introduce OPERATIONS

Author: dhilt

src/modules/buffer.js

@@ -1,3 +1,5 @@
+import { OPERATIONS } from './utils';
+
 export default function ScrollBuffer(elementRoutines, bufferSize, startIndex) {
   const buffer = Object.create(Array.prototype);
 
@@ -19,7 +21,7 @@ export default function ScrollBuffer(elementRoutines, bufferSize, startIndex) {
     append(items) {
       items.forEach((item) => {
         ++buffer.next;
-        buffer.insert('append', item);
+        buffer.insert(OPERATIONS.APPEND, item);
       });
       buffer.maxIndex = buffer.eof ? buffer.next - 1 : Math.max(buffer.next - 1, buffer.maxIndex);
     },
@@ -32,7 +34,7 @@ export default function ScrollBuffer(elementRoutines, bufferSize, startIndex) {
         else {
           --buffer.first;
         }
-        buffer.insert('prepend', item);
+        buffer.insert(OPERATIONS.PREPEND, item);
       });
       buffer.minIndex = buffer.bof ? buffer.minIndex = buffer.first : Math.min(buffer.first, buffer.minIndex);
     },
@@ -41,15 +43,15 @@ export default function ScrollBuffer(elementRoutines, bufferSize, startIndex) {
      * inserts wrapped element in the buffer
      * the first argument is either operation keyword (see below) or a number for operation 'insert'
      * for insert the number is the index for the buffer element the new one have to be inserted after
-     * operations: 'append', 'prepend', 'insert', 'remove', 'update', 'none'
+     * operations: 'append', 'prepend', 'insert', 'remove', 'none'
      */
     insert(operation, item, isTop) {
       const wrapper = {
         item: item
       };
 
-      if (operation % 1 === 0) {// it is an insert
-        wrapper.op = 'insert';
+      if (operation % 1 === 0) { // it is an insert
+        wrapper.op = OPERATIONS.INSERT;
         buffer.splice(operation, 0, wrapper);
         if(isTop) {
           buffer.first--;
@@ -60,10 +62,10 @@ export default function ScrollBuffer(elementRoutines, bufferSize, startIndex) {
       } else {
         wrapper.op = operation;
         switch (operation) {
-          case 'append':
+          case OPERATIONS.APPEND:
             buffer.push(wrapper);
             break;
-          case 'prepend':
+          case OPERATIONS.PREPEND:
             buffer.unshift(wrapper);
             break;
         }
@@ -152,7 +154,7 @@ export default function ScrollBuffer(elementRoutines, bufferSize, startIndex) {
     },
 
     getItems() {
-      return buffer.filter(item => item.op === 'none');
+      return buffer.filter(item => item.op === OPERATIONS.NONE);
     },
 
     getFirstItem() {

src/modules/utils.js

@@ -0,0 +1,8 @@
+export const OPERATIONS = {
+  NONE: 'none',
+  PREPEND: 'prepend',
+  APPEND: 'append',
+  INSERT: 'insert',
+  REMOVE: 'remove',
+  REMOVE_AND_SHIFT_TOP: 'remove and shift top index'
+};

src/ui-scroll.js

@@ -3,6 +3,7 @@ import ElementRoutines from './modules/elementRoutines.js';
 import ScrollBuffer from './modules/buffer.js';
 import Viewport from './modules/viewport.js';
 import Adapter from './modules/adapter.js';
+import { OPERATIONS } from './modules/utils';
 
 angular.module('ui.scroll', [])
 
@@ -311,20 +312,20 @@ angular.module('ui.scroll', [])
 
           buffer.forEach((wrapper, i) => {
             switch (wrapper.op) {
-              case 'prepend':
+              case OPERATIONS.PREPEND:
                 toBePrepended.unshift(wrapper);
                 break;
-              case 'append':
+              case OPERATIONS.APPEND:
                 insertWrapperContent(wrapper, i);
-                wrapper.op = 'none';
+                wrapper.op = OPERATIONS.NONE;
                 inserted.push(wrapper);
                 break;
-              case 'insert':
+              case OPERATIONS.INSERT:
                 promises = promises.concat(createElement(wrapper, i, viewport.insertElementAnimated));
-                wrapper.op = 'none';
+                wrapper.op = OPERATIONS.NONE;
                 inserted.push(wrapper);
                 break;
-              case 'remove':
+              case OPERATIONS.REMOVE:
                 toBeRemoved.push(wrapper);
             }
           });
@@ -334,7 +335,7 @@ angular.module('ui.scroll', [])
           if (toBePrepended.length)
             toBePrepended.forEach((wrapper) => {
               insertWrapperContent(wrapper);
-              wrapper.op = 'none';
+              wrapper.op = OPERATIONS.NONE;
             });
 
           buffer.forEach((item, i) => item.scope.$index = buffer.first + i);