From 678cc6cf72a79e6c71416623a3f6bd0634cd8c11 Mon Sep 17 00:00:00 2001
From: Adi Fatkhurozi <ady.fatkhurozi@gmail.com>
Date: Wed, 25 Oct 2023 09:43:11 +0700
Subject: [PATCH] fix: enhance function expression

---
 src/createParser.ts    | 40 ++++++++++++++++++++++++++++++++++++++++
 src/test/index.test.ts | 25 +++++++++++++++++++++++--
 2 files changed, 63 insertions(+), 2 deletions(-)

diff --git a/src/createParser.ts b/src/createParser.ts
index 50452e2..92a46b4 100644
--- a/src/createParser.ts
+++ b/src/createParser.ts
@@ -166,6 +166,46 @@ export function createParser(props: ExpressionParserConstructor = {}) {
 
       return filteredItems;
     },
+    unique: (state, items: any[], filterExpression?: string) => {
+      const filteredItems = items?.reduce(
+        (uniqueList: any[], item: any, index) => {
+          if (!filterExpression) {
+            if (uniqueList.includes(item)) return uniqueList;
+            return [...uniqueList, item]
+          } else {
+            const hasIncluded = uniqueList.some((uniqueItem) => {
+              const uniqueItemValue = parser.evaluate(
+                filterExpression,
+                {
+                  ...state.variables,
+                  _item_: uniqueItem,
+                  _index_: index
+                }
+              )
+              const currValue = parser.evaluate(
+                filterExpression,
+                {
+                  ...state.variables,
+                  _item_: item,
+                  _index_: index
+                }
+              )
+              return uniqueItemValue === currValue
+            })
+
+            if (hasIncluded) {
+              return uniqueList;
+            } else {
+              return [...uniqueList, item]
+            }
+          }
+        },
+        []
+      );
+
+      return filteredItems;
+
+    }
   }
 
   parser.setFunctions(functions)
diff --git a/src/test/index.test.ts b/src/test/index.test.ts
index b2e61f1..26a8a2d 100644
--- a/src/test/index.test.ts
+++ b/src/test/index.test.ts
@@ -52,12 +52,31 @@ describe('example', () => {
   })
   it('array method', () => {
     const parser = createParser();
+
+    expect(
+      parser.evaluate('unique(products)', {
+        products: [1, 1, 4, 5, 6, 6, 7, 7, 8, 8]
+      })
+    ).toEqual([1, 4, 5, 6, 7, 8])
+
     const products = [
       { name: 'Product 1', price: 150, quantity: 2 },
       { name: 'Product 2', price: 80, quantity: 0 },
       { name: 'Product 3', price: 200, quantity: 5 },
+      { name: 'Product 4', price: 120, quantity: 1 },
       { name: 'Product 4', price: 120, quantity: 1 }
     ];
+    expect(
+      parser.evaluate('unique(products, "_item_.name")', {
+        products
+      })
+    ).toEqual([
+      { name: 'Product 1', price: 150, quantity: 2 },
+      { name: 'Product 2', price: 80, quantity: 0 },
+      { name: 'Product 3', price: 200, quantity: 5 },
+      { name: 'Product 4', price: 120, quantity: 1 },
+    ])
+
     expect(
       parser.evaluate('filter(products, "_item_.price > 100 and _item_.quantity > 0")', {
         products
@@ -65,7 +84,8 @@ describe('example', () => {
     ).toEqual([
       { name: 'Product 1', price: 150, quantity: 2 },
       { name: 'Product 3', price: 200, quantity: 5 },
-      { name: 'Product 4', price: 120, quantity: 1 }
+      { name: 'Product 4', price: 120, quantity: 1 },
+      { name: 'Product 4', price: 120, quantity: 1 },
     ])
 
     expect(
@@ -77,6 +97,7 @@ describe('example', () => {
       'Product 2',
       'Product 3',
       'Product 4',
+      'Product 4',
     ])
 
     expect(
@@ -99,7 +120,7 @@ describe('example', () => {
       parser.evaluate('reduce(products, "_curr_ + _item_.price", 0)', {
         products
       })
-    ).toBe(550)
+    ).toBe(670)
   })
   it('object', () => {
     const parser = createParser();