Sass compiler now treats null-valued variables as unassigned (#12430).

Change-Id: I13a11b4c7d148646ad3eb5492d9dd8d736e63f39

11 files changed, 332 insertions, 252 deletions

diff --git a/theme-compiler/src/com/vaadin/sass/internal/parser/CharStream.java b/theme-compiler/src/com/vaadin/sass/internal/parser/CharStream.java
index c22f19451b..e43320453c 100644
--- a/theme-compiler/src/com/vaadin/sass/internal/parser/CharStream.java
+++ b/theme-compiler/src/com/vaadin/sass/internal/parser/CharStream.java
@@ -127,4 +127,4 @@ interface CharStream {
   void Done();
 
 }
-/* JavaCC - OriginalChecksum=deb80d024b50bdc8bfaadaf528157233 (do not edit this line) */
+/* JavaCC - OriginalChecksum=18aae0a549695f0fec96a11297b442bb (do not edit this line) */
diff --git a/theme-compiler/src/com/vaadin/sass/internal/parser/LexicalUnitImpl.java b/theme-compiler/src/com/vaadin/sass/internal/parser/LexicalUnitImpl.java
index cfd428e094..5035263588 100644
--- a/theme-compiler/src/com/vaadin/sass/internal/parser/LexicalUnitImpl.java
+++ b/theme-compiler/src/com/vaadin/sass/internal/parser/LexicalUnitImpl.java
@@ -247,6 +247,9 @@ public class LexicalUnitImpl implements LexicalUnit, SCSSLexicalUnit,
         case SCSS_VARIABLE:
             text = "$" + s;
             break;
+        case SCSS_NULL:
+            text = "";
+            break;
         case LexicalUnit.SAC_OPERATOR_COMMA:
             text = ",";
             break;
@@ -492,6 +495,11 @@ public class LexicalUnitImpl implements LexicalUnit, SCSSLexicalUnit,
         return new LexicalUnitImpl(line, column, previous, SCSS_VARIABLE, name);
     }
 
+    public static LexicalUnitImpl createNull(int line, int column,
+            LexicalUnitImpl previous) {
+        return new LexicalUnitImpl(line, column, previous, SCSS_NULL, "null");
+    }
+
     public static LexicalUnitImpl createNumber(int line, int column,
             LexicalUnitImpl previous, float v) {
         int i = (int) v;
diff --git a/theme-compiler/src/com/vaadin/sass/internal/parser/Parser.java b/theme-compiler/src/com/vaadin/sass/internal/parser/Parser.java
index 6b4a03b038..ab0f6161d7 100644
--- a/theme-compiler/src/com/vaadin/sass/internal/parser/Parser.java
+++ b/theme-compiler/src/com/vaadin/sass/internal/parser/Parser.java
@@ -2755,6 +2755,7 @@ boolean isPseudoElement = false;
           break label_70;
         }
       }
+                    exp = replaceNullValues(exp);
                     documentHandler.variable(name, exp, guarded);
     } catch (JumpException e) {
             skipAfterExpression();
@@ -2783,6 +2784,23 @@ boolean isPseudoElement = false;
     }
   }
 
+  LexicalUnitImpl replaceNullValues(LexicalUnitImpl unit) throws ParseException {
+    if(unit == null){
+        return null;
+    }
+    if (unit.getNextLexicalUnit() != null) {
+        unit.setNextLexicalUnit(replaceNullValues(unit.getNextLexicalUnit()));
+    }
+    if (unit.getLexicalUnitType() == SCSSLexicalUnit.SAC_IDENT
+            && "null".equals(unit.getStringValue())) {
+        LexicalUnitImpl next = unit.getNextLexicalUnit();
+        unit = LexicalUnitImpl.createNull(unit.getLineNumber(), unit.getColumnNumber(),
+                                          unit.getPreviousLexicalUnit());
+        unit.setNextLexicalUnit(next);
+    }
+    return unit;
+  }
+
   final public void controlDirective() throws ParseException {
     switch ((jj_ntk==-1)?jj_ntk():jj_ntk) {
     case IF_SYM:
@@ -6625,11 +6643,6 @@ LexicalUnitImpl result = null;
     return false;
   }
 
-  private boolean jj_3R_218() {
-    if (jj_3R_217()) return true;
-    return false;
-  }
-
   private boolean jj_3R_182() {
     Token xsp;
     xsp = jj_scanpos;
@@ -6643,6 +6656,11 @@ LexicalUnitImpl result = null;
     return false;
   }
 
+  private boolean jj_3R_218() {
+    if (jj_3R_217()) return true;
+    return false;
+  }
+
   private boolean jj_3R_217() {
     Token xsp;
     xsp = jj_scanpos;
@@ -6707,6 +6725,11 @@ LexicalUnitImpl result = null;
     return false;
   }
 
+  private boolean jj_3_7() {
+    if (jj_3R_186()) return true;
+    return false;
+  }
+
   private boolean jj_3R_290() {
     if (jj_scan_token(IDENT)) return true;
     return false;
@@ -6723,8 +6746,8 @@ LexicalUnitImpl result = null;
     return false;
   }
 
-  private boolean jj_3_7() {
-    if (jj_3R_186()) return true;
+  private boolean jj_3R_207() {
+    if (jj_scan_token(LBRACE)) return true;
     return false;
   }
 
@@ -6733,8 +6756,8 @@ LexicalUnitImpl result = null;
     return false;
   }
 
-  private boolean jj_3R_207() {
-    if (jj_scan_token(LBRACE)) return true;
+  private boolean jj_3R_206() {
+    if (jj_3R_190()) return true;
     return false;
   }
 
@@ -6751,11 +6774,6 @@ LexicalUnitImpl result = null;
     return false;
   }
 
-  private boolean jj_3R_206() {
-    if (jj_3R_190()) return true;
-    return false;
-  }
-
   private boolean jj_3_6() {
     if (jj_3R_185()) return true;
     if (jj_scan_token(LBRACE)) return true;
@@ -6783,11 +6801,6 @@ LexicalUnitImpl result = null;
     return false;
   }
 
-  private boolean jj_3R_310() {
-    if (jj_scan_token(STRING)) return true;
-    return false;
-  }
-
   private boolean jj_3R_259() {
     if (jj_scan_token(FUNCTION)) return true;
     Token xsp;
@@ -6801,6 +6814,26 @@ LexicalUnitImpl result = null;
     return false;
   }
 
+  private boolean jj_3R_250() {
+    if (jj_3R_263()) return true;
+    return false;
+  }
+
+  private boolean jj_3R_249() {
+    if (jj_3R_262()) return true;
+    return false;
+  }
+
+  private boolean jj_3R_248() {
+    if (jj_3R_261()) return true;
+    return false;
+  }
+
+  private boolean jj_3R_310() {
+    if (jj_scan_token(STRING)) return true;
+    return false;
+  }
+
   private boolean jj_3R_308() {
     if (jj_scan_token(STARMATCH)) return true;
     return false;
@@ -6876,21 +6909,6 @@ LexicalUnitImpl result = null;
     return false;
   }
 
-  private boolean jj_3R_250() {
-    if (jj_3R_263()) return true;
-    return false;
-  }
-
-  private boolean jj_3R_249() {
-    if (jj_3R_262()) return true;
-    return false;
-  }
-
-  private boolean jj_3R_248() {
-    if (jj_3R_261()) return true;
-    return false;
-  }
-
   private boolean jj_3R_223() {
     if (jj_scan_token(LBRACKET)) return true;
     Token xsp;
@@ -6909,6 +6927,16 @@ LexicalUnitImpl result = null;
     return false;
   }
 
+  private boolean jj_3R_183() {
+    if (jj_scan_token(COMMA)) return true;
+    Token xsp;
+    while (true) {
+      xsp = jj_scanpos;
+      if (jj_scan_token(1)) { jj_scanpos = xsp; break; }
+    }
+    return false;
+  }
+
   private boolean jj_3R_302() {
     if (jj_scan_token(INTERPOLATION)) return true;
     return false;
@@ -6924,6 +6952,37 @@ LexicalUnitImpl result = null;
     return false;
   }
 
+  private boolean jj_3R_260() {
+    if (jj_scan_token(DOT)) return true;
+    return false;
+  }
+
+  private boolean jj_3R_247() {
+    Token xsp;
+    xsp = jj_scanpos;
+    if (jj_3R_260()) jj_scanpos = xsp;
+    xsp = jj_scanpos;
+    if (jj_scan_token(72)) {
+    jj_scanpos = xsp;
+    if (jj_scan_token(49)) {
+    jj_scanpos = xsp;
+    if (jj_scan_token(50)) {
+    jj_scanpos = xsp;
+    if (jj_scan_token(52)) return true;
+    }
+    }
+    }
+    return false;
+  }
+
+  private boolean jj_3_5() {
+    Token xsp;
+    xsp = jj_scanpos;
+    if (jj_3R_183()) jj_scanpos = xsp;
+    if (jj_3R_184()) return true;
+    return false;
+  }
+
   private boolean jj_3R_266() {
     Token xsp;
     xsp = jj_scanpos;
@@ -6939,6 +6998,11 @@ LexicalUnitImpl result = null;
     return false;
   }
 
+  private boolean jj_3R_246() {
+    if (jj_scan_token(STRING)) return true;
+    return false;
+  }
+
   private boolean jj_3R_219() {
     Token xsp;
     xsp = jj_scanpos;
@@ -6962,59 +7026,52 @@ LexicalUnitImpl result = null;
     return false;
   }
 
-  private boolean jj_3R_183() {
-    if (jj_scan_token(COMMA)) return true;
-    Token xsp;
-    while (true) {
-      xsp = jj_scanpos;
-      if (jj_scan_token(1)) { jj_scanpos = xsp; break; }
-    }
-    return false;
-  }
-
-  private boolean jj_3R_301() {
-    if (jj_scan_token(IDENT)) return true;
+  private boolean jj_3R_245() {
+    if (jj_3R_259()) return true;
     return false;
   }
 
-  private boolean jj_3R_284() {
+  private boolean jj_3R_202() {
     Token xsp;
     xsp = jj_scanpos;
-    if (jj_3R_301()) {
+    if (jj_3R_246()) {
     jj_scanpos = xsp;
-    if (jj_3R_302()) return true;
+    if (jj_3R_247()) {
+    jj_scanpos = xsp;
+    if (jj_3R_248()) {
+    jj_scanpos = xsp;
+    if (jj_3R_249()) {
+    jj_scanpos = xsp;
+    if (jj_3R_250()) return true;
+    }
+    }
+    }
     }
     return false;
   }
 
-  private boolean jj_3R_260() {
-    if (jj_scan_token(DOT)) return true;
+  private boolean jj_3R_244() {
+    if (jj_scan_token(DIMEN)) return true;
     return false;
   }
 
-  private boolean jj_3R_247() {
+  private boolean jj_3R_301() {
+    if (jj_scan_token(IDENT)) return true;
+    return false;
+  }
+
+  private boolean jj_3R_284() {
     Token xsp;
     xsp = jj_scanpos;
-    if (jj_3R_260()) jj_scanpos = xsp;
-    xsp = jj_scanpos;
-    if (jj_scan_token(72)) {
-    jj_scanpos = xsp;
-    if (jj_scan_token(49)) {
-    jj_scanpos = xsp;
-    if (jj_scan_token(50)) {
+    if (jj_3R_301()) {
     jj_scanpos = xsp;
-    if (jj_scan_token(52)) return true;
-    }
-    }
+    if (jj_3R_302()) return true;
     }
     return false;
   }
 
-  private boolean jj_3_5() {
-    Token xsp;
-    xsp = jj_scanpos;
-    if (jj_3R_183()) jj_scanpos = xsp;
-    if (jj_3R_184()) return true;
+  private boolean jj_3R_243() {
+    if (jj_scan_token(KHZ)) return true;
     return false;
   }
 
@@ -7023,11 +7080,6 @@ LexicalUnitImpl result = null;
     return false;
   }
 
-  private boolean jj_3R_246() {
-    if (jj_scan_token(STRING)) return true;
-    return false;
-  }
-
   private boolean jj_3R_221() {
     if (jj_scan_token(DOT)) return true;
     Token xsp;
@@ -7039,32 +7091,18 @@ LexicalUnitImpl result = null;
     return false;
   }
 
-  private boolean jj_3R_245() {
-    if (jj_3R_259()) return true;
+  private boolean jj_3R_242() {
+    if (jj_scan_token(HZ)) return true;
     return false;
   }
 
-  private boolean jj_3R_202() {
-    Token xsp;
-    xsp = jj_scanpos;
-    if (jj_3R_246()) {
-    jj_scanpos = xsp;
-    if (jj_3R_247()) {
-    jj_scanpos = xsp;
-    if (jj_3R_248()) {
-    jj_scanpos = xsp;
-    if (jj_3R_249()) {
-    jj_scanpos = xsp;
-    if (jj_3R_250()) return true;
-    }
-    }
-    }
-    }
+  private boolean jj_3R_298() {
+    if (jj_3R_221()) return true;
     return false;
   }
 
-  private boolean jj_3R_298() {
-    if (jj_3R_221()) return true;
+  private boolean jj_3R_241() {
+    if (jj_scan_token(MS)) return true;
     return false;
   }
 
@@ -7093,13 +7131,23 @@ LexicalUnitImpl result = null;
     return false;
   }
 
-  private boolean jj_3R_244() {
-    if (jj_scan_token(DIMEN)) return true;
+  private boolean jj_3R_240() {
+    if (jj_scan_token(SECOND)) return true;
     return false;
   }
 
-  private boolean jj_3R_243() {
-    if (jj_scan_token(KHZ)) return true;
+  private boolean jj_3R_239() {
+    if (jj_scan_token(GRAD)) return true;
+    return false;
+  }
+
+  private boolean jj_3R_238() {
+    if (jj_scan_token(RAD)) return true;
+    return false;
+  }
+
+  private boolean jj_3R_237() {
+    if (jj_scan_token(DEG)) return true;
     return false;
   }
 
@@ -7108,8 +7156,8 @@ LexicalUnitImpl result = null;
     return false;
   }
 
-  private boolean jj_3R_242() {
-    if (jj_scan_token(HZ)) return true;
+  private boolean jj_3R_236() {
+    if (jj_scan_token(EXS)) return true;
     return false;
   }
 
@@ -7134,6 +7182,11 @@ LexicalUnitImpl result = null;
     return false;
   }
 
+  private boolean jj_3R_235() {
+    if (jj_scan_token(REM)) return true;
+    return false;
+  }
+
   private boolean jj_3R_275() {
     Token xsp;
     xsp = jj_scanpos;
@@ -7155,11 +7208,6 @@ LexicalUnitImpl result = null;
     return false;
   }
 
-  private boolean jj_3R_241() {
-    if (jj_scan_token(MS)) return true;
-    return false;
-  }
-
   private boolean jj_3R_280() {
     if (jj_3R_222()) return true;
     return false;
@@ -7191,13 +7239,13 @@ LexicalUnitImpl result = null;
     return false;
   }
 
-  private boolean jj_3R_282() {
-    if (jj_3R_223()) return true;
+  private boolean jj_3R_234() {
+    if (jj_scan_token(LEM)) return true;
     return false;
   }
 
-  private boolean jj_3R_240() {
-    if (jj_scan_token(SECOND)) return true;
+  private boolean jj_3R_282() {
+    if (jj_3R_223()) return true;
     return false;
   }
 
@@ -7206,6 +7254,11 @@ LexicalUnitImpl result = null;
     return false;
   }
 
+  private boolean jj_3R_233() {
+    if (jj_scan_token(EMS)) return true;
+    return false;
+  }
+
   private boolean jj_3R_273() {
     Token xsp;
     xsp = jj_scanpos;
@@ -7229,23 +7282,23 @@ LexicalUnitImpl result = null;
     return false;
   }
 
-  private boolean jj_3R_239() {
-    if (jj_scan_token(GRAD)) return true;
+  private boolean jj_3R_232() {
+    if (jj_scan_token(PX)) return true;
     return false;
   }
 
-  private boolean jj_3R_238() {
-    if (jj_scan_token(RAD)) return true;
+  private boolean jj_3R_231() {
+    if (jj_scan_token(IN)) return true;
     return false;
   }
 
-  private boolean jj_3R_237() {
-    if (jj_scan_token(DEG)) return true;
+  private boolean jj_3R_230() {
+    if (jj_scan_token(PC)) return true;
     return false;
   }
 
-  private boolean jj_3R_236() {
-    if (jj_scan_token(EXS)) return true;
+  private boolean jj_3R_229() {
+    if (jj_scan_token(MM)) return true;
     return false;
   }
 
@@ -7259,11 +7312,6 @@ LexicalUnitImpl result = null;
     return false;
   }
 
-  private boolean jj_3R_235() {
-    if (jj_scan_token(REM)) return true;
-    return false;
-  }
-
   private boolean jj_3R_198() {
     if (jj_3R_222()) return true;
     Token xsp;
@@ -7274,13 +7322,13 @@ LexicalUnitImpl result = null;
     return false;
   }
 
-  private boolean jj_3R_279() {
-    if (jj_3R_223()) return true;
+  private boolean jj_3R_228() {
+    if (jj_scan_token(CM)) return true;
     return false;
   }
 
-  private boolean jj_3R_234() {
-    if (jj_scan_token(LEM)) return true;
+  private boolean jj_3R_279() {
+    if (jj_3R_223()) return true;
     return false;
   }
 
@@ -7294,6 +7342,11 @@ LexicalUnitImpl result = null;
     return false;
   }
 
+  private boolean jj_3R_227() {
+    if (jj_scan_token(PT)) return true;
+    return false;
+  }
+
   private boolean jj_3R_196() {
     if (jj_3R_220()) return true;
     Token xsp;
@@ -7325,13 +7378,13 @@ LexicalUnitImpl result = null;
     return false;
   }
 
-  private boolean jj_3R_233() {
-    if (jj_scan_token(EMS)) return true;
+  private boolean jj_3R_226() {
+    if (jj_scan_token(PERCENTAGE)) return true;
     return false;
   }
 
-  private boolean jj_3R_232() {
-    if (jj_scan_token(PX)) return true;
+  private boolean jj_3R_209() {
+    if (jj_3R_254()) return true;
     return false;
   }
 
@@ -7345,8 +7398,8 @@ LexicalUnitImpl result = null;
     return false;
   }
 
-  private boolean jj_3R_231() {
-    if (jj_scan_token(IN)) return true;
+  private boolean jj_3R_225() {
+    if (jj_scan_token(NUMBER)) return true;
     return false;
   }
 
@@ -7369,8 +7422,8 @@ LexicalUnitImpl result = null;
     return false;
   }
 
-  private boolean jj_3R_230() {
-    if (jj_scan_token(PC)) return true;
+  private boolean jj_3R_224() {
+    if (jj_3R_258()) return true;
     return false;
   }
 
@@ -7380,41 +7433,6 @@ LexicalUnitImpl result = null;
     return false;
   }
 
-  private boolean jj_3R_229() {
-    if (jj_scan_token(MM)) return true;
-    return false;
-  }
-
-  private boolean jj_3R_228() {
-    if (jj_scan_token(CM)) return true;
-    return false;
-  }
-
-  private boolean jj_3R_227() {
-    if (jj_scan_token(PT)) return true;
-    return false;
-  }
-
-  private boolean jj_3R_226() {
-    if (jj_scan_token(PERCENTAGE)) return true;
-    return false;
-  }
-
-  private boolean jj_3R_209() {
-    if (jj_3R_254()) return true;
-    return false;
-  }
-
-  private boolean jj_3R_225() {
-    if (jj_scan_token(NUMBER)) return true;
-    return false;
-  }
-
-  private boolean jj_3R_224() {
-    if (jj_3R_258()) return true;
-    return false;
-  }
-
   private boolean jj_3R_201() {
     Token xsp;
     xsp = jj_scanpos;
@@ -7503,12 +7521,6 @@ LexicalUnitImpl result = null;
     return false;
   }
 
-  private boolean jj_3_2() {
-    if (jj_3R_180()) return true;
-    if (jj_3R_181()) return true;
-    return false;
-  }
-
   private boolean jj_3R_254() {
     if (jj_3R_189()) return true;
     return false;
@@ -7519,57 +7531,45 @@ LexicalUnitImpl result = null;
     return false;
   }
 
-  private boolean jj_3R_204() {
-    if (jj_scan_token(COMMA)) return true;
-    Token xsp;
-    while (true) {
-      xsp = jj_scanpos;
-      if (jj_scan_token(1)) { jj_scanpos = xsp; break; }
-    }
-    if (jj_3R_203()) return true;
-    return false;
-  }
-
-  private boolean jj_3R_251() {
-    if (jj_3R_181()) return true;
+  private boolean jj_3R_208() {
+    if (jj_3R_184()) return true;
     return false;
   }
 
-  private boolean jj_3R_203() {
+  private boolean jj_3R_187() {
     Token xsp;
     xsp = jj_scanpos;
-    if (jj_3R_251()) {
+    if (jj_3R_208()) {
     jj_scanpos = xsp;
-    if (jj_3R_252()) return true;
-    }
-    while (true) {
-      xsp = jj_scanpos;
-      if (jj_3_2()) { jj_scanpos = xsp; break; }
-    }
-    while (true) {
-      xsp = jj_scanpos;
-      if (jj_scan_token(1)) { jj_scanpos = xsp; break; }
+    if (jj_3R_209()) return true;
     }
     return false;
   }
 
-  private boolean jj_3R_208() {
-    if (jj_3R_184()) return true;
+  private boolean jj_3_9() {
+    if (jj_3R_188()) return true;
     return false;
   }
 
-  private boolean jj_3R_187() {
+  private boolean jj_3_2() {
+    if (jj_3R_180()) return true;
+    if (jj_3R_181()) return true;
+    return false;
+  }
+
+  private boolean jj_3R_204() {
+    if (jj_scan_token(COMMA)) return true;
     Token xsp;
-    xsp = jj_scanpos;
-    if (jj_3R_208()) {
-    jj_scanpos = xsp;
-    if (jj_3R_209()) return true;
+    while (true) {
+      xsp = jj_scanpos;
+      if (jj_scan_token(1)) { jj_scanpos = xsp; break; }
     }
+    if (jj_3R_203()) return true;
     return false;
   }
 
-  private boolean jj_3_9() {
-    if (jj_3R_188()) return true;
+  private boolean jj_3R_251() {
+    if (jj_3R_181()) return true;
     return false;
   }
 
@@ -7593,23 +7593,26 @@ LexicalUnitImpl result = null;
     return false;
   }
 
-  private boolean jj_3_1() {
-    if (jj_3R_179()) return true;
+  private boolean jj_3R_263() {
+    if (jj_scan_token(UNICODERANGE)) return true;
     return false;
   }
 
-  private boolean jj_3R_185() {
-    if (jj_3R_203()) return true;
+  private boolean jj_3R_203() {
     Token xsp;
+    xsp = jj_scanpos;
+    if (jj_3R_251()) {
+    jj_scanpos = xsp;
+    if (jj_3R_252()) return true;
+    }
     while (true) {
       xsp = jj_scanpos;
-      if (jj_3R_204()) { jj_scanpos = xsp; break; }
+      if (jj_3_2()) { jj_scanpos = xsp; break; }
+    }
+    while (true) {
+      xsp = jj_scanpos;
+      if (jj_scan_token(1)) { jj_scanpos = xsp; break; }
     }
-    return false;
-  }
-
-  private boolean jj_3R_263() {
-    if (jj_scan_token(UNICODERANGE)) return true;
     return false;
   }
 
@@ -7636,6 +7639,21 @@ LexicalUnitImpl result = null;
     return false;
   }
 
+  private boolean jj_3_1() {
+    if (jj_3R_179()) return true;
+    return false;
+  }
+
+  private boolean jj_3R_185() {
+    if (jj_3R_203()) return true;
+    Token xsp;
+    while (true) {
+      xsp = jj_scanpos;
+      if (jj_3R_204()) { jj_scanpos = xsp; break; }
+    }
+    return false;
+  }
+
   private boolean jj_3R_215() {
     if (jj_scan_token(MINUS)) return true;
     Token xsp;
@@ -7658,11 +7676,6 @@ LexicalUnitImpl result = null;
     return false;
   }
 
-  private boolean jj_3R_265() {
-    if (jj_scan_token(INTERPOLATION)) return true;
-    return false;
-  }
-
   private boolean jj_3_3() {
     if (jj_3R_179()) return true;
     return false;
@@ -7698,16 +7711,6 @@ LexicalUnitImpl result = null;
     return false;
   }
 
-  private boolean jj_3R_192() {
-    if (jj_scan_token(SEMICOLON)) return true;
-    Token xsp;
-    while (true) {
-      xsp = jj_scanpos;
-      if (jj_scan_token(1)) { jj_scanpos = xsp; break; }
-    }
-    return false;
-  }
-
   private boolean jj_3R_210() {
     if (jj_scan_token(COMMA)) return true;
     Token xsp;
@@ -7740,6 +7743,31 @@ LexicalUnitImpl result = null;
     return false;
   }
 
+  private boolean jj_3R_265() {
+    if (jj_scan_token(INTERPOLATION)) return true;
+    return false;
+  }
+
+  private boolean jj_3R_216() {
+    if (jj_scan_token(GUARDED_SYM)) return true;
+    Token xsp;
+    while (true) {
+      xsp = jj_scanpos;
+      if (jj_scan_token(1)) { jj_scanpos = xsp; break; }
+    }
+    return false;
+  }
+
+  private boolean jj_3R_192() {
+    if (jj_scan_token(SEMICOLON)) return true;
+    Token xsp;
+    while (true) {
+      xsp = jj_scanpos;
+      if (jj_scan_token(1)) { jj_scanpos = xsp; break; }
+    }
+    return false;
+  }
+
   private boolean jj_3R_189() {
     if (jj_scan_token(VARIABLE)) return true;
     Token xsp;
@@ -7779,16 +7807,6 @@ LexicalUnitImpl result = null;
     return false;
   }
 
-  private boolean jj_3R_216() {
-    if (jj_scan_token(GUARDED_SYM)) return true;
-    Token xsp;
-    while (true) {
-      xsp = jj_scanpos;
-      if (jj_scan_token(1)) { jj_scanpos = xsp; break; }
-    }
-    return false;
-  }
-
   private boolean jj_3R_191() {
     if (jj_3R_216()) return true;
     return false;
diff --git a/theme-compiler/src/com/vaadin/sass/internal/parser/Parser.jj b/theme-compiler/src/com/vaadin/sass/internal/parser/Parser.jj
index 482b8597d3..9e1b781a6a 100644
--- a/theme-compiler/src/com/vaadin/sass/internal/parser/Parser.jj
+++ b/theme-compiler/src/com/vaadin/sass/internal/parser/Parser.jj
@@ -1491,6 +1491,7 @@ void variable() :
 		":" ( <S> )* exp=expr() ( guarded=guarded() )?(";"(<S>)*)+
 		//raw=skipStatementUntilSemiColon()
 		{
+		    exp = replaceNullValues(exp);
 		    documentHandler.variable(name, exp, guarded);
 		}
 	}catch (JumpException e) {
@@ -1520,6 +1521,24 @@ void variable() :
 	}
 }
 
+JAVACODE
+LexicalUnitImpl replaceNullValues(LexicalUnitImpl unit) {
+    if(unit == null){
+        return null;
+    }
+    if (unit.getNextLexicalUnit() != null) {
+        unit.setNextLexicalUnit(replaceNullValues(unit.getNextLexicalUnit()));
+    }
+    if (unit.getLexicalUnitType() == SCSSLexicalUnit.SAC_IDENT
+            && "null".equals(unit.getStringValue())) {
+        LexicalUnitImpl next = unit.getNextLexicalUnit();
+        unit = LexicalUnitImpl.createNull(unit.getLineNumber(), unit.getColumnNumber(), 
+                                          unit.getPreviousLexicalUnit());
+        unit.setNextLexicalUnit(next);
+    }
+    return unit;
+}
+
 void controlDirective() :
 {}
 {
diff --git a/theme-compiler/src/com/vaadin/sass/internal/parser/SCSSLexicalUnit.java b/theme-compiler/src/com/vaadin/sass/internal/parser/SCSSLexicalUnit.java
index 709d1d3576..84b0563493 100644
--- a/theme-compiler/src/com/vaadin/sass/internal/parser/SCSSLexicalUnit.java
+++ b/theme-compiler/src/com/vaadin/sass/internal/parser/SCSSLexicalUnit.java
@@ -22,6 +22,8 @@ public interface SCSSLexicalUnit extends LexicalUnit {
     static final short SCSS_OPERATOR_LEFT_PAREN = 101;
     static final short SCSS_OPERATOR_RIGHT_PAREN = 102;
 
+    static final short SCSS_NULL = 110;
+
     static final short SAC_LEM = 200;
     static final short SAC_REM = 201;
 
diff --git a/theme-compiler/src/com/vaadin/sass/internal/parser/Token.java b/theme-compiler/src/com/vaadin/sass/internal/parser/Token.java
index 26d1121f96..ba29df7d33 100644
--- a/theme-compiler/src/com/vaadin/sass/internal/parser/Token.java
+++ b/theme-compiler/src/com/vaadin/sass/internal/parser/Token.java
@@ -143,4 +143,4 @@ public class Token implements java.io.Serializable {
   }
 
 }
-/* JavaCC - OriginalChecksum=dad2146dc89e68f66e77382c9e448fb7 (do not edit this line) */
+/* JavaCC - OriginalChecksum=8b653fc6be4ca9bd10137ee3ad4c32c4 (do not edit this line) */
diff --git a/theme-compiler/src/com/vaadin/sass/internal/parser/TokenMgrError.java b/theme-compiler/src/com/vaadin/sass/internal/parser/TokenMgrError.java
index f093357e96..1757cf6705 100644
--- a/theme-compiler/src/com/vaadin/sass/internal/parser/TokenMgrError.java
+++ b/theme-compiler/src/com/vaadin/sass/internal/parser/TokenMgrError.java
@@ -159,4 +159,4 @@ public class TokenMgrError extends Error
     this(LexicalError(EOFSeen, lexState, errorLine, errorColumn, errorAfter, curChar), reason);
   }
 }
-/* JavaCC - OriginalChecksum=c7c96e9cf4a9320d03dd722437439354 (do not edit this line) */
+/* JavaCC - OriginalChecksum=525946b34c715198d7c29f668b049f5d (do not edit this line) */
diff --git a/theme-compiler/src/com/vaadin/sass/internal/tree/RuleNode.java b/theme-compiler/src/com/vaadin/sass/internal/tree/RuleNode.java
index cc6dbb7b75..a8fa87eb0a 100644
--- a/theme-compiler/src/com/vaadin/sass/internal/tree/RuleNode.java
+++ b/theme-compiler/src/com/vaadin/sass/internal/tree/RuleNode.java
@@ -58,13 +58,18 @@ public class RuleNode extends Node implements IVariableNode {
 
     @Override
     public String toString() {
-        StringBuilder builder = new StringBuilder();
-        builder.append(variable).append(": ").append(value.toString());
-        builder.append(important ? " !important;" : ";");
+        String stringValue = value.toString()
+                + (important ? " !important" : "");
+        if (!"".equals(stringValue.trim())) {
+            stringValue = variable + ": " + stringValue + ";";
+        } else {
+            stringValue = "";
+        }
+
         if (comment != null) {
-            builder.append(comment);
+            stringValue += comment;
         }
-        return builder.toString();
+        return stringValue;
     }
 
     public boolean isImportant() {
diff --git a/theme-compiler/src/com/vaadin/sass/internal/visitor/VariableNodeHandler.java b/theme-compiler/src/com/vaadin/sass/internal/visitor/VariableNodeHandler.java
index 6da035426e..a794def8cb 100644
--- a/theme-compiler/src/com/vaadin/sass/internal/visitor/VariableNodeHandler.java
+++ b/theme-compiler/src/com/vaadin/sass/internal/visitor/VariableNodeHandler.java
@@ -17,16 +17,20 @@
 package com.vaadin.sass.internal.visitor;
 
 import com.vaadin.sass.internal.ScssStylesheet;
+import com.vaadin.sass.internal.parser.SCSSLexicalUnit;
 import com.vaadin.sass.internal.tree.VariableNode;
 
 public class VariableNodeHandler {
 
     public static void traverse(VariableNode node) {
-        if (ScssStylesheet.getVariable(node.getName()) == null
-                || !node.isGuarded()) {
+        VariableNode variable = ScssStylesheet.getVariable(node.getName());
+        if (!node.isGuarded()
+                || variable == null
+                || variable.getExpr() == null
+                || (variable.getExpr().getLexicalUnitType() == SCSSLexicalUnit.SCSS_NULL && variable
+                        .getExpr().getNextLexicalUnit() == null)) {
             ScssStylesheet.addVariable(node);
         }
         node.getParentNode().removeChild(node);
     }
-
 }
diff --git a/theme-compiler/tests/resources/automatic/css/variable-defaults-with-null.css b/theme-compiler/tests/resources/automatic/css/variable-defaults-with-null.css
new file mode 100644
index 0000000000..0e3483817b
--- /dev/null
+++ b/theme-compiler/tests/resources/automatic/css/variable-defaults-with-null.css
@@ -0,0 +1,5 @@
+.test {
+  first: "Non-null";
+  second: "Also non-null";
+  third: "Not null"; 
+}
\ No newline at end of file
diff --git a/theme-compiler/tests/resources/automatic/scss/variable-defaults-with-null.scss b/theme-compiler/tests/resources/automatic/scss/variable-defaults-with-null.scss
new file mode 100644
index 0000000000..0bfa374304
--- /dev/null
+++ b/theme-compiler/tests/resources/automatic/scss/variable-defaults-with-null.scss
@@ -0,0 +1,19 @@
+$var: null;
+$var: "Non-null" !default;
+
+$var2: null;
+$var2: "Also non-null" !default;
+$var2: "Null content" !default;
+
+$list-of-nulls: null null;
+$list-of-nulls: "Non-null" !default; 
+
+$mixed-list: null "Not null" null;
+$mixed-list: "null" !default;
+
+.test {
+    first: $var;
+    second: $var2;
+    hidden: $list-of-nulls;
+    third: $mixed-list;
+}
\ No newline at end of file