Interpret only variables in CSS function CSS. fix #52

Author: Horcrux7

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

@@ -1,7 +1,7 @@
 /**
  * MIT License (MIT)
  *
- * Copyright (c) 2014 - 2016 Volker Berlin
+ * Copyright (c) 2014 - 2019 Volker Berlin
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
@@ -297,6 +297,11 @@ public void appendTo( CssFormatter formatter ) {
                 case "range":
                     range( formatter ).appendTo( formatter );
                     return;
+                case "calc":
+                    formatter.append( super.toString() ).append( '(' );
+                    SelectorUtils.appendToWithPlaceHolder( formatter, get( 0 ).stringValue( formatter ), 0, false, this );
+                    formatter.append( ')' );
+                    return;
             }
             if( type == UNKNOWN ) {
                 eval( formatter );

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

@@ -896,6 +896,15 @@ private Expression parseExpression( char leftOperator ) {
                             op = parseParameterList();
                             right = new Operation( reader, op.getOperands().get( 0 ), '~' );
                             break;
+                        case "calc":
+                            ch = read();
+                            while( ch != ')' ) {
+                                builder.append( ch );
+                                ch = read();
+                            }
+                            op = new Operation( reader, new ValueExpression( reader, trim( builder ), Expression.STRING ), ';' );
+                            right = new FunctionExpression( reader, str, op );
+                            break;
                         default:
                             right = new FunctionExpression( reader, str, parseParameterList() );
                     }

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

@@ -22,4 +22,7 @@
   function2: - -3;
   function3: -floor(-2.3);
   function4: 3;
+  calcWithSpace: calc(100% - 98px);
+  calcCompact: calc(100%-98px);
+  calcVariable: calc(90% -10px);
 }

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

@@ -23,4 +23,10 @@
   function2: - floor(-2.3);
   function3: (-floor(-2.3));
   function4: (0-floor(-2.3));
+
+  calcWithSpace: calc(100% - 98px); 
+  calcCompact: calc(100%-98px);
+  @a : 90%;
+  @b : 10px;
+  calcVariable: calc(@a -@b);
 }