From f2bb8970a419245f9dd2fbb355ca98c11e10b2ed Mon Sep 17 00:00:00 2001
From: Daniil Sedov <42098239+Gusarich@users.noreply.github.com>
Date: Fri, 19 Apr 2024 17:36:31 +0800
Subject: [PATCH] feat: `isEmpty` map method (#266)

---
 CHANGELOG.md                 |  1 +
 src/abi/map.ts               | 29 +++++++++++++++++++++++++++++
 src/test/feature-map.spec.ts | 23 +++++++++++++++++++++++
 src/test/features/maps.tact  |  4 ++++
 4 files changed, 57 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 03a3f71a2..c9c092867 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Display an error for integer overflow at compile-time: PR [#200](https://github.com/tact-lang/tact/pull/200)
 - Non-modifying `StringBuilder`'s `concat` method for chained string concatenations: PR [#217](https://github.com/tact-lang/tact/pull/217)
 - `toString` extension function for `Address` type: PR [#224](https://github.com/tact-lang/tact/pull/224)
+- `isEmpty` method for `Map` type: PR [#266](https://github.com/tact-lang/tact/pull/266)
 
 ### Changed
 
diff --git a/src/abi/map.ts b/src/abi/map.ts
index 1605201f9..0c7d0f8fa 100644
--- a/src/abi/map.ts
+++ b/src/abi/map.ts
@@ -354,4 +354,33 @@ export const MapFunctions: Map<string, AbiFunction> = new Map([
             },
         },
     ],
+    [
+        "isEmpty",
+        {
+            name: "isEmpty",
+            resolve(ctx, args, ref) {
+                // Check arguments
+                if (args.length !== 1) {
+                    throwError("isEmpty expects one argument", ref); // Ignore self argument
+                }
+                const self = args[0];
+                if (!self || self.kind !== "map") {
+                    throwError("isEmpty expects a map as self argument", ref); // Should not happen
+                }
+
+                return { kind: "ref", name: "Bool", optional: false };
+            },
+            generate: (ctx, args, exprs, ref) => {
+                if (args.length !== 1) {
+                    throwError("isEmpty expects one argument", ref); // Ignore self argument
+                }
+                const self = args[0];
+                if (!self || self.kind !== "map") {
+                    throwError("isEmpty expects a map as self argument", ref); // Should not happen
+                }
+
+                return `null?(${writeExpression(exprs[0], ctx)})`;
+            },
+        },
+    ],
 ]);
diff --git a/src/test/feature-map.spec.ts b/src/test/feature-map.spec.ts
index 806683fa4..fc98a570e 100644
--- a/src/test/feature-map.spec.ts
+++ b/src/test/feature-map.spec.ts
@@ -41,6 +41,7 @@ describe("feature-map", () => {
 
             // Initial state
             expect((await contract.getIntMap1()).size).toBe(0);
+            expect(await contract.getIntMap1IsEmpty()).toBe(true);
             expect((await contract.getIntMap2()).size).toBe(0);
             expect((await contract.getIntMap3()).size).toBe(0);
             expect((await contract.getIntMap4()).size).toBe(0);
@@ -518,6 +519,28 @@ describe("feature-map", () => {
                 expect(await contract.getAddrMap7_5Value(addr)).toBe(null);
                 expect(await contract.getAddrMap7_6Value(addr)).toBe(null);
             }
+
+            // Test isEmpty
+
+            expect(await contract.getIntMap1IsEmpty()).toBe(true);
+
+            await contract.send(
+                treasure,
+                { value: toNano(1) },
+                { $$type: "SetIntMap1", key: 1n, value: 1n },
+            );
+            await system.run();
+
+            expect(await contract.getIntMap1IsEmpty()).toBe(false);
+
+            await contract.send(
+                treasure,
+                { value: toNano(1) },
+                { $$type: "SetIntMap1", key: 1n, value: null },
+            );
+            await system.run();
+
+            expect(await contract.getIntMap1IsEmpty()).toBe(true);
         } catch (e) {
             if (e instanceof ComputeError) {
                 if (e.logs) {
diff --git a/src/test/features/maps.tact b/src/test/features/maps.tact
index 522ac8aab..8d91e9644 100644
--- a/src/test/features/maps.tact
+++ b/src/test/features/maps.tact
@@ -775,4 +775,8 @@ contract MapTestContract {
     get fun mapAsCell(): Cell? {
         return self.addrMap7_6.asCell();
     }
+
+    get fun intMap1IsEmpty(): Bool {
+        return self.intMap1.isEmpty();
+    }
 }
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