Add flush option 'api'.

It acts similar to tracing=api, i.e., it will generate the flush* methods but without a method body.
This allows to use the same code base for both incremental and non-incremental variants.

src/java/org/jastadd/Configuration.java

@@ -317,7 +317,8 @@ public class Configuration {
       .addAcceptedValue("full", "flushing of all computed values (combines attr, coll, and rewrite)")
       .addDefaultValue("attr", "adds flushing of attributes (syn,inh)")
       .addDefaultValue("coll", "adds flushing of collection attributes")
-      .addAcceptedValue("rewrite", "adds flushing of rewrites");
+      .addAcceptedValue("rewrite", "adds flushing of rewrites")
+      .addAcceptedValue("api", "flushing is disabled, but generate methods");
 
   ValueOption packageNameOption = new ValueOption("package",
       "optional package name for generated classes");
@@ -1155,10 +1156,10 @@ public class Configuration {
   }
 
   /**
-   * @return {@code true} if --flush=none
+   * @return {@code true} if not --flush=api
    */
   public boolean flushEnabled() {
-    return !flushOption.hasValue("none");
+    return !flushOption.hasValue("api");
   }
 
   /**

src/template/flush/Flush.tt

@@ -26,10 +26,10 @@
 # POSSIBILITY OF SUCH DAMAGE.
 
 ASTNode.flushTreeCacheMethod [[
-$if(FlushEnabled)
 $if(#isASTNodeDecl)
   /** @apilevel low-level */
   public void $ASTNode.flushTreeCache() {
+$if(FlushEnabled)
     flushCache();
     if (children != null) {
       for (int i = 0; i < children.length; i++) {
@@ -42,61 +42,65 @@ $if(#isASTNodeDecl)
         }
       }
     }
-  }
 $endif
+  }
 $endif
 ]]
 
 ASTDecl.flushCacheMethod [[
-$if(FlushEnabled)
 $if(#isASTNodeDecl)
   /** @apilevel low-level */
   public void #name.flushCache() {
+$if(FlushEnabled)
     flushAttrAndCollectionCache();
-  }
 $endif
+  }
 $endif
 ]]
 
 
 ASTDecl.flushAttrAndCollectionCacheMethod [[
-$if(FlushEnabled)
 $if(#isASTNodeDecl)
   /** @apilevel internal */
   public void #name.flushAttrAndCollectionCache() {
+$if(FlushEnabled)
     $if(FlushAttr)
     flushAttrCache();
     $endif
     $if(FlushColl)
     flushCollectionCache();
     $endif
-  }
 $endif
+  }
 $endif
 ]]
 
 ASTDecl.flushAttrCacheMethod [[
-$if(FlushAttr)
   /** @apilevel internal */
   public void #name.flushAttrCache() {
+$if(FlushEnabled)
+  $if(FlushAttr)
     $if(!#isASTNodeDecl)
     super.flushAttrCache();
     $endif
     $FlushAttrCacheBody
-  }
   $endif
+$endif
+  }
 ]]
 
 ASTDecl.flushCollectionCacheMethod [[
-$if(FlushColl)
   /** @apilevel internal */
   public void #name.flushCollectionCache() {
+$if(FlushEnabled)
+  $if(FlushColl)
     $if(!#isASTNodeDecl)
     super.flushCollectionCache();
     $endif
     #flushCollectionCacheCode
-  }
   $endif
+$endif
+  }
 ]]
 
 # TODO: Figure out if this can be removed