From 389a19f61f0b90dd211816a9a3d3bf830829900b Mon Sep 17 00:00:00 2001
From: Danny Nguyen <dann.ngu@gmail.com>
Date: Tue, 11 Sep 2018 16:28:42 -0700
Subject: [PATCH] Add option for custom search function

---
 demo/src/app/dummy.component.html  |  5 +++++
 demo/src/app/dummy.component.ts    |  4 ++++
 src/dropdown/dropdown.component.ts | 10 +++++++++-
 src/dropdown/search-filter.pipe.ts | 14 +++++---------
 4 files changed, 23 insertions(+), 10 deletions(-)

diff --git a/demo/src/app/dummy.component.html b/demo/src/app/dummy.component.html
index 4873b403..7862a6d8 100644
--- a/demo/src/app/dummy.component.html
+++ b/demo/src/app/dummy.component.html
@@ -10,4 +10,9 @@ <h3>Dropdown Demo</h3>
     With search and buttons:
     <ss-multiselect-dropdown [options]="data.options" [settings]="settings" [ngModel]="data.selectedItems"></ss-multiselect-dropdown>
   </p>
+
+  <p>
+    With custom prefix search and buttons:
+    <ss-multiselect-dropdown [options]="data.options" [settings]="settings" [ngModel]="data.selectedItems" [searchFunction]=prefixSearchFunction></ss-multiselect-dropdown>
+  </p>
 </div>
diff --git a/demo/src/app/dummy.component.ts b/demo/src/app/dummy.component.ts
index 86ba1131..dc311eac 100644
--- a/demo/src/app/dummy.component.ts
+++ b/demo/src/app/dummy.component.ts
@@ -17,4 +17,8 @@ export class DummyComponent {
     showCheckAll: true,
     showUncheckAll: true
   };
+
+  prefixSearchFunction(str: string): RegExp {
+    return new RegExp('^' + str, 'i');
+  }
 }
diff --git a/src/dropdown/dropdown.component.ts b/src/dropdown/dropdown.component.ts
index 2508766e..3993b53c 100644
--- a/src/dropdown/dropdown.component.ts
+++ b/src/dropdown/dropdown.component.ts
@@ -64,6 +64,7 @@ export class MultiselectDropdownComponent
   @Input() texts: IMultiSelectTexts;
   @Input() disabled: boolean = false;
   @Input() disabledSelection: boolean = false;
+  @Input() searchFunction: (str: string) => RegExp = this._escapeRegExp;
 
   @Output() selectionLimitReached = new EventEmitter();
   @Output() dropdownClosed = new EventEmitter();
@@ -277,7 +278,8 @@ export class MultiselectDropdownComponent
       options,
       value,
       this.settings.searchMaxLimit,
-      this.settings.searchMaxRenderedItems
+      this.settings.searchMaxRenderedItems,
+      this.searchFunction
     );
   }
 
@@ -709,4 +711,10 @@ export class MultiselectDropdownComponent
       e.stopPropagation();
     }
   }
+  
+  private _escapeRegExp(str: string): RegExp {
+    const regExpStr = str.replace(/[\-\[\]\/\{\}\(\)\*\+\?\.\\\^\$\|]/g, "\\$&");
+    return new RegExp(regExpStr, 'i');
+  }
+
 }
diff --git a/src/dropdown/search-filter.pipe.ts b/src/dropdown/search-filter.pipe.ts
index bf5fd2b6..5dcd6bad 100644
--- a/src/dropdown/search-filter.pipe.ts
+++ b/src/dropdown/search-filter.pipe.ts
@@ -20,7 +20,8 @@ export class MultiSelectSearchFilter implements PipeTransform {
     options: IMultiSelectOption[],
     str = '',
     limit = 0,
-    renderLimit = 0
+    renderLimit = 0,
+    searchFunction: (str: string) => RegExp,
   ): IMultiSelectOption[] {
     str = str.toLowerCase();
 
@@ -34,7 +35,7 @@ export class MultiSelectSearchFilter implements PipeTransform {
 
     const filteredOpts = this._searchCache.hasOwnProperty(str)
       ? this._searchCache[str]
-      : this._doSearch(options, str, limit);
+      : this._doSearch(options, str, limit, searchFunction);
 
     const isUnderLimit = options.length <= limit;
 
@@ -61,7 +62,7 @@ export class MultiSelectSearchFilter implements PipeTransform {
     return options;
   }
 
-  private _doSearch(options: IMultiSelectOption[], str: string, limit: number) {
+  private _doSearch(options: IMultiSelectOption[], str: string, limit: number, searchFunction: (str: string) => RegExp) {
     const prevStr = str.slice(0, -1);
     const prevResults = this._searchCache[prevStr];
     const prevResultShift = this._prevSkippedItems[prevStr] || 0;
@@ -72,7 +73,7 @@ export class MultiSelectSearchFilter implements PipeTransform {
 
     const optsLength = options.length;
     const maxFound = limit > 0 ? Math.min(limit, optsLength) : optsLength;
-    const regexp = new RegExp(this._escapeRegExp(str), 'i');
+    const regexp = searchFunction(str);
     const filteredOpts: IMultiSelectOption[] = [];
 
     let i = 0, founded = 0, removedFromPrevResult = 0;
@@ -127,9 +128,4 @@ export class MultiSelectSearchFilter implements PipeTransform {
   private _limitRenderedItems<T>(items: T[], limit: number): T[] {
     return items.length > limit && limit > 0 ? items.slice(0, limit) : items;
   }
-
-  private _escapeRegExp(str: string): string {
-    return str.replace(/[\-\[\]\/\{\}\(\)\*\+\?\.\\\^\$\|]/g, "\\$&");
-  }
-
 }