Started refactor

2022-08-09 22:07:30 +02:00
parent 9b0ad40f55
commit 892eec10d5
10 changed files with 1048 additions and 0 deletions
--- a/src_v2/parser/builder_api.nim
+++ b/src_v2/parser/builder_api.nim
@@ -0,0 +1,92 @@
+import std/sugar
+import std/collections/sequtils
+import std/strformat
+import std/strutils
+import results
+import fusion/matching
+import ./parser_internals
+import ./parser_types
+
+# proc tryParseBuildOrg*[T](
+#   builder: Builder[T],
+#   builderFns: seq[
+#     Builder[T] -> BuilderResult[T]
+#   ],
+#   stopAtParserFn = endOfStream
+# ): BuilderResult[T] =
+
+#   # Mutating accumulators
+#   var builderAcc: BuilderResult[T] = BuilderResult.ok(builder)
+
+#   while builderAcc.isOk() and builderAcc.tryParser(stopAtParserFn).isErr()
+#     for fn in builderFns:
+#       fn
+
+proc tryParseBuild*[T](
+  builder: Builder[T],
+  builderFns: seq[tuple[
+    parserFn: Parser -> ParserResult,
+    builderFn: seq[ParserToken] -> seq[T],
+  ]],
+  defaultBuilderFn: seq[ParserToken] -> seq[T],
+  stopAtParserFn = newline,
+  concatFn = concat[T],
+): BuilderResult[T] =
+  ## Parse text in `builder` by checking the `builderFns` list for a sucessful `parserFn`.
+  ## The `ok` `parserFn` result will be merged into the `Builder[T].tree` by using the `concatFn`.
+  ## Otherwise continue taking any character until the `stopAtParserFn` condition is found.
+  ## Any non-matching tokens will be converted using the `defaultBuilderFn`.
+  let (parser, tree) = builder
+
+  # Mutating accumulators
+  var parserAcc: ParserResult = ParserResult.ok(parser)
+  var builderAcc: Builder[T] = builder
+
+  while parserAcc.isOk() and parserAcc.flatMap(stopAtParserFn).isErr():
+    # Empty the parser tokens as we want to seperate them for the next parser in the sequence
+    let emptyParser = parserAcc.map(emptyTokens)
+
+    # Find the first matching parser and convert its tokens
+    var found = false
+    for fn in builderFns:
+      let (parserFn, builderFn) = fn
+
+      let parseResult = emptyParser.flatMap(parserFn)
+      if parseResult.isOk():
+        let okParser = parseResult.unsafeGet()
+
+        # Convert all previous unmatched tokens via the `defaultBuilderTokens`
+        let defaultBuilderTokens = parserAcc
+        .foldTokens(
+          onError = _ => newSeq[T](),
+          onSuccess = defaultBuilderFn,
+        )
+
+        found = true
+        parserAcc = parseResult.map(emptyTokens)
+        builderAcc = builder.initBuilder(
+          okParser,
+          concatFn(
+            builderAcc.tree,
+            defaultBuilderTokens,
+            builderFn(okParser.tokens),
+          )
+        )
+        break
+
+    if not found:
+      parserAcc = parserAcc.flatMap(anyCh)
+
+  let defaultBuilderTokens = parserAcc
+  .foldTokens(
+    onError = _ => newSeq[T](),
+    onSuccess = defaultBuilderFn,
+  )
+
+  BuilderResult[T].ok(builder.initBuilder(
+    builderAcc.parser,
+    concatFn(
+      builderAcc.tree,
+      defaultBuilderTokens,
+    ),
+  ))
--- a/src_v2/parser/parser_internals.nim
+++ b/src_v2/parser/parser_internals.nim
@@ -0,0 +1,242 @@
+import std/[
+  options,
+  strutils,
+  strformat,
+  collections/sequtils,
+  sugar,
+]
+import results
+import fp/[
+  maybe,
+]
+import ../utils/str
+import ./parser_types
+
+# -- Types
+
+type parserFnT = proc(t0: Parser): ParserResult {.nosideeffect.}
+
+# -- Utilities
+
+func lookBack*(count: int): (parserFnT) =
+  return func(parser: Parser): ParserResult =
+    let state = parser.state
+    let newIndex = state.position - 1
+
+    Parser(
+      state: ParserState(
+        stream: state.stream,
+        position: newIndex,
+        lastPosition: parser.state.position,
+      ),
+      tokens: parser.tokens,
+    ).ok()
+
+# -- Parsing Functions
+
+func ch*(expectedChars: set[char]): parserFnT {.inline.} =
+  return func(parser: Parser): ParserResult =
+    let state = parser.state
+    let newIndex = state.position + 1
+
+    if newIndex > (state.stream.len - 1):
+      return err(ParserError(
+        kind: endOfStringErr,
+        expected: &"{expectedChars.prettyExpectedSet()}",
+        index: newIndex,
+        parser: parser,
+      ))
+    else:
+      let foundChar = state.stream[newIndex]
+      if foundChar in expectedChars:
+        return Parser(
+          state: ParserState(
+            stream: state.stream,
+            position: newIndex,
+            lastPosition: parser.state.position,
+          ),
+          tokens: parser.tokens & initParserToken(foundChar)
+        ).ok()
+      else:
+        return err(ParserError(
+          kind: charMismatchErr,
+          unexpected: &"{foundChar}",
+          expected: &"{expectedChars.prettyExpectedSet()}",
+          index: newIndex,
+          parser: parser,
+        ))
+
+func ch*(expectedChar: char): parserFnT {.inline.} =
+  return func(parser: Parser): ParserResult =
+    let state = parser.state
+    let newIndex = state.position + 1
+
+    if newIndex > (state.stream.len - 1):
+      return err(ParserError(
+        kind: endOfStringErr,
+        expected: &"{expectedChar}",
+        index: newIndex,
+        parser: parser,
+      ))
+    else:
+      let foundChar = state.stream[newIndex]
+      if expectedChar == foundChar:
+        return Parser(
+          state: ParserState(
+            stream: state.stream,
+            position: newIndex,
+            lastPosition: parser.state.position,
+          ),
+          tokens: parser.tokens & initParserToken(foundChar)
+        ).ok()
+      else:
+        return err(ParserError(
+          kind: charMismatchErr,
+          unexpected: &"{foundChar}",
+          expected: &"{expectedChar}",
+          index: newIndex,
+          parser: parser,
+        ))
+
+const anyCh* = ch(AllChars)
+
+func str*(s: string): parserFnT {.inline.} =
+  return func(parser: Parser): ParserResult =
+    var p = parser.ok()
+    for c in s.items:
+      p = p.flatMap(ch(c))
+    return p
+
+# -- Parsing API
+
+func optional*(parserFn: parserFnT): parserFnT {.inline.} =
+  ## Parse characters and ignore failure
+  return func(parser: Parser): ParserResult =
+    let newParser = parserFn(parser)
+
+    if newParser.isOk():
+      newParser
+    else:
+      parser.ok()
+
+func ignore*(parserFn: parserFnT): parserFnT {.inline.} =
+  ## Parse characters but throw success tokens away
+  return func(parser: Parser): ParserResult =
+    return parserFn(parser)
+    .map((x: Parser) => Parser(
+      state: x.state,
+      tokens: parser.tokens,
+    ))
+
+func manyUntilPerformant*(acceptFn: parserFnT, stopFn: parserFnT): parserFnT {.inline.} =
+  ## Parse characters but throw success tokens away
+  return func(parser: Parser): ParserResult =
+    let startPosition = parser.state.position
+    var res: ParserResult = parser.ok()
+
+    while res.isOk() and res.flatMap(stopFn).isErr():
+      res = res.flatMap(acceptFn)
+
+    return res.map((p: Parser) => Parser(
+      state: ParserState(
+        stream: p.state.stream,
+        position: p.state.position,
+        lastPosition: p.state.lastPosition,
+      ),
+      tokens: @[
+        ParserToken(
+          kind: parserTokenString,
+          stringValue: p.state.stream[(startPosition - 1)..p.state.position],
+        )
+      ]
+    ))
+
+func anyUntilPerformant*(stopFn: parserFnT): parserFnT {.inline.} =
+  manyUntilPerformant(ch(AllChars), stopFn)
+
+func manyUntil*(acceptFn: parserFnT, stopFn: parserFnT): parserFnT {.inline.} =
+  ## Parse characters but throw success tokens away
+  return func(parser: Parser): ParserResult =
+    var res: ParserResult = parser.ok()
+    while res.isOk() and res.flatMap(stopFn).isErr():
+      res = res.flatMap(acceptFn)
+    return res
+
+func anyUntil*(stopFn: parserFnT): parserFnT {.inline.} =
+  manyUntil(anyCh, stopFn)
+
+func choice*(parsers: seq[parserFnT]): parserFnT {.inline} =
+  return func(parser: Parser): ParserResult {.closure, nosideeffect.} =
+    var errors: seq[ParserResult] = newSeq[ParserResult]()
+    var found = Nothing[ParserResult]()
+
+    for fn in parsers:
+      let fnResult: ParserResult = fn(parser)
+
+      if fnResult.isOk():
+        found = fnResult.just
+        break
+      else:
+        errors = errors & fnResult
+
+    return found
+    .fold(
+      func(): ParserResult =
+        let prettyErrors = errors.map((x: ParserResult) => x.error().expected)
+        err(ParserError(
+          kind: choiceMismatchErr,
+          index: parser.state.position + 1,
+          expected: &"Choice ({prettyErrors})",
+          unexpected: errors[0].error().unexpected,
+          parser: parser,
+        )),
+      func(x: ParserResult): ParserResult = x,
+    )
+
+
+func `+`*(parserFnA: parserFnT, parserFnB: parserFnT): parserFnT {.inline.} =
+  ## Parse characters and ignore failure
+  return func(parser: Parser): ParserResult =
+    parserFnA(parser).flatMap(parserFnB)
+
+func parseSeq*(parser: ParserResult, xs: seq[parserFnT]): ParserResult =
+  xs.foldl(a.flatMap(b), parser)
+
+# -- Parsing Aliases
+
+func endOfStream*(parser: Parser): ParserResult =
+  let index = parser.state.position + 1
+  if index == parser.state.stream.len:
+    ok(parser)
+  else:
+    err(ParserError(
+      kind: endOfStringErr,
+      expected: &"EndOfString",
+      index: index,
+      parser: parser,
+    ))
+
+const newlineParser = choice(@[
+  ch(NewLines),
+  endOfStream,
+])
+
+func newline*(parser: Parser): ParserResult =
+  newlineParser(parser)
+  .mapErr((x: ParserError) => x.setErrorExpectedField("Newline"))
+
+const whitespaceParser = choice(@[
+  ch(Whitespace),
+  newlineParser,
+])
+func whitespace*(parser: Parser): ParserResult =
+  whitespaceParser(parser)
+  .mapErr((x: ParserError) => x.setErrorExpectedField("Whitespace"))
+
+# -- Parsing Helpers
+
+const parseBetweenDelimiter* = func(start: parserFnT, stop: parserFnT): parserFnT {.closure.} =
+  ignore(start) + anyUntil(stop + whitespace) + ignore(start)
+
+const parseBetweenPair* = func(delimiterParser: parserFnT): parserFnT {.closure.} =
+  parseBetweenDelimiter(delimiterParser, delimiterParser)
--- a/src_v2/parser/parser_types.nim
+++ b/src_v2/parser/parser_types.nim
@@ -0,0 +1,489 @@
+import std/strutils
+import std/strformat
+import std/collections/sequtils
+import std/sugar
+import results
+import fp/maybe
+import fusion/matching
+import ../utils/str
+import ../utils/fp
+
+{.experimental: "caseStmtMacros".}
+
+type
+  ParserState* = ref object
+    stream*: string
+    position*, lastPosition*: int
+
+  parserTokenCharValueT* = char
+  parserTokenStringValueT* = string
+  ParserTokenKind* = enum
+    parserTokenChar
+    parserTokenString
+  ParserToken* = ref object
+    case kind*: ParserTokenKind
+      of parserTokenChar:
+        charValue*: parserTokenCharValueT
+      of parserTokenString:
+        stringValue*: parserTokenStringValueT
+
+  Parser* = ref object
+    state*: ParserState
+    tokens*: seq[ParserToken]
+  ParserErrorKind* = enum
+    choiceMismatchErr
+    charMismatchErr
+    endOfStringErr
+  ParserError* = ref object
+    kind*: ParserErrorKind
+    unexpected*: string
+    expected*: string
+    index*: int
+    parser*: Parser
+  ParserResult* = Result[Parser, ParserError]
+
+  Builder*[T] = tuple[
+    parser: Parser,
+    tree: seq[T]
+  ]
+
+  BuilderResult*[T] = Result[Builder[T], (Builder[T], string)]
+
+  # SingleBuilder*[T] = tuple[
+  #   parser: Parser,
+  #   tree: T
+  # ]
+  # SingleBuilderResult*[T] = Result[SingleBuilder[T], (SingleBuilder[T], string)]
+
+# -- Initalizers
+
+func initParserToken*(x: char): ParserToken = ParserToken(kind: parserTokenChar, charValue: x)
+func initParserToken*(x: string): ParserToken = ParserToken(kind: parserTokenString, stringValue: x)
+
+func initParser*(str: string): Parser =
+  Parser(
+    state: ParserState(
+      stream: str,
+      position: -1,
+      lastPosition: 0,
+    ),
+    tokens: newSeq[ParserToken](),
+  )
+
+proc initParserResult*(str: string): ParserResult =
+  ParserResult.ok(initParser(str))
+
+proc initBuilder*[T](t: Builder[T], parser: Parser, tree: seq[T]): Builder[T] =
+  Builder[T]((
+    parser,
+    tree
+  ))
+
+# -- Getters
+
+func tokenStringValue*(x: ParserToken): string =
+  ## Get the Token value `x` as a string.
+  case x.kind:
+    of parserTokenChar:
+      $x.charValue
+    of parserTokenString:
+      x.stringValue
+
+func tokensToString*(tokens: seq[ParserToken]): string =
+  tokens.foldl(a & b.tokenStringValue(), "")
+
+# -- Modifiers
+
+func flattenParserTokens*(parser: Parser): ParserResult =
+  return ParserResult.ok(
+    Parser(
+      state: parser.state,
+      tokens: @[
+        ParserToken(
+          kind: parserTokenString,
+          stringValue: parser.tokens.foldl(a & b.tokenStringValue(), "")
+        )
+      ]
+    )
+  )
+
+func emptyTokens*(parser: Parser): Parser =
+  Parser(
+    state: parser.state,
+    tokens: newSeq[ParserToken](),
+  )
+
+proc foldTokens*[T](
+  parserResult: ParserResult,
+  onError: ParserError -> T,
+  onSuccess: seq[ParserToken] -> T,
+): T =
+  if parserResult.isOk():
+    onSuccess(parserResult.unsafeGet().tokens)
+  else:
+    let err = parserResult.error()
+    onError(err)
+
+func setErrorExpectedField*(err: ParserError, expected: string): ParserError =
+  ParserError(
+    kind: err.kind,
+    unexpected: err.unexpected,
+    expected: expected,
+    index: err.index,
+    parser: err.parser,
+  )
+
+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]),
+  )))
+
+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 applyParsersToSingle*[T](
+  builder: Builder[T],
+  parsers: seq[Parser -> ParserResult],
+  tokenFoldFn: (seq[ParserToken], T) -> T,
+  optional = false,
+  initT: T,
+  isFirst: bool,
+): BuilderResult[T] =
+  # Apply the current parsing functions and convert to text tokens wrapped in ParserResult
+  let newParser = ParserResult.ok(Parser(
+    state: builder[0].state,
+    tokens: @[]
+  ))
+  .parseSeq(parsers)
+
+  newParser
+  .foldTokens(
+    (err: ParserError) => BuilderResult[T].err((builder, "foo")),
+    (newTokens: seq[ParserToken]) => (
+      if optional and newTokens.len == 0:
+        BuilderResult[T].ok(builder)
+      else:
+        BuilderResult[T].ok(
+          builder.initBuilder(
+            newParser.unsafeGet(),
+            builder.tree
+            .last()
+            .filter(x => not isFirst)
+            .orElse(just(initT))
+            .map((x: T) => @[tokenFoldFn(newTokens, x)])
+            .getOrElse(newSeq[T]())
+          )
+        )
+    )
+  )
+
+## TODO Implement applyParsersSeqToSingle with this function by forming the concatFn
+proc applyParsersToSeq*[T](
+  builder: Builder[T],
+  parsers: seq[Parser -> ParserResult],
+  tokenFoldFn: (seq[ParserToken], T) -> T,
+  # concatFn = `&`,
+  optional = false,
+  isFirst: bool,
+): BuilderResult[T] =
+  # Apply the current parsing functions and convert to text tokens wrapped in ParserResult
+  let newParser = ParserResult.ok(Parser(
+    state: builder[0].state,
+    tokens: @[]
+  ))
+  .parseSeq(parsers)
+
+  newParser
+  .foldTokens(
+    (err: ParserError) => BuilderResult[T].err((builder, "foo")),
+    (newTokens: seq[ParserToken]) => (
+      if optional and newTokens.len == 0:
+        BuilderResult[T].ok(builder)
+      else:
+        BuilderResult[T].ok(
+          builder.initBuilder(
+            newParser.unsafeGet(),
+            builder.tree & builder.tree
+          )
+        )
+    )
+  )
+
+proc applyParsersSeqToSingle*[T](
+  builderResult: BuilderResult[T],
+  initT: T,
+  xs: seq[tuple[
+    parsers: seq[Parser -> ParserResult],
+    tokenFoldFn: (seq[ParserToken], T) -> T,
+    ignoreEmpty: bool,
+  ]],
+): BuilderResult[T] =
+    xs.foldl(
+      a.flatMap((builder: Builder[T]) => applyParsersToSingle(
+        builder = builder,
+        parsers = b.parsers,
+        tokenFoldFn = b.tokenFoldFn,
+        optional = b.ignoreEmpty,
+        initT = initT,
+        isFirst = a == builderResult
+      )),
+      builderResult
+    )
+
+proc applyParsersSeqToSeq*[T](
+  builderResult: BuilderResult[T],
+  xs: seq[tuple[
+    parsers: seq[Parser -> ParserResult],
+    tokenFoldFn: (seq[ParserToken], T) -> T,
+    ignoreEmpty: bool,
+    # concatFn: (seq[T], seq[T]) -> seq[T],
+  ]],
+): BuilderResult[T] =
+    xs.foldl(
+      a.flatMap((builder: Builder[T]) => applyParsersToSeq(
+        builder = builder,
+        parsers = b.parsers,
+        tokenFoldFn = b.tokenFoldFn,
+        optional = b.ignoreEmpty,
+        isFirst = a == builderResult,
+        # concatFn = concatFn
+      )),
+      builderResult
+    )
+
+proc applyParsers*[T](
+  builder: Builder[T],
+  parsers: seq[Parser -> ParserResult],
+  tokenFoldFn: (seq[ParserToken], 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)
+
+  newParser
+  .foldTokens(
+    (err: ParserError) => BuilderResult[T].err((builder, "foo")),
+    (newTokens: seq[ParserToken]) => BuilderResult[T].ok(
+      builder.initBuilder(newParser.unsafeGet(), tokenFoldFn(newTokens, builder[1]))
+    ),
+  )
+
+proc applyParsersSeq*[T](
+  builder: BuilderResult[T],
+  xs: seq[tuple[
+    parsers: seq[Parser -> ParserResult],
+    tokenFoldFn: (seq[ParserToken], seq[T]) -> seq[T],
+  ]]): BuilderResult[T] =
+    xs.foldl(a.flatMap((x: Builder[T]) => x.applyParsers(b[0], b[1])), builder)
+
+
+proc foldBuilder*[T, T2](
+  builderResult: BuilderResult[T],
+  onError: string -> T2,
+  onSuccess: seq[T] -> T2,
+): T =
+  if builderResult.isOk():
+    onSuccess(builderResult.unsafeGet().tree)
+  else:
+    let err = builderResult.error()
+    onError(err[1])
+
+# proc parseBuildOr*[T](
+#   ## Checks
+#   builderResult: BuilderResult[T],
+#   builders: seq[tuple[
+#     parsers: seq[Parser -> ParserResult],
+#     tokenFoldFn: (seq[ParserToken], T) -> T,
+#   ]],
+#   defaultBuilder: tuple[
+#     defaultParser: Parser -> ParserResult,
+#     defaultFoldFn: (seq[ParserToken], T) -> T,
+#   ],
+#   until:
+# ): BuilderResult[T] =
+
+
+# -- Stringifiers
+
+func pprint*(x: ParserToken): string =
+  let str = tokenStringValue(x)
+  let escapedChar = if str == "\n": "\\n"
+                    else: str
+  &"""ParserToken("{escapedChar}")
+"""
+
+func `$`*(x: ParserToken): string = pprint(x)
+
+const LEFT_HIGHLIGHT_CHAR = ">>"
+const RIGHT_HIGHLIGHT_CHAR = "<<"
+func highlightStreamPosition(stream: string, position: int): string =
+  if position < 0: return stream
+  if position > stream.len - 1: return stream
+
+  let aIndex = position - 1
+  let a = if aIndex < 0: ""
+          else: stream[0..aIndex]
+
+  let ch = stream[position]
+
+  let bIndex = position + 1
+  let b = if bIndex > stream.len - 1: ""
+          else: stream[bIndex..stream.len - 1]
+
+  return a & LEFT_HIGHLIGHT_CHAR & ch & RIGHT_HIGHLIGHT_CHAR & b
+
+func highlightStreamPosition2(stream: string, position: int): string =
+  if position < 0: return stream
+  if position > stream.len - 1: return stream
+
+  let ch = stream[position]
+
+  let (lineStartPosition, lineEndPosition) =
+    case ch:
+      of '\n':
+        let lineStartPosition = (position - 1).max(0)
+        let lineEndPosition = (position + 1).min(stream.len - 1)
+        (lineStartPosition, lineEndPosition)
+      else:
+        (position, position)
+
+  let startIndex = stream.rfind("\n", 0, lineStartPosition)
+  let lineStartIndex =
+    case startIndex:
+      of -1: 0
+      else: startIndex + 1
+
+  let endIndex = stream.find("\n", lineEndPosition)
+  let lineEndIndex =
+    case endIndex:
+      of -1: stream.len
+      else: endIndex
+
+  let spaceChars = " ".repeat((position - lineStartIndex).max(0))
+  let lineChars = "_".repeat((lineEndIndex - position).max(0) + 10)
+
+  let escapedChar =
+    case ch:
+      of '\n': "\\n"
+      of ' ': "\\s"
+      else: $ch
+
+  let insertMessageAtIndex =
+    case ch:
+      # Print indicator for newlines on the previous line, which looks better for the reader
+      of '\n': (lineEndIndex - 1).max(1)
+      else: lineEndIndex
+
+  let beforeNewline =
+    case (startIndex, ch):
+      # Always print newline for newline at the stream begin
+      of (-1, '\n'): "\n"
+      # Don't insert a newline when the character is a newline between newlines
+      of (_, '\n'): ""
+      else: "\n"
+
+  # debugEcho "char: " & $ch
+  # debugEcho "position: " & $position
+  # debugEcho "startIndex: " & $lineStartIndex
+  # debugEcho "endIndex: " & $lineEndIndex
+  # debugEcho "insertMessageAtIndex: " & $insertMessageAtIndex
+
+  stream.dup(insert(&"{beforeNewline}{spaceChars}^{lineChars} Char at \"{escapedChar}\"\n", insertMessageAtIndex))
+
+proc `$`*(x: ParserState): string =
+  &"""ParserState(
+  stream: "{x.stream.highlightStreamPosition(x.position)}",
+  position: {x.position},
+  lastPosition: {x.lastPosition},
+)"""
+
+proc `$`*(x: Parser): string =
+  &"""Parser(
+  state: {indentAfterNewline($x.state, 2)},
+  tokens: {indentAfterNewline($x.tokens, 2)},
+)"""
+
+proc `$`*(x: ParserError): string =
+  case x:
+    of charMismatchErr(expected: @expected, parser: @parser, index: @index, unexpected: @unexpected):
+      # TODO: Only works for single line right now
+      let original = parser.state.stream
+      .deleteAfterNewline(parser.state.position)
+      let errSpace = " ".repeat(max(0, index))
+
+      &"""Parsing Error (Character Mismatch Error):
+{original}
+{errSpace}^ Expected '{expected}' but got '{unexpected}'"""
+    of choiceMismatchErr(expected: @expected, parser: @parser, index: @index, unexpected: @unexpected):
+      let original = parser.state.stream
+      .deleteAfterNewline(parser.state.position)
+      let errSpace = " ".repeat(max(0, index))
+
+      &"""Parsing Error (Character Mismatch Error):
+{original}
+{errSpace}^ Expected '{expected}' but got '{unexpected}'"""
+
+    of endOfStringErr(parser: @parser, index: @index):
+      let original = parser.state.stream
+      .deleteAfterNewline(parser.state.position)
+      let errSpace = " ".repeat(max(0, index))
+
+      &"""Parsing Error (EndOfString Expected):
+{original}
+{errSpace}^ Expected 'EndOfString' at {index} but got {original.len - 1}"""
+
+    else: "ParseError"
+
+when isMainModule:
+  let test1 = """ABC
+
+D
+
+EFG"""
+  echo test1.highlightStreamPosition2(test1.find("B"))
+  echo "=============="
+  echo test1.highlightStreamPosition2(test1.find("C"))
+  echo "=============="
+  echo test1.highlightStreamPosition2(test1.find("D"))
+  echo "=============="
+  echo test1.highlightStreamPosition2(test1.find("\n"))
+  echo "=============="
+  echo test1.highlightStreamPosition2(test1.find("\n", test1.find("\n") + 1))
+
+
+  # echo "\n1\n".rfind('\n', 0, 2)
+
+  # block highlightStreamPosition:
+  #   let s = "abc"
+  #   # Out of bounds
+  #   assert s.highlightStreamPosition(-1) == s
+  #   assert s.highlightStreamPosition(s.len) == s
+  #   # Regular highlighting
+  #   assert s.highlightStreamPosition(0) == LEFT_HIGHLIGHT_CHAR & "a" & RIGHT_HIGHLIGHT_CHAR & "bc"
+  #   assert s.highlightStreamPosition(1) == "a" & LEFT_HIGHLIGHT_CHAR & "b" & RIGHT_HIGHLIGHT_CHAR & "c"
+  #   assert s.highlightStreamPosition(2) == "ab" & LEFT_HIGHLIGHT_CHAR & "c" & RIGHT_HIGHLIGHT_CHAR
--- a/src_v2/parser/utils.nim
+++ b/src_v2/parser/utils.nim
@@ -0,0 +1,31 @@
+import std/sugar
+import std/collections/sequtils
+import results
+import ./parser_types
+
+type StringBuilderT* = string
+type StringBuilder* = Builder[StringBuilderT]
+type StringBuilderResult* = BuilderResult[StringBuilderT]
+
+proc stringConcat*(typeInfo: StringBuilderT, seperator = ""):
+                  (seq[ParserToken], seq[StringBuilderT]) -> seq[StringBuilderT] =
+
+  return proc(xs: seq[ParserToken], ys: seq[StringBuilderT]): seq[StringBuilderT] =
+    return ys & xs.foldl(a & b.tokenStringValue() & seperator, typeInfo)
+
+proc initStringBuilder*(str: string): StringBuilderResult =
+  StringBuilderResult
+  .ok(StringBuilder((
+    parser: initParser(str),
+    tree: newSeq[StringBuilderT](),
+  )))
+
+proc fold*[T, E, T2](
+  self: Result[T, E],
+  onError: E -> T2,
+  onSuccess: T -> T2,
+): T2 =
+  if self.isOk():
+    onSuccess(self.unsafeGet())
+  else:
+    onError(self.error())