Fix corner case with automatic semicolon logic (#128)

* Add test cases

* Fix corner case with automatic semicolon logic

* 0.8.4

* Misc

* Account for empty lines

* Improve solution

* Add pipe operator to prefixes

* Bump mo-fmt

package.json

@@ -1,6 +1,6 @@
 {
     "name": "prettier-plugin-motoko",
-    "version": "0.8.3",
+    "version": "0.8.4",
     "description": "A code formatter for the Motoko smart contract language.",
     "main": "lib/environments/node.js",
     "browser": "lib/environments/web.js",

packages/mo-fmt/package.json

@@ -1,6 +1,6 @@
 {
     "name": "mo-fmt",
-    "version": "0.8.3",
+    "version": "0.8.4",
     "description": "An easy-to-use Motoko formatter command.",
     "main": "src/cli.js",
     "bin": {
@@ -22,7 +22,7 @@
         "commander": "^9.4.0",
         "fast-glob": "^3.2.11",
         "prettier": "^3.0",
-        "prettier-plugin-motoko": "^0.8.3"
+        "prettier-plugin-motoko": "^0.8.4"
     },
     "devDependencies": {
         "@rollup/plugin-commonjs": "^22.0.2",

src/parsers/motoko-tt-parse/preprocess.ts

@@ -2,6 +2,8 @@ import { ParserOptions } from 'prettier';
 import outOfCharacter from 'out-of-character';
 import wasm from '../../wasm';
 
+const skipAutomaticSemiForNextLinePrefixes = ['.', '|>', ')', '}', ']'];
+
 function getLineIndices(code: string): number[] {
     const indices = [];
     for (let i = 0; i < code.length; i++) {
@@ -67,6 +69,7 @@ export default function preprocess(
             .map((line, i) => {
                 const trimmedLine = line.trim();
                 if (!trimmedLine) {
+                    nextIndent = -1;
                     return line;
                 }
 
@@ -83,8 +86,14 @@ export default function preprocess(
 
                 if (
                     trimmedLine === '}' &&
-                    // Skip when part of a path expression
-                    !nextLineMaskedCommentsTrimmed.startsWith('.') &&
+                    // Skip if prefix found on next line
+                    (!nextLineMaskedCommentsTrimmed ||
+                        skipAutomaticSemiForNextLinePrefixes.every(
+                            (prefix) =>
+                                !nextLineMaskedCommentsTrimmed.startsWith(
+                                    prefix,
+                                ),
+                        )) &&
                     // Skip first block for if/else, try/catch
                     !/^(else|catch)([^a-zA-Z0-9_]|$)/.test(
                         nextLineMaskedCommentsTrimmed,

tests/formatter.test.ts

@@ -354,6 +354,11 @@ describe('Motoko formatter', () => {
             'if () {} else {};\n',
         );
         expect(await format('{\n}\n.A')).toStrictEqual('{}.A;\n');
+        expect(
+            await format('[\n  {\n  abc;\n  }\n  { 123 }\n];\n', {
+                trailingComma: 'none',
+            }),
+        ).toStrictEqual('[\n  {\n    abc;\n  },\n  { 123 }\n];\n');
     });
 
     test('automatic semicolons with line comment', async () => {
@@ -424,6 +429,34 @@ describe('Motoko formatter', () => {
         expect(await format('[\na,b]')).toStrictEqual('[\n  a,\n  b,\n];\n');
         expect(await format('[\na,]')).toStrictEqual('[\n  a,\n];\n');
         expect(await format('x : [\nT\n]')).toStrictEqual('x : [\n  T\n];\n');
+        expect(await format('x : [\n  { abc; }\n];\n')).toEqual(
+            'x : [{ abc }];\n',
+        );
+        await expectFormatted('x : [{\n  abc;\n}] = 1;\n');
+        await expectFormatted('x : [{\n  abc;\n}] = 1;\n');
+        await expectFormatted('type T = [{\n  abc;\n}];\n');
+        await expectFormatted('let x = [\n  {\n    abc;\n  },\n];\n');
+        expect(
+            await format(
+                `
+public type T = {
+  x : [
+    {
+      a : A;
+      fn : shared query A -> async T;
+    }
+  ];
+}`,
+            ),
+        ).toEqual(
+            `
+public type T = {
+  x : [{
+    a : A;
+    fn : shared query A -> async T;
+  }];
+};`.trim() + '\n',
+        );
     });
 
     test('comma-parentheses', async () => {