fix escaped expressions inside calc() function. fix #60

Author: Horcrux7

src/com/inet/lib/less/LessParser.java

@@ -898,22 +898,33 @@ private Expression parseExpression( char leftOperator ) {
                             break;
                         case "calc":
                             int parenthesisCount = 0;
+                            right = null;
                             CALC: do {
                                 ch = read();
                                 switch( ch ) {
+                                    case '~':
+                                        if( isWhitespace( builder ) ) {
+                                            right = new Operation( reader, parseExpression( ch ), ch );
+                                            continue;
+                                        }
+                                        break;
                                     case '(':
                                         parenthesisCount++;
                                         break;
                                     case ')':
                                         if( parenthesisCount == 0 ) {
+                                            String val = trim( builder );
+                                            if( right == null ) {
+                                                right = new ValueExpression( reader, val, Expression.STRING );
+                                            }
                                             break CALC;
                                         }
                                         parenthesisCount--;
                                         break;
                                 }
                                 builder.append( ch );
                             } while( true );
-                            op = new Operation( reader, new ValueExpression( reader, trim( builder ), Expression.STRING ), ';' );
+                            op = new Operation( reader, right, ';' );
                             right = new FunctionExpression( reader, str, op );
                             break;
                         default:

test/com/inet/lib/less/samples/general/minus.css

@@ -26,6 +26,7 @@
   calcCompact: calc(100%-98px);
   calcVariable: calc(90% -10px);
   calcNested: calc(100% - (2 * 2em));
+  calcEscaped: calc(100% - (2 * 2em));
 }
 :root {
   --main-bg-color: pink;

test/com/inet/lib/less/samples/general/minus.less

@@ -30,6 +30,7 @@
   @b : 10px;
   calcVariable: calc(@a -@b);
   calcNested: calc(100% - (2 * 2em));
+  calcEscaped: calc(~"100% - (2 * 2em)");
 }
 :root {
   --main-bg-color: pink;