feat(filter): add filter unique (#11)

packages/environment/src/filters.ts

@@ -1562,6 +1562,87 @@ export const tojson = nunjucksFunction(["o", "indent"])(function tojson(
   );
 });
 
+function syncUnique(
+  evalCtx: EvalContext,
+  value: unknown,
+  caseSensitive: boolean = false,
+  attribute: string | number | null = null,
+): unknown[] {
+  let arr = syncList(value);
+
+  if (attribute !== null) {
+    arr = arr.map(syncMakeAttrGetter(evalCtx.environment, attribute));
+  }
+
+  const res: unknown[] = [];
+
+  for (const item of arr) {
+    if (
+      !res.some((x) =>
+        caseSensitive ? x === item : ignoreCase(x) === ignoreCase(item),
+      )
+    )
+      res.push(item);
+  }
+
+  return res;
+}
+
+async function asyncUnique(
+  evalCtx: EvalContext,
+  value: unknown,
+  caseSensitive: boolean = false,
+  attribute: string | number | null = null,
+): Promise<unknown[]> {
+  const arr = await asyncList(value);
+
+  if (attribute !== null) {
+    const attrGetter = asyncMakeAttrGetter(evalCtx.environment, attribute);
+    for (let i = 0; i < arr.length; i++) {
+      arr[i] = await attrGetter(arr[i]);
+    }
+  }
+  return syncUnique(evalCtx, arr, caseSensitive);
+}
+
+const doUnique: {
+  (
+    evalCtx: EvalContext<true>,
+    value: unknown,
+    caseSensitive: boolean,
+    attribute: string | number | null,
+  ): Promise<unknown>;
+  (
+    evalCtx: EvalContext<false>,
+    value: unknown,
+    caseSensitive: boolean,
+    attribute: string | number | null,
+  ): unknown;
+} = (
+  evalCtx: EvalContext,
+  value: unknown,
+  caseSensitive: boolean = false,
+  attribute: string | number | null = null,
+): any => {
+  return evalCtx.isAsync()
+    ? asyncUnique(evalCtx, value, caseSensitive, attribute)
+    : syncUnique(evalCtx, value, caseSensitive, attribute);
+};
+
+/**
+ * Returns a list of unique items from the given iterable.
+ *
+ * @param value The iterable to get unique items from.
+ * @param case_sensitive Treat upper and lower case strings as distinct.
+ * @param attribute Filter objects with unique values for this attribute.
+ */
+export const unique = nunjucksFunction(
+  ["value", "case_sensitive", "attribute"],
+  {
+    passArg: "evalContext",
+  },
+)(doUnique);
+
 export default {
   abs,
   // attr,
@@ -1609,7 +1690,7 @@ export default {
   title,
   trim,
   truncate,
-  // unique,
+  unique,
   upper,
   urlencode,
   urlize,

test/asyncFilters.test.ts

@@ -1,7 +1,17 @@
 import { Environment } from "@nunjucks/environment";
-import { markSafe } from "@nunjucks/runtime";
+import { markSafe, str } from "@nunjucks/runtime";
 import { describe, expect, it } from "@jest/globals";
 
+class Magic {
+  value: any;
+  constructor(value: any) {
+    this.value = value;
+  }
+  toString() {
+    return str(this.value);
+  }
+}
+
 async function* asyncGen<T>(
   iter: Iterable<T>,
 ): AsyncGenerator<T, void, unknown> {
@@ -171,4 +181,27 @@ describe("filters in async environment", () => {
     );
     expect(await tmpl.render({ users })).toBe("john|jane");
   });
+
+  describe("unique", () => {
+    it("basic", async () => {
+      const items = () => asyncGen(["b", "A", "a", "b"]);
+      const tmpl = env.fromString("{{ items()|unique|join }}");
+      expect(await tmpl.render({ items })).toBe("bA");
+    });
+
+    it("case sensitive", async () => {
+      const items = () => asyncGen("bAab");
+      const tmpl = env.fromString("{{ items()|unique(true)|join }}");
+      expect(await tmpl.render({ items })).toBe("bAa");
+    });
+
+    it("attribute", async () => {
+      const items = () =>
+        asyncGen([3, 2, 4, 1, 2].map((val) => new Magic(val)));
+      const tmpl = env.fromString(
+        "{{ items()|unique(attribute='value')|join }}",
+      );
+      expect(await tmpl.render({ items })).toBe("3241");
+    });
+  });
 });

test/filters.test.ts

@@ -562,17 +562,17 @@ describe("filters", () => {
     });
   });
 
-  describe.skip("unique", () => {
+  describe("unique", () => {
     it("basic", () => {
-      const tmpl = env.fromString('{{ "".join(["b", "A", "a", "b"]|unique) }}');
+      const tmpl = env.fromString('{{ ["b", "A", "a", "b"]|unique|join }}');
       expect(tmpl.render()).toBe("bA");
     });
+
     it("case sensitive", () => {
-      const tmpl = env.fromString(
-        '{{ "".join(["b", "A", "a", "b"]|unique(true)) }}',
-      );
+      const tmpl = env.fromString('{{ "bAab"|unique(true)|join }}');
       expect(tmpl.render()).toBe("bAa");
     });
+
     it("attribute", () => {
       const items = [3, 2, 4, 1, 2].map((val) => new Magic(val));
       const tmpl = env.fromString("{{ items|unique(attribute='value')|join }}");