From ce07cbc8dad85886d6f331610fb01010f5c6e34f Mon Sep 17 00:00:00 2001
From: Florian Schroedl <flo.schroedl@gmail.com>
Date: Thu, 20 Jan 2022 17:00:00 +0100
Subject: [PATCH] Parser transformation

---
 src/test.nim | 102 ++++++++++++++++++++++++++-------------------------
 1 file changed, 53 insertions(+), 49 deletions(-)

diff --git a/src/test.nim b/src/test.nim
index 95191fd..5857f8c 100644
--- a/src/test.nim
+++ b/src/test.nim
@@ -37,7 +37,7 @@ type
   ParserResult* = Result[Parser, ParserError]
 
   Builder*[T] = tuple[
-    parser: ParserResult,
+    parser: Parser,
     tree: seq[T]
   ]
   BuilderResult*[T] = Result[Builder[T], (Builder[T], string)]
@@ -109,7 +109,7 @@ proc `$`*(x: ParserError): string =
 {errSpace}^ Expected '{expected}' but got '{unexpected}'"""
     else: "ParseError"
 
-proc initParser(str: string): ParserResult =
+proc initParser(str: string): Parser =
   Parser(
     state: ParserState(
       stream: str,
@@ -117,7 +117,7 @@ proc initParser(str: string): ParserResult =
       lastPosition: 0,
     ),
     tokens: newSeq[Token](),
-  ).ok()
+  )
 
 func ch(expectedChars: set[char]): (Parser -> ParserResult) {.inline.} =
   return func(parser: Parser): ParserResult =
@@ -262,67 +262,71 @@ proc foldTokens[T](
     let err = parserResult.error()
     onError(err)
 
+proc merge[T](t: Builder[T], parser: Parser, tree: seq[T]): Builder[T] =
+  Builder[T]((
+    parser,
+    tree
+  ))
 
-# proc mapTree[T](builder: BuilderResult[T], fn: Builder[T] -> Builder[T]) =
-#   builder.map(proc(b: Builder) =
-#                 (@parser, @builder) := builder
-#                 b
-#   )
+proc applyParsers[T](
+  builder: Builder[T],
+  parsers: seq[Parser -> ParserResult],
+  tokenFoldFn: (seq[Token], seq[T]) -> seq[T],
+): BuilderResult[T] =
+  # proc nested(b: Builder[T]): BuilderResult[T] =
+  let newParser = ParserResult.ok(Parser(
+    state: builder[0].state,
+    tokens: @[]
+  ))
+  .parseSeq(parsers)
 
-# proc applyParserTokens[T](builder: BuilderResult, fn: seq[Token] -> T): BuilderResult =
-#   (@parser, @builder) := builder
-#   parser.foldTokens(
-#     proc(x: ParserError): BuilderResult = err(x),
-#     proc(xs: seq[Token]): BuilderResult = ok(parser, builder.map()),
-#   )
+  newParser
+  .foldTokens(
+    (err: ParserError) => BuilderResult[T].err((builder, "foo")),
+    (newTokens: seq[Token]) => BuilderResult[T].ok(
+      builder.merge(newParser.unsafeGet(), tokenFoldFn(newTokens, builder[1]))
+    ),
+  )
+
+proc mapTree[T](builder: BuilderResult[T], fn: seq[T] -> seq[T]): BuilderResult[T] =
+  builder.map(proc(b: Builder[T]): Builder[T] = Builder((
+    parser: b[0],
+    tree: fn(b[1]),
+  )))
 
 
 when isMainModule:
-  # let fooParser = initParser("FOO___BAR")
-  # .parseSeq(@[
-  #   str("FOO"),
-  #   ignore(str("___")),
-  #   ch('B'),
-  #   ch('B'),
-  #   ch('A'),
-  #   ch('R'),
-  # ])
-  # .foldTokens(
-  #   err => $err,
-  #   xs => xs.foldl(a & b.value, "")
-  # )
-
-  # echo initParser("BB").parseSeq(@[
-  #   choice(@[ch(Digits), ch('B')]),
-  # ])
-
   let parseHeadingStars = @[
     manyUntil(ch('*'), ch(' ')),
     ignore(ch(' '))
   ]
-  # proc buildHeadingStars(stars: ParserResult, builder: OrgElement): OrgElement =
-  #   builder.level = stars.get().len
-
-  # let todoKeywords = @[
-  #   "TODO",
-  # ]
-  # let todoDoneKeywords = @[
-  #   "DONE",
-  # ]
-  # let parseHeadingTodo = @[
-
-  # ]
 
   # let buildHeadingStars =
-  type StringBuilder = BuilderResult[string]
+  type StringBuilderT = string
+  type StringBuilder = Builder[StringBuilderT]
+  type StringBuilderResult = BuilderResult[StringBuilderT]
 
-  let sampleBuilder: StringBuilder = StringBuilder.ok(Builder((
-    parser: initParser(""),
-    tree: newSeq[string](),
+  proc stringConcat(typeInfo: StringBuilderT):
+                   (seq[Token], seq[StringBuilderT]) -> seq[StringBuilderT] =
+    return proc(xs: seq[Token], ys: seq[StringBuilderT]): seq[StringBuilderT] =
+      return ys & xs.foldl(a & b.value, typeInfo)
+
+  let sampleBuilder: StringBuilderResult = StringBuilderResult
+  .ok(StringBuilder((
+    parser: initParser("**** Some stars"),
+    tree: newSeq[StringBuilderT](),
   )))
+  .flatMap((x: StringBuilder) => x.applyParsers(
+    parsers = parseHeadingStars,
+    tokenFoldFn = stringConcat("Stars: ")
+  ))
+  .flatMap((x: StringBuilder) => x.applyParsers(
+    parsers = parseHeadingStars,
+    tokenFoldFn = stringConcat("Stars: ")
+  ))
+
 
   echo sampleBuilder
-  # .mapTree((x: string) => x)
 
 
   # @[