implements "@import (optional)"

Author: Horcrux7

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

@@ -26,6 +26,7 @@
  */
 package com.inet.lib.less;
 
+import java.io.IOException;
 import java.io.Reader;
 import java.net.MalformedURLException;
 import java.net.URL;
@@ -450,7 +451,6 @@ private void importFile( FormattableContainer currentRule, final String name ) {
                             break;
                         case "optional":
                             isOptional = true;
-                            System.err.println( "not implemented @import keyword: " + keywordStr ); //TODO
                             break;
                         case "once":
                             isMultiple = false;
@@ -577,6 +577,10 @@ private void importFile( FormattableContainer currentRule, final String name ) {
             }
         } catch( LessException ex ) {
             throw ex;
+        } catch( IOException ex ) {
+            if( !isOptional ) {
+                throw new LessException( ex );
+            }
         } catch( Exception ex ) {
             throw new LessException( ex );
         } finally {

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

@@ -0,0 +1,12 @@
+.slash {
+  a: 1.5;
+  b: 1.5;
+  e: a / b;
+  f: a / b;
+  g: a / b;
+  h: a / b;
+}
+.slash2 {
+  background: url("img.jpg") center / 100px;
+  background: url(abc/img.jpg);
+}

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

@@ -0,0 +1,2 @@
+@import (optional) "DoesNotExists.less";
+@import (optional) "slash.less";