Allow blob to be empty

Author: J-Fields

src/vimscript/expression/evaluate.ts

@@ -878,8 +878,8 @@ export class EvaluationContext {
             return bool(x.items.length === 0);
           case 'dict_val':
             return bool(x.items.size === 0);
-          // TODO:
-          // case 'blob':
+          case 'blob':
+            return bool(x.data.byteLength === 0);
           default:
             return bool(false);
         }

src/vimscript/expression/parser.ts

@@ -38,7 +38,7 @@ import {
 
 // TODO: Support dots between bytes
 const blobParser: Parser<BlobValue> = regexp(/0[z]/i).then(
-  regexp(/[0-1a-z]+/i).map<BlobValue>((hexData) => {
+  regexp(/[0-1a-z]*/i).map<BlobValue>((hexData) => {
     if (hexData.length % 2 !== 0) {
       throw VimError.fromCode(ErrorCode.BlobLiteralShouldHaveAnEvenNumberOfHexCharacters);
     }

test/vimscript/expression.test.ts

@@ -589,12 +589,14 @@ suite('Vimscript expressions', () => {
       exprTest("empty('')", { value: bool(true) });
       exprTest('empty([])', { value: bool(true) });
       exprTest('empty({})', { value: bool(true) });
+      exprTest('empty(0z)', { value: bool(true) });
 
       exprTest('empty(1)', { value: bool(false) });
       exprTest('empty(1.0)', { value: bool(false) });
       exprTest("empty('xyz')", { value: bool(false) });
       exprTest('empty([0])', { value: bool(false) });
       exprTest("empty({'k': 'v'})", { value: bool(false) });
+      exprTest('empty(0z00)', { value: bool(false) });
     });
 
     suite('function', () => {