From 6c77594dafb3ecddd77b463a0b9fbfbaf622f198 Mon Sep 17 00:00:00 2001
From: Florian Schroedl <flo.schroedl@gmail.com>
Date: Sat, 15 Oct 2022 10:30:45 +0200
Subject: [PATCH] Migrate tryParser functions

---
 src_v2/parser/builder_api.nim | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/src_v2/parser/builder_api.nim b/src_v2/parser/builder_api.nim
index f97aaa6..b7546e4 100644
--- a/src_v2/parser/builder_api.nim
+++ b/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[