Issue 7016 - Convert serialization functions into generators

lib/filterClasses.js

Index: lib/filterClasses.js
===================================================================
--- a/lib/filterClasses.js
+++ b/lib/filterClasses.js
@@ -138,23 +138,24 @@
       else if (subscription == this._subscriptions)
       {
         this._subscriptions = null;
       }
     }
   },
 
   /**
-   * Serializes the filter to an array of strings for writing out on the disk.
-   * @param {string[]} buffer  buffer to push the serialization results into
+   * Generates serialized filter.
+   * @yields {string}
    */
-  serialize(buffer)
+  *serialize()
   {
-    buffer.push("[Filter]");
-    buffer.push("text=" + this.text);
+    let text = this;

[Manish Jethani, 2018/10/14 20:05:36]

This should be:

  let {text} = this;

It's working now purely by accident because `toString` is getting called, which
returns the text value.

+    yield "[Filter]";
+    yield "text=" + text;
   },
 
   toString()
   {
     return this.text;
   }
 };
 
@@ -321,17 +322,17 @@
    * @type {string}
    */
   reason: null,
 
   /**
    * See Filter.serialize()
    * @inheritdoc
    */
-  serialize(buffer) {}
+  *serialize() {}
 });
 
 /**
  * Class for comments
  * @param {string} text see {@link Filter Filter()}
  * @constructor
  * @augments Filter
  */
@@ -343,17 +344,17 @@
 
 CommentFilter.prototype = extend(Filter, {
   type: "comment",
 
   /**
    * See Filter.serialize()
    * @inheritdoc
    */
-  serialize(buffer) {}
+  *serialize() {}
 });
 
 /**
  * Abstract base class for filters that can get hits
  * @param {string} text
  *   see {@link Filter Filter()}
  * @param {string} [domains]
  *   Domains that the filter is restricted to separated by domainSeparator
@@ -609,27 +610,28 @@
 
     return !(sitekeys && sitekeys.length) && (!domains || domains.get(""));
   },
 
   /**
    * See Filter.serialize()
    * @inheritdoc
    */
-  serialize(buffer)
+  *serialize()
   {
-    if (this._disabled || this._hitCount || this._lastHit)
+    let {_disabled, _hitCount, _lastHit} = this;
+    if (_disabled || _hitCount || _lastHit)
     {
-      Filter.prototype.serialize.call(this, buffer);
+      yield* Filter.prototype.serialize.call(this);
       if (this._disabled)

[Manish Jethani, 2018/10/14 20:05:36]

We extracted the values first so we would use them throughout the function.
Let's remove the `this.` prefix from these lines.

-        buffer.push("disabled=true");
+        yield "disabled=true";
       if (this._hitCount)
-        buffer.push("hitCount=" + this._hitCount);
+        yield "hitCount=" + this._hitCount;
       if (this._lastHit)
-        buffer.push("lastHit=" + this._lastHit);
+        yield "lastHit=" + this._lastHit;
     }
   }
 });
 
 /**
  * Abstract base class for RegExp-based filters
  * @param {string} text see {@link Filter Filter()}
  * @param {string} regexpSource