shiftTop instead of _op = 'isTop'

Author: dhilt

src/modules/adapter.js

@@ -1,3 +1,5 @@
+import { OPERATIONS } from './utils';
+
 class Adapter {
 
   constructor($scope, $parse, $attr, viewport, buffer, doAdjust, reload) {
@@ -168,16 +170,17 @@ class Adapter {
     }
     let position = this.buffer.indexOf(wrapper);
     if (!newItems.reverse().some(newItem => newItem === wrapper.item)) {
-      wrapper.op = 'remove';
+      wrapper.op = OPERATIONS.REMOVE;
+      // try to catch "first" edge case on remove
       if (!options.immutableTop && position === 0 && !newItems.length) {
-        wrapper._op = 'isTop'; // to catch "first" edge case on remove
+        wrapper.shiftTop = true; 
       }
     }
     newItems.forEach((newItem) => {
       if (newItem === wrapper.item) {
         position--;
       } else {
-        // 3 parameter (isTop) is to catch "first" edge case on insert
+        // 3 parameter (shiftTop) is to catch "first" edge case on insert
         this.buffer.insert(position + 1, newItem, !options.immutableTop && position === -1);
       }
     });

src/modules/buffer.js

@@ -45,15 +45,15 @@ export default function ScrollBuffer(elementRoutines, bufferSize, startIndex) {
      * for insert the number is the index for the buffer element the new one have to be inserted after
      * operations: 'append', 'prepend', 'insert', 'remove', 'none'
      */
-    insert(operation, item, isTop) {
+    insert(operation, item, shiftTop) {
       const wrapper = {
         item: item
       };
 
       if (operation % 1 === 0) { // it is an insert
         wrapper.op = OPERATIONS.INSERT;
         buffer.splice(operation, 0, wrapper);
-        if(isTop) {
+        if (shiftTop) {
           buffer.first--;
         }
         else {
@@ -81,21 +81,21 @@ export default function ScrollBuffer(elementRoutines, bufferSize, startIndex) {
         }
         return buffer.splice(arg1, arg2 - arg1);
       }
-      // removes single item(wrapper) from the buffer
+      // removes single item (wrapper) from the buffer
       buffer.splice(buffer.indexOf(arg1), 1);
-      if(arg1._op === 'isTop' && buffer.first === this.getAbsMinIndex()) {
+      if (arg1.shiftTop && buffer.first === this.getAbsMinIndex()) {
         this.incrementMinIndex();
       }
       else {
         this.decrementMaxIndex();
       }
-      if(arg1._op === 'isTop') {
+      if (arg1.shiftTop) {
         buffer.first++;
       }
       else {
         buffer.next--;
       }
-      if(!buffer.length) {
+      if (!buffer.length) {
         buffer.first = 1;
         buffer.next = 1;
       }
@@ -104,34 +104,34 @@ export default function ScrollBuffer(elementRoutines, bufferSize, startIndex) {
     },
 
     incrementMinIndex() {
-      if(buffer.minIndexUser !== null) {
-        if(buffer.minIndex > buffer.minIndexUser) {
+      if (buffer.minIndexUser !== null) {
+        if (buffer.minIndex > buffer.minIndexUser) {
           buffer.minIndexUser++;
           return;
         }
-        if(buffer.minIndex === buffer.minIndexUser) {
+        if (buffer.minIndex === buffer.minIndexUser) {
           buffer.minIndexUser++;
         }
       }
       buffer.minIndex++;
     },
 
     decrementMaxIndex() {
-      if(buffer.maxIndexUser !== null && buffer.maxIndex <= buffer.maxIndexUser) {
+      if (buffer.maxIndexUser !== null && buffer.maxIndex <= buffer.maxIndexUser) {
         buffer.maxIndexUser--;
       }
       buffer.maxIndex--;
     },
 
     getAbsMinIndex() {
-      if(buffer.minIndexUser !== null) {
+      if (buffer.minIndexUser !== null) {
         return Math.min(buffer.minIndexUser, buffer.minIndex);
       }
       return buffer.minIndex;
     },
 
     getAbsMaxIndex() {
-      if(buffer.maxIndexUser !== null) {
+      if (buffer.maxIndexUser !== null) {
         return Math.max(buffer.maxIndexUser, buffer.maxIndex);
       }
       return buffer.maxIndex;

src/modules/padding.js

@@ -15,16 +15,16 @@ class CacheProto {
     this.sort((a, b) => ((a.index < b.index) ? -1 : ((a.index > b.index) ? 1 : 0)));
   }
 
-  remove(argument, _isTop) {
+  remove(argument, _shiftTop) {
     const index = argument % 1 === 0 ? argument : argument.scope.$index;
-    const isTop = argument % 1 === 0 ? _isTop : argument._op === 'isTop';
+    const shiftTop = argument % 1 === 0 ? _shiftTop : argument.shiftTop;
     for (let i = this.length - 1; i >= 0; i--) {
       if (this[i].index === index) {
         this.splice(i, 1);
         break;
       }
     }
-    if(!isTop) {
+    if (!shiftTop) {
       for (let i = this.length - 1; i >= 0; i--) {
         if (this[i].index > index) {
           this[i].index--;
@@ -50,7 +50,7 @@ Object.getOwnPropertyNames(CacheProto.prototype).forEach(methodName =>
 );
 
 function generateElement(template) {
-  if(template.nodeType !== Node.ELEMENT_NODE) {
+  if (template.nodeType !== Node.ELEMENT_NODE) {
     throw new Error('ui-scroll directive requires an Element node for templating the view');
   }
   let element;

src/modules/utils.js

@@ -1,8 +1,7 @@
 export const OPERATIONS = {
-  NONE: 'none',
   PREPEND: 'prepend',
   APPEND: 'append',
   INSERT: 'insert',
   REMOVE: 'remove',
-  REMOVE_AND_SHIFT_TOP: 'remove and shift top index'
+  NONE: 'none'
 };

src/modules/viewport.js

@@ -35,7 +35,7 @@ export default function Viewport(elementRoutines, buffer, element, viewportContr
       if (!container) {
         return true;
       }
-      if(container !== viewport) {
+      if (container !== viewport) {
         viewport.css('height', window.getComputedStyle(container[0]).height);
       }
       return viewport.height() > 0;
@@ -137,15 +137,15 @@ export default function Viewport(elementRoutines, buffer, element, viewportContr
 
       let topPaddingHeight = 0, topCount = 0;
       topPadding.cache.forEach(item => {
-        if(item.index < buffer.first) {
+        if (item.index < buffer.first) {
           topPaddingHeight += item.height;
           topCount++;
         }
       });
 
       let bottomPaddingHeight = 0, bottomCount = 0;
       bottomPadding.cache.forEach(item => {
-        if(item.index >= buffer.next) {
+        if (item.index >= buffer.next) {
           bottomPaddingHeight += item.height;
           bottomCount++;
         }
@@ -201,9 +201,9 @@ export default function Viewport(elementRoutines, buffer, element, viewportContr
       bottomPadding.cache.clear();
     },
 
-    removeCacheItem(item, isTop) {
-      topPadding.cache.remove(item, isTop);
-      bottomPadding.cache.remove(item, isTop);
+    removeCacheItem(item, shiftTop) {
+      topPadding.cache.remove(item, shiftTop);
+      bottomPadding.cache.remove(item, shiftTop);
     },
 
     removeItem(item) {