Implement try-catch statements

CHANGELOG.md

@@ -13,6 +13,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Reserve mode constants in `@stdlib/reserve`, namely `ReserveExact`, `ReserveAllExcept`, `ReserveAtMost`, `ReserveAddOriginalBalance`, `ReserveInvertSign`, `ReserveBounceIfActionFail`: PR [#173](https://github.com/tact-lang/tact/pull/173)
 - JSON Schema for `tact.config.json`: PR [#194](https://github.com/tact-lang/tact/pull/194)
 - Display an error for integer overflow at compile-time: PR [#200](https://github.com/tact-lang/tact/pull/200)
+- Try-Catch statements: PR [#212](https://github.com/tact-lang/tact/pull/212)
 - 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)
 - Bitwise XOR operation (`^`): PR [#238](https://github.com/tact-lang/tact/pull/238)

src/generator/writers/writeFunction.ts

@@ -169,6 +169,30 @@ export function writeStatement(
         });
         ctx.append(`}`);
         return;
+    } else if (f.kind === "statement_try") {
+        ctx.append(`try {`);
+        ctx.inIndent(() => {
+            for (const s of f.statements) {
+                writeStatement(s, self, returns, ctx);
+            }
+        });
+        ctx.append("} catch (_) { }");
+        return;
+    } else if (f.kind === "statement_try_catch") {
+        ctx.append(`try {`);
+        ctx.inIndent(() => {
+            for (const s of f.statements) {
+                writeStatement(s, self, returns, ctx);
+            }
+        });
+        ctx.append(`} catch (_, ${id(f.catchName)}) {`);
+        ctx.inIndent(() => {
+            for (const s of f.catchStatements) {
+                writeStatement(s, self, returns, ctx);
+            }
+        });
+        ctx.append(`}`);
+        return;
     }
 
     throw Error("Unknown statement kind");

src/grammar/ast.ts

@@ -474,6 +474,22 @@ export type ASTStatementRepeat = {
     ref: ASTRef;
 };
 
+export type ASTStatementTry = {
+    kind: "statement_try";
+    id: number;
+    statements: ASTStatement[];
+    ref: ASTRef;
+};
+
+export type ASTStatementTryCatch = {
+    kind: "statement_try_catch";
+    id: number;
+    statements: ASTStatement[];
+    catchName: string;
+    catchStatements: ASTStatement[];
+    ref: ASTRef;
+};
+
 //
 // Unions
 //
@@ -487,7 +503,9 @@ export type ASTStatement =
     | ASTCondition
     | ASTStatementWhile
     | ASTStatementUntil
-    | ASTStatementRepeat;
+    | ASTStatementRepeat
+    | ASTStatementTry
+    | ASTStatementTryCatch;
 export type ASTNode =
     | ASTExpression
     | ASTStruct
@@ -514,6 +532,8 @@ export type ASTNode =
     | ASTStatementWhile
     | ASTStatementUntil
     | ASTStatementRepeat
+    | ASTStatementTry
+    | ASTStatementTryCatch
     | ASTReceive
     | ASTLvalueRef
     | ASTString
@@ -728,6 +748,19 @@ export function traverse(node: ASTNode, callback: (node: ASTNode) => void) {
             traverse(e, callback);
         }
     }
+    if (node.kind === "statement_try") {
+        for (const e of node.statements) {
+            traverse(e, callback);
+        }
+    }
+    if (node.kind === "statement_try_catch") {
+        for (const e of node.statements) {
+            traverse(e, callback);
+        }
+        for (const e of node.catchStatements) {
+            traverse(e, callback);
+        }
+    }
     if (node.kind === "op_binary") {
         traverse(node.left, callback);
         traverse(node.right, callback);

src/grammar/clone.ts

@@ -113,6 +113,17 @@ export function cloneNode<T extends ASTNode>(src: T): T {
             condition: cloneNode(src.condition),
             statements: src.statements.map(cloneNode),
         });
+    } else if (src.kind === "statement_try") {
+        return cloneASTNode({
+            ...src,
+            statements: src.statements.map(cloneNode),
+        });
+    } else if (src.kind === "statement_try_catch") {
+        return cloneASTNode({
+            ...src,
+            statements: src.statements.map(cloneNode),
+            catchStatements: src.catchStatements.map(cloneNode),
+        });
     } else if (src.kind === "def_function") {
         return cloneASTNode({
             ...src,

src/grammar/grammar.ohm

@@ -97,6 +97,7 @@ Tact {
               | StatementWhile
               | StatementRepeat
               | StatementUntil
+              | StatementTry
     StatementBlock = "{" Statement* "}"
     StatementLet = let id ":" Type "=" Expression ";"
     StatementReturn = return Expression ";" --withExpression
@@ -119,6 +120,8 @@ Tact {
     StatementWhile = while "(" Expression ")" "{" Statement* "}"
     StatementRepeat = repeat "(" Expression ")" "{" Statement* "}"
     StatementUntil = do "{" Statement* "}" until "(" Expression ")" ";"
+    StatementTry = try "{" Statement* "}" ~catch --simple
+                 | try "{" Statement* "}" catch "(" id ")" "{" Statement* "}" --withCatch
 
     // L-value
     LValue = id "." LValue --more
@@ -262,6 +265,8 @@ Tact {
             | repeat 
             | do 
             | until 
+            | try
+            | catch
             | as  
             | mutates
             | extends
@@ -288,6 +293,8 @@ Tact {
     repeat = "repeat" ~idPart
     do = "do" ~idPart
     until = "until" ~idPart
+    try = "try" ~idPart
+    catch = "catch" ~idPart
     as = "as" ~idPart
     mutates = "mutates" ~idPart
     extends = "extends" ~idPart

src/grammar/grammar.ts

@@ -823,6 +823,34 @@ semantics.addOperation<ASTNode>("resolve_statement", {
             ref: createRef(this),
         });
     },
+    StatementTry_simple(_arg0, _arg1, arg2, _arg3) {
+        return createNode({
+            kind: "statement_try",
+            statements: arg2.children.map((v) => v.resolve_statement()),
+            ref: createRef(this),
+        });
+    },
+    StatementTry_withCatch(
+        _arg0,
+        _arg1,
+        arg2,
+        _arg3,
+        _arg4,
+        _arg5,
+        arg6,
+        _arg7,
+        _arg8,
+        arg9,
+        _arg10,
+    ) {
+        return createNode({
+            kind: "statement_try_catch",
+            statements: arg2.children.map((v) => v.resolve_statement()),
+            catchName: arg6.sourceString,
+            catchStatements: arg9.children.map((v) => v.resolve_statement()),
+            ref: createRef(this),
+        });
+    },
 });
 
 // LValue

src/test/__snapshots__/feature-try-catch.spec.ts.snap

@@ -0,0 +1,103 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`feature-ternary should implement try-catch statements correctly 1`] = `
+[
+  {
+    "$seq": 1,
+    "events": [
+      {
+        "$type": "storage-charged",
+        "amount": "0.000000007",
+      },
+      {
+        "$type": "received",
+        "message": {
+          "body": {
+            "text": "increment",
+            "type": "text",
+          },
+          "bounce": true,
+          "from": "@treasure(treasure)",
+          "to": "kQAZccETl-kyR0WEGf-7CT-k7zXmJGLmD8_jF9zsGay7wpHn",
+          "type": "internal",
+          "value": "10",
+        },
+      },
+      {
+        "$type": "processed",
+        "gasUsed": 3929n,
+      },
+    ],
+  },
+  {
+    "$seq": 2,
+    "events": [
+      {
+        "$type": "storage-charged",
+        "amount": "0.000000007",
+      },
+      {
+        "$type": "received",
+        "message": {
+          "body": {
+            "text": "incrementTryCatch",
+            "type": "text",
+          },
+          "bounce": true,
+          "from": "@treasure(treasure)",
+          "to": "kQAZccETl-kyR0WEGf-7CT-k7zXmJGLmD8_jF9zsGay7wpHn",
+          "type": "internal",
+          "value": "10",
+        },
+      },
+      {
+        "$type": "processed",
+        "gasUsed": 4507n,
+      },
+    ],
+  },
+  {
+    "$seq": 3,
+    "events": [
+      {
+        "$type": "storage-charged",
+        "amount": "0.000000007",
+      },
+      {
+        "$type": "received",
+        "message": {
+          "body": {
+            "text": "tryCatchRegisters",
+            "type": "text",
+          },
+          "bounce": true,
+          "from": "@treasure(treasure)",
+          "to": "kQAZccETl-kyR0WEGf-7CT-k7zXmJGLmD8_jF9zsGay7wpHn",
+          "type": "internal",
+          "value": "10",
+        },
+      },
+      {
+        "$type": "processed",
+        "gasUsed": 12023n,
+      },
+      {
+        "$type": "sent",
+        "messages": [
+          {
+            "body": {
+              "text": "hello world 1",
+              "type": "text",
+            },
+            "bounce": true,
+            "from": "kQAZccETl-kyR0WEGf-7CT-k7zXmJGLmD8_jF9zsGay7wpHn",
+            "to": "@treasure(treasure)",
+            "type": "internal",
+            "value": "9.986741",
+          },
+        ],
+      },
+    ],
+  },
+]
+`;

src/test/feature-try-catch.spec.ts

@@ -0,0 +1,47 @@
+import { toNano } from "@ton/core";
+import { ContractSystem } from "@tact-lang/emulator";
+import { __DANGER_resetNodeId } from "../grammar/ast";
+import { TryCatchTester } from "./features/output/try-catch_TryCatchTester";
+
+describe("feature-ternary", () => {
+    beforeEach(() => {
+        __DANGER_resetNodeId();
+    });
+    it("should implement try-catch statements correctly", async () => {
+        // Init
+        const system = await ContractSystem.create();
+        const treasure = system.treasure("treasure");
+        const contract = system.open(await TryCatchTester.fromInit());
+        await contract.send(treasure, { value: toNano("10") }, null);
+        await system.run();
+
+        // Check methods
+        expect(await contract.getTestTryCatch1()).toEqual(7n);
+        expect(await contract.getTestTryCatch2()).toEqual(101n);
+        expect(await contract.getTestTryCatch3()).toEqual(4n);
+
+        // Check state rollbacks
+        const tracker = system.track(contract);
+
+        expect(await contract.getGetCounter()).toEqual(0n);
+        await contract.send(treasure, { value: toNano("10") }, "increment");
+        await system.run();
+        expect(await contract.getGetCounter()).toEqual(1n);
+        await contract.send(
+            treasure,
+            { value: toNano("10") },
+            "incrementTryCatch",
+        );
+        await system.run();
+        expect(await contract.getGetCounter()).toEqual(1n);
+        await contract.send(
+            treasure,
+            { value: toNano("10") },
+            "tryCatchRegisters",
+        );
+        await system.run();
+        expect(await contract.getGetCounter()).toEqual(2n);
+
+        expect(tracker.collect()).toMatchSnapshot();
+    });
+});