feat(combinators/many1): add many1 combinator

src/combinators/many.ts

@@ -20,7 +20,6 @@ export function many<T>(parser: Parser<T>): Parser<Array<T>> {
             return {
               isOk: true,
               pos: nextPos,
-              input,
               value: values
             }
           }
@@ -29,3 +28,25 @@ export function many<T>(parser: Parser<T>): Parser<Array<T>> {
     }
   }
 }
+
+export function many1<T>(parser: Parser<T>): Parser<Array<T>> {
+  return {
+    parse(input, pos) {
+      const result = many(parser).parse(input, pos)
+
+      switch (result.isOk && result.value.length > 0) {
+        case true: {
+          return result
+        }
+
+        case false: {
+          return {
+            isOk: false,
+            pos: result.pos,
+            expected: 'at least one successful application of the parser'
+          }
+        }
+      }
+    }
+  }
+}

tests/combinators/many.spec.ts

@@ -1,7 +1,7 @@
-import { many } from '@lib/combinators/many'
+import { many, many1 } from '@lib/combinators/many'
 import { string } from '@lib/parsers/string'
 
-import { run, result, should } from '@tests/@helpers'
+import { run, result, should, testFailure } from '@tests/@helpers'
 
 describe(many, () => {
   it('should succeed with an array of matched strings', () => {
@@ -20,3 +20,17 @@ describe(many, () => {
     should.matchState(actual, expected)
   })
 })
+
+describe(many1, () => {
+  it('should succeed with an array of matched strings', () => {
+    const parser = many1(string('x!'))
+    const actual = run(parser, 'x!x!x!')
+    const expected = result(true, ['x!', 'x!', 'x!'])
+
+    should.matchState(actual, expected)
+  })
+
+  it('should fail if nothing matched', () => {
+    testFailure('y!y!y!', () => many1(string('x!')))
+  })
+})