Migrate tryParser functions

src_v2/parser/builder_api.nim

@@ -14,6 +14,30 @@ import ./parser_api
 
 # -- Builder API
 
+proc tryParser*[T](
+  builder: Builder[T],
+  parser: Parser -> ParserResult,
+): BuilderResult[T] =
+  ## Try out a `parser` on a `builder`
+  ## When succesful return the original builder, otherwise return an error
+  ParserResult.ok(Parser(
+    state: builder[0].state,
+    tokens: @[]
+  ))
+  .flatMap(parser)
+  .foldTokens(
+    (err: ParserError) => BuilderResult[T].err((builder, "Error")),
+    (newTokens: seq[ParserToken]) => BuilderResult[T].ok(builder),
+  )
+
+proc tryParser*[T](
+  builder: BuilderResult[T],
+  parser: Parser -> ParserResult,
+): BuilderResult[T] =
+  ## Try out a `parser` on a `builder` result
+  ## When succesful return the ok builder, otherwise return an error
+  builder.flatMap((x: Builder[T]) => tryParser(x, parser))
+
 proc tryTokenize*[T](
   builder: Builder[T],
   builderFns: seq[tuple[