diff --git a/include/ulib/internal/common.h b/include/ulib/internal/common.h
index 870ad122..72e39853 100644
--- a/include/ulib/internal/common.h
+++ b/include/ulib/internal/common.h
@@ -127,7 +127,7 @@ enum StringAllocationType {
 };
 
 enum StringAllocationIndex {
-   STR_ALLOCATE_INDEX_SOAP         = 14,
+   STR_ALLOCATE_INDEX_SOAP         = 18,
    STR_ALLOCATE_INDEX_IMAP         = STR_ALLOCATE_INDEX_SOAP+14,
    STR_ALLOCATE_INDEX_SSI          = STR_ALLOCATE_INDEX_IMAP+4,
    STR_ALLOCATE_INDEX_NOCAT        = STR_ALLOCATE_INDEX_SSI+2,
diff --git a/include/ulib/internal/platform.h b/include/ulib/internal/platform.h
index 855a3de1..5ee66d8c 100644
--- a/include/ulib/internal/platform.h
+++ b/include/ulib/internal/platform.h
@@ -267,6 +267,8 @@
 #else
 #  define PATH_SEPARATOR '/'
 #  ifdef __clang__
+#     define U_COMPILER_RVALUE_REFS
+#     define U_COMPILER_DELETE_MEMBERS
 #     define IS_DIR_SEPARATOR(c)  (c) == '/' /* to avoid warning: equality comparison with extraneous parentheses... */
 #  else
 #     define IS_DIR_SEPARATOR(c) ((c) == '/')
diff --git a/include/ulib/string.h b/include/ulib/string.h
index 2ebe2a0a..e18de7f8 100644
--- a/include/ulib/string.h
+++ b/include/ulib/string.h
@@ -935,6 +935,10 @@ public:
    static const UString* str_true;
    static const UString* str_false;
    static const UString* str_response;
+   static const UString* str_zero;
+   static const UString* str_nostat;
+   static const UString* str_tsa;
+   static const UString* str_soap;
    // SOAP
    static const UString* str_ns;
    static const UString* str_boolean;
@@ -1003,7 +1007,7 @@ public:
    static const UString* str_sqlite_name;
    static const UString* str_dbdir;
 #ifdef U_HTTP2_DISABLE
-   static ustringrep stringrep_storage[66];
+   static ustringrep stringrep_storage[70];
 #else
    static const UString* str_authority;
    static const UString* str_method;
@@ -1071,7 +1075,7 @@ public:
    static const UString* str_via;
    static const UString* str_www_authenticate;
 
-   static ustringrep stringrep_storage[132];
+   static ustringrep stringrep_storage[136];
 #endif
 
    static void str_allocate(int which);
@@ -1400,7 +1404,7 @@ public:
    void swap(UString& lhs, UString& rhs) { lhs.swap(rhs); }
 
 #ifdef U_COMPILER_RVALUE_REFS
-# if !defined(__GNUC__) // || GCC_VERSION_NUM >= 60000 // hope
+# if !defined(__GNUC__) || (defined(DEBUG) && GCC_VERSION_NUM < 50300) // || GCC_VERSION_NUM >= 60000 // hope
    UString(UString && str)
       {
       U_TRACE_NO_PARAM(0, "UString::UString(move)")
diff --git a/src/ulib/lemon/expression.cpp b/src/ulib/lemon/expression.cpp
index 7786efc0..6da7473c 100644
--- a/src/ulib/lemon/expression.cpp
+++ b/src/ulib/lemon/expression.cpp
@@ -23,7 +23,6 @@
 ** input grammar file:
 */
 #include <stdio.h>
-#include <assert.h>
 /************ Begin %include sections from the grammar ************************/
 #line 1 "expression.y"
 
@@ -31,6 +30,8 @@
 #include <ulib/dynamic/dynamic.h>
 #include <ulib/utility/string_ext.h>
 
+#include <assert.h>
+
 typedef long (*lPFv)(void);
 typedef long (*lPFll)(long, long);
 
@@ -48,7 +49,7 @@ void token_destructor(UString* token) {
    delete token;
 }
 
-#line 51 "expression.c"
+#line 53 "expression.c"
 /**************** End of %include directives **********************************/
 /* These constants specify the various numeric values for terminal symbols
 ** in a format understandable to "makeheaders".  This section is blank unless
@@ -521,19 +522,19 @@ static void yy_destructor(
     case 22: /* VALUE */
     case 23: /* COMMA */
 {
-#line 30 "expression.y"
+#line 32 "expression.y"
  token_destructor((yypminor->yy0)); 
-#line 526 "expression.c"
+#line 528 "expression.c"
 }
       break;
     case 25: /* params */
 {
-#line 32 "expression.y"
+#line 34 "expression.y"
 
    U_TRACE(0, "::params_destructor(%p)", (yypminor->yy49))
    delete (yypminor->yy49);
 
-#line 536 "expression.c"
+#line 538 "expression.c"
 }
       break;
 /********* End destructor definitions *****************************************/
@@ -706,11 +707,11 @@ static void yyStackOverflow(yyParser *yypParser, YYMINORTYPE *yypMinor){
    /* Here code is inserted which will execute if the parser
    ** stack every overflows */
 /******** Begin %stack_overflow code ******************************************/
-#line 54 "expression.y"
+#line 56 "expression.y"
 
    U_TRACE_NO_PARAM(0, "::stack_overflow()")
    U_WARNING("Parse stack overflow");
-#line 713 "expression.c"
+#line 715 "expression.c"
 /******** End %stack_overflow code ********************************************/
    expressionParserARG_STORE; /* Suppress warning about unused %extra_argument var */
 }
@@ -857,7 +858,7 @@ static void yy_reduce(
   */
 /********** Begin reduce actions **********************************************/
       case 0: /* input ::= booleanExpression */
-#line 77 "expression.y"
+#line 79 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "input ::= booleanExpression(yymsp[0].minor.yy3)")
 
@@ -870,10 +871,10 @@ static void yy_reduce(
 
    delete yymsp[0].minor.yy3;
 }
-#line 873 "expression.c"
+#line 875 "expression.c"
         break;
       case 1: /* booleanExpression ::= booleanExpression booleanCond equalityExpression */
-#line 90 "expression.y"
+#line 92 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "booleanExpression(yygotominor.yy3) ::= booleanExpression(yymsp[-2].minor.yy3) booleanCond(yymsp[-1].minor.yy12) equalityExpression(yymsp[0].minor.yy3)")
 
@@ -894,10 +895,10 @@ static void yy_reduce(
 
    U_INTERNAL_DUMP("yygotominor.yy3 = %V", yygotominor.yy3->rep)
 }
-#line 897 "expression.c"
+#line 899 "expression.c"
         break;
       case 2: /* booleanExpression ::= equalityExpression */
-#line 111 "expression.y"
+#line 113 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "booleanExpression(yygotominor.yy3) ::= equalityExpression(yymsp[0].minor.yy3)")
 
@@ -909,10 +910,10 @@ static void yy_reduce(
 
    U_INTERNAL_DUMP("yygotominor.yy3 = %V", yygotominor.yy3->rep)
 }
-#line 912 "expression.c"
+#line 914 "expression.c"
         break;
       case 3: /* equalityExpression ::= equalityExpression equalityCond relationalExpression */
-#line 123 "expression.y"
+#line 125 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "equalityExpression(yygotominor.yy3) ::= equalityExpression(yymsp[-2].minor.yy3) equalityCond(yymsp[-1].minor.yy12) relationalExpression(yymsp[0].minor.yy3)")
 
@@ -947,10 +948,10 @@ static void yy_reduce(
 
    U_INTERNAL_DUMP("yygotominor.yy3 = %V", yygotominor.yy3->rep)
 }
-#line 950 "expression.c"
+#line 952 "expression.c"
         break;
       case 4: /* equalityExpression ::= relationalExpression */
-#line 158 "expression.y"
+#line 160 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "equalityExpression(yygotominor.yy3) ::= relationalExpression(yymsp[0].minor.yy3)")
 
@@ -962,10 +963,10 @@ static void yy_reduce(
 
    U_INTERNAL_DUMP("yygotominor.yy3 = %V", yygotominor.yy3->rep)
 }
-#line 965 "expression.c"
+#line 967 "expression.c"
         break;
       case 5: /* relationalExpression ::= relationalExpression relationalCond additiveExpression */
-#line 170 "expression.y"
+#line 172 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "relationalExpression(yygotominor.yy3) ::= relationalExpression(yymsp[-2].minor.yy3) relationalCond(yymsp[-1].minor.yy12) additiveExpression(yymsp[0].minor.yy3)")
 
@@ -997,10 +998,10 @@ static void yy_reduce(
 
    U_INTERNAL_DUMP("yygotominor.yy3 = %V", yygotominor.yy3->rep)
 }
-#line 1000 "expression.c"
+#line 1002 "expression.c"
         break;
       case 6: /* relationalExpression ::= additiveExpression */
-#line 202 "expression.y"
+#line 204 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "relationalExpression(yygotominor.yy3) ::= additiveExpression(yymsp[0].minor.yy3)")
 
@@ -1012,10 +1013,10 @@ static void yy_reduce(
 
    U_INTERNAL_DUMP("yygotominor.yy3 = %V", yygotominor.yy3->rep)
 }
-#line 1015 "expression.c"
+#line 1017 "expression.c"
         break;
       case 7: /* additiveExpression ::= additiveExpression additiveCond multiplicativeExpression */
-#line 214 "expression.y"
+#line 216 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "additiveExpression(yygotominor.yy3) ::= additiveExpression(yymsp[-2].minor.yy3) additiveCond(yymsp[-1].minor.yy12) multiplicativeExpression(yymsp[0].minor.yy3)")
 
@@ -1036,10 +1037,10 @@ static void yy_reduce(
 
    U_INTERNAL_DUMP("yygotominor.yy3 = %V", yygotominor.yy3->rep)
 }
-#line 1039 "expression.c"
+#line 1041 "expression.c"
         break;
       case 8: /* additiveExpression ::= multiplicativeExpression */
-#line 235 "expression.y"
+#line 237 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "additiveExpression(yygotominor.yy3) ::= multiplicativeExpression(yymsp[0].minor.yy3)")
 
@@ -1051,10 +1052,10 @@ static void yy_reduce(
 
    U_INTERNAL_DUMP("yygotominor.yy3 = %V", yygotominor.yy3->rep)
 }
-#line 1054 "expression.c"
+#line 1056 "expression.c"
         break;
       case 9: /* multiplicativeExpression ::= multiplicativeExpression multiplicativeCond unaryExpression */
-#line 247 "expression.y"
+#line 249 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "multiplicativeExpression(yygotominor.yy3) ::= multiplicativeExpression(yymsp[-2].minor.yy3) multiplicativeCond(yymsp[-1].minor.yy12) unaryExpression(yymsp[0].minor.yy3)")
 
@@ -1067,7 +1068,7 @@ static void yy_reduce(
         Blo = yymsp[-2].minor.yy3->strtol(),
         Dlo = yymsp[0].minor.yy3->strtol();
 
-   if (Dlo == 0) yygotominor.yy3 = U_NEW(UString(U_STRING_FROM_CONSTANT("0")));
+   if (Dlo == 0) yygotominor.yy3 = U_NEW(UString(*UString::str_zero));
    else
       {
       lo = (yymsp[-1].minor.yy12 == U_TK_MULT ? Blo * Dlo :
@@ -1082,10 +1083,10 @@ static void yy_reduce(
 
    U_INTERNAL_DUMP("yygotominor.yy3 = %V", yygotominor.yy3->rep)
 }
-#line 1085 "expression.c"
+#line 1087 "expression.c"
         break;
       case 10: /* multiplicativeExpression ::= unaryExpression */
-#line 275 "expression.y"
+#line 277 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "multiplicativeExpression(yygotominor.yy3) ::= unaryExpression(yymsp[0].minor.yy3)")
 
@@ -1097,10 +1098,10 @@ static void yy_reduce(
 
    U_INTERNAL_DUMP("yygotominor.yy3 = %V", yygotominor.yy3->rep)
 }
-#line 1100 "expression.c"
+#line 1102 "expression.c"
         break;
       case 11: /* unaryExpression ::= NOT primaryExpression */
-#line 287 "expression.y"
+#line 289 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "unaryExpression(yygotominor.yy3) ::= NOT primaryExpression(yymsp[0].minor.yy3)")
 
@@ -1115,10 +1116,10 @@ static void yy_reduce(
    U_INTERNAL_DUMP("yygotominor.yy3 = %V", yygotominor.yy3->rep)
   yy_destructor(yypParser,18,&yymsp[-1].minor);
 }
-#line 1118 "expression.c"
+#line 1120 "expression.c"
         break;
       case 12: /* unaryExpression ::= primaryExpression */
-#line 301 "expression.y"
+#line 303 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "unaryExpression(yygotominor.yy3) ::= primaryExpression(yymsp[0].minor.yy3)")
 
@@ -1130,10 +1131,10 @@ static void yy_reduce(
 
    U_INTERNAL_DUMP("yygotominor.yy3 = %V", yygotominor.yy3->rep)
 }
-#line 1133 "expression.c"
+#line 1135 "expression.c"
         break;
       case 13: /* primaryExpression ::= LPAREN booleanExpression RPAREN */
-#line 313 "expression.y"
+#line 315 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "primaryExpression(yygotominor.yy3) ::= LPAREN booleanExpression(yymsp[-1].minor.yy3) RPAREN")
 
@@ -1147,10 +1148,10 @@ static void yy_reduce(
   yy_destructor(yypParser,20,&yymsp[-2].minor);
   yy_destructor(yypParser,21,&yymsp[0].minor);
 }
-#line 1150 "expression.c"
+#line 1152 "expression.c"
         break;
       case 14: /* primaryExpression ::= value */
-#line 325 "expression.y"
+#line 327 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "primaryExpression(yygotominor.yy3) ::= value(yymsp[0].minor.yy3)")
 
@@ -1162,10 +1163,10 @@ static void yy_reduce(
 
    U_INTERNAL_DUMP("yygotominor.yy3 = %V", yygotominor.yy3->rep)
 }
-#line 1165 "expression.c"
+#line 1167 "expression.c"
         break;
       case 15: /* value ::= VALUE */
-#line 337 "expression.y"
+#line 339 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "value(yygotominor.yy3) ::= VALUE(yymsp[0].minor.yy0)")
 
@@ -1177,10 +1178,10 @@ static void yy_reduce(
 
    U_INTERNAL_DUMP("yygotominor.yy3 = %V", yygotominor.yy3->rep)
 }
-#line 1180 "expression.c"
+#line 1182 "expression.c"
         break;
       case 16: /* value ::= value VALUE */
-#line 349 "expression.y"
+#line 351 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "value(yygotominor.yy3) ::= value(yymsp[-1].minor.yy3) VALUE(yymsp[0].minor.yy0)")
 
@@ -1196,163 +1197,163 @@ static void yy_reduce(
 
    U_INTERNAL_DUMP("yygotominor.yy3 = %V", yygotominor.yy3->rep)
 }
-#line 1199 "expression.c"
+#line 1201 "expression.c"
         break;
       case 17: /* booleanCond ::= OR */
-#line 365 "expression.y"
+#line 367 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "booleanCond(yygotominor.yy12) ::= OR")
    yygotominor.yy12 = U_TK_OR;
   yy_destructor(yypParser,2,&yymsp[0].minor);
 }
-#line 1208 "expression.c"
+#line 1210 "expression.c"
         break;
       case 18: /* booleanCond ::= AND */
-#line 369 "expression.y"
+#line 371 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "booleanCond(yygotominor.yy12) ::= AND")
    yygotominor.yy12 = U_TK_AND;
   yy_destructor(yypParser,1,&yymsp[0].minor);
 }
-#line 1217 "expression.c"
+#line 1219 "expression.c"
         break;
       case 19: /* equalityCond ::= EQ */
-#line 373 "expression.y"
+#line 375 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "equalityCond(yygotominor.yy12) ::= EQ")
    yygotominor.yy12 = U_TK_EQ;
   yy_destructor(yypParser,3,&yymsp[0].minor);
 }
-#line 1226 "expression.c"
+#line 1228 "expression.c"
         break;
       case 20: /* equalityCond ::= NE */
-#line 377 "expression.y"
+#line 379 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "equalityCond(yygotominor.yy12) ::= NE")
    yygotominor.yy12 = U_TK_NE;
   yy_destructor(yypParser,4,&yymsp[0].minor);
 }
-#line 1235 "expression.c"
+#line 1237 "expression.c"
         break;
       case 21: /* equalityCond ::= STARTS_WITH */
-#line 381 "expression.y"
+#line 383 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "equalityCond(yygotominor.yy12) ::= STARTS_WITH")
    yygotominor.yy12 = U_TK_STARTS_WITH;
   yy_destructor(yypParser,9,&yymsp[0].minor);
 }
-#line 1244 "expression.c"
+#line 1246 "expression.c"
         break;
       case 22: /* equalityCond ::= ENDS_WITH */
-#line 385 "expression.y"
+#line 387 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "equalityCond(yygotominor.yy12) ::= ENDS_WITH")
    yygotominor.yy12 = U_TK_ENDS_WITH;
   yy_destructor(yypParser,10,&yymsp[0].minor);
 }
-#line 1253 "expression.c"
+#line 1255 "expression.c"
         break;
       case 23: /* equalityCond ::= IS_PRESENT */
-#line 389 "expression.y"
+#line 391 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "equalityCond(yygotominor.yy12) ::= IS_PRESENT")
    yygotominor.yy12 = U_TK_IS_PRESENT;
   yy_destructor(yypParser,11,&yymsp[0].minor);
 }
-#line 1262 "expression.c"
+#line 1264 "expression.c"
         break;
       case 24: /* equalityCond ::= CONTAINS */
-#line 393 "expression.y"
+#line 395 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "equalityCond(yygotominor.yy12) ::= CONTAINS")
    yygotominor.yy12 = U_TK_CONTAINS;
   yy_destructor(yypParser,12,&yymsp[0].minor);
 }
-#line 1271 "expression.c"
+#line 1273 "expression.c"
         break;
       case 25: /* relationalCond ::= GT */
-#line 397 "expression.y"
+#line 399 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "relationalCond(yygotominor.yy12) ::= GT")
    yygotominor.yy12 = U_TK_GT;
   yy_destructor(yypParser,5,&yymsp[0].minor);
 }
-#line 1280 "expression.c"
+#line 1282 "expression.c"
         break;
       case 26: /* relationalCond ::= GE */
-#line 401 "expression.y"
+#line 403 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "relationalCond(yygotominor.yy12) ::= GE")
    yygotominor.yy12 = U_TK_GE;
   yy_destructor(yypParser,6,&yymsp[0].minor);
 }
-#line 1289 "expression.c"
+#line 1291 "expression.c"
         break;
       case 27: /* relationalCond ::= LT */
-#line 405 "expression.y"
+#line 407 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "relationalCond(yygotominor.yy12) ::= LT")
    yygotominor.yy12 = U_TK_LT;
   yy_destructor(yypParser,7,&yymsp[0].minor);
 }
-#line 1298 "expression.c"
+#line 1300 "expression.c"
         break;
       case 28: /* relationalCond ::= LE */
-#line 409 "expression.y"
+#line 411 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "relationalCond(yygotominor.yy12) ::= LE")
    yygotominor.yy12 = U_TK_LE;
   yy_destructor(yypParser,8,&yymsp[0].minor);
 }
-#line 1307 "expression.c"
+#line 1309 "expression.c"
         break;
       case 29: /* additiveCond ::= PLUS */
-#line 413 "expression.y"
+#line 415 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "additiveCond(yygotominor.yy12) ::= PLUS")
    yygotominor.yy12 = U_TK_PLUS;
   yy_destructor(yypParser,13,&yymsp[0].minor);
 }
-#line 1316 "expression.c"
+#line 1318 "expression.c"
         break;
       case 30: /* additiveCond ::= MINUS */
-#line 417 "expression.y"
+#line 419 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "additiveCond(yygotominor.yy12) ::= MINUS")
    yygotominor.yy12 = U_TK_MINUS;
   yy_destructor(yypParser,14,&yymsp[0].minor);
 }
-#line 1325 "expression.c"
+#line 1327 "expression.c"
         break;
       case 31: /* multiplicativeCond ::= MULT */
-#line 421 "expression.y"
+#line 423 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "multiplicativeCond(yygotominor.yy12) ::= MULT")
    yygotominor.yy12 = U_TK_MULT;
   yy_destructor(yypParser,15,&yymsp[0].minor);
 }
-#line 1334 "expression.c"
+#line 1336 "expression.c"
         break;
       case 32: /* multiplicativeCond ::= DIV */
-#line 425 "expression.y"
+#line 427 "expression.y"
 {
    U_TRACE(0, "multiplicativeCond(yygotominor.yy12) ::= DIV")
    yygotominor.yy12 = U_TK_DIV;
   yy_destructor(yypParser,16,&yymsp[0].minor);
 }
-#line 1343 "expression.c"
+#line 1345 "expression.c"
         break;
       case 33: /* multiplicativeCond ::= MOD */
-#line 429 "expression.y"
+#line 431 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "multiplicativeCond(yygotominor.yy12) ::= MOD")
    yygotominor.yy12 = U_TK_MOD;
   yy_destructor(yypParser,17,&yymsp[0].minor);
 }
-#line 1352 "expression.c"
+#line 1354 "expression.c"
         break;
       case 34: /* primaryExpression ::= FN_CALL LPAREN RPAREN */
-#line 434 "expression.y"
+#line 436 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "primaryExpression(yygotominor.yy3) ::= FN_CALL(yymsp[-2].minor.yy0) LPAREN RPAREN")
 
@@ -1373,10 +1374,10 @@ static void yy_reduce(
   yy_destructor(yypParser,20,&yymsp[-1].minor);
   yy_destructor(yypParser,21,&yymsp[0].minor);
 }
-#line 1376 "expression.c"
+#line 1378 "expression.c"
         break;
       case 35: /* primaryExpression ::= FN_CALL LPAREN params RPAREN */
-#line 453 "expression.y"
+#line 455 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "primaryExpression(yygotominor.yy3) ::= FN_CALL(yymsp[-3].minor.yy0) LPAREN params(yymsp[-1].minor.yy49) RPAREN")
 
@@ -1398,10 +1399,10 @@ static void yy_reduce(
   yy_destructor(yypParser,20,&yymsp[-2].minor);
   yy_destructor(yypParser,21,&yymsp[0].minor);
 }
-#line 1401 "expression.c"
+#line 1403 "expression.c"
         break;
       case 36: /* params ::= VALUE */
-#line 473 "expression.y"
+#line 475 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "params(yygotominor.yy49) ::= VALUE(yymsp[0].minor.yy0)")
 
@@ -1415,10 +1416,10 @@ static void yy_reduce(
 
    delete yymsp[0].minor.yy0;
 }
-#line 1418 "expression.c"
+#line 1420 "expression.c"
         break;
       case 37: /* params ::= params COMMA VALUE */
-#line 487 "expression.y"
+#line 489 "expression.y"
 {
    U_TRACE_NO_PARAM(0, "params(yygotominor.yy49) ::= params(yymsp[-2].minor.yy49) COMMA VALUE(yymsp[0].minor.yy0)")
 
@@ -1434,7 +1435,7 @@ static void yy_reduce(
    delete yymsp[0].minor.yy0;
   yy_destructor(yypParser,23,&yymsp[-1].minor);
 }
-#line 1437 "expression.c"
+#line 1439 "expression.c"
         break;
       default:
         break;
@@ -1484,13 +1485,13 @@ static void yy_parse_failed(
   /* Here code is inserted which will be executed whenever the
   ** parser fails */
 /************ Begin %parse_failure code ***************************************/
-#line 42 "expression.y"
+#line 44 "expression.y"
 
    U_TRACE_NO_PARAM(0, "::parse_failure()")
    U_INTERNAL_ASSERT_POINTER(result)
    result->clear();
    U_WARNING("Parse failure!");
-#line 1493 "expression.c"
+#line 1495 "expression.c"
 /************ End %parse_failure code *****************************************/
   expressionParserARG_STORE; /* Suppress warning about unused %extra_argument variable */
 }
@@ -1507,13 +1508,13 @@ static void yy_syntax_error(
   expressionParserARG_FETCH;
 #define TOKEN (yyminor.yy0)
 /************ Begin %syntax_error code ****************************************/
-#line 48 "expression.y"
+#line 50 "expression.y"
 
    U_TRACE_NO_PARAM(0, "::syntax_error()")
    U_INTERNAL_ASSERT_POINTER(result)
    result->clear();
    U_WARNING("Syntax error!");
-#line 1516 "expression.c"
+#line 1518 "expression.c"
 /************ End %syntax_error code ******************************************/
   expressionParserARG_STORE; /* Suppress warning about unused %extra_argument variable */
 }
@@ -1534,12 +1535,12 @@ static void yy_accept(
   /* Here code is inserted which will be executed whenever the
   ** parser accepts */
 /*********** Begin %parse_accept code *****************************************/
-#line 37 "expression.y"
+#line 39 "expression.y"
 
    U_TRACE_NO_PARAM(0, "::parse_accept()")
    U_INTERNAL_ASSERT_POINTER(result)
    U_INTERNAL_DUMP("result = %V", result->rep)
-#line 1542 "expression.c"
+#line 1544 "expression.c"
 /*********** End %parse_accept code *******************************************/
   expressionParserARG_STORE; /* Suppress warning about unused %extra_argument variable */
 }
diff --git a/src/ulib/net/server/plugin/mod_fcgi.cpp b/src/ulib/net/server/plugin/mod_fcgi.cpp
index f0e284f5..6071559b 100644
--- a/src/ulib/net/server/plugin/mod_fcgi.cpp
+++ b/src/ulib/net/server/plugin/mod_fcgi.cpp
@@ -233,7 +233,7 @@ int UFCGIPlugIn::handlerInit()
          if (UHTTP::valias == 0) UHTTP::valias = U_NEW(UVector<UString>(2U));
 
          UHTTP::valias->push_back(*UHTTP::fcgi_uri_mask);
-         UHTTP::valias->push_back(U_STRING_FROM_CONSTANT("/nostat"));
+         UHTTP::valias->push_back(*UString::str_nostat);
 
          environment_type = (UHTTP::fcgi_uri_mask->equal(U_CONSTANT_TO_PARAM("*.php")) ? U_PHP : U_CGI);
 
diff --git a/src/ulib/net/server/plugin/mod_scgi.cpp b/src/ulib/net/server/plugin/mod_scgi.cpp
index 4172c9d3..d8d3ec6d 100644
--- a/src/ulib/net/server/plugin/mod_scgi.cpp
+++ b/src/ulib/net/server/plugin/mod_scgi.cpp
@@ -111,7 +111,7 @@ int USCGIPlugIn::handlerInit()
          if (UHTTP::valias == 0) UHTTP::valias = U_NEW(UVector<UString>(2U));
 
          UHTTP::valias->push_back(*UHTTP::scgi_uri_mask);
-         UHTTP::valias->push_back(U_STRING_FROM_CONSTANT("/nostat"));
+         UHTTP::valias->push_back(*UString::str_nostat);
 
          U_RETURN(U_PLUGIN_HANDLER_PROCESSED | U_PLUGIN_HANDLER_GO_ON);
 #     endif
diff --git a/src/ulib/net/server/plugin/mod_soap.cpp b/src/ulib/net/server/plugin/mod_soap.cpp
index 7bd94a82..8cac2981 100644
--- a/src/ulib/net/server/plugin/mod_soap.cpp
+++ b/src/ulib/net/server/plugin/mod_soap.cpp
@@ -62,8 +62,8 @@ int USoapPlugIn::handlerInit()
 #  else
       if (UHTTP::valias == 0) UHTTP::valias = U_NEW(UVector<UString>(2U));
 
-      UHTTP::valias->push_back(U_STRING_FROM_CONSTANT("/soap"));
-      UHTTP::valias->push_back(U_STRING_FROM_CONSTANT("/nostat"));
+      UHTTP::valias->push_back(*UString::str_soap);
+      UHTTP::valias->push_back(*UString::str_nostat);
 
       U_RETURN(U_PLUGIN_HANDLER_PROCESSED | U_PLUGIN_HANDLER_GO_ON);
 #  endif
diff --git a/src/ulib/net/server/plugin/mod_tsa.cpp b/src/ulib/net/server/plugin/mod_tsa.cpp
index c7cd8f12..13cdd94d 100644
--- a/src/ulib/net/server/plugin/mod_tsa.cpp
+++ b/src/ulib/net/server/plugin/mod_tsa.cpp
@@ -69,8 +69,8 @@ int UTsaPlugIn::handlerInit()
 #  else
       if (UHTTP::valias == 0) UHTTP::valias = U_NEW(UVector<UString>(2U));
 
-      UHTTP::valias->push_back(U_STRING_FROM_CONSTANT("/tsa"));
-      UHTTP::valias->push_back(U_STRING_FROM_CONSTANT("/nostat"));
+      UHTTP::valias->push_back(*UString::str_tsa);
+      UHTTP::valias->push_back(*UString::str_nostat);
 
       U_RETURN(U_PLUGIN_HANDLER_PROCESSED | U_PLUGIN_HANDLER_GO_ON);
 #  endif
diff --git a/src/ulib/string.cpp b/src/ulib/string.cpp
index 1c8f1118..51c06a36 100644
--- a/src/ulib/string.cpp
+++ b/src/ulib/string.cpp
@@ -45,6 +45,10 @@ const UString* UString::str_point;
 const UString* UString::str_true;
 const UString* UString::str_false;
 const UString* UString::str_response;
+const UString* UString::str_zero;
+const UString* UString::str_nostat;
+const UString* UString::str_tsa;
+const UString* UString::str_soap;
 // SOAP
 const UString* UString::str_ns;
 const UString* UString::str_boolean;
@@ -179,9 +183,9 @@ const UString* UString::str_vary;
 const UString* UString::str_via;
 const UString* UString::str_www_authenticate;
 
-ustringrep UString::stringrep_storage[132] = {
+ustringrep UString::stringrep_storage[136] = {
 #else
-ustringrep UString::stringrep_storage[66] = {
+ustringrep UString::stringrep_storage[70] = {
 #endif
    { U_STRINGREP_FROM_CONSTANT("host") },
    { U_STRINGREP_FROM_CONSTANT("chunked") },
@@ -196,6 +200,10 @@ ustringrep UString::stringrep_storage[66] = {
    { U_STRINGREP_FROM_CONSTANT("true") },
    { U_STRINGREP_FROM_CONSTANT("false") },
    { U_STRINGREP_FROM_CONSTANT("response") },
+   { U_STRINGREP_FROM_CONSTANT("0") },
+   { U_STRINGREP_FROM_CONSTANT("/nostat") },
+   { U_STRINGREP_FROM_CONSTANT("/tsa") },
+   { U_STRINGREP_FROM_CONSTANT("/soap") },
    { U_STRINGREP_FROM_CONSTANT("") },
    // SOAP
    { U_STRINGREP_FROM_CONSTANT("ns") },
@@ -347,12 +355,12 @@ void UString::str_allocate(int which)
       U_INTERNAL_ASSERT_EQUALS(str_true, 0)
       U_INTERNAL_ASSERT_EQUALS(str_false, 0)
       U_INTERNAL_ASSERT_EQUALS(str_response, 0)
+      U_INTERNAL_ASSERT_EQUALS(str_zero, 0)
+      U_INTERNAL_ASSERT_EQUALS(str_nostat, 0)
+      U_INTERNAL_ASSERT_EQUALS(str_tsa, 0)
+      U_INTERNAL_ASSERT_EQUALS(str_soap, 0)
       U_INTERNAL_ASSERT_EQUALS(UHashMap<void*>::pkey, 0)
 
-#  if defined(__GNUC__) && GCC_VERSION_NUM == 50300
-   // UStringRep::string_rep_null->hold();
-#  endif
-
       U_NEW_ULIB_OBJECT(str_host,             UString(stringrep_storage+0));
       U_NEW_ULIB_OBJECT(str_chunked,          UString(stringrep_storage+1));
       U_NEW_ULIB_OBJECT(str_without_mac,      UString(stringrep_storage+2));
@@ -366,8 +374,12 @@ void UString::str_allocate(int which)
       U_NEW_ULIB_OBJECT(str_true,             UString(stringrep_storage+10));
       U_NEW_ULIB_OBJECT(str_false,            UString(stringrep_storage+11));
       U_NEW_ULIB_OBJECT(str_response,         UString(stringrep_storage+12));
+      U_NEW_ULIB_OBJECT(str_zero,             UString(stringrep_storage+13));
+      U_NEW_ULIB_OBJECT(str_nostat,           UString(stringrep_storage+14));
+      U_NEW_ULIB_OBJECT(str_tsa,              UString(stringrep_storage+15));
+      U_NEW_ULIB_OBJECT(str_soap,             UString(stringrep_storage+16));
 
-      uustringrep key1 = { stringrep_storage+13 };
+      uustringrep key1 = { stringrep_storage+17 };
 
       UHashMap<void*>::pkey = key1.p2;
 
@@ -512,7 +524,7 @@ void UString::str_allocate(int which)
    else if ((which & STR_ALLOCATE_HTTP2) != 0)
       {
       U_INTERNAL_ASSERT_EQUALS(str_authority, 0)
-      U_INTERNAL_ASSERT_EQUALS(U_NUM_ELEMENTS(stringrep_storage), 132)
+      U_INTERNAL_ASSERT_EQUALS(U_NUM_ELEMENTS(stringrep_storage), 136)
 
       U_NEW_ULIB_OBJECT(str_authority,                   UString(stringrep_storage+STR_ALLOCATE_INDEX_HTTP2+0));
       U_NEW_ULIB_OBJECT(str_method,                      UString(stringrep_storage+STR_ALLOCATE_INDEX_HTTP2+1));
@@ -581,7 +593,7 @@ void UString::str_allocate(int which)
       U_NEW_ULIB_OBJECT(str_www_authenticate,            UString(stringrep_storage+STR_ALLOCATE_INDEX_HTTP2+64));
       }
 #else
-   U_INTERNAL_ASSERT_EQUALS(U_NUM_ELEMENTS(stringrep_storage), 66)
+   U_INTERNAL_ASSERT_EQUALS(U_NUM_ELEMENTS(stringrep_storage), 70)
 #endif
 }
 
diff --git a/src/ulib/utility/string_ext.cpp b/src/ulib/utility/string_ext.cpp
index c39f4717..8598f653 100644
--- a/src/ulib/utility/string_ext.cpp
+++ b/src/ulib/utility/string_ext.cpp
@@ -761,58 +761,44 @@ UString UStringExt::evalExpression(const UString& expr, const UString& environme
 
    int token_id;
    UTokenizer t(expr);
-   UString* ptoken = 0;
-   UString result = *UString::str_true;
-
-   static UString* token;
-
-   if (token == 0) token = U_NEW(UString);
+   UString token, result = *UString::str_true;
 
    void* pParser = expressionParserAlloc(malloc);
 
-   /**
-    * #ifdef DEBUG
-    *    (void) fprintf(stderr, "start parsing expr: \"%v\"\n", expr));
-    *
-    *    expressionParserTrace(stderr, (char*)"parser: ");
-    * #endif
-    */
+#ifdef U_TEST
+   (void) fprintf(stderr, "start parsing expr: %V\n", expr.rep);
 
-   while (result &&
-          (token_id = t.getTokenId(token)) > 0)
+    expressionParserTrace(stderr, (char*)"parser: ");
+#endif
+
+   while ((token_id = t.getTokenId(&token)) > 0)
       {
       if (token_id == U_TK_NAME)
          {
-         *token    = UStringExt::getEnvironmentVar(*token, &environment);
-          token_id = U_TK_VALUE;
+         token    = UStringExt::getEnvironmentVar(token, &environment);
+         token_id = U_TK_VALUE;
          }
       else if (token_id == U_TK_PID)
          {
-         *token    = UStringExt::getPidProcess();
-          token_id = U_TK_VALUE;
+         token    = UStringExt::getPidProcess();
+         token_id = U_TK_VALUE;
          }
 
-      expressionParser( pParser, token_id, ptoken = U_NEW(UString(*token)), &result);
+      expressionParser(pParser, token_id, U_NEW(UString(token)), &result);
+
+      U_INTERNAL_DUMP("result = %V", result.rep)
+
+      if (result.empty()) break;
       }
 
    expressionParser(pParser, 0, 0, &result);
 
    expressionParserFree(pParser, free);
 
-#if defined(DEBUG) && !defined(U_SUBSTR_INC_REF)
-   if (ptoken)
-      {
-      // (void) fprintf(stderr, "ended parsing expr: \"%v\"\n", expr));
+#if defined(U_TEST) && !defined(U_SUBSTR_INC_REF)
+   (void) fprintf(stderr, "ended parsing expr: %V\n", expr.rep);
 
-      U_INTERNAL_DUMP("ptoken->rep->parent->child = %d", ptoken->rep->parent->child)
-
-      if (ptoken->rep->parent->child >= 1)
-         {
-         token->clear();
-
-      // delete ptoken;
-         }
-      }
+   U_INTERNAL_DUMP("token.rep->parent->child = %d", token.rep->parent->child)
 #endif
 
    U_RETURN_STRING(result);