Fix bug in seq where it didn't work with array results

Author: MCluck90

src/seq.ts

@@ -60,11 +60,14 @@ export function seq<T1, T2, T3, T4, T5, T6, T7, T8>(
  * @param parsers Array of parsers to match
  */
 export function seq(parsers: Parser<unknown>[]): Parser<unknown> {
-  let parser = pair(parsers[0], parsers[1]);
+  let parser: Parser<unknown[]> = pair(parsers[0], parsers[1]);
 
   for (let i = 2; i < parsers.length; i++) {
-    parser = pair(parser, parsers[i]);
+    parser = pair(parser, parsers[i]).map(([previousSet, next]) => [
+      ...previousSet,
+      next,
+    ]);
   }
 
-  return parser.map((result) => result.flat(parsers.length));
+  return parser;
 }

tests/seq.test.ts

@@ -1,6 +1,7 @@
 import { boolean } from '../src/boolean';
 import { ParseError } from '../src/error';
 import { integer } from '../src/numbers';
+import { oneOrMore, text, zeroOrMore } from '../src/parser';
 import { seq } from '../src/seq';
 import { whitespace } from '../src/whitespace';
 import { assertSuccessfulParse } from './util';
@@ -97,4 +98,15 @@ describe('seq', () => {
     assertSuccessfulParse(result);
     expect(result).toEqual([1, true, ' ', 2, false, ' ', 3, true]);
   });
+
+  test('allows mixing in array results', () => {
+    const result = seq([
+      integer,
+      oneOrMore(text('x')),
+      integer,
+      zeroOrMore(text('y')),
+    ]).parseToEnd('1xxx2y');
+    assertSuccessfulParse(result);
+    expect(result).toEqual([1, ['x', 'x', 'x'], 2, ['y']]);
+  });
 });