Implement stridx()

Author: J-Fields

src/vimscript/expression/evaluate.ts

@@ -1195,15 +1195,19 @@ export class EvaluationContext {
       }
       case 'str2nr': {
         const [s, _base] = getArgs(1, 2);
-        const base = _base ? toInt(_base) : 10
+        const base = _base ? toInt(_base) : 10;
         if (![2, 8, 10, 16].includes(base)) {
           throw VimError.fromCode(ErrorCode.InvalidArgument474);
         }
         // TODO: Skip prefixes like 0x
-        const parsed = Number.parseInt(toString(s!), base)
+        const parsed = Number.parseInt(toString(s!), base);
         return int(isNaN(parsed) ? 0 : parsed);
       }
-      // TODO: stridx()
+      case 'stridx': {
+        const [haystack, needle, start] = getArgs(2, 3);
+
+        return int(toString(haystack!).indexOf(toString(needle!), start ? toInt(start) : 0));
+      }
       case 'string': {
         const [x] = getArgs(1);
         return str(displayValue(x!));

test/vimscript/expression.test.ts

@@ -743,6 +743,12 @@ suite('Vimscript expressions', () => {
       exprTest('str2nr("DEADBEEF", 9)', { error: ErrorCode.InvalidArgument474 });
     });
 
+    suite('stridx', () => {
+      exprTest('stridx("0123456789", "6")', { value: int(6) });
+      exprTest('stridx("0123456789", "456")', { value: int(4) });
+      exprTest('stridx("0123456789", "X")', { value: int(-1) });
+    });
+
     suite('string', () => {
       exprTest('string("")', { value: str('') });
       exprTest('string(123)', { value: str('123') });