,7 @@ void lisp2irep(const lispexprt &src, irept &dest)
 void irep2lisp(const irept &src, lispexprt &dest)
 {
   dest.clear();
-  dest.value="";
+  dest.value.clear();
   dest.type=lispexprt::List;
 
 #ifdef NAMED_SUB_IS_FORWARD_LIST
@@ -65,7 +65,7 @@ void irep2lisp(const irept &src, lispexprt &dest)
   {
     lispexprt name;
     name.type=lispexprt::String;
-    name.value="";
+    name.value.clear();
     dest.push_back(name);
 
     lispexprt sub;

Original file line number	Diff line number	Diff line change
`@@ -287,13 +287,13 @@ std::string expr2ct::convert_rec(`
`287`	`287`	`if(width==config.ansi_c.int_width)`
`288`	`288`	`{`
`289`	`289`	`if(is_signed)`
`290`		`- sign_str="";`
	`290`	`+ sign_str.clear();`
`291`	`291`	`return q+sign_str+"int"+d;`
`292`	`292`	`}`
`293`	`293`	`else if(width==config.ansi_c.long_int_width)`
`294`	`294`	`{`
`295`	`295`	`if(is_signed)`
`296`		`- sign_str="";`
	`296`	`+ sign_str.clear();`
`297`	`297`	`return q+sign_str+"long int"+d;`
`298`	`298`	`}`
`299`	`299`	`else if(width==config.ansi_c.char_width)`
`@@ -304,19 +304,19 @@ std::string expr2ct::convert_rec(`
`304`	`304`	`else if(width==config.ansi_c.short_int_width)`
`305`	`305`	`{`
`306`	`306`	`if(is_signed)`
`307`		`- sign_str="";`
	`307`	`+ sign_str.clear();`
`308`	`308`	`return q+sign_str+"short int"+d;`
`309`	`309`	`}`
`310`	`310`	`else if(width==config.ansi_c.long_long_int_width)`
`311`	`311`	`{`
`312`	`312`	`if(is_signed)`
`313`		`- sign_str="";`
	`313`	`+ sign_str.clear();`
`314`	`314`	`return q+sign_str+"long long int"+d;`
`315`	`315`	`}`
`316`	`316`	`else if(width==128)`
`317`	`317`	`{`
`318`	`318`	`if(is_signed)`
`319`		`- sign_str="";`
	`319`	`+ sign_str.clear();`
`320`	`320`	`return q + sign_str + "__int128" + d;`
`321`	`321`	`}`
`322`	`322`	`else`
Original file line number	Diff line number	Diff line change
`@@ -66,7 +66,7 @@ void cpp_namet::convert(`
`66`	`66`	`identifier+=name_component;`
`67`	`67`
`68`	`68`	`if(id=="::")`
`69`		`- base_name="";`
	`69`	`+ base_name.clear();`
`70`	`70`	`else`
`71`	`71`	`base_name+=name_component;`
`72`	`72`	`}`
Original file line number	Diff line number	Diff line change
`@@ -29,9 +29,9 @@ class cpp_tokent`
`29`	`29`	`{`
`30`	`30`	`kind=0;`
`31`	`31`	`data.clear();`
`32`		`- text="";`
	`32`	`+ text.clear();`
`33`	`33`	`line_no=0;`
`34`		`- filename="";`
	`34`	`+ filename.clear();`
`35`	`35`	`}`
`36`	`36`
`37`	`37`	`void swap(cpp_tokent &token)`
Original file line number	Diff line number	Diff line change
`@@ -1270,7 +1270,7 @@ void cpp_typecheck_resolvet::show_identifiers(`
`1270`	`1270`	`else if(id_expr.id() == ID_pod_constructor)`
`1271`	`1271`	`{`
`1272`	`1272`	`out << "constructor ";`
`1273`		`- id="";`
	`1273`	`+ id.clear();`
`1274`	`1274`	`}`
`1275`	`1275`	`else if(id_expr.id()==ID_template_function_instance)`
`1276`	`1276`	`{`
Original file line number	Diff line number	Diff line change
`@@ -129,7 +129,7 @@ int armcc_modet::doit()`
`129`	`129`	`}`
`130`	`130`	`else`
`131`	`131`	`{`
`132`		`- compiler.output_file_object="";`
	`132`	`+ compiler.output_file_object.clear();`
`133`	`133`	`compiler.output_file_executable="a.out";`
`134`	`134`	`}`
`135`	`135`
Original file line number	Diff line number	Diff line change
`@@ -94,7 +94,7 @@ int cw_modet::doit()`
`94`	`94`	`}`
`95`	`95`	`else`
`96`	`96`	`{`
`97`		`- compiler.output_file_object="";`
	`97`	`+ compiler.output_file_object.clear();`
`98`	`98`	`compiler.output_file_executable="a.out";`
`99`	`99`	`}`
`100`	`100`
Original file line number	Diff line number	Diff line change
`@@ -659,7 +659,7 @@ int gcc_modet::doit()`
`659`	`659`	`}`
`660`	`660`	`else`
`661`	`661`	`{`
`662`		`- compiler.output_file_object="";`
	`662`	`+ compiler.output_file_object.clear();`
`663`	`663`	`compiler.output_file_executable="a.out";`
`664`	`664`	`}`
`665`	`665`
`@@ -721,14 +721,14 @@ int gcc_modet::doit()`
`721`	`721`	`{`
`722`	`722`	`language=arg_it->arg;`
`723`	`723`	`if(language=="none")`
`724`		`- language="";`
	`724`	`+ language.clear();`
`725`	`725`	`}`
`726`	`726`	`}`
`727`	`727`	`else if(has_prefix(arg_it->arg, "-x"))`
`728`	`728`	`{`
`729`	`729`	`language=std::string(arg_it->arg, 2, std::string::npos);`
`730`	`730`	`if(language=="none")`
`731`		`- language="";`
	`731`	`+ language.clear();`
`732`	`732`	`}`
`733`	`733`	`}`
`734`	`734`	`}`
Original file line number	Diff line number	Diff line change
`@@ -123,7 +123,7 @@ int ld_modet::doit()`
`123`	`123`	`}`
`124`	`124`	`else`
`125`	`125`	`{`
`126`		`- compiler.output_file_object = "";`
	`126`	`+ compiler.output_file_object.clear();`
`127`	`127`	`compiler.output_file_executable = "a.out";`
`128`	`128`	`}`
`129`	`129`
Original file line number	Diff line number	Diff line change
`@@ -438,7 +438,7 @@ void ms_cl_cmdlinet::process_cl_option(const std::string &s)`
`438`	`438`	`if(s.size()==2)`
`439`	`439`	`{`
`440`	`440`	`option.islong=false;`
`441`		`- option.optstring="";`
	`441`	`+ option.optstring.clear();`
`442`	`442`	`option.optchar=s[1];`
`443`	`443`	`optnr=getoptnr(option.optchar);`
`444`	`444`	`}`
`@@ -474,7 +474,7 @@ void ms_cl_cmdlinet::process_cl_option(const std::string &s)`
`474`	`474`	`if(ms_cl_prefix.size()==1)`
`475`	`475`	`{`
`476`	`476`	`option.islong=false;`
`477`		`- option.optstring="";`
	`477`	`+ option.optstring.clear();`
`478`	`478`	`option.optchar=ms_cl_prefix[0];`
`479`	`479`	`optnr=getoptnr(option.optchar);`
`480`	`480`	`}`
Original file line number	Diff line number	Diff line change
`@@ -454,7 +454,7 @@ void dump_ct::convert_compound(`
`454`	`454`	`if(comp_type.id()==ID_c_bit_field &&`
`455`	`455`	`to_c_bit_field_type(comp_type).get_width()==0)`
`456`	`456`	`{`
`457`		`- comp_name="";`
	`457`	`+ comp_name.clear();`
`458`	`458`	`s=type_to_string(comp_type);`
`459`	`459`	`}`
`460`	`460`
`@@ -504,7 +504,7 @@ void dump_ct::convert_compound(`
`504`	`504`	`typedef_map.insert({typedef_str, typedef_infot(typedef_str)});`
`505`	`505`	`PRECONDITION(!td_map_entry.second);`
`506`	`506`	`if(!td_map_entry.first->second.early)`
`507`		`- td_map_entry.first->second.type_decl_str="";`
	`507`	`+ td_map_entry.first->second.type_decl_str.clear();`
`508`	`508`	`os << "typedef ";`
`509`	`509`	`}`
`510`	`510`