refactor: Move TextField.maybeNegate() to end and make static (#1044)

* refactor: Move private method maybeNegate() to end of TextField

This was code review feedback on #790

* refactor: Make method maybeNegate() static, as spotted by WebStorm

Author: claremacrae

src/Query/Filter/TextField.ts

@@ -8,17 +8,14 @@ import { FilterOrErrorMessage } from './Filter';
  * value, such as the description or file path.
  */
 export abstract class TextField extends Field {
-    private maybeNegate(match: boolean, filterMethod: String) {
-        return filterMethod.match(/not/) ? !match : match;
-    }
     public createFilterOrErrorMessage(line: string): FilterOrErrorMessage {
         const result = new FilterOrErrorMessage();
         const match = Field.getMatch(this.filterRegexp(), line);
         if (match !== null) {
             const filterMethod = match[1];
             if (['includes', 'does not include'].includes(filterMethod)) {
                 result.filter = (task: Task) =>
-                    this.maybeNegate(
+                    TextField.maybeNegate(
                         TextField.stringIncludesCaseInsensitive(
                             this.value(task),
                             match[2],
@@ -35,7 +32,7 @@ export abstract class TextField extends Field {
 
                 if (query !== null) {
                     result.filter = (task: Task) =>
-                        this.maybeNegate(
+                        TextField.maybeNegate(
                             this.value(task).match(
                                 new RegExp(query[1], query[2]),
                             ) !== null,
@@ -76,4 +73,8 @@ export abstract class TextField extends Field {
      * @protected
      */
     protected abstract value(task: Task): string;
+
+    private static maybeNegate(match: boolean, filterMethod: String) {
+        return filterMethod.match(/not/) ? !match : match;
+    }
 }